Mars -> Exobiology -> Homeclick!

Cette page en franšaisCliquez!


News from Mars Global Surveyor:

This section presented news from the space probe Mars Global Surveyor. The probe has been orbiting Mars since 1997 and ceased functioning on November 2006.

See also:

Click! The "Mars" section of this site.
Click! Latest Mars exobiology news.
Click! Latest news from the Mars Global Surveyor probe (This page).
Click! Latest news from the Mars Odyssey probe.
Click! Latest news from the Beagle 2 / Mars Express probes.
Click! Latest news from the Mars Spirit and Opportunity rovers.
Cliquez! Latest news from the Phoenix Mars probe.

11.02.2006The end of MGS.
12.06.2006MGS provides proof of liquid water flow on Mars again.
11.13.2003MGS provides proof of persistent liquid water flow on Mars.
06.06.2003Liquid water mud flows observed on Mars.
06.02.2003And France too: successful launch for Mars Express.
02.14.2003South pole of Mars is also mostly water ice.
12.06.2001NASA's Global Surveyor sees possible climate change on Mars.

The End of MGS:

Mars Global Surveyor last communicated with Earth on Nov. 2, 2006. Within 11 hours, depleted batteries likely left the spacecraft unable to control its orientation.


MGS provide proof of persistent liquid water flows on Mars again:

Dec. 6, 2006

Dwayne Brown/Erica Hupp
Headquarters, Washington

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.

RELEASE: 06-362


WASHINGTON - NASA photographs have revealed bright new deposits seen in two gullies on Mars that suggest water carried sediment through them sometime during the past seven years.

"These observations give the strongest evidence to date that water still flows occasionally on the surface of Mars," said Michael Meyer, lead scientist for NASA's Mars Exploration Program, Washington.

Liquid water, as opposed to the water ice and water vapor known to exist at Mars, is considered necessary for life. The new findings heighten intrigue about the potential for microbial life on Mars. The Mars Orbiter Camera on NASA's Mars Global Surveyor provided the new evidence of the deposits in images taken in 2004 and 2005.

"The shapes of these deposits are what you would expect to see if the material were carried by flowing water," said Michael Malin of Malin Space Science Systems, San Diego. "They have finger-like branches at the downhill end and easily diverted around small obstacles." Malin is principal investigator for the camera and lead author of a report about the findings published in the journal Science.

The atmosphere of Mars is so thin and the temperature so cold that liquid water cannot persist at the surface. It would rapidly evaporate or freeze. Researchers propose that water could remain liquid long enough, after breaking out from an underground source, to carry debris downslope before totally freezing. The two fresh deposits are each several hundred meters or yards long.

The light tone of the deposits could be from surface frost continuously replenished by ice within the body of the deposit. Another possibility is a salty crust, which would be a sign of water's effects in concentrating the salts. If the deposits had resulted from dry dust slipping down the slope, they would likely be dark, based on the dark tones of dust freshly disturbed by rover tracks, dust devils and fresh craters on Mars.

Mars Global Surveyor has discovered tens of thousands of gullies on slopes inside craters and other depressions on Mars. Most gullies are at latitudes of 30 degrees or higher. Malin and his team first reported the discovery of the gullies in 2000. To look for changes that might indicate present-day flow of water, his camera team repeatedly imaged hundreds of the sites. One pair of images showed a gully that appeared after mid-2002. That site was on a sand dune, and the gully-cutting process was interpreted as a dry flow of sand.

Today's announcement is the first to reveal newly deposited material apparently carried by fluids after earlier imaging of the same gullies. The two sites are inside craters in the Terra Sirenum and the Centauri Montes regions of southern Mars.

"These fresh deposits suggest that at some places and times on present-day Mars, liquid water is emerging from beneath the ground and briefly flowing down the slopes. This possibility raises questions about how the water would stay melted below ground, how widespread it might be, and whether there's a below-ground wet habitat conducive to life. Future missions may provide the answers," said Malin.

Besides looking for changes in gullies, the orbiter's camera team assessed the rate at which new impact craters appear. The camera photographed approximately 98 percent of Mars in 1999 and approximately 30 percent of the planet was photographed again in 2006. The newer images show 20 fresh impact craters, ranging in diameter from 7 feet (2 meters) to 486 feet (148 meters) that were not present approximately seven years earlier. These results have important implications for determining the ages of features on the surface of Mars. These results also approximately match predictions and imply that Martian terrain with few craters is truly young.

Mars Global Surveyor began orbiting Mars in 1997. The spacecraft is responsible for many important discoveries. NASA has not heard from the spacecraft since early November. Attempts to contact it continue. Its unprecedented longevity has allowed monitoring Mars for over several years past its projected lifetime.

NASA's Jet Propulsion Laboratory, Pasadena, manages the Mars Global Surveyor mission for the NASA Science Mission Directorate, Washington.

For more information about NASA's Mars missions, visit:

MGS provides proof of persistent liquid water flows on Mars:

On, Malin Space Science System has announced that Mars Global Surveyor has now provided the proof that there were persistent liquid water flow on Mars.

