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Mars Observer, launched by NASA in September 25, 1992, was the first of the proposed Observer series of planetary missions, and was designed to study the geoscience and climate of Mars. Contact with the spacecraft was lost three days before scheduled orbit insertion and was never re-established.

Design and Objectives

The primary science objectives for the mission were to:

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 bus and electronics of the Observer series of spacecraft, used to study the terrestrial planets and near-Earth asteroids, were derived from the Satcom-K and DMSP/TIROS spacecraft. The rectangular bus section was 2.1 x 1.5 x 1.1 m. During the cruise phase of the mission, the high-gain antenna and the booms for the magnetometer (MAG/ER) and gamma-ray spectrometer (GRS) were partially deployed. When fully deployed, the two booms were each 6 m long. The 1.5 m diameter high-gain antenna was, when fully deployed, on a 5.5 m boom to allow for clearance over the solar array when the antenna was pointed toward Earth.

Pointing control for the spacecraft was maintained through the use of four reaction wheels. Attitude information was provided by a horizon sensor (which defined the direction of the nadir when the spacecraft is in Martian orbit), a 6-slit star scanner (for inertial attitude), gyros and accelerometers (for measuring angular rates and linear accelerations), and five sun sensor heads tied into a single sun sensor electronics box.

Power was provided through a six-panel solar array which, when fully deployed, measured 7.0 x 3.7 m. During the cruise phase, however, only four panels were deployed (due to the proximity of the spacecraft to the sun) to reduce the amount of power generated. During periods when the spacecraft was in Mars' shadow, energy was to be provided by two Ni-Cd batteries, each with a capacity of 43 ampere-hours.

The interplanetary cruise phase of the mission was intended primarily for spacecraft and instrument checkout and calibration. Two periods of data collection for the MAG/ER and GRS and one for the gravity wave experiment were planned for this phase as well. During the four month period from Mars orbital insertion until the spacecraft was to achieve its final mapping orbit, only data collection for the MAG/ER, GRS, and Thermal Emission Spectrometer (TES) were scheduled. The mapping phase of the mission was scheduled to nominally last one Martian year. Mars Observer was also to support the acquisition of data from the Russian Mars 1994 mission through the use of the joint French-Russian-American Mars Balloon Relay instrument.

Pre-Launch Problems

Prior to the spacecraft's launch, NASA found the Mars Observer to be "seriously contaminated with metal filings, paint chips and other trash" during a routine inspection.^[1] The spacecraft was subsequently removed from its Titan 34D rocket, and taken to a hanger for cleaning.^[1] The launch delay proved to be manageable, and the Observer launched from Cape Canaveral at 1:05 PM Eastern Daylight Time on September 25, 1992.^[2]

Communications lost

Three days before scheduled orbit insertion, there was an "inexplicable" loss of contact with Mars Observer on August 21, 1993, at 9 P.M. Eastern Daylight Time.^[3] After no response was received from Observer, new commands were sent every 20 minutes in the hopes that the spacecraft had simply drifted off course, but the efforts proved fruitless.^[3] It is not known whether the spacecraft was able to follow its automatic programming and go into Mars orbit or if it flew by Mars and is now in a heliocentric orbit.

It was speculated that there may have been an explosion in a propellant line during pressurization procedures just before the orbital insertion engine burn. It is believed that hypergolic fuel may have leaked past valves in the system during cruise to Mars, allowing the fuel and oxidizer to combine prematurely before reaching the combustion chamber. The engine was derived from that of an Earth orbital satellite and was not designed to lie dormant for months before being fired.

Although none of the primary objectives of the mission were achieved, cruise mode data were collected up to loss of contact. The total cost of the Mars Observer mission including development, construction, launch, and ground support is estimated at US$980 million. However, science instruments originally developed for Mars Observer are being used by three other orbiters, the Mars Global Surveyor, launched in 1996, Mars Odyssey, launched in 2001, and the Mars Reconnaissance Orbiter, launched in 2005.

References

^ ^a ^b Wilford, John Noble (1992-08-28). "Mishap Delays Mission to Mars". New York Times. Retrieved 2008-06-21.
^ Wilford, John Noble (1992-09-26). "U.S. Launches A Spacecraft On a Mars Trip". New York Times. Retrieved 2008-06-21.
^ ^a ^b Wilford, John Noble (1993-08-23). "NASA Loses Communication With Mars Observer". New York Times. Retrieved 2008-06-17.

External links

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
NASA - Mars Observer

28°33′43″N 80°34′38″W / 28.56194°N 80.57722°W / 28.56194; -80.57722

[trash-1] Wilford, John Noble (1992-08-28). "Mishap Delays Mission to Mars". New York Times. Retrieved 2008-06-21.

[launch-2] Wilford, John Noble (1992-09-26). "U.S. Launches A Spacecraft On a Mars Trip". New York Times. Retrieved 2008-06-21.

[commloss-3] Wilford, John Noble (1993-08-23). "NASA Loses Communication With Mars Observer". New York Times. Retrieved 2008-06-17.

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 == Communications lost ==
-Three days before scheduled orbit insertion, there was an "inexplicable" loss of contact with Mars Observer on [[August 21]], [[1993]], at 9 P.M. [[Eastern Daylight Time]].<ref name="commloss">{{cite web |url=http://query.nytimes.com/gst/fullpage.html?res=9F0CE0D7163FF930A1575BC0A965958260&sec=&spon=&pagewanted=1 |title=NASA Loses Communication With Mars Observer  |accessdate=2008-06-17 |last=Wilford |first=John Noble |date=1993-08-23 |publisher=New York Times}}</ref> After no response was received from Observer, new commands were send every 20 minutes in the hopes that the spacecraft had simply drifted off course, but the efforts proved fruitless.<ref name=commloss/> It is not known whether the spacecraft was able to follow its automatic programming and go into Mars orbit or if it flew by Mars and is now in a [[heliocentric orbit]].
+Three days before scheduled orbit insertion, there was an "inexplicable" loss of contact with Mars Observer on [[August 21]], [[1993]], at 9 P.M. [[Eastern Daylight Time]].<ref name="commloss">{{cite web |url=http://query.nytimes.com/gst/fullpage.html?res=9F0CE0D7163FF930A1575BC0A965958260&sec=&spon=&pagewanted=1 |title=NASA Loses Communication With Mars Observer  |accessdate=2008-06-17 |last=Wilford |first=John Noble |date=1993-08-23 |publisher=New York Times}}</ref> After no response was received from Observer, new commands were sent every 20 minutes in the hopes that the spacecraft had simply drifted off course, but the efforts proved fruitless.<ref name=commloss/> It is not known whether the spacecraft was able to follow its automatic programming and go into Mars orbit or if it flew by Mars and is now in a [[heliocentric orbit]].
 It was speculated that there may have been an explosion in a propellant line during pressurization procedures just before the orbital insertion engine burn. It is believed that hypergolic fuel may have leaked past valves in the system during cruise to Mars, allowing the fuel and oxidizer to combine prematurely before reaching the combustion chamber. The engine was derived from that of an Earth orbital satellite and was not designed to lie dormant for months before being fired.