Tag Archives: atmosphere

Last Martian Ice Age still waning

The neutron and gamma-ray spectrometers on NASA’s Mars Odyssey discovered that water ice lies at shallow depths from the polar regions down to latitudes of about 55° north and south. Images of very recent craters by the HiRISE camera on … Continue reading

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Wind triggers activity in north polar dunes

The sand sea surrounding the Martian north pole covers an area about a third the size of Earth’s Arabian Desert and is roughly equal in size to the Kalahari. Dunes are a common feature on Mars, just as in terrestrial … Continue reading

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UV light makes methane from meteorites

Methane gas, which can arise from both biological and geological sources, was detected in the Martian atmosphere by observations from Earth-based telescopes in 2003 and from the Mars Express orbiter (2004). As methane breaks down relatively quickly under Martian conditions, … Continue reading

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Mars has carbon — it’s just not biological

A highly detailed study of 11 meteorites that have come from Mars shows that although 10 of them contain the organic element carbon, the source of the carbon is not biological in origin. Instead, the carbon lies as molecules inside … Continue reading

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Did ice and dust make layered deposits in Valles Marineris?

Vast mounds of layered material lie in numerous places throughout the giant canyon system of Valles Marineris, and especially in Candor Chasma, Ophir Chasma, and Melas Chasma. The origin of these “interior layered deposits” (ILDs) have been debated since they … Continue reading

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Seasonal changes seen in south polar gullies

Images from the HiRISE camera on NASA’s Mars Reconnaissance Orbiter have captured the first visible evidence for seasonal changes in gullies on slopes in the south polar region of Mars. Giving a report (PDF) at the 43rd Lunar and Planetary … Continue reading

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Home Plate’s volcanic bomb landed with a splat

One of the unusual features that Mars Exploration Rover Spirit discovered at Home Plate, a former hydrothermal vent in the Columbia Hills, was a “bomb sag,” complete with its partially embedded volcanic bomb. To geologists, volcanic bombs are rocks or … Continue reading

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When Apollinaris Patera went boom

Stretching more than 5,000 kilometers (3,000 miles) between the two volcanic centers of Tharsis and Elysium is a geological enigma, the Medusae Fossae formation. The formation, which lies in several separate patches, appears to be made of easily eroded materials, … Continue reading

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Early Martian surface radiation not too strong for life

During the Noachian period (about 4.5 to 3.5 billion years ago), the Martian atmosphere was substantially thicker than it is currently, and the planet had a magnetosphere with a surface field strength about as strong as Earth’s today. Both factors … Continue reading

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Did lake-effect storms make Martian snowbelts?

Numerous places on Mars show erosion by precipitation, whether as rainfall or runoff from melting snow. The precipitation could have come from a thicker atmosphere or a temporary boost in atmospheric temperature and density following a large impact. Both scenarios … Continue reading

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