Mariner Mark II
Encyclopedia
Mariner Mark II was NASA
's planned family of unmanned spacecraft
for the exploration of the outer solar system that were to be developed and operated by JPL between 1990 through the year 2010.
After the “flagship” multibillion-dollar missions of the 1970s, in the 1980s NASA was looking for a new, more affordable direction for the 1990s and beyond. Two projects were conceived by NASA's Solar System Exploration Committee in 1983, the Planetary Observer program
, and Mariner Mark II.
The Observer program, starting with the Mars Observer
, was envisioned as a series of low-cost missions to the inner solar system, based on commercial Earth satellites, while the Mariner Mark II was to be a series of large spacecraft for the exploration of the outer solar system.
Mariner Mark II spacecraft were to utilize common design, hardware and software solutions, much of it derived from previous missions such as Voyager
and Galileo as well as select new technologies, such as advanced gyroscopes, all with the aim of cutting costs. It was hoped that this new approach would reduce the mission costs to about $400 million each, about half the price of Galileo.
The first two missions of the project were to be a mission to Saturn and its moon Titan, the Saturn Orbiter/Titan Probe, or SOTP (later Cassini
) and the Comet Rendezvous Asteroid Flyby
(CRAF), both of which were approved by Congress in 1990.
Other planned Mariner Mark II based spacecraft were an ESA led follow-on to CRAF, the Comet Nucleus Sample Return or CNSR (later Rosetta), Pluto Flyby, a flyby of Pluto
and a Neptune
orbiter with an atmospheric probe (Neptune Orbiter
).
However, Congressionally imposed reductions to FY 1992-93 funding requirements forced NASA to terminate the CRAF mission and to delay the Cassini launch from April 1996 to October 1997. In order to save it, NASA was forced to significantly redesign Cassini to reduce the total program cost, mass and power requirements, while maintaining the October 1997 launch aboard a Titan IV
launch vehicle.
NASA would replace the Mariner Mark II program with the lower cost Discovery Program
.
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 planned family of unmanned 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....
for the exploration of the outer solar system that were to be developed and operated by JPL between 1990 through the year 2010.
After the “flagship” multibillion-dollar missions of the 1970s, in the 1980s NASA was looking for a new, more affordable direction for the 1990s and beyond. Two projects were conceived by NASA's Solar System Exploration Committee in 1983, the Planetary Observer program
Planetary Observer program
The Planetary Observer program is a cancelled space exploration program designed by NASA to provide cheaper planetary orbiters by utilising Earth-orbiting satellite components and technology, using solar panels for power, and a common spacecraft bus platform for all Planetary Observer-class probes...
, and Mariner Mark II.
The Observer program, starting with the Mars Observer
Mars Observer
The Mars Observer spacecraft, also known as the Mars Geoscience/Climatology Orbiter, was a 1,018-kilogram robotic space probe launched by NASA on September 25, 1992 to study the Martian surface, atmosphere, climate and magnetic field...
, was envisioned as a series of low-cost missions to the inner solar system, based on commercial Earth satellites, while the Mariner Mark II was to be a series of large spacecraft for the exploration of the outer solar system.
Mariner Mark II spacecraft were to utilize common design, hardware and software solutions, much of it derived from previous missions such as Voyager
Voyager program
The Voyager program is a U.S program that launched two unmanned space missions, scientific probes Voyager 1 and Voyager 2. They were launched in 1977 to take advantage of a favorable planetary alignment of the late 1970s...
and Galileo as well as select new technologies, such as advanced gyroscopes, all with the aim of cutting costs. It was hoped that this new approach would reduce the mission costs to about $400 million each, about half the price of Galileo.
The first two missions of the project were to be a mission to Saturn and its moon Titan, the Saturn Orbiter/Titan Probe, or SOTP (later Cassini
Cassini-Huygens
Cassini–Huygens is a joint NASA/ESA/ASI spacecraft mission studying the planet Saturn and its many natural satellites since 2004. Launched in 1997 after nearly two decades of gestation, it includes a Saturn orbiter and an atmospheric probe/lander for the moon Titan, although it has also returned...
) and the Comet Rendezvous Asteroid Flyby
Comet Rendezvous Asteroid Flyby
The Comet Rendezvous Asteroid Flyby was a cancelled plan for a NASA led exploratory mission designed by the Jet Propulsion Laboratory during the mid-to-late 1980s and early 1990s, that planned to send a spacecraft to encounter an asteroid, and then to rendezvous with a comet and fly alongside it...
(CRAF), both of which were approved by Congress in 1990.
Other planned Mariner Mark II based spacecraft were an ESA led follow-on to CRAF, the Comet Nucleus Sample Return or CNSR (later Rosetta), Pluto Flyby, a flyby of Pluto
Pluto
Pluto, formal designation 134340 Pluto, is the second-most-massive known dwarf planet in the Solar System and the tenth-most-massive body observed directly orbiting the Sun...
and a Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...
orbiter with an atmospheric probe (Neptune Orbiter
Neptune Orbiter
Neptune Orbiter was a proposed NASA unmanned planetary spacecraft to explore the planet Neptune. It was envisioned that it would be launched sometime around 2016 and take 8 to 12 years to reach the planet; however, no longer lists any possible launch date. The Neptune Orbiter was designed to...
).
However, Congressionally imposed reductions to FY 1992-93 funding requirements forced NASA to terminate the CRAF mission and to delay the Cassini launch from April 1996 to October 1997. In order to save it, NASA was forced to significantly redesign Cassini to reduce the total program cost, mass and power requirements, while maintaining the October 1997 launch aboard a Titan IV
Titan IV
The Titan IV family of space boosters were used by the U.S. Air Force. They were launched from Cape Canaveral Air Force Station, Florida, and Vandenberg Air Force Base, California. At the time of its introduction, the Titan IV was the "largest unmanned space booster used by the Air Force."The...
launch vehicle.
NASA would replace the Mariner Mark II program with the lower cost Discovery Program
Discovery Program
NASA's Discovery Program is a series of lower-cost, highly-focused American scientific space missions that are exploring the Solar System. It was founded in 1992 to implement then-NASA Administrator Daniel S. Goldin's vision of "faster, better, cheaper" planetary missions...
.
External links
- "Assessment of CRAF and Cassini missions" by Dr. Robert O. Pepin, chair of the Committee on Planetary and Lunar Exploration of the National Academy of SciencesUnited States National Academy of SciencesThe National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...
, 1988 - "On the CRAF/Cassini Mission" by DDr. Louis J. Lanzerotti, chair of the Space Studies Board, of the National Academy of SciencesUnited States National Academy of SciencesThe National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...
, 1992 - "Exploring the Trans-Neptunian Solar System" National Academy of Sciences