NASAThe National Aeronautics and Space Administration is an agency of the United States government, responsible for the nation's public space program. NASA was established by the National Aeronautics and Space Act on July 29, 1958, replacing its predecessor, the National Advisory Committee for...
's
Mars Exploration Rover (
MER)
Mission is an ongoing robotic mission of exploring
MarsMars is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the "Red Planet" because of its reddish appearance, due to iron oxide prevalent on its surface....
, that began in 2003 with the sending of two
roverThere are two main types of rovers.A rover is a space exploration vehicle designed to move across the surface of a planet or other astronomical body. Some rovers have been designed to transport members of a human spaceflight crew; others have been partially or fully autonomous robots...
s — MER-A
SpiritSpirit, mission designation MER-A , is the first of the two rovers of NASA's Mars Exploration Rover Mission. It landed successfully on Mars on 04:35 Ground UTC on January 4, 2004, three weeks before its twin Opportunity landed on the other side of the planet...
and MER-B
OpportunityOpportunity, mission designation MER-B , is the second of the two rovers of NASA's Mars Exploration Rover Mission. It landed successfully at Meridiani Planum on Mars on January 25, 2004 05:05 Ground UTC , three weeks after its twin Spirit had landed on the other side of the planet...
— to explore the Martian surface and
geologyGeology is the science and study of the solid and liquid matter that constitutes the Earth. The field of geology encompasses the study of the composition, structure, physical properties, dynamics, and history of Earth materials, and the processes by which they are formed, moved, and changed...
.
Primary among the mission's scientific objectives is to search for and characterize a wide range of
rocksIn geology, rock is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
and
soilSoil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics. It is composed of particles of broken rock that have been altered by chemical and...
s that hold clues to past water activity on Mars. The mission is part of NASA's Mars Exploration Program which includes three previous successful landers: the two
VikingNASA's Viking program consisted of a pair of space probes sent to Mars, Viking 1 and Viking 2. Each vehicle 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...
landers in 1976 and
PathfinderThe Mars Pathfinder later called The Carl Sagan Memorial Station was launched on December 4, 1996 by NASA aboard a Delta II just a month after the Mars Global Surveyor was launched. After a 7-month voyage it landed on Ares Vallis, in a region called Chryse Planitia on Mars, in the Oxia Palus...
in 1997.
The total cost of building, launching, landing and operating the rovers on the surface for the initial 90 Martian-day (SOL) primary mission was US$820 million. Since the rovers have continued to function beyond their initial 90 SOL primary mission, they have each received five mission extensions. The fifth mission extension was granted in October 2007, and runs to the end of 2009. The total cost of the first four mission extensions was $104 million and the fifth mission extension is expected to cost at least $20 million.
In July 2007, during the fourth mission extension, Martian dust storms blocked sunlight to the rovers and threatened the ability of the craft to gather energy through their
solar panelA photovoltaic module or photovoltaic panel is a packaged interconnected assembly of photovoltaic cells, also known as solar cells. The photovoltaic module, known more commonly as the solar panel, is then used as a component in a larger photovoltaic system to offer electricity for commercial and...
s, causing engineers to fear that one or both of them might be permanently disabled. However, the dust storms lifted, allowing them to resume operations.
On May 1, 2009, during its fifth mission extension, Spirit became stuck in soft soil on Mars. NASA is carefully analyzing the situation to get the rover back on track, still monitoring the situation using test rovers on Earth as of October, 2009. The latest news about efforts to free the rover from the soft soil on Mars is available at the “Free Spirit” website.
In recognition of the vast amount of
scientific informationNASA's 2003 Mars Exploration Rover Mission has amassed an enormous amount of scientific information related to the Martian geology and atmosphere, as well as providing some astronomical observations from Mars. This article covers information gathered by the Opportunity rover during the initial...
amassed by both rovers, two
asteroidthumb|260px|right|[[253 Mathilde]], a [[C-type asteroid]] measuring about across. Photograph taken in 1997 by the [[NEAR Shoemaker]] probe.Asteroids, sometimes called minor planets or planetoids, are small Solar System bodies in orbit around the Sun, especially in the inner Solar System; they are...
s have been named in their honor:
37452 SpiritAsteroid 37452 Spirit was discovered on September 24, 1960 by Ingrid van Houten-Groeneveld, Cornelis Johannes van Houten, and Tom Gehrels. The asteroid was spotted by examining photographic plates of images taken by telescopes at the Palomar Observatory. 37452 Spirit is part of a small group of...
and
39382 OpportunityAsteroid 39382 Opportunity was discovered on September 24, 1960, by Ingrid van Houten-Groeneveld, Cornelis Johannes van Houten and Tom Gehrels. The asteroid was spotted by examining photographic plates taken by telescopes at the Palomar Observatory....
.
The mission is managed for
NASAThe National Aeronautics and Space Administration is an agency of the United States government, responsible for the nation's public space program. NASA was established by the National Aeronautics and Space Act on July 29, 1958, replacing its predecessor, the National Advisory Committee for...
by the
Jet Propulsion LaboratoryJet 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 situated in the northern portion of Pasadena...
, which designed, built and is operating the rovers.
Objectives
The scientific objectives of the Mars Exploration Rover mission are to:
- Search for and characterize a variety of rocks and soils that hold clues to past water
Water is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
activity. In particular, samples sought will include those that have minerals deposited by water-related processes such as precipitationIn meteorology, precipitation is any product of the condensation of atmospheric water vapor that is deposited on the Earth's surface. The main forms of precipitation include rain, snow, ice pellets, and graupel...
, evaporationWater vapor or water vapour , also aqueous vapor, is the gas phase of water. Water vapor is one state of the water cycle within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice...
, sedimentary cementationSedimentary rock is the type of rock that is formed by sedimentation of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....
or hydrothermal activity.
- Determine the distribution and composition of minerals, rocks, and soils surrounding the landing sites.
- Determine what geologic processes
The geology of Mars, also known as areology , refers to the study of the composition, structure, physical properties, history, and the processes that shape the planet Mars.-Elemental composition:...
have shaped the local terrain and influenced the chemistry. Such processes could include water or wind erosion, sedimentation, hydrothermal mechanisms, volcanism, and cratering.
- Perform calibration and validation of surface observations made by Mars Reconnaissance Orbiter
NASA's Mars Reconnaissance Orbiter is a multipurpose spacecraft designed to conduct reconnaissance and exploration of Mars from orbit....
instruments. This will help determine the accuracy and effectiveness of various instruments that survey Martian geologyThe geology of Mars, also known as areology , refers to the study of the composition, structure, physical properties, history, and the processes that shape the planet Mars.-Elemental composition:...
from orbit.
- Search for iron
Iron is a metallic chemical element with the symbol Fe and atomic number 26. Iron is a group 8 and period 4 element and is therefore classified as a transition metal. Iron and iron alloys are by far the most common metals and the most common ferromagnetic materials in everyday use...
-containing minerals, identify and quantify relative amounts of specific mineral types that contain water or were formed in water, such as iron-bearing carbonates.
- Characterize the mineralogy
Mineralogy is an Earth Science focused around the chemistry, crystal structure, and physical properties of minerals. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, as well as their...
and textures of rocks and soils and determine the processes that created them.
- Search for geological clues to the environmental conditions
Environmental science is an interdisciplinary field that involves both the physical sciences and the social sciences . It encompasses the surrounding conditions that affect man and other organisms...
that existed when liquid water was present.
- Assess whether those environments were conducive to life
Life is a characteristic that distinguishes objects that have self-sustaining biological processes from those that do not—either because such functions have ceased , or else because they lack such functions and are classified as "inanimate."In biology, the science of living organisms, "life"...
.
During the next two decades, NASA will conduct several missions to address whether life ever arose on Mars. The search begins with determining whether the Martian environment was ever suitable for life. Life, as we understand it, requires water, so the history of water on Mars is critical to finding out if the martian environment was ever conducive to life. Although the Mars Exploration Rovers do not have the ability to detect life directly, they are offering very important information on the habitability of the environment in the planet's history.
