Mars Observer
JPL | ||
COSPAR ID | 1992-063A | |
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SATCAT no. | 22136![]() | |
Website | archived | |
Mission duration | 330 days Mission failure | |
Spacecraft properties | ||
Bus | Mars Observer bus (AS-4000-TIROS/DMSP hybrid) | |
Manufacturer | General Electric Astro Space | |
Launch mass | 1,018 kilograms (2,244 lb) | |
Power | 1,147 watts | |
Start of mission | ||
Launch date | September 25, 1992, 17:05:01 | UTC|
Rocket | LC-40 | |
Contractor | Martin Marietta | |
End of mission | ||
Last contact | August 21, 1993, 01:00 | UTC|
Orbital parameters | ||
Reference system | Semi-major axis 3,766.159 kilometers (2,340.183 mi) | |
Eccentricity | 0.004049 | |
Inclination | 92.869 degrees | |
Epoch | Planned December 6, 1993 | |
Flyby of Mars (failed insertion) | ||
Closest approach | August 24, 1993 | |
The Mars Observer spacecraft, also known as the Mars Geoscience/Climatology Orbiter, was a
Mission background
History
In 1984, a high priority mission to Mars was set forth by the Solar System Exploration Committee. Then titled the Mars Geoscience/Climatology Orbiter, the Martian
Mars Observer was originally planned to be launched in 1990 by a
- Determine the global elemental and mineralogical character of the surface material.
- Define globally the topography and gravitational field.
- Establish the nature of the Martian magnetic field.
- Determine the temporal and spatial distribution, abundance, sources, and sinks of volatiles and dust over a seasonal cycle.
- Explore the structure and circulation of the atmosphere.
The program's total cost is estimated at $813 million.[7]
Spacecraft design
The Mars Observer spacecraft had a mass of 1,018 kilograms (2,244 lb). Its bus measured 1.1 meters tall, 2.2 meters wide, and 1.6 meters deep. The spacecraft was based on previous satellite designs, originally intended and developed to orbit Earth. The RCA AS-4000 Ku-band satellite design was used extensively for the spacecraft bus, propulsion, thermal protection, and solar array. RCA TIROS and DMSP Block 50-2 satellite designs were also utilized in the implementing the Attitude and Articulation Control System (AACS), command and data handling subsystem, and power subsystem, into Mars Observer. Other elements such as the bipropellant components and high-gain antenna were designed specifically for the mission.[8][7][9]
Attitude control and propulsion
- The spacecraft was three-axis stabilized with four reaction wheels and twenty-four thrusters with 1,346 kilograms of propellant. The propulsion system was a high thrust, monomethyl hydrazine/nitrogen tetroxide bipropellant system for larger maneuvers and a lower thrust hydrazine monopropellant system for minor orbital corrections during the mission. Of the bipropellant thrusters, four located on the aft, provide 490 newtons of thrust for course corrections, control of the spacecraft during the Mars orbital insertion maneuver and large orbit corrections during the mission; another four, located on along the sides of the spacecraft, provide 22 newtons for controlling roll maneuvers. Of the hydrazine thrusters, eight provide 4.5 newtons to control orbit trim maneuvers; another eight provide 0.9 newtons for offsetting, or "desaturating", the reaction wheels. To determine the orientation of the spacecraft, a horizon sensor, a 6-slit star scanner, and five Sun sensors were included.[8][9]
Communications
![](http://upload.wikimedia.org/wikipedia/commons/thumb/9/92/Mars_Observer_-_HGA_diagram.png/100px-Mars_Observer_-_HGA_diagram.png)
- For telecommunications, the spacecraft included a two-axis X-band using two GFP NASA X-band transponders (NXTs) and two GFP command detector units (CDUs). An assembly of six low-gain antennas, and a single medium-gain antenna were also included, to be used during the cruise phase while the high-gain antenna remained stowed, and for contingency measures should communications through the high-gain antenna become restricted. When broadcasting to the Deep Space Network, a maximum of 10.66 kilobytes/second could be achieved while the spacecraft could receive commands at a maximum bandwidth of 62.5 bytes per second.[5][8][7][9]
Power
- Power was supplied to the spacecraft through a six panel
Computer
- The computing system on the spacecraft was a retooling of the system used on the TIROS and DMSP satellites. The semiautonomous system was able to store up to 2,000 commands in the included 64 kilobytes of random-access memory, and execute them at a maximum rate of 12.5 commands/second; commands could also provide sufficient autonomous operation of the spacecraft for up to sixty days. To record data, redundant digital tape recorders (DTR) were included and each capable of storing up to 187.5 megabytes, for later playback to the Deep Space Network.[8]
Scientific instruments
Mars Observer Camera (MOC) | ||||
