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Phoenix (spacecraft)

Phoenix (spacecraft)

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Phoenix was a robotic spacecraft
Robotic spacecraft
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...

 on a space exploration
Space exploration
Space exploration is the use of space technology to explore outer space. Physical exploration of space is conducted both by human spaceflights and by robotic spacecraft....

 mission on Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

 under the Mars Scout Program
Mars Scout Program
The Mars Scout Program was a NASA initiative to send a series of small, low-cost robotic missions to Mars, competitively selected from innovative proposals by the scientific community. The program would have had an array of missions destined to reach Mars, and study it at low costs. Each Scout...

. The Phoenix lander
Lander (spacecraft)
A lander is a spacecraft which descends toward and comes to rest on the surface of an astronomical body. For bodies with atmospheres, the landing is called atmospheric reentry and the lander descends as a re-entry vehicle...

 descended on Mars on May 25, 2008. Mission scientists used instruments aboard the lander to search for environments suitable for microbial life on Mars
Life on Mars
Scientists have long speculated about the possibility of life on Mars owing to the planet's proximity and similarity to Earth. Fictional Martians have been a recurring feature of popular entertainment of the 20th and 21st centuries, but it remains an open question whether life currently exists on...

, and to research the history of water there.

The multi-agency program was headed by the Lunar and Planetary Laboratory
Lunar and Planetary Laboratory
The Lunar and Planetary Laboratory is a research center for planetary science located in Tucson, Arizona. It is also a graduate school, constituting the Department of Planetary Sciences at the University of Arizona...

 at the University of Arizona
University of Arizona
The University of Arizona is a land-grant and space-grant public institution of higher education and research located in Tucson, Arizona, United States. The University of Arizona was the first university in the state of Arizona, founded in 1885...

, under the direction of NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

's Jet Propulsion Laboratory
Jet Propulsion Laboratory
Jet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is headquartered in the city of Pasadena on the border of La Cañada Flintridge and Pasadena...

. The program was a partnership of universities in the United States, Canada, Switzerland, Denmark, Germany, the United Kingdom, NASA, the Canadian Space Agency, the Finnish Meteorological Institute
Finnish Meteorological Institute
The Finnish Meteorological Institute is the government agency responsible for gathering and reporting weather data and forecasts in Finland. It is a part of the Ministry of Transport and Communications but it operates semi-autonomously....

, Lockheed Martin Space Systems
Lockheed Martin Space Systems
Lockheed Martin Space Systems Company is one of the four major business divisions of Lockheed Martin. It is headquartered in Denver, Colorado with additional sites in Sunnyvale, California; Newtown, Pennsylvania; Huntsville, Alabama; and elsewhere in the US and UK...

, MacDonald Dettwiler & Associates
MacDonald Dettwiler
MacDonald, Dettwiler and Associates Ltd. is a Richmond, British Columbia-based Canadian aerospace, information services and products company, employing over 3000 people throughout Canada, the United States and the United Kingdom, under the MDA brand name....

 (MDA) and other aerospace companies. It was the first mission to Mars led by a public university in NASA history. The mission underscored the value of university-led management. It was led directly from the University of Arizona
University of Arizona
The University of Arizona is a land-grant and space-grant public institution of higher education and research located in Tucson, Arizona, United States. The University of Arizona was the first university in the state of Arizona, founded in 1885...

's campus in Tucson, with project management at the Jet Propulsion Laboratory in Pasadena, Calif., and project development at Lockheed Martin in Denver, Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

. The operational funding for the mission extended through November 10, 2008.

Phoenix is NASA's sixth successful landing out of seven attempts and is the most recent spacecraft
Spacecraft
A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....

 to land successfully on Mars as well as the first successful landing in a Martian polar region. The lander completed its mission in August 2008, and made a last brief communication with Earth on November 2 as available solar power dropped with the Martian winter. The mission was declared concluded on November 10, 2008, after engineers were unable to re-contact the craft. After unsuccessful attempts to contact the lander by the Mars Odyssey orbiter up to and past the Martian summer solstice on May 12, 2010, JPL declared the lander to be dead. Like the two Mars Exploration Rover
Mars Exploration Rover
NASA's Mars Exploration Rover Mission is an ongoing robotic space mission involving two rovers, Spirit and Opportunity, exploring the planet Mars...

s, the program was considered a success because it completed all planned science experiments and observations.

Program overview


The mission had two goals. One was to study the geologic history of water, the key to unlocking the story of past climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...

. The second was evaluate past or potential planetary habitability
Planetary habitability
Planetary habitability is the measure of a planet's or a natural satellite's potential to sustain life. Life may develop directly on a planet or satellite or be transferred to it from another body, a theoretical process known as panspermia...

 in the ice-soil boundary. Phoenixs instruments were suitable for uncovering information on the geological and possibly biological history of the Martian Arctic. Phoenix was the first mission to return data from either of the poles, and contributed to NASA's main strategy for Mars exploration, "Follow the water."

The primary mission was anticipated to last 90 sols
Timekeeping on Mars
Various schemes have been used or proposed to keep track of time and date on the planet Mars independently of Earth time and calendars.Mars has an axial tilt and a rotation period similar to those of Earth. Thus it experiences seasons of spring, summer, autumn and winter much like Earth, and its...

 (Martian days) – just over 92 Earth days. However, the craft exceeded its expected operational lifetime by a little over two months before succumbing to the increasing cold and dark of an advancing Martian winter. Researchers had hoped that the lander would survive into the Martian winter so that it could witness polar ice developing around it – perhaps up to 1 metre of solid carbon dioxide ice could have appeared. Even had it survived some of the winter, the intense cold would have prevented it from lasting all the way through.
The mission was chosen to be a fixed lander rather than a rover because:
  1. costs were reduced through reuse of earlier equipment
  2. the area of Mars where Phoenix is landing is thought to be relatively uniform and thus traveling is of less value; and
  3. the equipment weight that would be required to allow Phoenix to travel can instead be dedicated to more and better scientific instruments.


The 2003–2004 observations of methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

 gas on Mars were made remotely by three teams working with separate data. If the methane is truly present in the atmosphere of Mars
Atmosphere of Mars
The atmosphere of Mars is relatively thin and is composed mostly of carbon dioxide . There has been interest in studying its composition since the detection of trace amounts of methane, which may indicate the presence of life on Mars, but may also be produced by a geochemical process, volcanic or...

, then something must be producing it on the planet now, because the gas is broken down by radiation on Mars within 300 years, therefore the importance to search for biological potential or habitability
Planetary habitability
Planetary habitability is the measure of a planet's or a natural satellite's potential to sustain life. Life may develop directly on a planet or satellite or be transferred to it from another body, a theoretical process known as panspermia...

 of the Martian arctic's soils. Methane could also be the product of a geochemical process or the result of volcanic or hydrothermal activity. Other future missions may enable us to discover whether life does indeed exist on Mars today.

History of the program


While the proposal for Phoenix was being written, the Mars Odyssey Orbiter
2001 Mars Odyssey
2001 Mars Odyssey is a robotic spacecraft orbiting the planet Mars. The project was developed by NASA, and contracted out to Lockheed Martin, with an expected cost for the entire mission of US$297 million. Its mission is to use spectrometers and electronic imagers to hunt for evidence of past or...

 used its gamma ray spectrometer and found the distinctive signature of hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 on some areas of the Martian surface
Martian Surface
The study of surface characteristics is a broad category of Mars science that examines the nature of the materials making up the Martian surface. The study evolved from telescopic and remote-sensing techniques developed by astronomers to study planetary surfaces...

, and the only plausible source of hydrogen on Mars would be water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

 in the form of ice, frozen below the surface. The mission was therefore funded on the expectation that Phoenix would find water ice on the arctic plains of Mars. In August 2003 NASA selected the University of Arizona
University of Arizona
The University of Arizona is a land-grant and space-grant public institution of higher education and research located in Tucson, Arizona, United States. The University of Arizona was the first university in the state of Arizona, founded in 1885...

 "Phoenix" mission for launch in 2007. It was hoped this would be the first in a new line of smaller, low-cost, Scout
Mars Scout Program
The Mars Scout Program was a NASA initiative to send a series of small, low-cost robotic missions to Mars, competitively selected from innovative proposals by the scientific community. The program would have had an array of missions destined to reach Mars, and study it at low costs. Each Scout...

 missions in the agency's exploration of Mars
Exploration of Mars
The exploration of Mars has been an important part of the space exploration programs of the Soviet Union, the United States, Europe, and Japan. Dozens of robotic spacecraft, including orbiters, landers, and rovers, have been launched toward Mars since the 1960s...

 program. The selection was the result of an intense two-year competition with proposals from other institutions. The $325 million NASA award is more than six times larger than any other single research grant in University of Arizona history.

Peter H. Smith
Peter Smith (scientist)
Peter H. Smith is a Senior Research Scientist at the Lunar and Planetary Laboratory of the University of Arizona, where he holds the inaugural Thomas R. Brown Distinguished Chair in Integrative Science...

 of the University of Arizona Lunar and Planetary Laboratory, as Principal Investigator, along with 24 Co-Investigators, were selected to lead the mission. The mission was named after the Phoenix
Phoenix (mythology)
The phoenix or phenix is a mythical sacred firebird that can be found in the mythologies of the Arabian, Persians, Greeks, Romans, Egyptians, Chinese, Indian and Phoenicians....