History
On January 21, 2004, the
Deep Space NetworkThe Deep Space Network, or DSN, is an international network of large antennas and communication facilities that supports interplanetary spacecraft missions, and radio and radar astronomy observations for the exploration of the solar system and the universe. The network also supports selected...
lost contact with
Spirit, for reasons originally thought to be related to a
thunderstormA thunderstorm, also known as an electrical storm, a lightning storm, a hailstorm, or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically-assigned cloud type associated with the...
over
AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the continental mainland , the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans...
. The rover transmitted a message with no data, but later that day missed another communications session with the
Mars Global SurveyorThe Mars Global Surveyor was a US spacecraft developed by NASA's Jet Propulsion Laboratory and launched November 1996. It began the United States's return to Mars after a 10-year absence. It completed its primary mission in January 2001 and was in its third extended mission phase when, on , the...
. The next day, JPL managed to receive a beep from the rover, indicating that it was in fault mode. On the 23rd, the flight team succeeded in making the rover send. The fault was believed to have been caused by an error in the rover's
Flash memoryFlash memory is a non-volatile computer storage that can be electrically erased and reprogrammed. It is a technology that is primarily used in memory cards and USB flash drives for general storage and transfer of data between computers and other digital products...
subsystem. The rover did not perform any scientific activities for 10 days, while engineers updated its software and ran tests. The problem was corrected by reformatting
Spirit's flash memory and upgrading the software with a patch to avoid memory overload;
Opportunity was also upgraded with the patch as a precaution.
Spirit returned to full scientific operations by 5 February. This has to date been the most serious anomaly in the mission.
On March 23, 2004, a news conference was held announcing "major discoveries" of evidence of past liquid
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
on the Martian surface. A delegation of scientists showed pictures and data revealing a stratified pattern and cross bedding in the rocks of the outcrop inside a crater in
Meridiani PlanumMeridiani Planum is a plain located 2 degrees south of Mars' equator , in the westernmost portion of Terra Meridiani. It hosts a rare occurrence of gray crystalline hematite...
, landing site of MER-B,
Opportunity, suggesting that water once flowed in the region. The irregular distribution of
chlorineChlorine Chlorine Chlorine ( , from the Greek word 'χλωρóς' (khlôros, meaning 'pale green'), is the chemical element with atomic number 17 and symbol Cl. It is a halogen, found in the periodic table in group 17 (formerly VII, VIIa, or VIIb). As the chloride ion, which is part of common salt and...
and
bromineBromine , is a chemical element with the symbol Br and atomic number 35. A halogen element, bromine is a reddish-brown volatile liquid at standard room temperature that is intermediate in reactivity between chlorine and iodine. Bromine vapors are corrosive and toxic. Approximately 556,000 metric...
also suggests that the place was once the shoreline of a salty sea, now evaporated.
On April 8, 2004, NASA announced that it was extending the mission life of the rovers from 3 to 8 months. It immediately provided additional funding of US $15 million through September, and $2.8 million per month for continuing operations.
On April 30, 2004,
Opportunity arrived at
Endurance craterEndurance is an impact crater on Mars that was visited by the Opportunity rover from May until December 2004. Mission scientists named the crater after the ship Endurance that sailed to the Antarctic in an exploration voyage organized by Ernest Shackleton.The rover entered the crater interior on...
, taking about 5 days to drive the 200 meters.
On September 22, 2004, NASA announced that it was extending the mission life of the rovers for another 6 months.
Opportunity was to leave Endurance crater, visit its discarded heat shield, and proceed to
Victoria craterVictoria is an impact crater on Mars located at 2.05°S, 5.50°W in Meridiani Planum, visited by the Mars Exploration Rover Opportunity. It is roughly 730 metres wide, nearly eight times the size of the crater Endurance, visited by Opportunity from sols 95 to 315...
.
Spirit was to attempt to climb to the top of the Columbia Hills.
On April 6, 2005, with the two rovers still functioning well, NASA announced another 18 month extension of the mission to September 2006.
Opportunity was to visit the "Etched Terrain" and
Spirit was to climb a rocky slope toward the top of
Husband HillHusband Hill is one of the Columbia Hills in Gusev crater, Mars. It was named in honor of Rick D. Husband, an astronaut and commander of the Space Shuttle Columbia during its final mission, during which it disintegrated upon atmospheric reentry .In 2005, the Spirit rover, as part of its exploration...
.
On August 21, 2005, Spirit
reached the summit of Husband Hill after 581 sols and a journey of 4.81 kilometers (2.99 mi).
Spirit
celebrated its one Martian year anniversary (669 sols or 687 Earth days) on November 20, 2005. Opportunity
celebrated its anniversary on December 12, 2005. At the beginning of the mission, it was expected that the rovers would not survive much longer than 90 Martian days. The Columbia Hills were "just a dream" according to rover driver Chris Leger.
On February 7, 2006, Spirit
reached the semicircular rock formation known as Home PlateHome Plate is a plateau roughly 90 m across within the Columbia Hills, Mars. It is informally named for its similarity in shape to a baseball home plate...
. It is a layered rock outcrop that puzzles and excites scientists. It is thought that its rocks are explosive volcanic deposits, though other possibilities exist, including impact deposits or wind/water borne sediment.
On March 13, 2006, Spirit's
front right wheel ceased working while the rover was moving itself to McCool HillMcCool Hill is the tallest of the Columbia Hills in Gusev crater, Mars. It was named in honor of William C. McCool, an astronaut of the Space Shuttle Columbia during its final mission where it disintegrated during atmospheric reentry .The hill was to be Spirit rover's next target...
. Her drivers attempted to drag the dead wheel behind Spirit, but this only worked until reaching an impassable sandy area on the lower slopes. Drivers directed Spirit
to a smaller sloped feature, dubbed "Low Ridge Haven", where she spent the long Martian winter, waiting for spring and increased solar power levels suitable for driving.
On September 26, 2006, Spaceflight Now reported that NASA has extended mission for the two rovers through September 2007.
On September 27, 2006, Opportunity
reached the rim of Victoria crater.
Spirit
had lasted over 1,000 Martian days exploring Gusev Crater as of October 25, 2006. Opportunity
had lasted over 1,000 Martian days exploring Meridiani Planum as of November 16, 2006. As of January 24, 2007, the rovers had lasted on Mars more than three years. (Although Opportunity
landed on January 25, the year 2004 was a leap yearA leap year is a year containing one or more extra days in order to keep the calendar year synchronized with the astronomical or seasonal year....
.)
On February 6, 2007, Opportunity
became the first spacecraft to traverse 10,000 meters - 10 kilometers - on the surface of Mars.
On June 28, 2007, Opportunity
was poised to enter Victoria Crater from its perch on the rim of Duck Bay., but due to extensive dust storms, it was indefinitely delayed until the dust had cleared and power returned to safe levels.
On August 28, 2007, Spirit
and Opportunity
resumed driving after hunkering down during raging dust storms that limited solar power to a level that nearly caused the permanent failure of both rovers.
On October 1, 2007, both Spirit
and Opportunity
entered their fifth mission extension that could possibly extend operations into 2009, allowing the rovers to have spent five years exploring the Martian surface, pending their continued survival.
On January 3, 2008, Spirit
entered its fourth year of exploration of Gusev craterGusev is a crater on the planet Mars and is located at 175.4°E 14.6°S. The crater is about 170 kilometers in diameter and formed approximately three to four billion years ago...
.
On January 25, 2008, Opportunity
entered its fourth year of exploration of Meridiani PlanumMeridiani Planum is a plain located 2 degrees south of Mars' equator , in the westernmost portion of Terra Meridiani. It hosts a rare occurrence of gray crystalline hematite...
.
