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Mars Express radar gives strong evidence for former Mars ocean

Mars Express radar gives strong evidence for former Mars ocean

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ESA’s Mars Express has returned strong evidence for an ocean once covering part of Mars. Using radar, it has detected sediments reminiscent of an ocean floor within the boundaries of previously identified, ancient shorelines on Mars.

The MARSIS radar was deployed in 2005 and has been collecting data ever since. Jérémie Mouginot, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG) and the University of California, Irvine, and colleagues have analysed more than two years of data and found that the northern plains are covered in low-density material. “We interpret these as sedimentary deposits, maybe ice-rich,” says Dr Mouginot. “It is a strong new indication that there was once an ocean here.”

The existence of oceans on ancient Mars has been suspected before and features reminiscent of shorelines have been tentatively identified in images from various spacecraft. But it remains a controversial issue.

Two oceans have been proposed: 4 billion years ago, when warmer conditions prevailed, and also 3 billion years ago when subsurface ice melted, possibly as a result of enhanced geothermal activity, creating outflow channels that drained the water into areas of low elevation.

Mars Express radar investigation “MARSIS penetrates deep into the ground, revealing [...]

Rocky mounds and a plateau on Mars

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When Mars Express set sail for the crater named after Portuguese navigator Ferdinand Magellan, it found a windblown plateau and mysterious rocky mounds nearby.

Stretching across 190 x 112 km, this region of Mars covers an area of about 21 280 sq km, which is roughly the size of Slovenia. It is located to the southwest of the volcanic region Tharsis on the southern highlands of Mars, near the crater Magellan.

Named after the famous Portuguese navigator and explorer Ferdinand Magellan, the impact crater is about 100 km across. Only a small portion of the crater rim is visible in this image, sitting at the lower right, because the Mars Express High-Resolution Stereo Camera (HRSC) has zeroed in on some intriguing features nearby.

In the west of this region (at the upper edge of the main image) there are light-coloured, irregular protrusions. These features are up to 2 km tall and are probably large rock fragments or mounds of rock. However, their formation is still debated.

One possibility is that the top layer of rock was shattered by the shockwaves from an impact. Another possible explanation would be from a process called subrosion. On [...]

Phobos Flyby Success

Phobos Flyby Success

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Mars Express encountered Phobos last night, smoothly skimming past at just 67 km, the closest any manmade object has ever approached Mars’ enigmatic moon. The data collected could help unlock the origin of not just Phobos but other ‘second generation’ moons.

Something is not right about Phobos. It looks like a solid object but previous flybys have shown that it is not dense enough to be solid all the way through. Instead, it must be 25-35% porous. This has led planetary scientists to believe that it is little more than a ‘rubble pile’ circling Mars. Such a rubble pile would be composed of blocks both large and small resting together, with possibly large spaces between them where they do not fit easily together.

Last night’s flyby was close enough to give scientists their most exquisite data yet about the gravitational field of Phobos. Mars Express locked onto the radio signal from Earth at around 21:20 CET (20:20 UT). The radio frequency oscillators on the ground are 100 000 times more stable than those on the spacecraft, so for this experiment, which required the best precision possible, the signal was sent up to Mars Express and then returned [...]

Mars, methane and mysteries


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Mars may not be as dormant as scientists once thought. The 2004 discovery of methane means that either there is life on Mars, or that volcanic activity continues to generate heat below the martian surface. ESA plans to find out which it is. Either outcome is big news for a planet once thought to be biologically and geologically inactive. The methane mystery started soon after December 2003, when ESA’s Mars Express arrived in orbit around the red planet. As the Planetary Fourier Spectrometer (PFS) began taking data, Vittorio Formisano, Istituto di Fisica dello Spazio Interplanetario CNR, Rome, and the rest of the instrument team saw a puzzling signal. As well as the atmospheric gases they were anticipating, such as carbon monoxide and water vapour, they also saw methane. “Methane was a surprise, we were not expecting that,” says Agustin Chicarro, ESA Mars Lead Scientist. The reason is that on Earth much of the methane in our atmosphere is released by evolved life forms, such as cattle digesting food. While there are ways to produce methane without life, such as by volcanic activity, it is the possible biological route that has focused attention on the discovery. The Mars [...]

Mars Express observes aurorae on the Red Planet


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Scientists using ESA’s Mars Express have produced the first crude map of aurorae on Mars. These displays of ultraviolet light appear to be located close to the residual magnetic fields generated by Mars’s crustal rocks. They highlight a number of mysteries about the way Mars interacts with electrically charged particles originating from the Sun.

The aurorae on Mars were discovered in 2004 using the SPICAM ultraviolet and infrared atmospheric spectrometer on board Mars Express. They are a powerful tool with which scientists can investigate the composition and structure of the Red Planet’s atmosphere.

Now Francois Leblanc, from the Service d’Aéronomie, IPSL/CNRS, France and colleagues have announced the results of coordinated observation campaigns using SPICAM, the MARSIS sub-surface sounding radar altimeter’s radar, and the energetic neutral atoms analyser, ASPERA’s electron spectrometer on Mars Express.

“Any future astronauts expecting a spectacular light show, similar to aurorae on Earth, may be in for a disappointment.” They have observed nine new auroral emission events, which have allowed them to make the first crude map of auroral activity on Mars. They see that the aurorae seem to be located near regions where the martian magnetic field is the strongest. MARSIS had previously observed [...]

Mars Express radar gauges water quantity around Mars’ south pole


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The amount of water trapped in frozen layers over Mars’ south polar region is equivalent to a liquid layer about 11 metres deep covering the planet.

This new estimate comes from mapping the thickness of the dusty ice by the Mars Express radar instrument that has made more than 300 virtual slices through layered deposits covering the pole. The radar sees through icy layers to the lower boundary, which in places is as deep as 3.7 kilometres below the surface.

“The south polar layered deposits of Mars cover an area as wide as a big portion of Europe. The amount of water they contain has been estimated before, but never with the level of confidence this radar makes possible,” said Dr Jeffrey Plaut of NASA’s Jet Propulsion Laboratory, Pasadena (California), co-Principal Investigator for the radar and lead author of the study.

The instrument, named the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS), is also mapping the thickness of similar layered deposits at the north pole of Mars.

“Our radar is doing its job extremely well,” said Prof. Giovanni Picardi of the University of Rome ‘La Sapienza’, Principal Investigator for the instrument. “MARSIS is showing to be [...]

First spectacular results from Mars Express


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ESA PR 05-2004. ESA’s Mars Express, successfully inserted into orbit around Mars on 25 December 2003, is about to reach its final operating orbit. The first scientific results already look very promising, as this first close-up image shows.

Although the seven scientific instruments on board Mars Express are still undergoing a thorough calibration phase, they have already started collecting amazing results. The first high-resolution images and spectra of Mars have already been acquired.

This first spectacular stereoscopic colour picture was taken on 14 January 2004 by ESA’s Mars Express satellite from 275 kilometres above the surface of Mars by the High Resolution Stereo Camera (HRSC). This image is available on the ESA Portal at: http://mars.esa.int

The picture shows a portion of a 1700 km long and 65 km wide swath which was taken in south-north direction across the Grand Canyon of Mars (Valles Marineris). It is the first image of this size that shows the surface of Mars in high resolution (12 metres per pixel), in colour, and in 3D. The total area of the image on the Martian surface (top left corner) corresponds to 120 000 km².

This perspective view was generated on a computer from the [...]