, a mythological bird that is repeatedly reborn from its own ashes. The Phoenix spacecraft contains several previously built components. The lander used for the 2007–08 mission is the modified Mars Surveyor 2001 Lander
Mars Surveyor 2001 Lander
The NASA Mars Surveyor 2001 Lander was a planned Mars probe which was canceled in May 2000 in the wake of the failures of the Mars Climate Orbiter and Mars Polar Lander missions in late 1999...

 (canceled in 2000), along with several of the instruments from both that and the previous unsuccessful Mars Polar Lander
Mars Polar Lander
The Mars Polar Lander, also referred to as the Mars Surveyor '98 Lander, was a 290-kilogram robotic spacecraft lander, launched by NASA on January 3, 1999, to study the soil and climate of Planum Australe, a region near the south pole on Mars, as part of the Mars Surveyor '98 mission...

 mission. Lockheed Martin
Lockheed Martin
Lockheed Martin is an American global aerospace, defense, security, and advanced technology company with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It is headquartered in Bethesda, Maryland, in the Washington Metropolitan Area....

, which built the lander, had kept the nearly complete lander in an environmentally controlled clean room from 2001 until the mission was funded by the NASA Scout Program
Mars Scout Program
The Mars Scout Program was a NASA initiative to send a series of small, low-cost robotic missions to Mars, competitively selected from innovative proposals by the scientific community. The program would have had an array of missions destined to reach Mars, and study it at low costs. Each Scout...

.

Phoenix was a partnership of universities, NASA centers, and the aerospace industry. The science instruments and operations were a University of Arizona
University of Arizona
The University of Arizona is a land-grant and space-grant public institution of higher education and research located in Tucson, Arizona, United States. The University of Arizona was the first university in the state of Arizona, founded in 1885...

 responsibility. NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

's Jet Propulsion Laboratory in Pasadena, California
Pasadena, California
Pasadena is a city in Los Angeles County, California, United States. Although famous for hosting the annual Rose Bowl football game and Tournament of Roses Parade, Pasadena is the home to many scientific and cultural institutions, including the California Institute of Technology , the Jet...

, managed the project and provided mission design and control. Lockheed Martin Space Systems
Lockheed Martin Space Systems
Lockheed Martin Space Systems Company is one of the four major business divisions of Lockheed Martin. It is headquartered in Denver, Colorado with additional sites in Sunnyvale, California; Newtown, Pennsylvania; Huntsville, Alabama; and elsewhere in the US and UK...

, Denver, Colorado
Denver, Colorado
The City and County of Denver is the capital and the most populous city of the U.S. state of Colorado. Denver is a consolidated city-county, located in the South Platte River Valley on the western edge of the High Plains just east of the Front Range of the Rocky Mountains...

, built and tested the spacecraft. The Canadian Space Agency provided a meteorological station, including an innovative Laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

-based atmospheric sensor. The co-investigator institutions included Malin Space Science Systems
Malin Space Science Systems
Malin Space Science Systems is a San Diego, California company that designs, develops, and operates instruments to fly on unmanned spacecraft. MSSS is headed by chief scientist and CEO Michael C. Malin....

 (California), Max Planck Institute for Solar System Research
Max Planck Institute for Solar System Research
The Max Planck Institute for Solar System Research is a research institute in Astronomy/Astrophysics, located in Lindau , Germany; 20 km north east of Göttingen. The exploration of our solar system is the central theme for the scientific research done at this Institute...

 (Germany), NASA Ames Research Center
NASA Ames Research Center
The Ames Research Center , is one of the United States of America's National Aeronautics and Space Administration 10 major field centers.The centre is located in Moffett Field in California's Silicon Valley, near the high-tech companies, entrepreneurial ventures, universities, and other...

 (California), NASA Johnson Space Center (Texas), MDA (Canada), Optech Incorporated (Canada)
Optech Incorporated
Optech Incorporated is a Canadian-owned for-profit company operating since 1974 and focusing on Laser-based survey systems.Optech Inc is known for its association with Phoenix, a spacecraft launched for Mars in 2007.- The company :...

, SETI Institute
SETI Institute
The SETI Institute is a not-for-profit organization whose mission is to “explore, understand and explain the origin, nature and prevalence of life in the universe”. SETI stands for the "search for extraterrestrial intelligence". One program is the use of both radio and optical telescopes to search...

, Texas A&M University
Texas A&M University
Texas A&M University is a coeducational public research university located in College Station, Texas . It is the flagship institution of the Texas A&M University System. The sixth-largest university in the United States, A&M's enrollment for Fall 2011 was over 50,000 for the first time in school...

, Tufts University
Tufts University
Tufts University is a private research university located in Medford/Somerville, near Boston, Massachusetts. It is organized into ten schools, including two undergraduate programs and eight graduate divisions, on four campuses in Massachusetts and on the eastern border of France...

, University of Colorado
University of Colorado at Boulder
The University of Colorado Boulder is a public research university located in Boulder, Colorado...

, University of Copenhagen
University of Copenhagen
The University of Copenhagen is the oldest and largest university and research institution in Denmark. Founded in 1479, it has more than 37,000 students, the majority of whom are female , and more than 7,000 employees. The university has several campuses located in and around Copenhagen, with the...

 (Denmark), University of Michigan
University of Michigan
The University of Michigan is a public research university located in Ann Arbor, Michigan in the United States. It is the state's oldest university and the flagship campus of the University of Michigan...

, University of Neuchâtel
University of Neuchâtel
The University of Neuchâtel is a French-speaking university in Neuchâtel, Switzerland. The University has five faculties and more than a dozen institutes, including arts and human sciences, natural sciences, law, economics and theology. The Faculty of Arts and Human Sciences is the largest...

 (Switzerland), University of Texas at Dallas
University of Texas at Dallas
The University of Texas at Dallas, also referred to as UT Dallas or UTD, is a public research university in the University of Texas System. The main campus is in the heart of the Richardson, Texas, Telecom Corridor, north of downtown Dallas...

, University of Washington
University of Washington
University of Washington is a public research university, founded in 1861 in Seattle, Washington, United States. The UW is the largest university in the Northwest and the oldest public university on the West Coast. The university has three campuses, with its largest campus in the University...

, Washington University in St. Louis
Washington University in St. Louis
Washington University in St. Louis is a private research university located in suburban St. Louis, Missouri. Founded in 1853, and named for George Washington, the university has students and faculty from all fifty U.S. states and more than 110 nations...

, and York University
York University
York University is a public research university in Toronto, Ontario, Canada. It is Canada's third-largest university, Ontario's second-largest graduate school, and Canada's leading interdisciplinary university....

 (Canada). Scientists from Imperial College London
Imperial College London
Imperial College London is a public research university located in London, United Kingdom, specialising in science, engineering, business and medicine...

 and Bristol University have provided hardware for the mission and were part of the team operating the microscope station.
On June 2, 2005, following a critical review of the project's planning progress and preliminary design, NASA approved the mission to proceed as planned. The purpose of the review was to confirm NASA's confidence in the mission.

Specifications


Mass
350 kg (771.6 lb)

Dimensions
About 5.5 m (18 ft) long with the solar panels deployed. The science deck by itself is about 1.5 m (4.9 ft) in diameter. From the ground to the top of the MET mast, the lander measures about 2.2 m (7.2 ft) tall.

Communications
X-band throughout the cruise phase of the mission and for its initial communication after separating from the third stage of the launch vehicle
Launch vehicle
In spaceflight, a launch vehicle or carrier rocket is a rocket used to carry a payload from the Earth's surface into outer space. A launch system includes the launch vehicle, the launch pad and other infrastructure....

. UHF links, relayed through Mars orbiters during the entry, descent and landing phase and while operating on the surface of Mars. The UHF system on Phoenix is compatible with relay capabilities of NASA’s Mars Odyssey, Mars Reconnaissance Orbiter
Mars Reconnaissance Orbiter
Mars Reconnaissance Orbiter is a NASA multipurpose spacecraft designed to conduct reconnaissance and Exploration of Mars from orbit...

 and with the European Space Agency’s Mars Express
Mars Express
Mars Express is a space exploration mission being conducted by the European Space Agency . The Mars Express mission is exploring the planet Mars, and is the first planetary mission attempted by the agency. "Express" originally referred to the speed and efficiency with which the spacecraft was...

. The interconnections use the Proximity-1 protocol.

Power
Power is generated using two gallium arsenide
Gallium(III) arsenide
Gallium arsenide is a compound of the elements gallium and arsenic. It is a III/V semiconductor, and is used in the manufacture of devices such as microwave frequency integrated circuits, monolithic microwave integrated circuits, infrared light-emitting diodes, laser diodes, solar cells and...

 solar array panels (total area 3.1 square metre) mounted to the cruise stage during cruise, and via two gallium arsenide solar array panels (total area 2.9 square metre) deployed from the lander after touchdown on the Martian surface. NiH2 battery
Nickel hydrogen battery
A nickel–hydrogen battery is a rechargeable electrochemical power source based on nickel and hydrogen. It differs from a nickel–metal hydride battery by the use of hydrogen in a pressurized cell at up to 1200 psi pressure.The cathode is made up of a dry sintered porous nickel plaque, which...

 with a capacity of 16 A·h.