On August 26, 2008, Opportunity
began to climb out of Victoria crater amidst concerns that power spikes, similar to those seen on Spirit before the failure of its right-front wheel, might prevent Opportunity
from ever being able to leave the crater in the event of the failure of one of its wheels. Project scientist Bruce Banerdt has also said, "We've done everything we entered Victoria Crater to do and more." Opportunity
will return to the plains in order to characterize Meridiani Planum's vast diversity of rocks—some of which may have been blasted out of craters such as Victoria. The rover had been exploring Victoria Crater since September 11, 2007.
On August 29, 2008, Opportunity
succeeded in climbing out of Victoria crater, using the same route it took on the way in.
On January 3, 2009, Spirit
marked 5 years on Mars. Since landing on Mars the two rovers had collectively sent back 250,000 images and traveled over 21 kilometers (13 miles).
On January 24, 2009, Opportunity
marked 5 years on Mars.
On March 7, 2009 Opportunity
first saw the rim of Endeavour craterEndeavour is an impact crater located in Meridiani Planum on Mars. Since August of 2008, Mars Exploration Rover-B Opportunity has been travelling towards it...
after driving about 3.2 kilometers (2 miles) since it left Victoria crater in August 2008.
On May 26, 2009 Opportunity
passed the 10 mile mark (more than 16 kilometers) on sol 1897 while on its way to Endeavour crater. Meanwhile, at Gusev crater, Spirit
was dug in deep into the Martian sand much as Opportunity
was at Purgatory Dune in 2005.
Spacecraft design
The Mars Exploration Rover was designed to be stowed in the nose of a Delta II rocket. Each spacecraft consists of several components:
- Rover: 185 kg (408 lb)
- Lander: 348 kg (767 lb)
- Backshell / Parachute: 209 kg (461 lb)
- Heat Shield: 78 kg (172 lb)
- Cruise Stage: 193 kg (425 lb)
- Propellant: 50 kg (110 lb)
Total mass is 1,063 kg (2,343 lb).
Cruise stage
The cruise stage is the component of the spacecraft that is used for travel from Earth to Mars. It is very similar to the Mars Pathfinder in design and is approximately 2.65 metersThe metre or meter is the basic unit of length in the International System of Units . Historically, the metre was defined by the French Academy of Sciences as the length between two marks on a platinum-iridium bar, which was designed to represent one ten-millionth of the distance from the Equator...
(8.7 ft) in diameterIn geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
and 1.6 m (5.2 ft) tall including the entry vehicle (see below).
The primary structure is aluminiumAluminium or aluminum is a silvery white and ductile member of the boron group of chemical elements. It has the symbol Al; its atomic number is 13. It is not soluble in water under normal circumstances....
with an outer ring of ribs covered by the solar panelA photovoltaic module or photovoltaic panel is a packaged interconnected assembly of photovoltaic cells, also known as solar cells. The photovoltaic module, known more commonly as the solar panel, is then used as a component in a larger photovoltaic system to offer electricity for commercial and...
s, which are about 2.65 m (8.7 ft) in diameter. Divided into five sections, the solar arrays can provide up to 600 wattThe watt is a derived unit of power in the International System of Units . It measures rate of energy conversion. One watt is equivalent to 1 joule of energy per second....
s of power near Earth and 300 W at Mars.
Heaters and multi-layer insulationMulti-layer insulation, or MLI, is thermal insulation composed of multiple layers of thin sheets often used on spacecraft. It is mainly intended to reduce heat loss by thermal radiation. In its basic form, it does not appreciably insulate against other thermal losses such as heat conduction or...
keep the electronics "warm". A freonFreon is DuPont's trade name for chlorofluorocarbon and hydrochlorofluorocarbons. In other countries the same family of chemical compounds are called Isceon, Ledon, Frigen, Kaltron, Flugene, Forane, Fridohna, Frigedohn, Algofrene, Asahiflon, Daiflon, Flon, Genetron, Kaiser, Isotron, Racon, Ucon,...
system removes heat from the flight computer and communications hardware inside the rover so they do not overheat. Cruise avionics systems allow the flight computer to interface with other electronics such as the sun sensors, star scanner and heaters.
Navigation
The star scanner (with a backup system) and sun sensor allowed the spacecraft to know its orientation in space by analyzing the position of the Sun and other stars in relation to itself. Sometimes the craft could be slightly off course; this was expected given the 500 million kilometer (320 million mile) journey. Thus navigators planned up to six trajectory correction maneuvers, along with health checks.
To ensure the spacecraft arrived at Mars in the right place for its landing, two light-weight, aluminium-lined tanks carried about 31 kg (about 68 lb) of hydrazineHydrazine is an inorganic chemical compound with the formula N2H4. It is a colourless liquid with an ammonia-like odor and is derived from the same industrial chemistry processes that manufacture ammonia...
propellantA propellant is a material that is used to move an object. This will often involve a chemical reaction. It may be a gas, liquid, plasma, or, before the chemical reaction, a solid....
. Along with cruise guidance and control systems, the propellant allowed navigators to keep the spacecraft on course. Burns and pulse firings of the propellant allowed three types of maneuvers:
- An axial burn uses pairs of thrusters to change spacecraft velocity;
- A lateral burn uses two "thruster clusters" (four thrusters per cluster) to move the spacecraft "sideways" through seconds-long pulses;
- Pulse mode firing uses coupled thruster pairs for spacecraft precession
Precession refers to a change in the orientation of the rotation axis of a rotating body. It can be defined as a change in direction of the rotation axis in which the second Euler angle is constant...
maneuvers (turns).
Communication
The spacecraft used a high-frequency X bandThe X-band is a segment of the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of X-band is rather indefinitely set at approximately 7.0 to 11.2 gigahertz . In radar engineering, the frequency range is specified...
radioRadio is the transmission of signals by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
wavelengthIn physics, the wavelength of a sinusoidal wave is the spatial period of the wave – the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
to communicate, which allowed for less power and smaller antennas than many older craft, which used S bandThe S band ranges from 2 to 4 GHz, crossing the conventional boundary between UHF and SHF at 3.0 GHz. It is part of the microwave band of the electromagnetic spectrum. The S band is used by weather radar, surface ship radar, and some communications satellites, especially those used by...
.
Navigators sent commands through two antennas on the cruise stage: a cruise low-gain antennaThe low-gain antenna is an antenna with a broad radiowave beam width. This very wide beam allows for a more reliable signal that is best used in mountainous regions, where the signal will propagate reasonably well regardless of terrain. The mountains become the equivalent of rocks in a stream,...
mounted inside the inner ring, and a cruise medium-gain antenna in the outer ring. The low-gain antenna was used close to Earth. It is omni-directional, so the transmission power that reached Earth fell fast with increasing distance. As the craft moved closer to Mars, the Sun and Earth moved closer in the sky as viewed from the craft, so less energy reached Earth. Then, the spacecraft switched to the medium-gain antenna, which directed the same amount of transmission power into a tighter beam toward Earth.
During flight, the spacecraft was spin-stabilizedA gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum. A mechanical gyroscope is essentially a spinning wheel or disk whose axle is free to take any orientation...
with a spin rate of 2 rpm. Periodic updates kept antennas pointed toward Earth and solar panels toward Sun.
Aeroshell
The aeroshell maintained a protective covering for the lander during the seven month voyage to Mars. Together with the lander and the rover, it constituted the "entry vehicle". Its main purpose was to protect the lander and the rover inside it from the intense heating of entry into the thin Martian atmosphere. It was based on the Mars Pathfinder and Mars Viking designs.