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Consists of narrow-angle and wide-angle telescopic cameras to study the meteorology/climatology and geoscience of Mars.[10]
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Mars Observer Laser Altimeter (MOLA) | ||||
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A
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Thermal Emission Spectrometer (TES) | ||||
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Uses three sensors (Michelson interferometer, solar reflectance sensor, broadband radiance sensor) to measure thermal infrared emissions to map the mineral content of surface rocks, frosts and the composition of clouds.[12]
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Pressure Modulator Infrared Radiometer (PMIRR) | ||||
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Uses narrow-band radiometric channels and two pressure modulation cells to measure atmospheric and surface emissions in the thermal infrared and a visible channel to measure dust particles and condensates in the atmosphere and on the surface at varying longitudes and seasons.[13]
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Gamma Ray Spectrometer (GRS) | ||||
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Records the spectrum of gamma rays and neutrons emitted by the radioactive decay of elements contained in the Martian surface.[14]
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Magnetometer and Electron Reflectometer (MAG/ER) | ||||
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Uses the components of the on-board telecommunications system and the stations of the Deep Space Network to collect data on the nature of the magnetic field and interactions the field may have with solar wind.[15]
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Radio Science experiment (RS) | ||||
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Collects data on the Martian atmospheric structure with a special emphasis on temporal changes near the polar regions.[16]
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Mars Balloon Relay (MBR) | ||||
Planned as augmentation to return data from the penetrators and surface stations of the Russian Mars '94 mission and from penetrators, surface stations, a rover, and a balloon from the Mars '96 mission.[17]
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Mission profile
Timeline of operations | ||||||||||||||||||||||||||||||||||||
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Items in red were unrealized events.
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Launch and trajectory
Mars Observer was launched on September 25, 1992, at 17:05:01 UTC by the
On August 25, 1992, particulate contamination was found within the spacecraft. After a full inspection, a cleaning was determined necessary and was performed on August 29. The suspected cause of the contamination were measures taken to protect the spacecraft prior to the landfall of Hurricane Andrew which struck the coast of Florida on August 24.[9][18][19]
Encounter with Mars
Mars Observer was scheduled to perform an
Intended operations
On August 24, 1993, Mars Observer would turn 180-degrees and ignite the bipropellant thrusters to slow the spacecraft, entering into a highly elliptical orbit. Over the next three months, subsequent "transfer to lower orbit" (TLO) maneuvers would be performed as the spacecraft reached
The primary mission was to begin on November 23, 1993, collecting data during one
Orbiting Mars at an approximate speed of 3.4 km/s, the spacecraft would travel around Mars in a north to south, polar orbit. As the spacecraft circles the planet, horizon sensors indicate the orientation of the spacecraft while the reaction wheels would maintain the orientation of the instruments, towards Mars. The chosen orbit was also Sun-synchronous, allowing the daylit side of Mars to always be captured during the mid-afternoon of each Martian Sol. While some instruments could provide a real-time data link when Earth was in view of the spacecraft, data would also be recorded to the digital tape recorders and played back to Earth each day. Over 75 gigabytes of scientific data was expected to be yielded during the primary mission, much more than any previous mission to Mars. The end of the operable life for the spacecraft was expected to be limited by the supply of propellant and the condition of the batteries.[21]
Communications loss
On August 21, 1993, at 01:00 UTC, three days prior to the scheduled
On January 4, 1994, an independent investigation board from the
Quoted from the report[23] |
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Because the telemetry transmitted from the Observer had been commanded off and subsequent efforts to locate or communicate with the spacecraft failed, the board was unable to find conclusive evidence pointing to a particular event that caused the loss of the Observer.
