191 Mars Global Surveyor

Nation: USA (69)

Objective(s): Mars orbit

Spacecraft: MGS

Spacecraft Mass: 1,030.5 kg

Mission Design and Management: NASA / JPL

Launch Vehicle: Delta 7925 (no. D239)

Launch Date and Time: 7 November 1996 / 17:00:49 UT

Launch Site: Cape Canaveral Air Force Station / Launch Complex 17A

Scientific Instruments:

1. Mars orbital camera (MOC)
1. Mars orbital laser altimeter (MOLA)
1. thermal emission spectrometer (TES)
1. magnetometer/electron reflectometer (MAG/ER)
1. radio science experiment (RS)
1. Mars relay antenna for future spacecraft (MR)

Results: Mars Global Surveyor was the first spacecraft in NASA's new Mars Surveyor Program, a new generation of American space probes to explore Mars every 26 months from 1996 to 2005, and formulated (in 1994) to economize costs and maximize returns by involving a single industrial partner with the Jet Propulsion Laboratory to design, build, and deliver a flight-worthy vehicle for Mars every two years. (A new Mars Exploration Program was inaugurated in 2000.) The Mars Global Surveyor spacecraft carried five instruments similar to those carried by the lost Mars Observer probe that fell silent in 1993. Among its instruments was a French-supplied radio relay experiment to serve as a downlink for future Mars landers, including for the then-planned Russian Mars 96 mission. After mid-course corrections on 21 November 1996 and 20 March 1997, Mars Global Surveyor entered a highly elliptical orbit around Mars on 12 September 1997 after engine ignition at 01:17 UT. Initial orbital parameters were 262 × 54,026 kilometers. Commencement of its planned two-year mission was delayed because one of its two solar panels (-Y) had not fully deployed soon after launch. The solar panels were designed to act as atmospheric brakes to alter its orbit. As a result, mission planners reconfigured the aerobraking process required to place the vehicle in its intended orbit: the modified aerobraking maneuver began on 17 September 1997 and lasted until 11 October. A second aerobraking phase lasted from November 1997 to March 1998 and a third one began in November 1998 whose goal was to reduce the high point of its orbit down to 450 kilometers. The revised maneuvers were finally completed on 4 February 1999 with a major burn from its main engine. A subsequent firing on 19 February finally put Mars Global Surveyor into a near-circular polar orbit at 235 kilometers—and on 9 March 1999, its mapping mission formally began. The orbit was Sun-synchronous, ensuring that all its images were taken by the spacecraft of the same surface features at different times under identical lighting conditions. Despite the early problems, Mars Global Surveyor, already during its movement to its new orbit, began to send back impressive data and high-resolution images of the surface of Mars. The spacecraft tracked the evolution of a dust storm, gathered information on the Martian terrain, found compelling evidence indicating the presence of liquid water at or near the surface (first announced by NASA on 22 June 2000). During its mission, Mars Global Surveyor also produced the first three-dimensional profiles of Mars' north pole using laser altimeter readings. The spacecraft's primary mission was concluded on 1 February 2001, by which time it had returned 83,000 images of Mars, more than all previous missions to Mars combined. In addition, the laser altimeter essentially mapped almost all of the planet, by firing approximately 500 billion pulses at the surface, providing topographical data that was more detailed than many places on Earth. On 1 February 2001, Mars Global Surveyor's mission was extended for a year, and then again on 1 February 2002, this time continuing 11 months. In the early 2000s, the spacecraft supported other missions to Mars, including that of Mars Odyssey (in 2001) and the Mars Exploration Rovers (in 2004) by providing either atmospheric data or relaying telemetry back to Earth. Between 2004 and 2006, it conducted experiments simultaneously with the European Mars Express. On 1 October 2006, mission planners, based on the recommendations of a Senior Review Board, once again extended its mission by another two years but only a month later, on 2 November, the spacecraft lost contact with Earth when attempting to orient a solar panel. Although weak signals were received three days later, on 21 November 2006, NASA announced that the mission of Mars Global Surveyor was over. The final problem was probably related to a flaw in the system's software.