Lander systems include a RAD6000
RAD6000
The RAD6000 radiation-hardened single board computer, based on the IBM RISC Single Chip CPU, was manufactured by IBM Federal Systems. IBM Federal Systems was sold to Loral, and by way of acquisition, ended up with Lockheed Martin and is currently a part of BAE Systems...

 based computer system for commanding the spacecraft and handling data. Other parts of the lander are an electrical system containing solar arrays and batteries, a guidance system to land the spacecraft, eight 1 lbf (4.4 N) and 5 lbf (22.2 N) monopropellant
Monopropellant
Monopropellants are propellants composed of chemicals or mixtures of chemicals which can be stored in a single container with some degree of safety. While stable under defined storage conditions, they react very rapidly under certain other conditions to produce a large volume of energetic gases...

 hydrazine
Hydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...

 engines built by Aerojet
Aerojet
Aerojet is an American rocket and missile propulsion manufacturer based primarily in Rancho Cordova, California with divisions in Redmond, Washington, Orange, Gainesville and Camden, Arkansas. Aerojet is owned by GenCorp. They are the only US propulsion company that provides both solid rocket...

-Redmond Operations for the cruise phase, twelve 68 lbf (302.5 N) Aerojet monopropellant hydrazine thrusters to land the Phoenix, mechanical and structural elements, and a heater system to ensure the spacecraft does not get too cold.

Launch


Phoenix was launched on August 4, 2007, at 5:26:34 a.m. EDT
Eastern Time Zone
The Eastern Time Zone of the United States and Canada is a time zone that falls mostly along the east coast of North America. Its UTC time offset is −5 hrs during standard time and −4 hrs during daylight saving time...

 (09:26:34 UTC) on a Delta 7925
Delta II
Delta II was an American space launch system, originally designed and built by McDonnell Douglas. Delta II is part of the Delta rocket family and was in service from 1989 until November 1, 2011...

 launch vehicle from Pad 17-A of the Cape Canaveral Air Force Station
Cape Canaveral Air Force Station
Cape Canaveral Air Force Station is an installation of the United States Air Force Space Command's 45th Space Wing, headquartered at nearby Patrick Air Force Base. Located on Cape Canaveral in the state of Florida, CCAFS is the primary launch head of America's Eastern Range with four launch pads...

. The launch was nominal with no significant anomalies. The Phoenix lander was placed on a trajectory
Trajectory
A trajectory is the path that a moving object follows through space as a function of time. The object might be a projectile or a satellite, for example. It thus includes the meaning of orbit—the path of a planet, an asteroid or a comet as it travels around a central mass...

 of such precision that its first trajectory course correction burn, performed on August 10, 2007 at 7:30 a.m. EDT (11:30 UTC), was only 18 m/s. The launch took place during a launch window
Launch window
Launch window is a term used in spaceflight to describe a time period in which a particular launch vehicle must be launched. If the rocket does not launch within the "window", it has to wait for the next window....

 extending from August 3, 2007 to August 24, 2007. Due to the small launch window the rescheduled launch of the Dawn mission (originally planned for July 7) had to stand down and was launched after Phoenix in September. The Delta 7925 was chosen due to its successful launch history, which includes launches of the Spirit and Opportunity Mars Exploration Rover
Mars Exploration Rover
NASA's Mars Exploration Rover Mission is an ongoing robotic space mission involving two rovers, Spirit and Opportunity, exploring the planet Mars...

s in 2003 and Mars Pathfinder
Mars Pathfinder
Mars Pathfinder was an American spacecraft that landed a base station with roving probe on Mars in 1997. It consisted of a lander, renamed the Carl Sagan Memorial Station, and a lightweight wheeled robotic rover named Sojourner.Launched on December 4, 1996 by NASA aboard a Delta II booster a...

 in 1996.

A noctilucent cloud
Noctilucent cloud
Night clouds or Noctilucent clouds are tenuous cloud-like phenomena that are the "ragged-edge" of a much brighter and pervasive polar cloud layer called polar mesospheric clouds in the upper atmosphere, visible in a deep twilight. They are made of crystals of water ice. The name means roughly night...

 was created by the exhaust gas
Exhaust gas
Exhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline/petrol, diesel fuel, fuel oil or coal. According to the type of engine, it is discharged into the atmosphere through an exhaust pipe, flue gas stack or propelling nozzle.It often disperses...

 from the Delta II
Delta II
Delta II was an American space launch system, originally designed and built by McDonnell Douglas. Delta II is part of the Delta rocket family and was in service from 1989 until November 1, 2011...

 7925 rocket used to launch Phoenix. The colors in the cloud formed from the prism-like effect of the ice particles present in the exhaust trail.

Landing

Mars Reconnaissance Orbiter (MRO) imaged Phoenix (lower left corner) in the line of sight to the 10-km-wide Heimdal Crater
Heimdal (Martian crater)
Heimdal is a relatively recent impact crater on the planet Mars. It lies in Vastitas Borealis, the northern plain. It is named after Heimdal, a town in Norway....

 (the craft is actually 20 km in front of it).
MRO imaged Phoenix suspended from its parachute during descent through the Martian atmosphere.
Phoenix landing site near N. polar cap MRO image of Phoenix on the surface of Mars. Also see a larger image showing the parachute / backshell, and heat shield.


The Jet Propulsion Laboratory made adjustments to the orbits of its two active satellites around Mars, Mars Reconnaissance Orbiter
Mars Reconnaissance Orbiter
Mars Reconnaissance Orbiter is a NASA multipurpose spacecraft designed to conduct reconnaissance and Exploration of Mars from orbit...

 and Mars Odyssey, and the European Space Agency
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...

 similarly adjusted the orbit of its Mars Express
Mars Express
Mars Express is a space exploration mission being conducted by the European Space Agency . The Mars Express mission is exploring the planet Mars, and is the first planetary mission attempted by the agency. "Express" originally referred to the speed and efficiency with which the spacecraft was...

 spacecraft to be in the right place on May 25, 2008 to observe Phoenix as it entered the atmosphere and then landed on the surface. This information helps designers to improve future landers. The projected landing area was an ellipse 100 km by 20 km covering terrain which has been informally named "Green Valley
Green Valley (Mars)
Green Valley is a region on Mars within Vastitas Borealis that was chosen as the landing site of NASA's Phoenix lander. It is located at 68.35 degrees north, 233 degrees east. The valley is about 50 kilometres wide but only about 250 metres deep; either it was filled in or was never any deeper than...

" and contains the largest concentration of water ice outside of the poles.

Phoenix entered the Martian atmosphere at nearly 21000 km (13,048.8 mi) per hour, and within 7 minutes had decreased its speed to 8 kilometres per hour (5 mph) before touching down on the surface. Confirmation of atmospheric entry was received at 4:46 p.m. PDT (23:46 UTC). Radio signals received at 4:53:44 p.m. PDT confirmed that Phoenix had survived its difficult descent and landed 15 minutes earlier, thus completing a 680 million km (422 million miles) flight from Earth.

For unknown reasons, the parachute was deployed about 7 seconds later than expected, leading to a landing position some 25–28 km long (east), near the edge of the predicted 99% landing ellipse.
Mars Reconnaissance Orbiter's
Mars Reconnaissance Orbiter
Mars Reconnaissance Orbiter is a NASA multipurpose spacecraft designed to conduct reconnaissance and Exploration of Mars from orbit...

 High Resolution Imaging Science Experiment (HiRISE)
HiRISE
High Resolution Imaging Science Experiment is a camera on board the Mars Reconnaissance Orbiter. The 65 kg , $40 million instrument was built under the direction of the University of Arizona's Lunar and Planetary Laboratory by Ball Aerospace & Technologies Corp....

 camera photographed Phoenix suspended from its parachute during its descent through the Martian atmosphere. This marks the first time ever one spacecraft has photographed another in the act of landing on a planet (the Moon not being a planet, but a satellite
Natural satellite
A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called its primary. The two terms are used synonymously for non-artificial satellites of planets, of dwarf planets, and of minor planets....

). The same camera also imaged Phoenix on the surface with enough resolution to distinguish the lander and its two solar cell arrays. Ground controllers used Doppler
Doppler effect
The Doppler effect , named after Austrian physicist Christian Doppler who proposed it in 1842 in Prague, is the change in frequency of a wave for an observer moving relative to the source of the wave. It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and recedes from...

 tracking data from Odyssey and Mars Reconnaissance Orbiter to determine the lander's precise location as 68.218830°N 234.250778°E.