Parts
The aeroshell was made of two main parts: a heat shieldA trans-atmospheric heat shield is a protective layer on a spacecraft or ballistic missile that is designed to protect it from the high temperature of atmospheric entry, on a body with an atmosphere, such as Earth, Mars and Venus....
and a backshell. The heat shield was flat and brownish, and protected the lander and rover from the intense heat from entry into the Martian atmosphere and acted as the first aerobrake for the spacecraft. The backshell was large, cone-shaped and painted white. It carried the parachuteA parachute is a device used to slow the motion of an object through an atmosphere by creating drag. Parachutes are made out of cloth, most commonly nylon....
and several components used in later stages of entry, descent, and landing, including:
- A parachute (stowed at the top of the backshell);
- The backshell electronics and batteries that fire off pyrotechnic devices like separation nuts, rockets and the parachute mortar;
- A Litton LN-200 Inertial Measurement Unit (IMU), which monitors and reports the orientation of the backshell as it swings under the parachute;
- Three large solid rocket
A solid rocket or a solid-fuel rocket is a rocket with a motor that uses solid propellants . The earliest rockets were solid-fueled and powered by gunpowder; they were used by the Chinese, Mongols and Arabs in warfare as early as the 13th century...
motors called RAD rockets (Rocket Assisted Descent), each providing about a ton of force (10 kilonewtons) for about 4 seconds;
- Three small solid rockets called TIRS (mounted so that they aim horizontally out the sides of the backshell) that provide a small horizontal kick to the backshell to help orient the backshell more vertically during the main RAD rocket burn.
Composition
Built by the Lockheed Martin Astronautics Co. in Denver, Colorado, the aeroshell is made of an aluminium honeycomb structure sandwiched between graphite-epoxy face sheets. The outside of the aeroshell is covered with a layer of phenolPhenol, also known as carbolic acid, is a toxic, white crystalline solid. Its chemical formula is C6H5OH and its structure is that of a hydroxyl group bonded to a phenyl ring, making it an aromatic compound.-Phenols:...
ic honeycomb. This honeycomb is filled with an ablativeAblation means removal of material from the surface of an object by vaporization, chipping, or other erosive processes. The term occurs in space physics associated with atmospheric reentry, in glaciology, medicine, and passive fire protection.-Space physics:...
material (also called an "ablator"), that dissipates heat generated by atmospheric friction.
The ablator itself is a unique blend of corkCork material is an impermeable, buoyant material, a subset of generic cork tissue that is harvested for commercial use primarily from Quercus suber that is endemic to southwest Europe and northwest Africa...
woodWood is an organic material; in the strict sense wood is produced as secondary xylem in the stems of trees . In a living tree it transfers water and nutrients to the leaves and other growing tissues, and has a support function, enabling woody plants to reach large sizes or to stand up for themselves...
, binderThe reaper-binder, or binder, was a farm implement that improved upon the reaper. The binder was invented in 1872 by Lauren Shmauren. In addition to cutting the small-grain crop, it would also tie the stems into small bundles, or sheaves...
and many tiny silica glass spheres. It was invented for the heat shields flown on the Viking Mars lander missions. A similar technology was used in the first US manned space missions MercuryMercury Program might refer to:*the first successful American manned spaceflight program, Project Mercury*an American post-rock band, The Mercury Program...
, Gemini and Apollo. It was specially formulated to react chemically with the Martian atmosphere during entry and carry heat away, leaving a hot wake of gas behind the vehicle. The vehicle slowed from 19000 km/hThe kilometre per hour is a unit of speed or velocity, expressing the number of kilometers traveled in one hour...
(about 12000 mphThe mile per hour is a unit of speed, measured in Imperial units expressing the number of international miles covered per hour.It is currently the unit used for speed limits, and speeds, on roads in the United Kingdom and United States...
) to about 1600 km/h (1000 mph) in about a minute, producing about 60 m/s² (6 gThe g-force experienced by an object is its acceleration relative to free-fall. The term g-force is considered a misnomer, as g-force is not a force but an acceleration....
) of accelerationIn physics, and more specifically kinematics, acceleration is the change in velocity over time. Because velocity is a vector, it can change in two ways: a change in magnitude and/or a change in direction. In one dimension, i.e. a line, acceleration is the rate at which something speeds up or slows...
on the lander and rover.
The backshell and heat shield are made of the same materials, but the heat shield has a thicker 1/2 inchAn inch is the name of a unit of length in a number of different systems, including Imperial units, and United States customary units. There are 36 inches in a yard and 12 inches in a foot...
(12.7 mm) layer of the ablator. Also, instead of being painted, the backshell was covered with a very thin aluminized PET filmBiaxially-oriented polyethylene terephthalate polyester film is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and aroma barrier properties and electrical insulation....
blanket to protect it from the cold of deep space. The blanket vaporized during Mars atmospheric entry.
Parachute
The parachute helped slow the spacecraft during entry, descent, and landing. It is located in the backshell.
Design
The 2003 parachute design was part of a long-term Mars parachute technology development effort and is based on the designs and experience of the Viking and Pathfinder missions. The parachute for this mission is 40% larger than Pathfinder's because the largest load for the Mars Exploration Rover is 80 to 85 kilonewtons (kN) or 18,000 to when the parachute fully inflates. By comparison, Pathfinder's inflation loads were approximately 35 kN (about 8,000 lbf). The parachute was designed and constructed in South Windsor, ConnecticutSouth Windsor is a town in Hartford County, Connecticut, United States. The population was 24,412 at the 2000 census.-Geography:According to the United States Census Bureau, the town has a total area of 28.7 square miles , of which, 28.0 square miles of it is land and 0.7 square...
by Pioneer Aerospace (website), the company that also designed the parachute for the StardustStardust is an American interplanetary mission of the NASA Jet Propulsion Laboratory, whose primary purpose was to investigate the makeup of the comet Wild 2 and its coma. It was launched on February 7, 1999 by NASA, travelled nearly 3 billion miles , and returned to Earth on January 15, 2006 to...
mission.
Composition
The parachute is made of two durable, lightweight fabrics: polyesterPolyester is a category of polymers which contain the ester functional group in their main chain. Although there are many polyesters, the term "polyester" as a specific material most commonly refers to polyethylene terephthalate...
and nylonNylon is a generic designation for a family of synthetic polymers known generically as polyamides and first produced on February 28, 1935 by Wallace Carothers at DuPont...
. A triple bridle made of KevlarKevlar is the registered trademark for a light, strong para-aramid synthetic fiber, related to other aramids such as Nomex and Technora.Developed at DuPont in 1965 by Stephanie Kwolek it was first commercially used in the early 1970s as a replacement for steel in racing tires...
connects the parachute to the backshell.
The amount of space available on the spacecraft for the parachute is so small that the parachute had to be pressure packed. Before launch, a team tightly folded the 48 suspension lines, three bridle lines, and the parachute. The parachute team loaded the parachute in a special structure that then applied a heavy weight to the parachute package several times. Before placing the parachute into the backshell, the parachute was heat set to sterilizeSterilization refers to any process that effectively kills or eliminates transmissible agents from a surface, equipment, article of food or medication, or biological culture medium. Sterilization does not, however, remove prions...
it.
Connected systems
Zylon Bridles: After the parachute was deployed at an altitude of about 10 km (6 miles) above the surface, the heatshield was released using 6 separation nuts and push-off springs. The lander then separated from the backshell and "rappelled" down a metal tape on a centrifugal braking system built into one of the lander petals. The slow descent down the metal tape placed the lander in position at the end of another bridle (tether), made of a nearly 20 m (65 ft) long braided ZylonZylon is a trademarked name for a range of thermoset polyurethane synthetic polymer materials manufactured by the Toyobo Corporation. Zylon was invented and developed by SRI International in the 1980s. Like Kevlar, Zylon is used in a number of applications that require very high strength with...
.
Zylon is an advanced fiber material similar to Kevlar that is sewn in a webbing pattern (like shoelace material) to make it stronger. The Zylon bridle provides space for airbag deployment, distance from the solid rocket motor exhaust stream, and increased stability. The bridle incorporates an electrical harness that allows the firing of the solid rockets from the backshell as well as provides data from the backshell inertial measurement unit (which measures rate and tilt of the spacecraft) to the flight computer in the rover.
Rocket assisted descent (RAD): motors. Because the atmospheric density of Mars is less than 1% of Earth's, the parachute alone could not slow down the Mars Exploration Rover enough to ensure a safe, low landing speed. The spacecraft descent was assisted by rockets that brought the spacecraft to a dead stop 10–15 m (30–50 ft) above the Martian surface.
