New Clues Suggest Wet Era on Early Mars Was Global (w/ Video)

Jun 24, 2010
Lyot Crater, pictured here, is one of at least nine craters in the northern lowlands of Mars with exposures of hydrated minerals detected from orbit, according to a June 25, 2010, report. Image Credit: NASA/ESA/JPL-Caltech/JHU-APL/IAS

(PhysOrg.com) -- Minerals in northern Mars craters seen by two orbiters suggest that a phase in Mars' early history with conditions favorable to life occurred globally, not just in the south.

Southern and northern Mars differ in many ways, so the extent to which they shared ancient environments has been open to question.

In recent years, the European Space Agency's Mars Express orbiter and NASA's have found clay minerals that are signatures of a wet environment at thousands of sites in the southern highlands of Mars, where rocks on or near the surface are about four billion years old. Until this week, no sites with those minerals had been reported in the northern lowlands, where younger has buried the older surface more deeply.

French and American researchers report in the journal Science this week that some large craters penetrating younger, overlying rocks in the northern lowlands expose similar mineral clues to ancient wet conditions.

"We can now say that the planet was altered on a global scale by about four billion years ago," said John Carter of the University of Paris, the report's lead author.

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Mars Express' OMEGA sensor has provided the first hints that there may be hydrated silicates beneath the northern plains of Mars, as well as in the southern highlands. This suggests that the early wet phase of Mars was global in extent. Credit: ESA (C. Carreau)

Other types of evidence about liquid water in later epochs on Mars tend to point to shorter durations of wet conditions or water that was more acidic or salty.

The researchers used the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), an instrument on the Mars Reconnaissance Orbiter, to check 91 craters in the northern lowlands. In at least nine, they found clays and clay-like minerals called phyllosilicates, or other hydrated silicates that form in wet environments on the surface or underground.

Earlier observations with the OMEGA spectrometer on Mars Express had tentatively detected phyllosilicates in a few craters of the northern plains, but the deposits are small, and CRISM can make focused observations on smaller areas than OMEGA.

"We needed the better spatial resolution to confirm the identifications," Carter said. "The two instruments have different strengths, so there is a great advantage to using both."

Observations of craters in northern Mars, including Stokes Crater, have found hydrated minerals indicating that a wet phase of early Martian history extended to the whole planet. Image Credit: NASA/ESA/JPL-Caltech/JHU-APL/MSSS/FU-Berlin

CRISM Principal Investigator Scott Murchie of Johns Hopkins University Applied Physics Laboratory, Laurel, Md., a co-author of the new report, said that the findings aid interpretation of when the wet environments on ancient Mars existed relative to some other important steps in the planet's early history.

The prevailing theory for how the northern part of the planet came to have a much lower elevation than the southern highlands is that a giant object slammed obliquely into northern , turning nearly half of the planet's surface into the solar system's largest impact crater. The new findings suggest that the formation of water-related minerals, and thus at least part of the wet period that may have been most favorable to life, occurred between that early giant impact and the later time when younger sediments formed an overlying mantle.

"That large impact would have eliminated any evidence for the surface environment in the north that preceded the impact," Murchie said. "It must have happened well before the end of the wet period."

The report's other two authors are Francois Poulet and OMEGA Principal Investigator Jean-Pierre Bibring, both of the University of Paris.

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User comments : 8

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JCincy
3 / 5 (2) Jun 24, 2010
Marvin the Martian, speaking of Earth: "Oh, I'm going to blow it up; it obstructs my view of Venus."

I wonder if Marvin was from North Mars or South Mars?
deatopmg
2 / 5 (3) Jun 24, 2010
So, if conditions for evolution of life on Mars were global and these conditions lasted a long time, as it now appears, then it is very highly probable that life still exists today, some of which is continually replenishing the small amount of oxygen present in the atmosphere and generating the methane found emanating from the moist soils. No unknown mysterious chemical reactions need to be invoked by the obfuscators.
yyz
5 / 5 (1) Jun 24, 2010
"No unknown mysterious chemical reactions need to be invoked by the obfuscators"

Wouldn't it be wise to rule out any abiogenic origin for Martian methane first?
deatopmg
2.3 / 5 (3) Jun 24, 2010
@VVz - Those are the mysterious, magical, unknown abiogenic chemical reactions invoked by NASA. I'm a chemist invoking Occam's razor; the simplest answer is life is generating both CH4 AND O2.
yyz
3 / 5 (1) Jun 24, 2010
@deatopmg, Just the same, I'll wait to see what consensus evolves among other astrochemists.
ubavontuba
2 / 5 (4) Jun 25, 2010
I vote for life as a reasonable suspicion too. Recently, NASA found a fibrous rock that looks quite like fossilized bio-material (similar to petrified wood samples).

Here's an image:

http://cdn.physor...rexa.jpg

Obviously this isn't proof of life, but it's an interesting find.
deepeast
5 / 5 (2) Jun 25, 2010
John Carter of the University of Paris, the report's lead author. Is this the same John Carter who is the Warlord of Mars and lives in the twin cities of Helium?
ubavontuba
1 / 5 (1) Jun 25, 2010
John Carter of the University of Paris, the report's lead author. Is this the same John Carter who is the Warlord of Mars and lives in the twin cities of Helium?
LOL! That's a great Edgar Rice Burroughs reference!