Phoenix landed in the Green Valley
Green Valley (Mars)
Green Valley is a region on Mars within Vastitas Borealis that was chosen as the landing site of NASA's Phoenix lander. It is located at 68.35 degrees north, 233 degrees east. The valley is about 50 kilometres wide but only about 250 metres deep; either it was filled in or was never any deeper than...

 of Vastitas Borealis
Vastitas Borealis
Vastitas Borealis is the largest lowland region of Mars. It is in the northerly latitudes of the planet and encircles the northern polar region. Vastitas Borealis is often simply referred to as the Northern plains or Northern lowlands of Mars. The plains lie 4–5 km below the mean radius of...

 on May 25, 2008, in the late Martian northern hemisphere spring (Ls=76.73), where the Sun shone on its solar panels the whole Martian day. By the Martian northern Summer solstice (June 25, 2008), the Sun appeared at its maximum elevation of 47.0 degrees. Phoenix experienced its first sunset at the start of September 2008.

The landing was made on a flat surface, with the lander reporting only 0.3 degrees of tilt. Just before landing, the craft used its thrusters to orient its solar panels along an east-west axis to maximize power generation. The lander waited 15 minutes before opening its solar panels, to allow dust to settle. The first images from the lander became available around 7:00 p.m. PDT (2008-05-26 02:00 UTC). The images show a surface strewn with pebbles and incised with small troughs into polygons about 5 m across and 10 cm high, with the expected absence of large rocks and hills.

Like the 1970s era Viking
Viking program
The Viking program consisted of a pair of American space probes sent to Mars, Viking 1 and Viking 2. Each spacecraft was composed of two main parts, an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface...

 spacecraft, Phoenix used rocket motors for its final descent. Experiments conducted by Nilton Renno, mission co-investigator from the University of Michigan, and his students have investigated how much surface dust would be kicked up on landing. Researchers at Tufts University, led by co-investigator Sam Kounaves, conducted additional in-depth experiments to identify the extent of the ammonia contamination from the hydrazine propellant and its possible effects on the chemistry experiments. In 2007, a report to the American Astronomical Society
American Astronomical Society
The American Astronomical Society is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC...

 by Washington State University
Washington State University
Washington State University is a public research university based in Pullman, Washington, in the Palouse region of the Pacific Northwest. Founded in 1890, WSU is the state's original and largest land-grant university...

 professor Dirk Schulze-Makuch, suggested that Mars might harbor peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...

-based life forms which the Viking landers failed to detect because of the unexpected chemistry. The hypothesis was proposed long after any modifications to Phoenix could be made. One of the Phoenix mission investigators, NASA astrobiologist Chris McKay, stated that the report "piqued his interest" and that ways to test the hypothesis with Phoenixs instruments would be sought.

Communications from the surface


The robotic arm
Robotic arm
A mechanical arm is a robotic, usually programmable, with similar functions to a human arm. The links of such a manipulator are connected by joints allowing either rotational motion or translational displacement. The links of the manipulator can be considered to form a kinematic chain...

's first movement was delayed by one day when, on May 27, 2008, commands from Earth were not relayed to the Phoenix lander on Mars. The commands went to NASA's Mars Reconnaissance Orbiter as planned, but the orbiter's Electra
Electra (radio)
Electra, more formally the Electra Proximity Payload, is a software-defined radio defined and implemented by the Jet Propulsion Laboratory for use between spacecraft. It is typically used by a lander to communicate with an orbiter that can then communicate with Earth...

 UHF radio system for relaying commands to Phoenix temporarily shut off. Without new commands, the lander instead carried out a set of activity commands sent May 26 as a backup. On May 27 the Mars Reconnaissance Orbiter relayed images and other information from those activities back to Earth.

The robotic arm was a critical part of the Phoenix Mars mission. On May 28, scientists leading the mission, sent commands to unstow its robotic arm and take more images of its landing site. The images revealed that the spacecraft landed where it had access to digging down a polygon across the trough and digging into its the center.

The polygonal cracking
Patterned ground
Patterned ground is a term used to describe the distinct, and often symmetrical geometric shapes formed by ground material in periglacial regions...

 in this area had previously been observed from orbit, and is similar to patterns seen in permafrost
Permafrost
In geology, permafrost, cryotic soil or permafrost soil is soil at or below the freezing point of water for two or more years. Ice is not always present, as may be in the case of nonporous bedrock, but it frequently occurs and it may be in amounts exceeding the potential hydraulic saturation of...

 areas in polar and high altitude regions of Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

. A likely formation mechanism is that permafrost ice contracts when the temperature decreases, creating a polygonal pattern of cracks, which are then filled by loose soil falling in from above. When the temperature increases and the ice expands back to its former volume, it thus cannot assume its former shape, but is forced to buckle upwards. (On Earth, liquid water would probably enter at times along with soil, creating additional disruption due to ice wedging
Ice wedge
An ice wedge is a crack in the ground formed by a narrow or thin piece of ice that measures up to 3-4 metres wide at ground level and extends downwards into the ground up to several metres. During the winter months, the water in the ground freezes and expands...

 when the contents of the cracks freeze.)

The Lander's Robotic Arm touched soil on the red planet for the first time on May 31, 2008. It scooped dirt and started sampling the Martian soil for ice after days of testing. Phoenixs Robotic Arm Camera took an image underneath the lander on sol 5 that shows patches of a smooth bright surface uncovered when thruster exhaust blew off overlying loose soil. It was later shown to be ice
Ice
Ice is water frozen into the solid state. Usually ice is the phase known as ice Ih, which is the most abundant of the varying solid phases on the Earth's surface. It can appear transparent or opaque bluish-white color, depending on the presence of impurities or air inclusions...

. Ray Arvidson of Washington University in St. Louis said: "We could very well be seeing rock, or we could be seeing exposed ice in the retrorocket blast zone."

Presence of shallow subsurface water ice



On June 19, 2008, NASA announced that die
Dice
A die is a small throwable object with multiple resting positions, used for generating random numbers...

-sized clumps of bright material in the "Dodo-Goldilocks" trench dug by the robotic arm had vaporized over the course of four days, strongly implying that they were composed of water ice which sublimated following exposure. While dry ice
Dry ice
Dry ice, sometimes referred to as "Cardice" or as "card ice" , is the solid form of carbon dioxide. It is used primarily as a cooling agent. Its advantages include lower temperature than that of water ice and not leaving any residue...

 also sublimates, under the conditions present it would do so at a rate much faster than observed.

On July 31, 2008, NASA announced that Phoenix confirmed the presence of water ice on Mars, as predicted on 2002 by the Mars Odyssey orbiter. During the initial heating cycle of a new sample, TEGA's mass spectrometer detected water vapor when the sample temperature reached 0 °C.
Liquid water cannot exist on the surface of Mars with its present low atmospheric pressure, except at the lowest elevations for short periods.

With Phoenix in good working order, NASA announced operational funding through September 30, 2008. The science team labored to determine whether the water ice ever thaws enough to be available for life processes and if carbon-containing chemicals and other raw materials for life are present.

Additionally during 2008 and early 2009 a debate emerged within NASA over the presence of 'blobs' which appeared on photos of the vehicle's landing struts, which have been variously described as being either water droplets or 'clumps of frost'. Due to the lack of consensus within the Phoenix science project, the issue had not been raised in any NASA news conferences.

One scientist believed that the lander's thrusters splashed a pocket of brine from just below the Martian surface onto the landing strut during the vehicle's landing. The salts would then have absorbed water vapor from the air, which would have explained how they appeared to grow in size during the first 44 Martian days before slowly evaporating as Mars temperature dropped.

Wet chemistry


On June 24, 2008, NASA's scientists launched a major series of tests. The robotic arm scooped up more soil and delivered it to 3 different on-board analyzers: an oven that baked it and tested the emitted gases, a microscopic imager, and a wet chemistry
Wet chemistry
Wet chemistry is a term used to refer to chemistry generally done in the liquid phase. It is also known as bench chemistry because many of the tests performed are done at a lab bench.-Materials:...

 lab. The lander's Robotic Arm scoop was positioned over the Wet Chemistry Lab delivery funnel on Sol 29 (the 29th Martian day after landing, i.e. June 24, 2008). The soil was transferred to the instrument on Sol 30 (June 25, 2008), and Phoenix performed the first wet chemistry tests. On Sol 31 (June 26, 2008) Phoenix returned the wet chemistry test results with information on the salts in the soil, and its acidity. The wet chemistry lab was part of the suite of tools called the Microscopy, Electrochemistry and Conductivity Analyzer (MECA).

Preliminary wet chemistry lab results showed the surface soil is moderately alkaline
Alkalinity
Alkalinity or AT measures the ability of a solution to neutralize acids to the equivalence point of carbonate or bicarbonate. The alkalinity is equal to the stoichiometric sum of the bases in solution...

, between pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

 8 and 9. Magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...

, sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

, potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...

 and chloride
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...

 ions were found; the overall level of salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...

 is modest. Chloride levels were low, and thus the bulk of the anions present were not initially identified. The pH and salinity level were viewed as benign from the standpoint of biology
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...

. TEGA analysis of its first soil sample indicated the presence of bound water and CO2 that were released during the final (highest-temperature, 1,000°C) heating cycle.