Radar altimeter unit: A radarRadar is an object detection system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain. The term RADAR was coined in 1941 as an acronym for RAdio Detection And...
altimeterAn altimeter is an instrument used to measure the altitude of an object above a fixed level. The measurement of altitude is called altimetry, which is related to the term bathymetry, the measurement of depth underwater.-Pressure altimeter:...
unit was used to determine the distance to the Martian surface. The radar's antenna is mounted at one of the lower corners of the lander tetrahedron. When the radar measurement showed the lander was the correct distance above the surface, the Zylon bridle was cut, releasing the lander from the parachute and backshell so that it was free and clear for landing. The radar data also enabled the timing sequence on airbag inflation and backshell RAD rocket firing.
Airbags
AirbagAn airbag is a vehicle safety device. It is an occupant restraint consisting of a flexible envelope designed to inflate rapidly in an automobile collision, to prevent vehicle occupants from striking interior objects such as the steering wheel or window....
s used in the Mars Exploration Rover mission are the same type that Mars PathfinderThe Mars Pathfinder later called The Carl Sagan Memorial Station was launched on December 4, 1996 by NASA aboard a Delta II just a month after the Mars Global Surveyor was launched. After a 7-month voyage it landed on Ares Vallis, in a region called Chryse Planitia on Mars, in the Oxia Palus...
used in 1997. They had to be strong enough to cushion the spacecraft if it landed on rocks or rough terrain and allow it to bounce across Mars' surface at freeway speeds after landing. The airbags had to be inflated seconds before touchdown and deflated once safely on the ground.
The airbags were made of VectranVectran is a manufactured fibre, spun from a liquid crystal polymer created by Celanese Acetate LLC and now manufactured by Kuraray Co., Ltd. Chemically it is an aromatic polyester.- Properties :...
, like those on Pathfinder. Vectran has almost twice the strength of other synthetic materials, such as Kevlar, and performs better in cold temperatures. Six 100 denier (10 mg/m) layers of Vectran protected one or two inner bladders of Vectran in 200 denier (20 mg/m). Using 100 denier (10 mg/m) leaves more fabric in the outer layers where it is needed, because there are more threads in the weave.
Each rover used four airbags with six lobes each, which were all connected. Connection was important, since it helped abate some of the landing forces by keeping the bag system flexible and responsive to ground pressure. The airbags were not attached directly to the rover, but were held to it by ropes crisscrossing the bag structure. The ropes gave the bags shape, making inflation easier. While in flight, the bags were stowed along with three gas generators that are used for inflation.
Lander
The spacecraft lander is a protective "shell" that houses the rover, and together with the airbags, protects it from the forces of impact.
The lander is a tetrahedronIn geometry, a tetrahedron is a polyhedron composed of four triangular faces, three of which meet at each vertex. A regular tetrahedron is one in which the four triangles are regular, or "equilateral", and is one of the Platonic solids...
shape whose sides open like petals. It is strong and light, and made of beams and sheets. The beams consist of layers of graphiteThe mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Greek γραφειν : "to draw/write", for its use in pencils, where it is commonly called lead, as distinguished from the actual metallic element lead...
fiber woven into a fabric that is lighter than aluminium and more rigid than steelSteel is an alloy consisting mostly of iron, with a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most cost-effective alloying material for iron, but various other alloying elements are used such as manganese, chromium, vanadium, and tungsten...
. Titanium fittings are glued and fitted onto the beams to allow it to be bolted together. The rover was held inside the lander by bolt-Fasteners:* A cap screw, as used in a bolted joint* Screw, a cylindrical threaded fastener* Deadbolt, a kind of locking mechanism* Bolt , an anchor point used in rock climbing-Weaponry:* Bolt , a mechanism used in firearms...
s and special nuts that were released after landing with small explosives.
Uprighting
After the lander stopped bouncing and rolling on the ground, it came to rest on the base of the tetrahedron or one of its sides. Then, the sides open to make the base horizontal and the rover upright. The sides are connected to the base by hinges, each of which has a motor strong enough to lift the lander. The rover plus lander has a massIn physics, mass commonly refers to any of three properties of matter, which have been shown experimentally to be equivalent: inertial mass, active gravitational mass and passive gravitational mass...
of about 533 kilograms (1,175 poundThe pound or pound-mass is a unit of mass used in the imperial, United States customary and other systems of measurement...
s). The rover alone weighs about 185 kg (408 lb). The gravity on Mars is about 38% of Earth's, so the motor does not need to be as powerful as it would on Earth.
The rover contains accelerometerAn accelerometer measures the acceleration it experiences relative to freefall.Single- and multi-axis models are available to detect magnitude and direction of the acceleration as a vector quantity, and can be used to sense orientation, vibration and shock...
s to detect which way is down (toward the surface of Mars) by measuring the pull of gravity. The rover computer then commanded the correct lander petal to open to place the rover upright. Once the base petal was down and the rover was upright, the other two petals were opened.
The petals initially opened to an equally flat position, so all sides of the lander were straight and level. The petal motors are strong enough so that if two of the petals come to rest on rocks, the base with the rover would be held in place like a bridge above the ground. The base will hold at a level even with the height of the petals resting on rocks, making a straight flat surface throughout the length of the open, flattened lander. The flight team on Earth could then send commands to the rover to adjust the petals to create a safe path for the rover to drive off the lander and onto the Martian surface without dropping off a steep rock.
Moving the payload onto Mars
The moving of the rover off the lander is called the egress phase of the mission. The rover must avoid having its wheels caught in the airbag material or falling off a sharp incline. To help this, a retraction system on the petals slowly drags the airbags toward the lander before the petals open. Small ramps on the petals fan out to fill spaces between the petals. They cover uneven terrain, rock obstacles, and airbag material, and form a circular area from which the rover can drive off in more directions. They also lower the step that the rover must climb down. They are nicknamed "batwings", and are made of Vectran cloth.
About three hours were allotted to retract the airbags and deploy the lander petals.
Rover design
The rovers are six-wheeled, solar-powered robots which stand 1.5 m (4.9 ft) high, 2.3 m (7.5 ft) wide and 1.6 m (5.2 ft) long. They weigh 180 kg (400 lb), 35 kg (80 lb) of which is the wheel and suspension system.
Drive system
Each rover has six wheels mounted on a rocker-bogieThe Rocker-Bogie system is the suspension arrangement used in the Mars rovers for both the Mars Pathfinder and Mars Exploration Rover missions. It is currently NASA's favored design....
suspension system that ensures wheels remain on the ground while driving over rough terrain. The design reduces the range of motion of the rover body by half, and allows the rover to go over obstacles or through holes that are more than a wheel diameter (250 mm or 10 inches) in size. Each wheel also has cleats, providing grip for climbing in soft sand and scrambling over rocks.
Each wheel has its own motor. The two front and two rear wheels each have individual steering motors. This allows the vehicle to turn in place, a full revolution, and to swerve and curve, making arching turns. The rover is designed to withstand a tilt of 45 degrees in any direction without overturning. However, the rover is programmed through its "fault protection limits" in its hazard avoidance software to avoid exceeding tilts of 30 degrees.
Each rover can spin one of its front wheels in place to grind deep into the terrain. It is to remain motionless while the digging wheel is spinning.
The rover has a top speed on flat hard ground of 50 mm/s (2 in/s). But its average speed is 10 mm/s because its hazard avoidance software causes it to stop every 10 seconds for 20 seconds to observe and understand the terrain it has driven into.
Power and electronic systems
When fully illuminated, the rover triplejunctionMultijunction photovoltaic cells are a sub-class of solar cell or photovoltaic cell developed for higher efficiency. These multijunction cells consist of multiple thin films produced using molecular beam epitaxy and / or metalorganic vapour phase epitaxy...
solar arrays generate about 140 watts for up to four hours per Martian day (sol). The rover needs about 100 watts to drive. Its power system includes two rechargeable lithium ion batteries weighing 7.15 kg (16 pounds) each, that provide energy when the sun is not shining, especially at night. Over time, the batteries will degrade and will not be able to recharge to full capacity.
