The Mars Global Surveyor (MGS) mission is designed as a rapid, low-cost recovery of the Mars Observer mission objectives. The science objectives involve high resolution imaging of the surface, studies of the topography and gravity, the role of water and dust on the surface and in the atmosphere of Mars, the weather and climate of Mars, the composition of the surface and atmosphere, and the existence and evolution of the Martian magnetic field.
The spacecraft began its Mars orbit insertion burn at 01:17 UT 12 September 1997 (9:17 p.m. EDT September 11) after a 10 month cruise phase. The time for the radio signal to travel from Mars to Earth is about 14 minutes, so the Earth received time for these events was 14 minutes later, or 9:31 p.m. EDT for the beginning of the orbit insertion burn. At 9:29 p.m. the spacecraft went behind Mars and contact was lost at Earth at 9:43 p.m., closest approach to Mars on this pass was at 9:30 p.m. The burn was completed at 9:39 p.m. and contact was re-established at Earth at 9:57 p.m. Mars Global Surveyor started in an elliptical (54,021 x 258 km altitude) 45 hour orbit.
Over the sixteen months after orbit insertion, aerobraking and thrusters will slowly convert the original elliptical capture orbit into a nearly circular 2 hour polar orbit with an average altitude of 378 km, allowing complete coverage of the planet every 7 days. The primary mapping mission will begin about March, 1999. (Primary mapping was originally scheduled to begin in March, 1998 but a malfunction of one of the solar panel supports delayed the aerobraking schedule for one year.) The spacecraft will be in a "sun-synchronous" orbit so that each image will be taken with the sun at the same mid-afternoon azimuth. Data will be acquired until April 2002. The spacecraft will also be used as a data relay for later U.S. and international missions over the following two years. Mars Global Surveyor is the first spacecraft to be launched in a decade-long exploration of Mars by NASA. Launches will be occurring every 26 months, in 1998, 2001, 2003 and 2005, involving orbiters, landers, rovers, and probes to Mars. Orbiters launched in 1998 and 2003 will contain other instruments to recover the planned Mars Observer objectives. More detailed information on Mars Global Surveyor is available from the NSSDCA Master Catalog.
The Mars Global Surveyor will consist of six primary investigations:
The Mars Orbiter Camera (MOC)
- Michael Malin, Malin Space Science Systems
The Mars Orbiter Camera will take high resolution images, on the order of a meter or so, of surface features. It will also take lower resolution images of the entire planet over time to enable research into the temporal changes in the atmosphere and on the surface.
Thermal Emission Spectrometer (TES)
- Phil Christensen, Arizona State University
The Thermal Emission Spectrometer is a Michelson interferometer that will measure the infrared spectrum of energy emitted by a target. This information will be used to study the composition of rock, soil, ice, atmospheric dust, and clouds.
Mars Orbiter Laser Altimeter (MOLA)
- David Smith, Goddard Space Flight Center
This instrument will measure the time it takes for a transmitted laser beam to reach the surface, reflect, and return. This time will give the distance, and hence the height of the surface. Combining these measurements will result in a topographic map of Mars.
Radio Science Investigations (RS)
- G. Leonard Tyler, Stanford University
Measurements of the Doppler shift of radio signals sent back to Earth will allow precise determination of changes in the orbit, which will allow for a model of the Mars gravity field. As the spacecraft passes over the poles on each orbit, radio signals pass through the Martian atmosphere on their way to Earth. The way in which the atmosphere affects these signals allows determination of its physical properties.
Magnetic Fields Investigation (MAG/ER)
- Mario Acuna, Goddard Space Flight Center
A magnetometer will be used to determine whether Mars has a magnetic field, and the strength and orientation of the field if one exists. An electron reflectometer will measure remnant crustal magnetization.
- Jacques Blamont, Centre National d'Etudes Spatiales
The Mars Relay experiment consists of an antenna which will route received signals through the Mars Observer Camera for transmission to Earth. The relay will be used to support surface landers and rovers from other Russian, European, and U.S. missions.
Images and information on the Cydonia Region and the "Face on Mars"
Images taken by Mars Global Surveyor
Mars Home Page
Mars Fact Sheet
NSSDCA Image Catalog images of Mars - Mars Global Surveyor pictures
More Image Catalog images of Mars - Photographs available from NSSDCA
Mars Pathfinder Mission Information
Viking Mission Information
Mars Global Surveyor Press Releases
Mars Global Surveyor
imaging scientists presented evidence for
ancient large bodies of water at a press briefing on Monday, December 4, 2000.
Images showing layered deposits on Mars may
indicate sedimentary rocks laid down in lakes 3.5 to 4.3 billion years ago.
For more information, see the
NASA press release
Images indicating evidence for possible sources of present day liquid water on Mars have been released. For further information, see the June 22, 2000 NASA Press Release.
Global topographic map of Mars released
- 27 May 1999
(273 K image)
Magnetometer data indicate past plate motions on Mars - 29 April 1999 (95 K image)
High gain antenna deployed - 29 March 1999
First 3-D view of Mars' north pole - 07 December 1998
Phobos appears to be covered with a thick layer of dust - 11 September 1998
Malfunction may delay high-gain antenna deployment - 10 August 1998
New evidence found for ancient water and thermal activity - 27 May 1998
MGS will attempt imaging areas of general interest - 26 March 1998
Early science results summary - 13 March 1998
Images of the south polar cap returned - 11 February 1998
Aerobraking resumed on 7 November - 11 November 1997
Aerobraking to resume - 30 October 1997
Aerobraking postponed to assess faulty solar panel - 14 October 1997
Martian magnetic field detected - 17 September 1997
Modified aerobraking configuration - 30 April 1997