On August 1, 2008, Aviation Week reported that "The White House has been alerted by NASA about plans to make an announcement soon on major new Phoenix lander discoveries concerning the "potential for life" on Mars, scientists tell Aviation Week & Space Technology." This led to a subdued media speculation on whether some evidence of past or present life had been discovered. To quell the speculation, NASA released preliminary and unconfirmed findings which suggest that Mars soil contains perchlorate
Perchlorate
Perchlorates are the salts derived from perchloric acid . They occur both naturally and through manufacturing. They have been used as a medicine for more than 50 years to treat thyroid gland disorders. They are used extensively within the pyrotechnics industry, and ammonium perchlorate is also a...

 and thus may not be as earth-like and life-friendly as thought earlier.

A 360-degree panorama assembled from images taken on sols 1 and 3 after landing. The upper portion has been vertically stretched by a factor of 8 to bring out details. Visible near the horizon at full resolution are the backshell and parachute (a bright speck above the right edge of the left solar array, about 300 m distant) and the heat shield and its bounce mark (two end-to-end dark streaks above the center of the left solar array, about 150 m distant); on the horizon, left of the weather mast, is a crater.

End of the mission


The solar-powered lander operated two months longer than its three-month prime mission. The lander was designed to last 90 days, and had been running on bonus time since the successful end of its primary mission in August 2008. On October 28, 2008, the spacecraft went into safe mode
Safe mode (spacecraft)
Safe mode is an operating mode of a modern spacecraft during which all non-essential systems are shut down and only essential functions such as thermal management, radio reception and attitude control are active.-Triggering events:...

 due to power constraints based on the insufficient amount of sunlight reaching the lander, as expected at this time of year. It was decided then to shut down the four heaters that keep the equipment warm, and upon bringing the spacecraft back from safe mode
Safe mode (spacecraft)
Safe mode is an operating mode of a modern spacecraft during which all non-essential systems are shut down and only essential functions such as thermal management, radio reception and attitude control are active.-Triggering events:...

, commands were sent to turn off two of the heaters rather than only one as was originally planned for the first step. The heaters involved provide heat to the robotic arm, TEGA instrument and a pyrotechnic unit on the lander that were unused since landing, so these three instruments were also shut down.

On November 10, Phoenix Mission Control reported the loss of contact with the Phoenix lander; the last signal was received on November 2. Immediately prior, Phoenix sent its final message: "Triumph" in binary code
Binary code
A binary code is a way of representing text or computer processor instructions by the use of the binary number system's two-binary digits 0 and 1. This is accomplished by assigning a bit string to each particular symbol or instruction...

. The demise of the craft occurred as a result of a dust storm that reduced power generation even further. While the spacecraft's work ended, the analysis of data from the instruments was in its earliest stages.

Communication attempts 2010


Though it was not designed to survive the frigid Martian winter, the spacecraft's safe mode
Safe mode (spacecraft)
Safe mode is an operating mode of a modern spacecraft during which all non-essential systems are shut down and only essential functions such as thermal management, radio reception and attitude control are active.-Triggering events:...

 kept the option open to reestablish communications if the lander could have recharged its batteries during the next Martian spring. However, its landing location is in an area that is usually part of the north polar ice cap during the Martian winter, and the lander was seen from orbit encased in dry ice
Dry ice
Dry ice, sometimes referred to as "Cardice" or as "card ice" , is the solid form of carbon dioxide. It is used primarily as a cooling agent. Its advantages include lower temperature than that of water ice and not leaving any residue...

. It is estimated that, at its peak, the layer of CO2 ice in the lander's vicinity would total about 30 grams/cm2, which is enough to make a dense slab of dry ice at least 7½ inches (19 cm) thick. It was considered unlikely that the spacecraft could endure this condition, as its fragile solar-cell arrays would have cracked and fallen off since they were not designed to support much weight.

Scientists attempted to make contact with Phoenix starting January 18, 2010, but were unsuccessful. Further attempts in February and April also failed to pick up any signal from the lander. Project manager Barry Goldstein announced on May 24, 2010 that the project was being formally closed down. Images from the Mars Reconnaissance Orbiter showed that its solar panels were apparently irretrievably damaged by freezing during the Martian winter.

Landscape


Unlike some other places visited on Mars with landers (Viking
Viking program
The Viking program consisted of a pair of American space probes sent to Mars, Viking 1 and Viking 2. Each spacecraft was composed of two main parts, an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface...

 and Pathfinder
Mars Pathfinder
Mars Pathfinder was an American spacecraft that landed a base station with roving probe on Mars in 1997. It consisted of a lander, renamed the Carl Sagan Memorial Station, and a lightweight wheeled robotic rover named Sojourner.Launched on December 4, 1996 by NASA aboard a Delta II booster a...

), nearly all the rocks near Phoenix are small. For about as far as the camera can see, the land is flat, but shaped into polygons between 2–3 meters in diameter and are bounded by troughs that are 20 cm to 50 cm deep. These shapes are due to ice in the soil expanding and contracting due to major temperature changes. The microscope showed that the soil on top of the polygons is composed of flat particles (probably a type of clay) and rounded particles. Also, unlike other places visited on Mars, the site has no ripples or dunes. Ice is present a few inches below the surface in the middle of the polygons, and along its edges, the ice is at least 8 inches deep. When the ice is exposed to the Martian atmosphere it slowly sublimates. Some dust devil
Dust devil
A dust devil is a strong, well-formed, and relatively long-lived whirlwind, ranging from small to large . The primary vertical motion is upward...

s were observed.

Weather


Snow was observed to fall from cirrus clouds. The clouds formed at a level in the atmosphere that was around −65 degrees C, so the clouds would have to be composed of water-ice, rather than carbon dioxide-ice (dry ice) because the temperature for forming carbon dioxide ice is much lower—less than −120 degrees C. As a result of the mission, it is now believed that water ice (snow) would have accumulated later in the year at this location. This represents a milestone in understanding Martian weather. Wind speeds ranged from 11 km to 58 km per hour. The usual average speed was 36 km per hour. These speeds sound high, but the atmosphere of Mars is very thin—less than 1 % of the Earth's—and so did not exert much force on the spacecraft. The highest temperature measured during the mission was −19.6°C, while the coldest was −97.7°C.

Climate cycles


Interpretation of the data transmitted from the craft was published in the journal Science. As per the peer reviewed data the presence of water ice has been confirmed and that the site had a wetter and warmer climate in the recent past. Finding calcium carbonate
Calcium carbonate
Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...

 in the Martian soil leads scientists to believe that the site had been wet or damp in the geological past. During seasonal or longer period diurnal cycles water may have been present as thin films. The tilt or obliquity of Mars changes far more than the Earth; hence times of higher humidity are probable. The data also confirms the presence of the chemical perchlorate. Perchlorate makes up a few tenths of a percent of the soil samples. Perchlorate is used as food by some bacteria on Earth. Another paper claims that the previously detected snow could lead to a buildup of water ice. The reports leaves the question of presence of organic compounds open ended since heating the samples containing perchlorate would have broken down the organic material.

Surface chemistry


Results published in the journal Science after the mission ended reported that chloride, bicarbonate, magnesium, sodium potassium, calcium, and possibly sulfate were detected in the samples. The pH was narrowed down to 7.7±0.5. Perchlorate (ClO4), a strong oxidizer at elevated temperatures, was detected. This was a significant discovery. The chemical has the potential of being used for rocket fuel and as a source of oxygen for future colonists. Under certain conditions perchlorate can inhibit life; however some microorganisms obtain energy from the substance (by anaerobic reduction). The chemical when mixed with water can greatly lower freezing points, in a manner similar to how salt is applied to roads to melt ice. So, perchlorate may be allowing small amounts of liquid water to form on Mars today. Gullies, which are common in certain areas of Mars, may have formed from perchlorate melting ice and causing water to erode soil on steep slopes.

Scientific payload


Phoenix carries improved versions of University of Arizona panoramic cameras and volatiles-analysis instrument from the ill-fated Mars Polar Lander
Mars Polar Lander
The Mars Polar Lander, also referred to as the Mars Surveyor '98 Lander, was a 290-kilogram robotic spacecraft lander, launched by NASA on January 3, 1999, to study the soil and climate of Planum Australe, a region near the south pole on Mars, as part of the Mars Surveyor '98 mission...

, as well as experiments that had been built for the canceled Mars Surveyor 2001 Lander
Mars Surveyor 2001 Lander
The NASA Mars Surveyor 2001 Lander was a planned Mars probe which was canceled in May 2000 in the wake of the failures of the Mars Climate Orbiter and Mars Polar Lander missions in late 1999...

, including a JPL trench-digging robot arm, a set of wet chemistry laboratories, and optical and atomic force microscopes. The science payload also includes a descent imager and a suite of meteorological instruments.

