The First Interplanetary Internet Service Provider:
Data from Mars Exploration Rovers MER-A (Spirit) and MER-B (Opportunity)
via the Mars Global Surveyor Mars Relay and Mars Orbiter Camera

Note added January 3-4, 2004: The MGS/MOC/MR Mars Relay system has today, for the first time, been demonstrated to work successfully in relaying data from a lander on the surface of Mars. In late 1999 and early 2000, the Mars Relay was used repeatedly to attempt communication with the Deep Space 2 and Mars Polar Lander spacecraft, to no avail. Today, the MR functioned perfectly during the Mars Exploration Rover, Spirit, entry, descent and landing, and again later in the day for a second relay event.

Originally intended to receive data from French and Russian landers for retransmission to Earth by the Mars Observer (MO) and, later, the Mars Global Surveyor (MGS) spacecraft, the Mars Relay (MR) was also to have played a key role in supporting the science data return from the Mars Polar Lander and the two Deep Space 2 microlanders. After those vehicles were lost on 3 December 1999, the MR and MOC were used to search for them.

When the Mars Exploration Rover (MER) Project was created in 2000, one of the primary requirements levied by NASA on the Project was that lander telemetry be monitored during descent and landing. The MER Project requested that MGS provide this telecommunications support. Initially intended only to acquire entry, descent, and landing (EDL) telemetry via UHF transmission, the MGS role has increased to also support post-landing mission phases, in particular the early period when each rover is preparing to drive off the lander (the "impact-to-egress" (ITE) period). MGS will also be used to return as much as one-third of the total mission science data.

From Mars to Earth

Data from the surface of Mars are sent by radio using either a direct-to-Earth link from an antenna on the lander, or through the Mars Relay antenna on the orbiting Mars Global Surveyor spacecraft, or through a relay on the Mars Odyssey orbiter. Read More...

Role of MGS MOC and Malin Space Science Systems

Malin Space Science Systems (MSSS) plays a unique role in the Mars Relay process. Data received by the Mars Relay antenna on Mars Global Surveyor (MGS) are stored in the Mars Orbiter Camera (MOC) buffer and returned to Earth with the MOC images. MSSS decompresses the raw data and transfers them to the Mars lander teams. Read More...

Relay from MER-A (Spirit) and MER-B (Opportunity)

The Mars Relay was the only link by which telemetry were returned from both MERs during Entry, Descent, and Landing. After landing, Mars Global Surveyor was used for several months to relay science data from both MERs. Read More...

International Origins and the History of Mars Relay

In the late 1980's, international cooperation in Mars exploration led to development of the Mars Relay antenna by the French space agency. The purpose was to relay data from 2 balloons that would be sent to the red planet onboard the USSR Mars '92 mission. The relay antenna was placed aboard the US Mars Observer spacecraft for this purpose. Today the Mars Relay aboard Mars Global Surveyor is expected to support the two Mars Exploration Rovers. Read More...

Mars Relay Technical Details

A lander on the surface radios its data to the Mars Global Surveyor as it passes overhead. The data are transfered to the Mars Orbiter Camera (MOC) for storage and relay back to Earth. Relayed data are received at Malin Space Science Systems, decompressed, and provided to the lander team. Read More...

Image Credits, this page--- Artwork modified from NASA/JPL/Caltech Mars Exploration Rovers, Mars Global Surveyor, and Deep Space 2 artwork; Photos modified from NASA/JSC, NASA/JPL/LMA, and NASA/JPL/MSSS photos.

© 2000, 2003, 2005 Malin Space Science Systems, Inc.