The Mars Orbiter Camera (MOC) on board Mars Global Surveyor took pictures started to take high resolution pictures of Mars in September 1997 and has now "only imaged about 3% of the Martian surface with its high resolution (1.5 to 12 meters, 5 to 40 feet, per pixel), narrow angle (NA) camera system." MSSS adds, "Thus, an important discovery from MOC can - and does - come at any time, even five and six years into the mission."

The scientific magazine Science has published on the Internet the most recent MOC discovery: an ancient, eroded, and exhumed sedimentary distributary alluvial area located in a crater at 24.3░S, 33.5░W.

The pictures prove that it is still possible for liquid water to flow across the Martian surface, sediments transported through valleys by water formed a fan-shaped deposit in a 64-kilometer (40 miles) - diameter crater northeast of Holden Crater.

MSSS explains:

"It provides clear, unequivocal evidence that some valleys on Mars experienced the same type of on-going, or, persistent, flow over long periods of time as rivers do on Earth. Second, because the fan is today a deposit of sedimentary rock, it demonstrates that some sedimentary rocks on Mars were, as has been suspected but never clearly demonstrated, deposited in a liquid (probably water) environment. Third, the general shape, pattern of its channels, and low topographic slopes provide circumstantial evidence that the feature was actually a delta - that is, a deposit made when a river or stream enters a body of water. In other words, the landform discovered by MOC may be the strongest indicator yet that some craters and other depressions on Mars once held lakes. Although hundreds of other locations on Mars where valleys enter craters and basins have been imaged by MOC, this is the first to show landforms like those presented here."

Liquid water mud flows observed on Mars:

Aerial photos of frozen Martian sand dunes by MGS have turned up evidence that every summer ice melts out of the dunes and sends rivers of mud flowing down the sides.

The already controversial discovery is the first time that liquid water has been announced to be observed on Mars. Similar patterns were already known, and were a source of scientific conflicts, since some scientists take their existence as evidence of water flow in the distant past, and others explain it as lava flow, landslides, or the movement of carbon dioxide ice.

Referring to the Russell Crater dune field where the mud flows were photographed, Dennis Reiss of the German Aerospace Center who made the discovery said: "these are good future landing sites to search for life."

Dr. Reiss said he studied images of the Russell Crater dunes over a full Martian year noted that the patterns slowly change, which excludes landslides and lava flow. He followed up with an analysis of the dunes' reflectivity and found out that solid carbon dioxide vaporizes in the spring thaw, leaving behind it a layer of water ice as daytime temperatures rise to around 25 C.

This implies that frozen water in the dunes turns liquid in the afternoon of spring and summer days. He said the liquid water then flows down the sides and leaves the telltale patterns. At night, temperatures fall again to -60 C, freezing the mud in place.

The findings are published in the current issue of Geophysical Research Letters.

Successfull launch for Mars Express:

CNES, the small French NASA counterpart, informs that the Mars Express was successfully launch from Ba´konur in Russia in the evening of June 2. The craft is correctly on its way to Mars, which it should reach in the end of December 2003. CNES reports: "The probe carries the Omega and Spicam instruments, developed under French expertise with support from CNES. In addition to the search for water and for possible life forms, scientists mainly hope to get a global view on Mars: its geology, its evolution."


Mars South polar cap also made of water ice:

See here.

NASA's Global Surveyor sees possible climate change on Mars:

There is no need to add much comment to this news item, I will simply reproduce the NASA announcement, to the word:

Mary Hardin
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone: 818/354-0344)

Tim Tawney
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 301/614-6573)

RELEASE: 01-240


The planet Mars we know today is a cold, dry, desert world, but suppose the Martian climate is changing even now, year to year and decade to decade?

New observations by NASA's Mars Global Surveyor spacecraft are expanding understanding of the Martian climate and may indicate the climate is changing significantly even today. This suggests even larger climate changes have occurred during the planet's recent history and may again in its future. The observations were made during a full Martian year, 687 Earth days.

If this is so, Mars might someday become warmer and wetter, as some scientists suggest it was during its early history. Papers detailing these observations are published in the Dec. 7, 2001, issue of Science magazine.

"If the environment of Mars has really changed by as much and over as short a time-scale as our observation implies, there should be attributes of Mars reflecting these changes that may be measurable by landers," said Dr. Michael Malin, principal investigator for Global Surveyor's camera system at Malin Space Science Systems, San Diego. "If Mars had a higher atmospheric pressure in the not-too-distant past, it is more likely that water was present as a liquid near the surface."

Liquid water is required to support known forms of life, and the presence of liquid water on Mars would make it more likely life may once have existed there.

"Detecting evidence of climate change and variability on Mars using Mars Global Surveyor data is an important aspect of telling us where to go on the surface this decade," said Dr. James Garvin, NASA's Lead Scientist for Mars Exploration, Headquarters, Washington. "Clearly, the polar regions are a good place where we would like to look for hydrothermal vents to see if they exist on Mars."