Robotic arm and camera


The Robotic Arm (RA) is designed to extend 2.35 m from its base on the lander, and has the ability to dig down to 0.5 m below the surface. It took samples of dirt and ice that were analyzed by other instruments on the lander. The arm was designed and built for the Jet Propulsion Laboratory by Alliance Spacesystems, LLC (a subsidiary of MacDonald Dettwiler & Associates (MDA)) in Pasadena, California. A rotating rasp-tool located in the heel of the scoop was used to cut into the strong permafrost. Cuttings from the Rasp were ejected into the heel of the scoop and transferred to the front for delivery to the instruments. The Rasp tool, also called the Icy Soils Acquisition Device (ISAD), was conceived of at the Jet Propulsion Laboratory. The flight version of the Rasp was designed and built by HoneyBee Robotics in Manhattan NY. Commands were sent for the arm to be deployed on May 28, 2008, beginning with the pushing aside of a protective covering intended to serve as a redundant precaution against potential contamination of Martian subsoil by Earthly life-forms.
The Robotic Arm Camera (RAC) attached to the Robotic Arm just above the scoop was able to take full-color pictures of the area, as well as verify the samples that the scoop returned, and examined the grains of the area where the Robotic Arm had just dug. The camera was made by the University of Arizona
University of Arizona
The University of Arizona is a land-grant and space-grant public institution of higher education and research located in Tucson, Arizona, United States. The University of Arizona was the first university in the state of Arizona, founded in 1885...

 and Max Planck Institute for Solar System Research
Max Planck Institute for Solar System Research
The Max Planck Institute for Solar System Research is a research institute in Astronomy/Astrophysics, located in Lindau , Germany; 20 km north east of Göttingen. The exploration of our solar system is the central theme for the scientific research done at this Institute...

, Germany.

Surface stereo imager


The Surface Stereo Imager (SSI) was the primary camera on the spacecraft. It is a stereo camera
Stereo camera
A stereo camera is a type of camera with two or more lenses with a separate image sensor or film frame for each lens. This allows the camera to simulate human binocular vision, and therefore gives it the ability to capture three-dimensional images, a process known as stereo photography. Stereo...

 that is described as "a higher resolution upgrade of the imager used for Mars Pathfinder
Mars Pathfinder
Mars Pathfinder was an American spacecraft that landed a base station with roving probe on Mars in 1997. It consisted of a lander, renamed the Carl Sagan Memorial Station, and a lightweight wheeled robotic rover named Sojourner.Launched on December 4, 1996 by NASA aboard a Delta II booster a...

 and the Mars Polar Lander
Mars Polar Lander
The Mars Polar Lander, also referred to as the Mars Surveyor '98 Lander, was a 290-kilogram robotic spacecraft lander, launched by NASA on January 3, 1999, to study the soil and climate of Planum Australe, a region near the south pole on Mars, as part of the Mars Surveyor '98 mission...

". It took several stereo images of the Martian Arctic, and also used the Sun as a reference, to measure the atmospheric distortion of the Martian atmosphere due to dust, air and other features. The camera was provided by the University of Arizona
University of Arizona
The University of Arizona is a land-grant and space-grant public institution of higher education and research located in Tucson, Arizona, United States. The University of Arizona was the first university in the state of Arizona, founded in 1885...

 in collaboration with the Max Planck Institute for Solar System Research
Max Planck Institute for Solar System Research
The Max Planck Institute for Solar System Research is a research institute in Astronomy/Astrophysics, located in Lindau , Germany; 20 km north east of Göttingen. The exploration of our solar system is the central theme for the scientific research done at this Institute...

.

Thermal and evolved gas analyzer



The Thermal and Evolved Gas Analyzer (TEGA) is a combination of a high-temperature furnace with a mass spectrometer. It was used to bake samples of Martian dust and determine its content. It has eight ovens, each about the size of a large ball-point pen, which were able to analyze one sample each, for a total of eight separate samples. Team members measured how much water vapor and carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 gas were given off, how much water ice the samples contained, and what minerals are present that may have formed during a wetter, warmer past climate. The instrument also measurred organic volatiles
Volatile organic compound
Volatile organic compounds are organic chemicals that have a high vapor pressure at ordinary, room-temperature conditions. Their high vapor pressure results from a low boiling point, which causes large numbers of molecules to evaporate or sublimate from the liquid or solid form of the compound and...

, such as methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

, down to 10 ppb
PPB
PPB can stand for:* Party political broadcast, a type of political programming in the United Kingdom* parts-per-billion, a unit of concentration* Portland Police Bureau, a police agency for the city of Portland...

. TEGA was built by the University of Arizona
University of Arizona
The University of Arizona is a land-grant and space-grant public institution of higher education and research located in Tucson, Arizona, United States. The University of Arizona was the first university in the state of Arizona, founded in 1885...

 and University of Texas at Dallas
University of Texas at Dallas
The University of Texas at Dallas, also referred to as UT Dallas or UTD, is a public research university in the University of Texas System. The main campus is in the heart of the Richardson, Texas, Telecom Corridor, north of downtown Dallas...

.

On May 29, 2008, electrical tests indicated an intermittent short circuit in TEGA, resulting from a glitch in one of the two filaments responsible for ionizing volatiles. NASA worked around the problem by configuring the backup filament as the primary and vice-versa.

On June 11 the first of the eight ovens was filled with the a soil sample after several tries to get the soil sample through the screen of TEGA. On June 17, it was announced that no water was found in this sample; however, since it had been exposed to the atmosphere for several days prior to entering the oven, any initial water ice it might have contained could have been lost via sublimation.

Mars Descent Imager


The Mars Descent Imager ("MARDI") was intended to take pictures of the landing site during the last three minutes of descent. As originally planned, it would have begun taking pictures after the aeroshell departed, about 8 km above the Martian soil.

Before launch, testing of the assembled spacecraft uncovered a potential data corruption problem with an interface card that was designed to route MARDI image data as well as data from various other parts of the spacecraft. The potential problem could occur if the interface card were to receive a MARDI picture during a critical phase of the spacecraft's final descent, at which point data from the spacecraft's Inertial Measurement Unit
Inertial measurement unit
An inertial measurement unit, or IMU, is an electronic device that measures and reports on a craft's velocity, orientation, and gravitational forces, using a combination of accelerometers and gyroscopes. IMUs are typically used to maneuver aircraft, including UAVs, among many others, and...

 could have been lost; this data was critical to controlling the descent and landing. This was judged to be an unacceptable risk, and it was decided to not use MARDI during the mission. As the flaw was discovered too late for repairs, the camera remained installed on Phoenix but it was not used to take pictures, nor was its built-in microphone used.

MARDI images had been intended to help pinpoint exactly where the lander has landed, and possibly help find potential science targets. It was also to be used to learn if the area where the lander lands is typical of the surrounding terrain. MARDI was built by Malin Space Science Systems
Malin Space Science Systems
Malin Space Science Systems is a San Diego, California company that designs, develops, and operates instruments to fly on unmanned spacecraft. MSSS is headed by chief scientist and CEO Michael C. Malin....

, and it is the lightest and most efficient camera ever to land on Mars. It would have used only 3 watt
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...

s of power during the imaging process, less than most other space cameras. It had originally been designed and built to perform the same function on the Mars Surveyor 2001 Lander
Mars Surveyor 2001 Lander
The NASA Mars Surveyor 2001 Lander was a planned Mars probe which was canceled in May 2000 in the wake of the failures of the Mars Climate Orbiter and Mars Polar Lander missions in late 1999...

 mission; after that mission was canceled, MARDI spent several years in storage until it was deployed on the Phoenix lander.

Microscopy, electrochemistry, and conductivity analyzer


The Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) is an instrument package originally designed for the canceled Mars Surveyor 2001 Lander
Mars Surveyor 2001 Lander
The NASA Mars Surveyor 2001 Lander was a planned Mars probe which was canceled in May 2000 in the wake of the failures of the Mars Climate Orbiter and Mars Polar Lander missions in late 1999...

 mission. It consists of a wet chemistry
Wet chemistry
Wet chemistry is a term used to refer to chemistry generally done in the liquid phase. It is also known as bench chemistry because many of the tests performed are done at a lab bench.-Materials:...

 lab (WCL), optical and atomic force microscope
Atomic force microscope
Atomic force microscopy or scanning force microscopy is a very high-resolution type of scanning probe microscopy, with demonstrated resolution on the order of fractions of a nanometer, more than 1000 times better than the optical diffraction limit...

, and a thermal and electrical conductivity probe. The Jet Propulsion Laboratory built MECA. A Swiss consortium led by the University of Neuchatel
University of Neuchâtel
The University of Neuchâtel is a French-speaking university in Neuchâtel, Switzerland. The University has five faculties and more than a dozen institutes, including arts and human sciences, natural sciences, law, economics and theology. The Faculty of Arts and Human Sciences is the largest...

 contributed the atomic force microscope.

Using MECA, researchers examined soil particles as small as 16 μm across; additionally, they attempted to determine the chemical composition of water soluble ions in the soil. They also measured electrical and thermal conductivity of soil particles using a probe on the robotic arm scoop.

Sample wheel and translation stage


This instrument presents 6 of 69 sample holders to an opening in the MECA instrument to which the robotic arm delivers the samples and then brings the samples to the optical microscope and the atomic force microscope. Imperial College London
Imperial College London
Imperial College London is a public research university located in London, United Kingdom, specialising in science, engineering, business and medicine...

 provided the microscope sample substrates.

Optical microscope


The optical microscope
Optical microscope
The optical microscope, often referred to as the "light microscope", is a type of microscope which uses visible light and a system of lenses to magnify images of small samples. Optical microscopes are the oldest design of microscope and were possibly designed in their present compound form in the...

, designed by the University of Arizona
University of Arizona
The University of Arizona is a land-grant and space-grant public institution of higher education and research located in Tucson, Arizona, United States. The University of Arizona was the first university in the state of Arizona, founded in 1885...