However, after conducting extensive analyses, the board reported that the most probable cause of the loss of communications with the spacecraft on August 21, 1993, was a rupture of the fuel (monomethyl hydrazine (MMH)) pressurization side of the spacecraft's propulsion system, resulting in a pressurized leak of both helium gas and liquid MMH under the spacecraft's thermal blanket. The gas and liquid would most likely have leaked out from under the blanket in an unsymmetrical manner, resulting in a net spin rate. This high spin rate would cause the spacecraft to enter into the "contingency mode," which interrupted the stored command sequence and thus, did not turn the transmitter on. Additionally, this high spin rate precluded proper orientation of the solar arrays, resulting in discharge of the batteries. However, the spin effect may be academic, because the released MMH would likely attack and damage critical electrical circuits within the spacecraft. The board's study concluded that the propulsion system failure most probably was caused by the inadvertent mixing and the reaction of nitrogen tetroxide (NTO) and MMH within titanium pressurization tubing, during the helium pressurization of the fuel tanks. This reaction caused the tubing to rupture, resulting in helium and MMH being released from the tubing, thus forcing the spacecraft into a catastrophic spin and also damaging critical electrical circuits. |
Aftermath
The Mars Exploration Program was formed officially in the wake of the Mars Observer's failure in September 1993.[24] The goals of that program include identifying the location of water, and preparing for crewed missions to Mars.[24]
See also
- Exploration of Mars
- List of missions to Mars
- Planetary Observer program
- Space exploration
- Unmanned space missions
References
- ^ JSTOR 3970693.
- PMID 17795582.
- ^ hdl:2014/27541.
- JSTOR 3973010.
- ^ a b c d Mark Wade. "Mars Observer". Encyclopedia Astronautica. Retrieved December 23, 2010.
- ^ Bibcode:1988msrs.work...25A.
- ^ a b c d e "Mars Observer". nssdc.gsfc.nasa.gov. NASA. Retrieved December 23, 2010.
- ^ hdl:2060/19870011586.
- ^ a b c d e f "MARS OBSERVER PRESS KIT" (Press release). NASA. September 1992. Archived from the original on February 16, 2004. Retrieved March 21, 2011.
{{cite press release}}
: CS1 maint: unfit URL (link) - ^ "Mars Observer Camera (MOC)". nssdc.gsfc.nasa.gov. NASA. Retrieved February 19, 2011.
- ^ "Mars Observer Laser Altimeter (MOLA)". nssdc.gsfc.nasa.gov. NASA. Retrieved February 19, 2011.
- ^ "Thermal Emission Spectrometer (TES)". nssdc.gsfc.nasa.gov. NASA. Retrieved February 19, 2011.
- ^ "Pressure Modulator Infrared Radiometer (PMIRR)". nssdc.gsfc.nasa.gov. NASA. Retrieved February 19, 2011.
- ^ "Gamma Ray Spectrometer (GRS)". nssdc.gsfc.nasa.gov. NASA. Retrieved February 19, 2011.
- ^ "Magnetometer and Electron Reflectometer (MAG/ER)". nssdc.gsfc.nasa.gov. NASA. Retrieved February 19, 2011.
- ^ "Radio Science (RS)". nssdc.gsfc.nasa.gov. NASA. Retrieved February 19, 2011.
- ^ "Mars Balloon Relay (MBR)". nssdc.gsfc.nasa.gov. NASA. Retrieved February 19, 2011.
- ^ John Noble Wilford (August 28, 1992). "Mishap Delays Mission to Mars". The New York Times. Retrieved June 21, 2008.
- ^ John Noble Wilford (September 26, 1992). "U.S. Launches A Spacecraft On a Mars Trip". The New York Times. Retrieved June 21, 2008.
- ^ Troy Brownfield (August 21, 2018). "When a 5,000-Pound Spacecraft Inexplicably Disappeared". Saturday Evening Post. Retrieved March 3, 2021.
- ^ a b c "Mars Observer: Mars Orbit Insertion Press Kit" (Press release). NASA. August 1993. Archived from the original on February 16, 2004. Retrieved March 21, 2011.
{{cite press release}}
: CS1 maint: unfit URL (link) - ^ a b John Noble Wilford (August 23, 1993). "NASA Loses Communication With Mars Observer". The New York Times. Retrieved June 17, 2008.
- ^ a b c "NASA Mars Observer Failure Board Press Release" (Text) (Press release). January 4, 1994.
- ^ a b Donna Shirley. "Mars Exploration Program Strategy: 1995–2020" (PDF). American Institute of Aeronautics and Astronautics. Archived from the original (PDF) on May 11, 2013. Retrieved October 18, 2012.
External links
- Mars Observer launch press kit Archived March 4, 2016, at the Wayback Machine
- Mars Observer Mission Profile by NASA's Solar System Exploration
- Mars Observer at NSSDC Master Catalog
- The Loss of Mars Observer at Malin Space Science Systems. Archived March 27, 2010, at the Wayback Machine
- NASA – Mars Observer