192 Mars 8 / Mars 96

Nation: Russia (106)

Objective(s): Mars orbit and landing

Spacecraft: M1 (no. 520)

Spacecraft Mass: 6,795 kg

Mission Design and Management: NPO imeni Lavochkina

Launch Vehicle: Proton-K + Blok D-2 (8K82K no. 392-02 + 11S824F no. 3L)

Launch Date and Time: 16 November 1996 / 20:48:53 UT

Launch Site: GIK-5 / Site 200/39

Scientific Instruments:

Orbiter:

1. Argus imaging complex
- TV camera (HRSC)
- spectroscopic camera (WAOSS)
- Omega infrared and optical spectrometer
1. infrared Fourier spectrometer (PFS)
1. Termoskan mapping radiometer
1. Svet mapping spectrometer
1. Spikam multi-channel spectrometer
1. ultraviolet spectrophotometer (UFS-M)
1. long-wave radar (RLK)
1. Foton gamma-ray spectrometer
1. Neytron-S neutron spectrometer
1. mass spectrometer (MAK)
1. Aspera-S ion and particles power and mass analyzer
1. Fonema omni non-scanning energy-mass ion analyzer
1. Dimio omni ionosphere energy mass spectrometer
1. Mari-prob ionospheric plasma spectrometers
1. Maremf electron analyzer/magnetometer
1. Elisma wave complex experiment
1. Sled-2 low energy charged particle spectrometer
1. precision gamma-ray spectrometer (PGS)
1. Lilas-2 cosmic and solar gamma-burst spectrometer
1. Evris stellar oscillation photometer
1. solar oscillation spectrometer (SOYa)
1. Radius-M dosimeter
1. tissue-equivalent dosimeter (TERS)

Small Autonomous Stations (MAS):

1. meteorology complex (MIS)
1. meteorology complex (DPI)
1. alpha-particle proton and x-ray spectrometer
1. Optimizm seismometer/magnetometer/ inclinometer
1. panoramic camera (PanCam)
1. descent phase camera (DesCam)
1. soil oxidization capacity instrument (MOx)

Penetrators:

1. PTV-1 camera
1. Mekom meteorological unit
1. Pegas gamma-ray spectrometer
1. Angstrem x-ray spectrometer
1. Alfa alpha/proton spectrometer
1. Neytron-P neutron spectrometer
1. Grunt accelerometers
1. Termozond temperature probes
1. Kamerton seismometer
1. IMAP-7 magnetometer

Results: Mars 8, the only Soviet/Russian lunar or planetary probe in the 1990s, was an ambitious mission to investigate the evolution of the Martian atmosphere, its surface, and its interior. Originally planned as two spacecraft, Mars 94 and Mars 96, the missions were delayed and became Mars 96 and Mars 98. Subsequently Mars 98 was cancelled leaving Mars 96 as the first Russian deep space mission beyond Earth orbit since the collapse of the Soviet Union. The entire spacecraft comprised an orbiter, two small autonomous stations, and two independent penetrators. The three-axis stabilized orbiter carried two platforms for pointing several optical instruments for studying the Martian surface and atmosphere. After an initial period in low orbit lasting three to four weeks acting as a relay to the landers, the orbiter was designed to spend approximately two Earth years in a 250 × 18,000-kilometer orbit at 101° inclination mapping Mars. The orbiter would have released the two 88-kilogram small autonomous stations (Malaya avtonomnaya stantsiya, MAS), four to five days before entering orbit. The small stations would have landed on the Martian surface, cushioned by an inflatable shell that was to split open after landing. The stations were to have transmitted data daily (initially) and then every three days for about 20 minutes each session. The stations would have also studied soil characteristics and taken photos on the surface. The two 123-kilogram penetrators, each 2.1 meters long, would have impacted the Martian surface at a velocity of 76 meters/second to reach about 6 to 8 meters in depth. The plan was for the orbiter to release them between 7 and 28 days after entering orbit. During their one-year lifetimes, the penetrators would have served as nodes of a seismic network. In the event, the Proton-K rocket successfully delivered the payload to Earth orbit (after the first firing of the Blok D-2 upper stage). Initial orbit parameters were 150.8 × 165.7 kilometers at 51.53° inclination. At that point, the Blok D-2 was to fire once again to place Mars 8 into an elliptical orbit, after which the Fregat propulsion module (with its S5.92 engine) would have sent the spacecraft on a Martian encounter trajectory. The Blok D-2 was to have fired at 10:57:46 UT on 16 November for 528 seconds but either didn't fire or shut down very soon after ignition, thus putting its precious payload into an incorrect and similar orbit of 143.7 × 169.6 kilometers. Mars 8 and its Fregat module then automatically separated from the Blok D-2. The latter seems to have fired (as planned earlier), placing Mars 8 in an 80 × 1,500-kilometer orbit that deposited the planetary probe in Earth's atmosphere, with reentry between 12:30 and 01:30 UT on November 17, probably over southern Chile. Various parts of the vehicle, including 200 grams of plutonium-238, must have survived the reentry although there have been no reports of detection. Mars 8 was scheduled to arrive in Mars orbit on 23 September 1997.

