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. 





References:
















Written by: 



K.S. Edgett





Text prepared by:


T.E. Montoya 


Original Text:  August 1992
Hypertext Version:  January 29, 1994