For comparison, the future Mars Science LaboratoryThe Mars Science Laboratory , known as Curiosity, is a NASA rover scheduled to be launched between October and December 2011 and perform the first-ever precision landing on Mars. The MSL rover will be over five times as heavy and carry over ten times the weight in scientific instruments as one of...
is expected to last approximately one Martian year using radioisotope thermoelectric generatorA radioisotope thermoelectric generator is an electrical generator which obtains its power from radioactive decay. In such a device, the heat released by the decay of a suitable radioactive material is converted into electricity by the Seebeck effect using an array of thermocouples.RTGs can be...
s to power its many instruments. Solar panels are also being considered, but RTGs provide versatility to work in dark environments and high latitudes where solar energy is not an efficient way to generate power.
It was thought that by the end of the 90-sol mission, the capability of the solar arrays to generate power would likely be reduced to about 50 watts. This was due to anticipated dust coverage on the solar arrays, and the change in season. But over three Earth years later, the rovers' power supplies hovered between 300 watt-hourThe kilowatt hour, or kilowatt-hour, is a unit of energy equal to 3,600,000 joules.Energy in watt hours is the multiplication of power in watts and time in hours....
s and 900 watt-hours per day, depending on dust coverage. Cleaning eventA cleaning event is when dust is removed from solar panels.The term started being used in 2004 as the Mars Exploration Rovers' solar panels started to benefit from these events. The rovers were expected to last about 90 sols on Mars, after which dust would cover their solar panels and reduce solar...
s (probably wind) have occurred more often than NASA expected, keeping the arrays relatively free of dust and extending the life of the mission. During a 2007 global dust storm on Mars, both rovers experienced some of the lowest power of the mission; Opportunity dipped to a mere 128 watt-hours. In November 2008 Spirit had overtaken this low-energy record with a production of only 89 watt-hours, due to dust storms in the region of Gusev crater.
The rovers run a VxWorksVxWorks is a real-time operating system made and sold by Wind River Systems of Alameda, California, USA. Intel acquired Wind River Systems on July 17, 2009.VxWorks is designed for use in embedded systems...
embedded operating systemAn embedded operating system is an operating system for embedded computer systems. These operating systems are designed to be very compact and efficient, forsaking many functions that non-embedded computer operating systems provide, and which may not be used by the specialized applications they run...
on a radiation-hardened 20 MHz RAD6000The 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...
CPUThe Central Processing Unit or processor is the portion of a computer system that carries out the instructions of a computer program, and is the primary element carrying out the computer's functions. This term has been in use in the computer industry at least since the early 1960s...
with 128 MBThe megabyte is an SI-multiple of the unit byte for digital information storage or transmission and is equal to 10
6 bytes. However, due to historical usage in computer-related fields it is still often used to represent 2
20 bytes. In rare cases, it is used to mean...
of DRAMDram or DRAM may refer to:As a unit of measure:* Dram , an imperial unit of mass and volume* Armenian dram, a monetary unit* Dirham, a unit of currency in several Arab nationsOther uses:* Dynamic random access memory...
with error detection and correction and 3 MB of EEPROMEEPROM stands for Electrically Erasable Programmable Read-Only Memory and is a type of non-volatile memory used in computers and other electronic devices to store small amounts of data that must be saved when power is removed, e.g., calibration...
. Each rover also has 256 MB of flash memoryFlash memory is a non-volatile computer storage that can be electrically erased and reprogrammed. It is a technology that is primarily used in memory cards and USB flash drives for general storage and transfer of data between computers and other digital products...
. To survive during all of the various mission phases, the rover's vital instruments must stay within a temperature of −40 °C to +40 °C (−40 °F to 104 °F). At night the rovers are heated by eight radioisotope heater units (RHU) which each continuously generate 1 WThe watt is a derived unit of power in the International System of Units . It measures rate of energy conversion. One watt is equivalent to 1 joule of energy per second....
of thermal energy from the decay of radioisotopes, along with electrical heaters that operate only when necessary. A sputtered goldGold is a chemical element with the symbol Au and an atomic number of 79. It has been a highly sought-after precious metal for coinage, jewelry, and other arts since the beginning of recorded history. The metal occurs as nuggets or grains in rocks, in veins and in alluvial deposits. Gold is...
film and a layer of silica aerogelAerogel is a manufactured material with the lowest bulk density of any known porous solid.
It is derived from a gel in which the liquid component of the gel has been replaced with a gas. The result is an extremely low-density solid with several remarkable...
are used for insulation.
Communication
The rover has a low-gainThe low-gain antenna is an antenna with a broad radiowave beam width. This very wide beam allows for a more reliable signal that is best used in mountainous regions, where the signal will propagate reasonably well regardless of terrain. The mountains become the equivalent of rocks in a stream,...
and a high-gain antennaThe high-gain antenna is an antenna with a focused, narrow radiowave beam width. This narrow beam width allows more precise targeting of the radio signal - also known as a directional antenna...
. The low-gain antenna is omnidirectionalAn omnidirectional antenna is an antenna system which radiates power uniformly in one plane with a directive pattern shape in a perpendicular plane...
, and transmits data at a low rate to Deep Space NetworkThe Deep Space Network, or DSN, is an international network of large antennas and communication facilities that supports interplanetary spacecraft missions, and radio and radar astronomy observations for the exploration of the solar system and the universe. The network also supports selected...
(DSN) antennas on Earth. The high-gain antenna is directional and steerable, and can transmit data to Earth at a higher rate.
The rovers also use the low-gain antennas to communicate with spacecraft orbiting Mars, the Mars Odyssey and (before its failure) the Mars Global SurveyorThe Mars Global Surveyor was a US spacecraft developed by NASA's Jet Propulsion Laboratory and launched November 1996. It began the United States's return to Mars after a 10-year absence. It completed its primary mission in January 2001 and was in its third extended mission phase when, on , the...
. The orbiters relay data from and to Earth; most data to Earth is relayed through Odyssey. The benefits of using the orbiters are that they are closer to the rovers than the antennas on Earth, and have view of Earth for much longer than the rovers. The orbiters communicate with the rovers using UHF antennas, which have shorter range than the low and high-gain antennas. One UHF antenna is on the rover and one is on a petal of the lander to aid in gaining information during the critical landing event.
The rovers have a total of 9 cameras, which produce 1024-pixel by 1024-pixel images at 12 bits per pixel,http://216.239.41.104/search?q=cache:qdeH3xRDiEEJ:tmo.jpl.nasa.gov/progress_report/42-155/155J.pdf+&hl=en&ie=UTF-8 but most images are truncated to 8 bits per pixel. They are then compressed using ICERICER is a wavelet-based image compression file format used by the NASA Mars Rovers. ICER has both lossy and lossless compression modes.The Mars Exploration Rovers “Spirit” and “Opportunity” both use ICER...
before being stored and sent to Earth. Navigation, thumbnail, and many other image types are compressed to approximately 1 bit/pixel. Lower bit rates (less than 0.5 bit/pixel) are used for certain wavelengths of multi-color panoramic images.
ICER is based on wavelets, and was designed specifically for deep-space applications. It produces progressive compression, both lossless and lossy, and incorporates an error-containment scheme to limit the effects of data loss on the deep-space channel. It outperforms the lossy JPEG image compressor and the lossless Rice compressor used by the MPF mission (Mars PathfinderThe Mars Pathfinder later called The Carl Sagan Memorial Station was launched on December 4, 1996 by NASA aboard a Delta II just a month after the Mars Global Surveyor was launched. After a 7-month voyage it landed on Ares Vallis, in a region called Chryse Planitia on Mars, in the Oxia Palus...
).
Scientific instrumentation
- Panoramic Camera (Pancam), for determining the texture, color, mineralogy
Mineralogy is an Earth Science focused around the chemistry, crystal structure, and physical properties of minerals. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, as well as their...
, and structure of the local terrain.
- Navigation Camera (Navcam), that has higher field of view but lower resolution and is monochromatic, for navigation and driving.