, is capable of making images of the Martian regolith
Regolith
Regolith is a layer of loose, heterogeneous material covering solid rock. It includes dust, soil, broken rock, and other related materials and is present on Earth, the Moon, some asteroids, and other terrestrial planets and moons.-Etymology:...

 with a resolution of 256 pixels/mm or 16 micrometers/pixel. The field of view of the microscope is a 2x2 mm sample holder to which the robotic arm delivers the sample. The sample is illuminated either by 9 red, green and blue LEDs or by 3 LEDs emitting ultraviolet light. The electronics for the readout of the CCD chip are shared with the robotic arm camera which has an identical CCD chip
Charge-coupled device
A charge-coupled device is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by "shifting" the signals between stages within the device one at a time...

.

Atomic force microscope


The atomic force microscope
Atomic force microscope
Atomic force microscopy or scanning force microscopy is a very high-resolution type of scanning probe microscopy, with demonstrated resolution on the order of fractions of a nanometer, more than 1000 times better than the optical diffraction limit...

 has access to a small area of the sample delivered to the optical microscope. The instrument scans over the sample with one of 8 silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

 crystal tips and measures the repulsion of the tip from the sample. The maximum resolution is 0.1 micrometre
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...

s. It was designed by the University of Neuchatel
University of Neuchâtel
The University of Neuchâtel is a French-speaking university in Neuchâtel, Switzerland. The University has five faculties and more than a dozen institutes, including arts and human sciences, natural sciences, law, economics and theology. The Faculty of Arts and Human Sciences is the largest...

.

Wet chemistry lab


The wet chemistry lab (WCL) sensor assembly and leaching solution were designed and built by Thermo Fisher Scientific
Thermo Fisher Scientific
Thermo Fisher Scientific is a large life sciences supply company that was created in 2006 by the merger of Thermo Electron and Fisher Scientific.-Predecessors and merger:...

. The WCL actuator assembly was designed and built by Starsys Research in Boulder, Colorado. Tufts University
Tufts University
Tufts University is a private research university located in Medford/Somerville, near Boston, Massachusetts. It is organized into ten schools, including two undergraduate programs and eight graduate divisions, on four campuses in Massachusetts and on the eastern border of France...

 developed the reagent pellets, barium ISE, ASV electrodes, and performed the preflight characterization of the sensor array.

The robotic arm scooped up some soil, put it in one of four wet chemistry lab cells, where water was added, and while stirring, an array of electrochemical sensors measured a dozen dissolved ions such as sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

, magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...

, calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

, and sulfate
Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...

 that have leached out from the soil into the water. This provided information on the biological compatibility of the soil, both for possible indigenous microbes and for possible future Earth visitors.

Every wet chemistry cell has 26 chemical sensors and a temperature sensor. The polymer Ion Selective Electrodes were able to determine the concentration of ions by measuring the change of electric potential within the sensor, which is separated from the wet chemistry cell by an ion selective membrane. The two gas sensing electrodes for oxygen and carbon dioxide work on the same principle and are separated from the wet chemistry cell by a gas permeable membrane. A gold micro-electrode array is used for the Cyclic voltammetry
Cyclic voltammetry
Cyclic voltammetry or CV is a type of potentiodynamic electrochemical measurement. In a cyclic voltammetry experiment the working electrode potential is ramped linearly versus time like linear sweep voltammetry. Cyclic voltammetry takes the experiment a step further than linear sweep voltammetry...

 and Anodic Stripping Voltammetry
Anodic stripping voltammetry
Anodic stripping voltammetry is a voltammetric method for quantitative determination of specific ionic species. The analyte of interest is electroplated on the working electrode during a deposition step, and oxidized from the electrode during the stripping step. The current is measured during the...

. Cyclic voltammetry is a method to study ions by applying a waveform of varying potential and measuring the current-voltage curve. Anodic Stripping Voltammetry
Anodic stripping voltammetry
Anodic stripping voltammetry is a voltammetric method for quantitative determination of specific ionic species. The analyte of interest is electroplated on the working electrode during a deposition step, and oxidized from the electrode during the stripping step. The current is measured during the...

 first deposits the metals onto the gold electrode with an applied potential. After the potential is reversed, the current is measured while the metals are stripped off the electrode.

The first measurement indicated that the surface layer contained water soluble salts and had a pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

 between 8 and 9. Additional tests on soil composition revealed the presence of perchlorate
Perchlorate
Perchlorates are the salts derived from perchloric acid . They occur both naturally and through manufacturing. They have been used as a medicine for more than 50 years to treat thyroid gland disorders. They are used extensively within the pyrotechnics industry, and ammonium perchlorate is also a...

.

Later publication of results in the journals Science and JGR reported that chloride, bicarbonate
Bicarbonate
In inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid...

, magnesium, sodium potassium, calcium, and possibly sulfate were detected in the samples. The pH was narrowed down to 7.7 + or – 0.5. Further data analysis has indicated that the soil contains soluble sulfate at a minimum of 1.1% wt % SO3 and provided a refined formulation of the soil.

Thermal and Electrical Conductivity Probe (TECP)


The MECA contains a Thermal and Electrical Conductivity Probe (TECP). TECP has four short fat probes and one port on the side of the housing that made the following measurements:
  • Martian Soil (Regolith
    Regolith
    Regolith is a layer of loose, heterogeneous material covering solid rock. It includes dust, soil, broken rock, and other related materials and is present on Earth, the Moon, some asteroids, and other terrestrial planets and moons.-Etymology:...

    ) temperature
  • Relative Humidity
  • Thermal conductivity
    Thermal conductivity
    In physics, thermal conductivity, k, is the property of a material's ability to conduct heat. It appears primarily in Fourier's Law for heat conduction....

  • Electrical conductivity
  • Dielectric permittivity
  • Wind speed
  • Atmospheric temperature


Three of the four probes have tiny heating elements and temperature sensors inside them. One probe uses internal heating elements to send out a pulse of heat, recording the time the pulse is sent and monitoring the rate at which the heat is dissipated away from the probe. Adjacent needles sense when the heat pulse arrives. The speed that the heat travels away from the probe as well as the speed that it travels between probes allows scientists to measure thermal conductivity specific heat (the ability of the regolith to conduct heat relative to its ability to store heat) and thermal diffusivity (the speed at which a thermal disturbance is propagated in the soil).

The probes also measured the dielectric permittivity
Permittivity
In electromagnetism, absolute permittivity is the measure of the resistance that is encountered when forming an electric field in a medium. In other words, permittivity is a measure of how an electric field affects, and is affected by, a dielectric medium. The permittivity of a medium describes how...

 and electrical conductivity, which can be used to calculate moisture and salinity of the regolith
Regolith
Regolith is a layer of loose, heterogeneous material covering solid rock. It includes dust, soil, broken rock, and other related materials and is present on Earth, the Moon, some asteroids, and other terrestrial planets and moons.-Etymology:...

. Needles 1 and 2 work in conjunction to measure salts in the regolith, heat the soil to measure thermal properties (thermal conductivity, specific heat and thermal diffusivity) of the regolith, and measure soil temperature. Needles 3 and 4 measure liquid water in the regolith. Needle 4 is a reference thermometer for needles 1 and 2.

The TECP humidity sensor is a relative humidity sensor, so it must be coupled with a temperature sensor in order to measure absolute humidity. Both the relative humidity sensor and a temperature sensor are attached directly to the circuit board of the TECP and are, therefore, assumed to be at the same temperature.

Meteorological station



The Meteorological Station (MET) recorded the daily weather of Mars
Climate of Mars
The climate of Mars has been an issue of scientific curiosity for centuries, not least because Mars is the only terrestrial planet whose surface can be directly observed in detail from the Earth....

 during the course of the Phoenix mission. It is equipped with a wind indicator and pressure and temperature sensors. The MET also contains a LIDAR
LIDAR
LIDAR is an optical remote sensing technology that can measure the distance to, or other properties of a target by illuminating the target with light, often using pulses from a laser...

 (light detection and ranging) device for sampling the number of dust particles in the air. It was designed in Canada by Optech and MDA, supported by the Canadian Space Agency. A team headed by York University
York University
York University is a public research university in Toronto, Ontario, Canada. It is Canada's third-largest university, Ontario's second-largest graduate school, and Canada's leading interdisciplinary university....

 oversaw the science operations of the station. The York University team includes contributions from the University of Alberta
University of Alberta
The University of Alberta is a public research university located in Edmonton, Alberta, Canada. Founded in 1908 by Alexander Cameron Rutherford, the first premier of Alberta and Henry Marshall Tory, its first president, it is widely recognized as one of the best universities in Canada...

, University of Aarhus
University of Aarhus
Aarhus University , located in the city of Aarhus, Denmark, is Denmark's second oldest and second largest university...

 (Denmark), Dalhousie University
Dalhousie University
Dalhousie University is a public research university located in Halifax, Nova Scotia, Canada. The university comprises eleven faculties including Schulich School of Law and Dalhousie University Faculty of Medicine. It also includes the faculties of architecture, planning and engineering located at...

