Extraterrestrial Relay from Mars

Crater interior from Opportunity via Mars Express. This false-colour image of the interior of ‘Endurance Crater’ on Mars was collected on 4 August 2004 by NASA’s Mars Exploration Rover Opportunity. The image, taken with the Rover’s panoramic camera, was relayed to Earth by ESA’s Mars Express together with other scientific data. Three separate frames, taken through red, green and blue filters, were combined to produce this colour image. Credit: ESA/JPL

ESA’s Mars Express has relayed pictures from one of NASA’s Mars rovers for the first time, as part of a set of interplanetary networking demonstrations. The demonstrations pave the way for future Mars missions to draw on joint interplanetary networking capabilities. ESA and NASA planned these demonstrations as part of continuing efforts to co-operate in space exploration.

On 4 August at 14:24 CEST, as Mars Express flew over one of NASA’s Mars exploration rovers, Opportunity, it successfully received data previously collected and stored by the rover. The data, including 15 science images from the rover’s nine cameras, were then downlinked to ESA’s European Space Operations Centre in Darmstadt (Germany) and immediately relayed to the Mars Exploration Rovers team based at the Jet Propulsion Laboratory in Pasadena, USA.

NASA orbiters Mars Odyssey and Mars Global Surveyor have so far relayed most of the data produced by the rovers since they landed in January. Communication compatibility between Mars Express and the rovers had already been demonstrated in February, although at a low rate that did not convey much data. The 4 August session, at a transmit rate of 42.6 megabits in about six minutes, set a new mark for international networking around another planet.

The success of this demonstration is the result of years of groundwork and was made possible because both Mars Express and the Mars rovers use the same communication protocol. This protocol, called Proximity-1, was developed by the international Consultative Committee for Space Data Systems, an international partnership for standardizing techniques for handling space data.

Mars Express was 1400 kilometers above the Martian surface during the 4 August session with Opportunity, with the goal of a reliable transfer of lots of data. Engineers for both agencies plan to repeat this display of international cooperation today, 10 August, with another set of Opportunity images.

"We’re delighted how well this has been working, and thankful to have Mars Express in orbit," said Richard Horttor of NASA’s Jet Propulsion Laboratory, Pasadena, California, project manager for NASA’s role in Mars Express. JPL engineer Gary Noreen of the Mars Network Office said: "the capabilities that our international teamwork is advancing this month could be important in future exploration of Mars."


The spherules, or blueberries, have become important to characterize an alien landscape.
Credit: NASA/JPL

In addition, Mars Express is verifying two other operating modes with Opportunity and the twin rover, Spirit, from a greater distance. On 3 and 6 August, when Mars Express listened to Spirit, it was about 6000 kilometers above the surface. At this range it successfully tracked a beacon from Spirit, demonstrating a capability that can be used to locate another craft during critical events, such as the descent to a planet’s surface, or for orbital rendezvous manouvers.

"Establishing a reliable communication network around Mars or other planets is crucial for future exploration missions, as it will allow improved coverage and also an increase in the amount of data that can be brought back to Earth," said Con McCarthy, from ESA’s Mars Express project, "the tracking mode will enable ESA and NASA to pinpoint a spacecraft’s position more accurately during critical mission phases."

The final session of the series, scheduled for 13 August with Opportunity, will demonstrate a mode for gaining navigational information from the ‘Doppler shift’ in the radio signal.

As noted by Dr. Ed Weiler, NASA Associate Administrator for Science, one first for this round of missions that has paid off early, has been the world’s only interplanetary satellite communication network. First images arrived via orbiters around Mars, as unique relay points for storing and transmitting the data-rich pictures only hours after touching down. The large amount of data — nearly 100 megabits — transmitted from the Spirit rover in a single relay session through NASA’s Mars Odyssey spacecraft was, according to mission manager, Jennifer Trosper, "like getting an upgrade to our Internet connection."

MER flight planning chronicled in the diary of the principal investigator for the science packages, Dr. Steven Squyres: Parts 1 * 2 * 3 * 4 * 5 * 6 * 7 * 8 * 9 * 10 * 11 * 12 .

Related Web Pages

Mars Rovers JPL
Spirit’s images and slideshow
Opportunity image gallery and slideshow
Mars Berries Once Rich in Iron-Water
NASA’s RATs Go Roving on Mars

Water Signs
Microscopic Imager
Gusev Crater
Pancam- Surveying the Martian Scene
Mössbauer spectrometer
Alpha Proton X-ray Spectrometer