- A mirror for the Miniature Thermal Emission Spectrometer (Mini-TES
]A Miniature Thermal Emission Spectrometer is an infrared spectrometer used for detecting the composition of a material from a distance...
), which identifies promising rocks and soils for closer examination, and determines the processes that formed them. It was built by Arizona State UniversityArizona State University is the largest public research university in the United States under a single administration, with total student enrollment of 68,064 as of fall 2009...
.
The cameras are mounted 1.5 meters high on the Pancam Mast Assembly. One motor turns the assembly horizontally a whole revolution. Another points the cameras vertically, at most straight up or down. A third motor points the Mini-TES, up to 30° above the horizon and 50° below. The assembly was built by Ball Aerospace & Technologies Corp., Boulder, ColoradoBoulder is a Home Rule Municipality that is the county seat and most populous city of Boulder County, Colorado, in the United States. Boulder is the 11th most populous city in the state of Colorado. The United States Census Bureau estimates that in 2008 the population of the city of Boulder was...
, as was the High-Gain Antenna Gimbal (HGAG).
Four monochromatic hazard cameras (HazcamHazcams are photographic cameras mounted on the front and rear of NASA's Spirit and Opportunity rover missions to Mars....
s) are mounted on the rover's body, two in front and two behind.
The instrument deployment device (IDD), also called the rover arm, holds the following:
- Mössbauer spectrometer (MB) MIMOS II, developed by Dr. Göstar Klingelhöfer at the Johannes Gutenberg
Johannes Gensfleisch zur Laden zum Gutenberg was a German goldsmith and printer who is credited with being the first European to use movable type printing, in around 1439, and the global inventor of the mechanical printing press...
University in MainzMainz is a city in Germany and the capital of the German federal state of Rhineland-Palatinate. It was a politically important seat of the Prince-elector of Mainz under the Holy Roman Empire, and previously was a Roman fort city which commanded the west bank of the Rhine and formed part of the...
, GermanyGermany , officially the Federal Republic of Germany , is a country in Central Europe. It is bordered to the north by the North Sea, Denmark, and the Baltic Sea; to the east by Poland and the Czech Republic; to the south by Austria and Switzerland; and to the west by France, Luxembourg, Belgium,...
, is used for close-up investigations of the mineralogy of iron-bearing rocks and soils.
- Alpha Particle
Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus; hence, it can be written as or . They have a net spin of zero, and normally a total energy of about 5 MeV...
X-RayX-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays...
Spectrometer (APXSAn Alpha Particle X-Ray Spectrometer is a device that analyses the chemical element composition of a sample from the scattered alpha particles, emitted protons , and fluorescent X-rays after the sample is irradidated with alpha particles and X-rays from radioactive sources...
), developed by the Max Planck Institute for ChemistryThe Max Planck Institute for Chemistry is a scientific research institute under the Max-Planck-Gesellschaft.Basic research in chemistry and related subjects is carried out at the four departments of the institute. The departments are independently led by their Directors.-The departments:The...
in MainzMainz is a city in Germany and the capital of the German federal state of Rhineland-Palatinate. It was a politically important seat of the Prince-elector of Mainz under the Holy Roman Empire, and previously was a Roman fort city which commanded the west bank of the Rhine and formed part of the...
, GermanyGermany , officially the Federal Republic of Germany , is a country in Central Europe. It is bordered to the north by the North Sea, Denmark, and the Baltic Sea; to the east by Poland and the Czech Republic; to the south by Austria and Switzerland; and to the west by France, Luxembourg, Belgium,...
, is used for close-up analysis of the abundances of elements that make up rocks and soils.
- Magnets, for collecting magnetic dust particles, developed by Jens Martin Knudsen
Jens Martin Knudsen was an internationally renowned Danish astrophysicist, particularly well known in his home country....
's group at the Niels Bohr Institute, CopenhagenCopenhagen ; ) is the capital and largest city of Denmark, with an urban area with a population of 1,167,569 and a metropolitan area with a population of 1,875,179...
. The particles are analyzed by the Mössbauer Spectrometer and X-rayX-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays...
Spectrometer to help determine the ratio of magnetic particles to non-magnetic particles and the composition of magnetic minerals in airborne dust and rocks that have been ground by the Rock Abrasion Tool. There are also magnets on the front of the rover, which are studied extensively by the Mössbauer spectrometer.
- Microscopic Imager (MI) for obtaining close-up, high-resolution images of rocks and soils. Development was led by Ken Herkenhoff's team at the USGS Astrogeology Research Program
The USGS Astrogeology Research Program has a rich history of participation in space exploration efforts and planetary mapping, starting in 1963 when the Flagstaff Science Center was established by Gene Shoemaker to provide lunar geologic mapping and assist in training astronauts destined for the...
.
- Rock Abrasion Tool (RAT), developed by Honeybee Robotics
Honeybee Robotics is a small robotics company located in Manhattan, New York. It was established in 1983 by Stephen Gorevan and Chris Chadman. Honeybee has particular expertise in developing and operating small mechanical tools used on Mars missions...
, for removing dusty and weathered rock surfaces and exposing fresh material for examination by instruments on-board.
The robotic arm is able to place instruments directly up against rock and soil targets of interest.
Naming of Spirit and Opportunity
The Spirit
and Opportunity rovers were named through a student essay competition. The winning entry was by Sofi Collis, a third-grade Russian-American student from Arizona.
I used to live in an orphanage. It was dark and cold and lonely. At night, I looked up at the sparkly sky and felt better. I dreamed I could fly there. In America, I can make all my dreams come true. Thank you for the 'Spirit' and the 'Opportunity.'
— Sofi Collis, age 9
Prior to this, during the development and building of the rovers, they were known as MER-1 (Opportunity
) and MER-2 (Spirit
). Internally NASA also uses the mission designations MER-A (Spirit
) and MER-B (Opportunity
) based on the order of landing on Mars (Spirit first then Opportunity).
SAP
The NASA team uses a software application called SAP to view images collected from the rover, and to plan its daily activities. There is a version available to the public called
MaestroMaestro is a publicly-available version of the software used by the NASA Mars Exploration Rover team to view images collected from the rovers and plan the team's daily activities...
.
Related
- Mars Exploration Rover (MER) Spirit rover
Spirit, mission designation MER-A , is the first of the two rovers of NASA's Mars Exploration Rover Mission. It landed successfully on Mars on 04:35 Ground UTC on January 4, 2004, three weeks before its twin Opportunity landed on the other side of the planet...
(MER-A) Opportunity roverOpportunity, mission designation MER-B , is the second of the two rovers of NASA's Mars Exploration Rover Mission. It landed successfully at Meridiani Planum on Mars on January 25, 2004 05:05 Ground UTC , three weeks after its twin Spirit had landed on the other side of the planet...
(MER-B) Scientific information from the Mars Exploration Rover missionNASA's 2003 Mars Exploration Rover Mission has amassed an enormous amount of scientific information related to the Martian geology and atmosphere, as well as providing some astronomical observations from Mars. This article covers information gathered by the Opportunity rover during the initial...
Cleaning eventA cleaning event is when dust is removed from solar panels.The term started being used in 2004 as the Mars Exploration Rovers' solar panels started to benefit from these events. The rovers were expected to last about 90 sols on Mars, after which dust would cover their solar panels and reduce solar...
- List of surface features of Mars seen by the Spirit rover List of surface features of Mars seen by the Opportunity rover
- Instruments
- APXS MIMOS II Mini-TES
]A Miniature Thermal Emission Spectrometer is an infrared spectrometer used for detecting the composition of a material from a distance...
Rock Abrasion ToolThe Rock Abrasion Tool is a grinding and brushing installation on NASA’s twin Mars Exploration Rovers, Spirit and Opportunity , which landed on Mars in January 2004...
(RAT) HazcamHazcams are photographic cameras mounted on the front and rear of NASA's Spirit and Opportunity rover missions to Mars....
