Mars Observer

Mars Observer was a NASA mission to study the surface, atmosphere, interior and magnetic field of Mars from Martian orbit. The mission was designed to operate for one full Martian year (687 Earth days) to permit observations of the planet through its four seasons. The mission specific objectives were to (1) determine the global elemental and mineralogical character of Mars' surface material, (2) define the planet's global topography and gravitational field, (3) establish the nature of the Martian magnetic field, (4) determine the time and space distribution, abundance, sources and sinks of volatile material and dust over a seasonal cycle, (5) explore the structure and aspects of the circulation of the Martian atmosphere. The spacecraft also carried a radio relay package designed to receive information from the planned Mars Balloon Experiment carried on the planned Soviet Mars '94 mission for retransmission back to Earth. Communications was lost with the spacecraft on August 22, 1993 as it was preparing to go into orbit around Mars, and no significant scientific data was returned.

Spacecraft
Design based on Earth-orbiting spacecraft (DMSP and TIROS). 3-axis stabilized, zero momentum bias using reaction wheels. Communications with Earth using X-band system and 1.5 m articulated HGA mounted on 6-meter boom. Deployed 3.7 x 6.5 meter solar array generated 1.1 - 1.5 kW. Hydrazine and bi-propellant propulsion systems to perform trajectory maneuvers, Mars orbit capture and circularization, and orbit maintenance. Deployable booms for instruments.

Payload
Gamma-ray spectrometer (GRS) - designed to measure the abundance of elements (uranium, thorium, potassium, iron and silicon, for example) on the surface of Mars. Thermal-emission spectrometer (TES) - intended to map the mineral content of surface rocks, frosts and the composition of clouds. Mars Observer Camera (MOC) - a line-scancamare designed to take low-resolution images of Mars on a daily basis for studies of the climate, and medium- and high-resolution images of selected areas to study surface geology and interactions between the surface and the atmosphere. Laser altimeter - intended to measure the topographic relief of the Martian surface. Pressure-modulator infrared radiometer (PMIRR) - designed to measure dust and condensates in the atmosphere, as well as profiles of temperature, water vapor and dust opacity as they change with latitude, longitude and season. Radio-science investigation - planned to use the spacecraft radio with an ultrastable oscillator to measure atmospheric refractivity as it varies with altitude to determine the temperature profile of the atmosphere, and will use tracking data to measure the gravity field of Mars. Magnetometer and electron reflectometer - designed to determine the nature of the magnetic field of Mars, and its interactions with the solar wind.

Country of Origin	United States
Customer/User	NASA, JPL
Manufacturer(s)	GE Astro Space
Size	2.9 x 2.9 x 3.2 meter bus, 24.5 sq. meter solar array
Orbit	11 month direct trajectory to Mars - Planned: 378 km altitude circular, sun-synchronous mapping orbit around Mars.
Related Sites	JPL Mars Observer Summary Page

Launch Facts

Name	Int'l Desig.	Date	Site	Vehicle	Orbit	Mass(kg)
Notes
Mars Observer	1992-063A	9/25/92	ESMC	Titan 3	Solar ?	2573
Planned Mars orbiter; lost contact during Mars orbit insertion burn