Tag: Mars Express

Mars Express has found more evidence that Mars once had oceans.

10:00 am

Mars Express has found more evidence that Mars once had oceans.

Two oceans have been proposed: 4 billion years ago, when warmer conditions prevailed, and also 3 billion years ago when subsurface ice melted following a large impact, creating outflow channels that drained the water into areas of low elevation.

“MARSIS penetrates deep into the ground, revealing the first 60–80 metres of the planet’s subsurface,” says Wlodek Kofman, leader of the radar team at IPAG. “Throughout all of this depth, we see the evidence for sedimentary material and ice.” The sediments revealed by MARSIS are areas of low radar reflectivity. Such sediments are typically low-density granular materials that have been eroded away by water and carried to their final destination.

This later ocean would however have been temporary. Within a million years or less, Dr Mouginot estimates, the water would have either frozen back in place and been preserved underground again, or turned into vapour and lifted gradually into the atmosphere. “I don’t think it could have stayed as an ocean long enough for life to form.”

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Mountains and buried ice on Mars

9:03 am

Mountains and buried ice on Mars.

New images from the high-resolution stereo camera on ESA’s Mars Express orbiter allow a closer inspection [of the Phlegra Montes mountain range] and show that almost every mountain is surrounded by ‘lobate debris aprons’ – curved features typically observed around plateaus and mountains at these latitudes. Previous studies have shown that this material appears to have moved down the mountain slopes over time, and looks similar to the debris found covering glaciers here on Earth.

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Mars Express takes a close look at the Mars volcano Tharsis Tholus

12:20 pm

Mars Express takes a close look at one of Mars’ giant volcanoes, Tharsis Tholus.

At least two large sections have collapsed around its eastern and western flanks during its four-billion-year history and these catastrophes are now visible as scarps up to several kilometers high. The main feature of Tharsis Tholus is, however, the caldera in its center. It has an almost circular outline, about 32 x 34 km, and is ringed by faults that have allowed the caldera floor to subside by as much as 2.7 km.

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Mars atmosphere has more water vapor than predicted

6:46 pm

Data from Mars Express has found that the Martian upper atmosphere has far more water vapor than predicted.

“The vertical distribution of water vapour is a key factor in the study of Mars’ hydrological cycle, and the old paradigm that it is mainly controlled by saturation physics now needs to be revised,” said Luca Maltagliati [of the Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS) in Guyancourt, France]. “Our finding has major implications for understanding the planet’s global climate and the transport of water from one hemisphere to the other.”

“The data suggest that much more water vapour is being carried high enough in the atmosphere to be affected by photodissociation,” added Franck Montmessin, also from LATMOS, who is the Principal Investigator for SPICAM and a co-author of the paper. “Solar radiation can split the water molecules into oxygen and hydrogen atoms, which can then escape into space. This has implications for the rate at which water has been lost from the planet and for the long-term evolution of the Martian surface and atmosphere.”

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