TES News

August/September 1992, Volume 1, No. 1

Thermal Emission Spectrometer Project
Mars Observer Space Flight Facility
Department of Geology, Arizona State University
Box 871404, Tempe, Arizona 85287-1404, U.S.A.

The Mars Observer Mission

Mars Observer is the next in a series of robotic spacecraft missions to the Red Planet which began with Mariner 4 in 1965 and continued through the spectacular Viking project of the late 1970's. The first U.S. space mission to be sent to Mars in 17 years is set to launch from the Kennedy Space Center, Florida, in September 1992. The spacecraft will ride aboard an expendable Titan III rocket, and will be boosted into interplanetary space using a new rocket motor called the Transfer Orbit Stage (TOS).

When the spacecraft reaches Mars in August 1993, it will go into a wide, elliptical orbit. The orbit will then be carefully adjusted over the course of four months, until it becomes nearly circular. Mars Observer's polar orbit will be Sun-synchronous, such that the spacecraft will always cross the equator at 2 AM and 2 PM local time. In December 1993, its seven science instruments will begin mapping the planet from an average altitude of 400 km (250 mi.).

TABLE 1: Mars Observer Science Instruments

Thermal Emission Spectrometer (TES)
Maps surface mineralogy; atmospheric dust and clouds; surface temperature.
Mars Observer Camera (MOC)
Photographs Mars in (a) global synoptic views and (b) selected moderate- and high-resolution [1.4 m (4.6 ft) per pixel] images.
Gamma Ray Spectrometer (GRS)
Determines elemental composition of Mars' surface; measures neutron emissions to detect hydrogen (which may indicate the presence of subsurface water).
Mars Observer Laser Altimeter (MOLA)
Maps the global topography.
Radio Science (RS)
Determines Mars' gravitational field; obtains temperature and pressure profiles of the atmosphere.
Magnetometer/electron reflectometer (MAG)
Finds global and local magnetic fields and monitors interactions with the solar wind.
Pressure Modulator Infrared Radiometer (PMIRR)
Obtains atmospheric profiles of temperature, water, and dust; determines variation in atmospheric pressure.
Mars Balloon Relay (MBR)
Designed to relay data from the Russian Mars '94 or Mars '96 balloon mission.

Mars Observer will conduct a global survey of the planet's atmosphere and surface. It will also monitor the changes that take place over the course of a martian year (687 Earth days). A detailed, global portrait of martian geology, climate, and weather will be derived from the data. This composite picture will be similar to the unprecedented perspective of the Earth that has been assembled from Earth-orbiting satellites such as Landsat.

Data from Mars Observer will allow a more complete comparison with the Earth, which should provide new insight as to how the climate and geology of both planets evolved. Mars Observer results will also be used in planning future missions to the Red Planet, perhaps including human exploration sometime in the 21st Century.

The Mars Observer spacecraft design is based upon communication and defense mapping satellites which routinely circle the Earth. The spacecraft was assembled under contract from NASA by the General Electric Astro-Space Division, Hightstown, New Jersey. At the time of the launch, the spacecraft's antenna, instrument booms, and solar array panels are folded close to the spacecraft bus, a box-shaped vehicle approximately 5 by 5 by 7 ft. in size. The main communications antenna is raised on an 18-ft boom to clear the 10 by 25 ft solar array, which is fully unfolded only when the spacecraft reaches Mars. The total spacecraft mass after launch is about 5400 pounds.

Mission operations for the Mars Observer Project are conducted at the Jet Propulsion Laboratory (JPL) in Pasadena, California. The Mars Observer Project Manager, David D. Evans, and the Project Scientist, Arden L. Albee, run the program at JPL. A new innovation in planetary space missions allows each of the seven science instruments to be controlled from the home institutions of the principal investigators. For example, the principal investigator for the Thermal Emission Spectrometer (TES) is Philip R. Christensen, a Professor of Geology at Arizona State University (ASU). Thus, TES will be controlled and data will be received at a facility at ASU. TES team members and participating scientists will visit ASU to operate the instrument and analyze the data.


Written by: 

K.S. Edgett

Text prepared by:
T.E. Montoya
Original Text:  August 1992
Hypertext Version:  January 29, 1994