, Finnish Meteorological Institute
Finnish Meteorological Institute
The Finnish Meteorological Institute is the government agency responsible for gathering and reporting weather data and forecasts in Finland. It is a part of the Ministry of Transport and Communications but it operates semi-autonomously....

, Optech, and the Geological Survey of Canada. Canadarm maker MacDonald Dettwiler and Associates (MDA)
MacDonald Dettwiler
MacDonald, Dettwiler and Associates Ltd. is a Richmond, British Columbia-based Canadian aerospace, information services and products company, employing over 3000 people throughout Canada, the United States and the United Kingdom, under the MDA brand name....

 of Richmond, B.C. built the MET.
The surface wind velocity, pressure and temperatures were also monitored over the mission (from the tell-tale
Tell-tale
A tell-tale or telltale is an indicator, signal, or sign that conveys the status of a situation, mechanism, or system.-Automotive:...

, pressure and temperature sensors) and show the evolution of the atmosphere with time. To measure dust and ice contribution to the atmosphere, a LIDAR was employed. The LIDAR collected information about the time-dependent structure of the planetary boundary layer
Planetary boundary layer
The planetary boundary layer , also known as the atmospheric boundary layer , is the lowest part of the atmosphere and its behavior is directly influenced by its contact with a planetary surface. On Earth it usually responds to changes in surface forcing in an hour or less...

 by investigating the vertical distribution of dust, ice, fog and clouds in the local atmosphere.
There are three temperature sensors (thermocouples) on a 1 m vertical mast (shown at left in its stowed position) at heights of approximately 250, 500 and 1000 mm above the lander deck. The sensors were referenced to a measurement of absolute temperature at the base of the mast. A pressure sensor built by Finnish Meteorological Institute is located in the Payload Electronics Box, which sits on the surface of the deck, and houses the acquisition electronics for the MET payload. The Pressure and Temperature sensors commenced operations on Sol 0 (May 26, 2008) and operate continuously, sampling once every 2 seconds.

The Telltale is a joint Canadian/Danish instrument (right) which provides a coarse estimate of wind speed and direction. The speed is based on the amount of deflection from vertical that is observed, while the wind direction is provided by which way this deflection occurs. A mirror, located under the telltale, and a calibration "cross," above (as observed through the mirror) are employed to increase the accuracy of the measurement. Either the SSI or RAC cameras could make this measurement, though the former was typically used. Periodic observations both day and night aid in understanding the diurnal
Day
A day is a unit of time, commonly defined as an interval equal to 24 hours. It also can mean that portion of the full day during which a location is illuminated by the light of the sun...

 variability of wind at the Phoenix landing site.

The wind speeds ranged from 11 km to 58 km per hour. The usual average speed was 36 km per hour. These speeds sound high, but remember that the atmospehere of Mars is very thin, less than 1 % of the Earth's.
The vertical pointing LIDAR detects multiple types of backscattering (for example Rayleigh scattering
Rayleigh scattering
Rayleigh scattering, named after the British physicist Lord Rayleigh, is the elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the light. The particles may be individual atoms or molecules. It can occur when light travels through...

 and Mie Scattering), with the delay between laser pulse generation and the return of light scattered by atmospheric particles determining the altitude at which scattering occurs. Additional information was obtained from backscattered light at different wavelengths (colors), and the Phoenix system transmitted both 532 nm and 1064 nm. Such wavelength dependence may make it possible to discriminate between ice and dust, and serve as an indicator of the effective particle size.
The Phoenix LIDAR laser is a passive Q-switched Nd:YAG laser with the dual wavelengths of 1064 nm and 532 nm. It operates at 100 Hz with a pulse width of 10 ns. The scattered light is received by two detectors that operate (green and IR) and the green signal is collected in both analog and photon counting modes.
The LIDAR was operated for the first time at noon on Sol 3 (May 29, 2008), recording the first surface extraterrestrial atmospheric profile. This first profile indicated well mixed dust in the first few kilometers of the atmosphere of Mars
Atmosphere of Mars
The atmosphere of Mars is relatively thin and is composed mostly of carbon dioxide . There has been interest in studying its composition since the detection of trace amounts of methane, which may indicate the presence of life on Mars, but may also be produced by a geochemical process, volcanic or...

, where the planetary boundary layer was observed by a marked decrease in scattering signal. The contour plot (right) shows the amount of dust as a function of time and altitude, with warmer colors (red-orange) indicating more dust, and cooler colors (blues-green), indicating less dust. There is also an instrumentation effect of the laser warming up, causing the appearance of dust increasing with time. A Layer at 3.5 km can be observed in the plot, which could be extra dust, or less likely given the time of sol this was acquired, a low altitude ice cloud.

The image on the left shows the Lidar laser operating on the surface of Mars, as observed by the SSI looking straight up, the laser is the vertical "line". Overhead dust can be seen both moving in the background, as well as passing through the laser beam in the form of bright sparkles. The fact that the beam appears to terminate is the result of the extremely small angle at which the SSI is observing the laser.

The laser device discovered snow falling from clouds; this was not known before the mission. It was also determined that cirrus clouds formed in the area.

Phoenix DVD


Attached to the deck of the lander (next to the US flag) is the "Phoenix DVD", compiled by the Planetary Society
Planetary Society
The Planetary Society is a large, publicly supported, non-government and non-profit organization that has many research projects related to astronomy...

. The disc contains Visions of Mars, a multimedia collection of literature and art about the Red Planet. Works include the text of H.G. Wells' War of the Worlds (and the radio broadcast
The War of the Worlds (radio)
The War of the Worlds was an episode of the American radio drama anthology series Mercury Theatre on the Air. It was performed as a Halloween episode of the series on October 30, 1938, and aired over the Columbia Broadcasting System radio network. Directed and narrated by actor and future filmmaker...

 by Orson Welles
Orson Welles
George Orson Welles , best known as Orson Welles, was an American film director, actor, theatre director, screenwriter, and producer, who worked extensively in film, theatre, television and radio...

), Percival Lowell's
Percival Lowell
Percival Lawrence Lowell was a businessman, author, mathematician, and astronomer who fueled speculation that there were canals on Mars, founded the Lowell Observatory in Flagstaff, Arizona, and formed the beginning of the effort that led to the discovery of Pluto 14 years after his death...

 Mars as the Abode of Life with a map of his proposed canals, Ray Bradbury
Ray Bradbury
Ray Douglas Bradbury is an American fantasy, horror, science fiction, and mystery writer. Best known for his dystopian novel Fahrenheit 451 and for the science fiction stories gathered together as The Martian Chronicles and The Illustrated Man , Bradbury is one of the most celebrated among 20th...

's The Martian Chronicles
The Martian Chronicles
The Martian Chronicles is a 1950 science fiction short story collection by Ray Bradbury that chronicles the colonization of Mars by humans fleeing from a troubled and eventually atomically devastated Earth, and the conflict between aboriginal Martians and the new colonists...

, and Kim Stanley Robinson
Kim Stanley Robinson
Kim Stanley Robinson is an American science fiction writer known for his award-winning Mars trilogy. His work delves into ecological and sociological themes regularly, and many of his novels appear to be the direct result of his own scientific fascinations, such as the fifteen years of research...

's Green Mars. There are also messages directly addressed to future Martian visitors or settlers from, among others, Carl Sagan
Carl Sagan
Carl Edward Sagan was an American astronomer, astrophysicist, cosmologist, author, science popularizer and science communicator in astronomy and natural sciences. He published more than 600 scientific papers and articles and was author, co-author or editor of more than 20 books...

 and Arthur C. Clarke
Arthur C. Clarke
Sir Arthur Charles Clarke, CBE, FRAS was a British science fiction author, inventor, and futurist, famous for his short stories and novels, among them 2001: A Space Odyssey, and as a host and commentator in the British television series Mysterious World. For many years, Robert A. Heinlein,...

. In 2006, The Planetary Society collected a quarter million names submitted through the Internet and placed them on the disc, which claims, on the front, to be "the first library on Mars." This Phoenix DVD is similar to the Voyager Golden Record
Voyager Golden Record
The Voyager Golden Records are phonograph records which were included aboard both Voyager spacecraft, which were launched in 1977. They contain sounds and images selected to portray the diversity of life and culture on Earth, and are intended for any intelligent extraterrestrial life form, or for...

 that was sent on the Voyager 1 & 2 missions.

The Phoenix DVD is made of a special silica glass designed to withstand the Martian environment, lasting for hundreds (if not thousands) of years on the surface while it awaits discoverers.

The text just below the center of the disk reads:

See also


  • Exploration of Mars
    Exploration of Mars
    The exploration of Mars has been an important part of the space exploration programs of the Soviet Union, the United States, Europe, and Japan. Dozens of robotic spacecraft, including orbiters, landers, and rovers, have been launched toward Mars since the 1960s...

  • 2007 in spaceflight
  • 2008 in spaceflight
    2008 in spaceflight
    The year 2008 contained several significant events in spaceflight, including the first flyby of Mercury by a spacecraft since 1975, the discovery of water ice on Mars by the Phoenix spacecraft, which landed in May, the first Chinese spacewalk in September, and the launch of the first Indian Lunar...


External links


LPL, LMSS, JPL and NASA links

Other links