193 Mars Pathfinder

Nation: USA (70)

Objective(s): Mars landing and roving operations

Spacecraft: Mars Pathfinder

Spacecraft Mass: 870 kg

Mission Design and Management: NASA / JPL

Launch Vehicle: Delta 7925 (no. D240)

Launch Date and Time: 4 December 1996 / 06:58:07 UT

Launch Site: Cape Canaveral Air Force Station / Launch Complex 17B

Scientific Instruments:

Pathfinder Lander:

1. IMP imager for Mars Pathfinder (including magnetometer and anemometer)
1. atmospheric and meteorology package (ASI/MET)

Sojourner Rover:

1. imaging system (three cameras)
1. laser striper hazard detection system
1. alpha proton x-ray spectrometer (APXS)
1. wheel abrasion experiment
1. materials adherence experiment
1. accelerometers

Results: Mars Pathfinder was an ambitious mission to send a lander and a separate remote-controlled rover to the surface of Mars, the second of NASA's Discovery missions. Launched one month after Mars Global Surveyor, Pathfinder was sent on a slightly shorter seven-month trajectory designed for arrival earlier. The main spacecraft included a 10.5-kilogram six-wheeled rover known as Sojourner capable of traveling 500 meters from the main ship at top speeds of 1 centimeter/second. The mission's primary goal was not only to demonstrate innovative, low-cost technologies, but also to return geological, soil, magnetic property and atmospheric data. After a 7-month traverse and four trajectory corrections (on 10 January, 3 February, 6 May, and 25 June 1997), Pathfinder arrived at Mars on 4 July 1997.

The spacecraft entered the atmosphere using an atmospheric entry aeroshell that slowed the spacecraft sufficiently for a supersonic parachute to deploy and slow the package to 68 meters/second. After separation of the aeroshell heatshield, the lander detached, and at about 355 meters above the surface, airbags inflated in less than a second. Three solid propellant retro-rockets reduced velocity further (firing about 100 meters above the surface) but were then discarded at 21.5 meters altitude—they flew up and away along with the parachute. The lander-within-the-airbag impacted on the surface at a velocity of 14 meters/second generating about 18 g's of acceleration. The package bounced at least 15 times before coming to rest, following which the airbags deflated revealing the lander. Landing time for Pathfinder was 16:56:55 UT on 4 July 1997 at 19° 7′ 48″ N / 33° 13′ 12″ W in Ares Vallis, about 19 kilometers southwest of the original target. The next day, Pathfinder deployed the Sojourner rover on the Martian surface via landing ramps. Sojourner was the first wheeled vehicle to be used on any planet. During its 83-day mission, the rover covered hundreds of square meters, returned 550 photographs and performed chemical analyses at 16 different locations near the lander. The latter meanwhile transmitted more than 16,500 images and 8.5 million measurements of atmospheric pressure, temperature, and windspeed. Data from the rover suggested that rocks at the landing site resembled terrestrial volcanic types with high silicon content, specifically a rock type known as andesite. Although the planned lifetime of Pathfinder and Sojourner were expected to be one month and one week respectively, these times were exceeded by 3 and 12 times respectively. Final contact with Pathfinder was at 10:23 UT on 27 September 1997. Although mission planners tried to reestablish contact for the next five months, the highly successful mission was officially declared over on 10 March 1998. After landing, Mars Pathfinder was renamed the Sagan Memorial Station after the late astronomer and planetologist Carl Sagan. In 2003, Sojourner was inducted into the Robot Hall of Fame. On 21 December 2006, NASA's Mars Reconnaissance Orbiter's HIRISE camera photographed the flood plain of the Ares and Tiu outflow channels; images clearly showed the Pathfinder and associated hardware.

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