Mars Global Surveyor

Launch data: Designation  24648 / 96062A Launch date  07 Nov 1996 - 17:00:49 UTC Launch site  CC, LC-17A Launch vehicle  Delta-7925 (#D239) Mission  Mars Orbiter Heliocentric orbit Perihelion / Aphelion   A.U. Eccentricity   Inclination   deg Period   min

Spacecraft data: Prime contractor  Martin Marietta Operator  NASA Platform   Mass at launch   kg Dry Mass   kg Basic shape   Dimensions (m)  1.8 long - 1.2 max dia Solar array   Stabilization   DC power   Design lifetime  6 years - In Mars orbit

Descriptions:

• MGS is the first mission of the Mars Surveyor Program, which is an aggressive series of orbiters and landers designed to provide new global and close-up images of Mars. MGS will be a polar orbiting spacecraft at Mars designed to monitor global weather and provide global maps of surface topography and distribution of minerals. After the initial elliptical capture orbit, four months of thruster firings and aerobraking manoeuvres will be used to reach the nearly circular mapping orbit. Mapping operations will begin in late January 1998. After collecting data for a full Martian year (approx.2 Earth years), the spacecraft will be used as a data relay station for future missions for an additional three years. Spacecraft: X-band uplink at 500 bps. X-band and Ka-band downlinks at 85.3 kbps max.1.5m articulated HGA on a 1.5m boom plus 4 LGAs. Dual-mode propulsion system (MMH/NTO) with one 596 N and twelve 4.45 N thrusters. Total propellant load 361 kg. Passive thermal control design.3-axis stabilised with 10 mrad control and 3 mrad knowledge using reaction wheels, thrusters, sun sensors, horizon sensors, celestial sensors, and IMU. Four articulated 1.7 m x 1.8 m solar panels (2 GaAs, 2 Si) provide 656 watts (980 W max). Two 20 Ahr NiH2 batteries.1750A-based central computer. Total data storage capacity is 3 gigabits.
• Payload: Mars Orbiter Laser Altimeter (MOLA) provides local and global maps of Martian topography with 2 to 30 meter vertical resolution.
  Mars Orbiter Camera (MOC) supports study of climate, surface geology, and surface and atmospheric interactions. Camera system includes wide angle (140 degree) and narrow angle (0.4 degree) optics for producing global coverage (7.5 km/pixel), selective moderate resolution images (280 m/pixel) and very selective high resolution (1.4 m/pixel) images.
  Magnetometer and Electron Reflectometer for global study of intrinsic magnetic field. Thermal Emission Spectrometer to map the mineral content of rocks, ice caps, and clouds.
  Radio Science (Ultrastable Oscillator) to study gravitational field, atmospheric refractive indices, and temperature profiles. Mars Balloon Relay to serve as a data relay for planned future surface stations and atmospheric experiments. Ka-Band Link Experiment (KaBLE) to provide Ka-band signal for atmospheric attenuation studies. MGS also carries a bipropellant liquid propulsion system.
  Total science payload mass is 78 kg.

Mission details:

• Mars Global Surveyor, NASA's probe to map the Martian surface and the first of three Mars probes due for launch this window, was launched at 1700 UTC on Nov 7, 1996.
• The McDonnell Douglas Delta 7925 launch vehicle took off from Cape Canaveral Launch Complex 17, with nine GEM solid motors attached to the Thor-derived first stage. First stage separation was four minutes into the flight, and the Delta second stage then ignited. The second stage uses an AJ-10-118 engine and a structure derived from the old Ablestar rockets used to launch the early Transits. The second stage cut off at 9 minutes into the flight, placing MGS into a 185 x 185 km x 28.5 deg orbit. At 1741 UTC the second stage ignited again for two minutes, and the vehicle entered a 173 x 4720 km x 28.5 deg orbit. The spin table on the second stage then began to rotate at 60 rpm, spinning up the third stage and payload to stabilized them. At 1744 the second stage separated and half a minute later the Thiokol Star 48 solid motor on the PAM-D third stage ignited to enter an escape trajectory. At 1752 the third stage deployed `yo-yo' masses on long wires to carry away the angular momentum and spin down the vehicle, and then separated from the MGS probe which is now en route to Mars.
• Mars Global Surveyor entered polar orbit around Mars on Sep 12, 1997. The burn began at 0117 UTC and ended at 0139 UTC. Orbit is 258 x 54021 km x 93.3 deg with a period of 44h59.5min. This orbit will be reduced by aerobraking to a low, circular mapping orbit over the next few months. MGS will be the first probe to enter a low orbit around Mars and is the highest inclination satellite of Mars to date, beating Viking 2's 80 degree inclination.
• The Mars Global Surveyor continues aerobraking. As of Oct 3, 1997 it was in a 110 x 48770 km x 93.3 deg orbit around Mars.
• Mars Global Surveyor resumed aerobraking on Nov 9, 1997. Orbit is now 135 x 45088 km x 93 deg. It will continue aerobraking for a few months and then pause again, before finally reaching its target sun-synchronous orbit in 1999 (instead of Jan 1998), a year later than planned due to the problem with its solar panel.
• Mars Global Surveyor is completing its aerobraking in Jan 1999, with orbit now 113 x 551 km x 93.1 deg around Mars.
• MGS made its aerobraking exit burn at 0811 UTC on Feb 4, 1999 raising periapsis out of the Martian atmosphere. It will enter its final mapping orbit on Feb 18. Orbit is currently 384 x 406 km x 93.0 deg.
• The Mars Global Surveyor probe has fallen silent after 10 years in space, the longest operating Mars probe in history. MGS was launched in 1996 Nov, entered Mars orbit in 1997 Sep, and after an extended aerobraking phase began its primary mission in 1999 Mar.
• The last definite signals from MGS were received at around 0h UTC on Nov 3, 2006; the spacecraft's solar array mechanism appears to have run into problems. The spacecraft was then in a 356 x 419 x 93.0 orbit.