Images from Global Surveyor's camera system show that pits -- often referred to as the "Swiss cheese" terrain -- at the southern polar ice cap of Mars have dramatically increased in diameter, indicating the material has evaporated rapidly compared to last year.

"The amount of change is much larger than any previous change we've seen on Mars and it is much larger than can be explained by the evaporation of water ice. We have calculated the only material that could have changed this much is carbon dioxide ice, what we know as dry ice," said Malin. "This means the Mars environment we see today may not be what it was a few hundred years ago, and may not be what will exist a few hundred years in the future."

A separate observation is providing more detail about the behavior of carbon dioxide in the Martian atmosphere. Carbon dioxide is a "greenhouse gas" believed to warm climates when its atmospheric concentration increases. The spacecraft's laser altimeter and radio tracking system have made precise measurements of the amount and density of carbon dioxide snow in both polar regions. This information gives scientists the first global measurement of the seasonal exchange of carbon dioxide between the atmosphere and surface.

Due to the tilt of the planet, Mars has seasons just like Earth. Scientists have long known the most important seasonal change on Mars is the autumn and winter "freezing out" of carbon dioxide from the atmosphere in the form of dry-ice frost and snow. The evaporation of the surface frost in spring and summer returns carbon dioxide to the atmosphere. Over the course of a Martian year, as much as a quarter of the atmosphere freezes out, but until now scientists didn't know precisely where and how much dry-ice frost and snow would pile up on the surface.

"We have measured how deep the dry-ice snow got on Mars over the course of a year. We have also measured the corresponding tiny change in the gravity field due to carbon dioxide being transported from one pole to the other with the seasons," said Dr. Maria Zuber, deputy principal investigator of the laser altimeter, at the Massachusetts Institute of Technology, Cambridge, and NASA's Goddard Space Flight Center, Greenbelt, Md.

"Snow on Mars is denser than snow on Earth and is really more like ice than snow. Understanding the present carbon dioxide cycle is an essential step towards understanding past Martian climates," Zuber said.

NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif., manages the Mars Global Surveyor mission for NASA's Office of Space Science, Washington. JPL is a division of the California Institute of Technology, Pasadena.

11.12.2001 - Active volcanism still today:

Scientists evaluated a new Mars late last week during the Geological Society of America's (GSA) annual meeting, held in Boston, Massachusetts.

New data by the Mars Global Surveyor (MGS) camera, and the Mars Orbiter Laser Altimeter (MOLA) show evidence for ongoing volcanic activity, with geological features tied to recent floods. Both these volcanic and hydrologic events are young, geologically speaking, and could perhaps still occur on Mars in the future, bolstering the prospect that life is firmly rooted on the red planet.

Past studies have shown some volcanic flows likely traveled over ice-rich ground. At least one flow originated from the long rift-type vents of the Cerberus Fossae on Mars. Also, recent floods originated from the vent system, perhaps depositing water in the shallow subsurface for later volcanic flows to interact with.

Susan Sakimoto, a NASA Goddard Earth Science and Technology Center scientist in Greenbelt, Maryland, along with several research colleagues, reported that that new data reveals regionally extensive lava eruptions on Mars. Moreover, they believe that a strong case can be made for both volcanic and hydrologic features in those areas being young and related in origin.

Sakamoto explained:

"From the apparent age range of flows within the region, this is clearly a long-lived volcanic province. Future hydrologic and/or volcanic events are still conceivable."

"These are absolutely beautiful examples of plains volcanism. Based on the convergence of fluvial and volcanic features in the topography, evidence for their interaction, their inter-linked deposits, flow model results of the eruption rates, and the episodic nature of the eruption style, and their youth, it is clear to us that the potential for continuing eruptions in the next several tens of millions of years ought to be good."

"I am one of a growing number of planetary scientists who are starting to seriously think that Mars may well be still 'percolating' volcanically," Sakimoto told The Cerberus Fossae/Elysium Basin region has apparently been erupting fairly periodically over at least the last hundred million years, up until the recent geologic past -- a few million years, she said.

"While we might have to wait several million years (or more) to catch another pulse of floods or lava, there seems little reason to think the region has recently shut down after 100-plus million years of sporadic activity," Sakimoto argued.

"So, I am using 'active' only in the Martian geology sense of the word. I do think there is a reasonably decent chance of them erupting again, but the time scales are most definitely geologic, rather than human," she concluded.

Among the ramifications of the new discovery is a potential for ongoing thermal and water sources to sustain or start an environment compatible with life. This environment may have occurred in recent Martian geologic time, and could still be present today, according to Sakimoto.

It must not be forgotten that scientists have recently learned that bacterial life on Earth is able to sustain million years of complete metabolic and chemical inactivity and simply revive when conditions allow it.

Valid XHTML 1.0 Strict

 Feedback  |  Top  |  Back  |  Forward  |  Map  |  List |  Home
This page was last updated on May 26, 2008.