Pancam Navcam
- Communication
- Low gain antenna High gain antenna 2001 Mars Odyssey
2001 Mars Odyssey is a robotic spacecraft orbiting the planet Mars. Its mission is to use spectrometers and imagers to hunt for evidence of past or present water and volcanic activity on Mars. It is hoped that the data Odyssey obtains will help answer the question of whether life has ever existed...
Mars Reconnaissance OrbiterNASA's Mars Reconnaissance Orbiter is a multipurpose spacecraft designed to conduct reconnaissance and exploration of Mars from orbit....
Deep Space NetworkThe Deep Space Network, or DSN, is an international network of large antennas and communication facilities that supports interplanetary spacecraft missions, and radio and radar astronomy observations for the exploration of the solar system and the universe. The network also supports selected...
Goldstone DSCCThe Goldstone Deep Space Communications Complex — commonly called the Goldstone Observatory — is located in California's Mojave Desert . Operated by ITT Corporation for the Jet Propulsion Laboratory, its main purpose is to track and communicate with space missions. It includes the...
X-Band
- Other Systems
- Delta II Heavy
Delta II is a space launch system originally designed and built by McDonnell Douglas. Delta II is part of the Delta rocket family and has been in service since 1989...
MaestroMaestro is a publicly-available version of the software used by the NASA Mars Exploration Rover team to view images collected from the rovers and plan the team's daily activities...
VxWorksVxWorks is a real-time operating system made and sold by Wind River Systems of Alameda, California, USA. Intel acquired Wind River Systems on July 17, 2009.VxWorks is designed for use in embedded systems...
RAD6000The 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...
Radioisotope heater unitRadioisotope heater units are small devices that provide heat through radioactive decay. They are similar to tiny radioisotope thermoelectric generators , and normally provide about one watt of heat each, derived from the decay of a few grams of plutonium 238, although other radioactive isotopes...
Rocker-bogieThe Rocker-Bogie system is the suspension arrangement used in the Mars rovers for both the Mars Pathfinder and Mars Exploration Rover missions. It is currently NASA's favored design....
Multijunction photovoltaic cellMultijunction photovoltaic cells are a sub-class of solar cell or photovoltaic cell developed for higher efficiency. These multijunction cells consist of multiple thin films produced using molecular beam epitaxy and / or metalorganic vapour phase epitaxy...
Lithium ion batteryLithium-ion batteries are a type of rechargeable battery in which lithium ions move from the negative electrode to the positive electrode during discharge, and from the cathode to the anode during charge.Lithium-ion batteries are common in portable consumer electronics because of their high...
- Supporting Institutions
- NASA
The National Aeronautics and Space Administration is an agency of the United States government, responsible for the nation's public space program. NASA was established by the National Aeronautics and Space Act on July 29, 1958, replacing its predecessor, the National Advisory Committee for...
JPLJet 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 situated in the northern portion of Pasadena...
Boeing IDSBoeing Integrated Defense Systems is a unit of The Boeing Company responsible for defense and aerospace products and services. Integrated Defense Systems was formed in 2002 by combining the former "Military Aircraft and Missile Systems" and "Space and Communications" divisions...
Cornell UniversityCornell University is a private university located in Ithaca, New York, USA, that is a member of the Ivy League.Cornell counts more than 255,000 living alumni, 28 Rhodes Scholars and 41 Nobel laureates affiliated with the university as faculty or students...
Deep Space NetworkThe Deep Space Network, or DSN, is an international network of large antennas and communication facilities that supports interplanetary spacecraft missions, and radio and radar astronomy observations for the exploration of the solar system and the universe. The network also supports selected...
Arizona State UniversityArizona State University is the largest public research university in the United States under a single administration, with total student enrollment of 68,064 as of fall 2009...
Ball Aerospace Johannes Gutenberg University Max Planck Institute for ChemistryThe Max Planck Institute for Chemistry is a scientific research institute under the Max-Planck-Gesellschaft.Basic research in chemistry and related subjects is carried out at the four departments of the institute. The departments are independently led by their Directors.-The departments:The...
Niels Bohr InstituteThe Niels Bohr Institute is a research institute at the University of Copenhagen. The research of the institute spans astronomy, geophysics, nanotechnology, particle physics, quantum mechanics and biophysics....
USGS Astrogeology Research ProgramThe USGS Astrogeology Research Program has a rich history of participation in space exploration efforts and planetary mapping, starting in 1963 when the Flagstaff Science Center was established by Gene Shoemaker to provide lunar geologic mapping and assist in training astronauts destined for the...
Honeybee RoboticsHoneybee Robotics is a small robotics company located in Manhattan, New York. It was established in 1983 by Stephen Gorevan and Chris Chadman. Honeybee has particular expertise in developing and operating small mechanical tools used on Mars missions...
- 37452 Spirit
Asteroid 37452 Spirit was discovered on September 24, 1960 by Ingrid van Houten-Groeneveld, Cornelis Johannes van Houten, and Tom Gehrels. The asteroid was spotted by examining photographic plates of images taken by telescopes at the Palomar Observatory. 37452 Spirit is part of a small group of...
& 39382 OpportunityAsteroid 39382 Opportunity was discovered on September 24, 1960, by Ingrid van Houten-Groeneveld, Cornelis Johannes van Houten and Tom Gehrels. The asteroid was spotted by examining photographic plates taken by telescopes at the Palomar Observatory....
See also
- Opportunity rover
Opportunity, mission designation MER-B , is the second of the two rovers of NASA's Mars Exploration Rover Mission. It landed successfully at Meridiani Planum on Mars on January 25, 2004 05:05 Ground UTC , three weeks after its twin Spirit had landed on the other side of the planet...
(MER-B)
- Spirit rover
Spirit, mission designation MER-A , is the first of the two rovers of NASA's Mars Exploration Rover Mission. It landed successfully on Mars on 04:35 Ground UTC on January 4, 2004, three weeks before its twin Opportunity landed on the other side of the planet...
(MER-A)
- 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...
- Space exploration
Space exploration is the use of astronomy and space technology to explore outer space. Physical exploration of space is conducted both by human spaceflights and by robotic spacecraft....
- Atmospheric reentry
Atmospheric reentry refers to the movement of human-made or natural objects as they enter the atmosphere of a planet from outer space, in the case of Earth from an altitude above the "edge of space." This article primarily addresses the process of controlled reentry of vehicles which are intended...
- Syd Lieberman, official storyteller of the Mars Exploration Mission
Syd Lieberman is a noted American storyteller who has been telling stories professionally since 1982.He is a frequent performer at the National Storytelling Festival in Jonesborough, Tennessee...
- Lunokhod programme
Lunokhod 1 and 2 were a pair of Soviet robotic lunar rovers landed on the Moon in 1970 and 1973, respectively. They were in operation concurrently with the Zond series of flyby missions. The Lunokhod missions were primarily designed to explore the surface and return pictures...
(Lunar rovers)
- Mars Science Laboratory
The Mars Science Laboratory , known as Curiosity, is a NASA rover scheduled to be launched between October and December 2011 and perform the first-ever precision landing on Mars. The MSL rover will be over five times as heavy and carry over ten times the weight in scientific instruments as one of...
(next planned NASA Mars Rover)
Further reading
- Roving Mars: Spirit, Opportunity, and the Exploration of the Red Planet by Steve Squyres
Steven W. Squyres is the Goldwin Smith Professor of Astronomy at Cornell University in Ithaca, New York. His research area is in planetary sciences, with a focus on large solid bodies in the solar system such as the terrestrial planets and the moons of the Jovian planets. Squyres is principal...
(published August 2005; ISBN 1-4013-0149-5)
- Postcards from Mars: The First Photographer on the Red Planet by Jim Bell
James Dalton Bell is an American crypto-anarchist who created the idea of arranging for anonymously-sponsored assassination payments via the Internet, which he called "assassination politics". Bell was targeted and identified by the Federal government of the United States as a "techno-terrorist". ...
(published November 2006; ISBN 0-5259-4985-2)
- Technical papers by JPL Robotics Engineers
- Interview: The driver behind NASA's Mars Rovers from Australian PC World
NASA
Instrumentation
Other