by Timothy Oleson Monday, October 6, 2014
As Curiosity and Opportunity rove around Mars, the Mars Reconnaissance Orbiter (MRO), Mars Express and Mars Odyssey orbit above, and scientists on Earth study the Red Planet from afar, new findings are announced almost weekly. Here are a few of the latest updates.
The U.S. Geological Survey (USGS) has produced a new, detailed geologic map of the Red Planet’s surface using data collected over 16 years by four Mars-orbiting spacecraft: Mars Global Surveyor, Mars Odyssey, Mars Express and MRO. The new map offers a substantially updated view of Mars compared to earlier versions, which used data from the Mariner 9 and Viking Orbiter missions. The map illustrates, among other details, that three times more of the planet’s surface formed about 4 billion years ago than was previously thought. The map “will enable researchers to evaluate potential landing sites for future Mars missions” and “will provide geologic context for regional and local scientific investigations for many years to come,” said USGS Acting Director Suzette Kimball in a statement. The map is available for download at http://pubs.usgs.gov/sim/3292/.
Mars is too cold year-round to support pure liquid water, but scientists mimicking the Martian surface in a laboratory have found that liquid brines can form under realistic conditions. When the researchers placed grains of calcium perchlorate salt in contact with water ice — both of which are known to be present in Martian soils — in a simulated Mars atmosphere, the ice began melting when the temperature was above minus 73 degrees Celsius. The work suggests that liquid brine solutions may form temporarily during the Martian spring, when parts of Mars' surface warm above that temperature for several hours each day, reported Erik Fischer of the University of Michigan and colleagues in Geophysical Research Letters. Such short-lived liquid brines could explain the formation of gullies observed on crater rims, and could offer habitable environments for microbes, according to a press release about the findings.
As this issue of EARTH went to press, NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) had just successfully arrived in orbit around Mars. It was expected to be joined a few days later by India’s Mars Orbiter Mission (MOM). MAVEN will study Mars' upper atmosphere with the goal of understanding the planet’s loss of volatile elements and gases to space over time; as India’s first interplanetary mission, MOM is partly intended as a technological test, although it is also equipped with instruments to study Mars' surface and atmosphere, including measuring methane levels. The pair join the trio of orbiters and pair of rovers currently exploring the planet.
Press time for EARTH also preceded the close flyby of Comet Siding Spring past Mars on Oct. 19. First observed in January 2013, the comet is expected to pass within about 132,000 kilometers of Mars — roughly a third of the distance between Earth and the moon — and to shower the Red Planet with dust. Siding Spring’s passing offers a rare opportunity, of which NASA and the European Space Agency hope to take advantage, to view a comet and its tail up close. But both agencies are also taking precautions to protect the Mars fleet from the potentially damaging debris streaming off the comet.
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