Mars Express observes aurorae on the Red PlanetNovember 24, 2008Scientists 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. 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 higher-than-expected electrons in similar regions. This suggests, although it does not prove, that the magnetic fields help to create the aurorae. On Earth, aurorae are more commonly known as the northern and southern lights. They are confined to the polar regions and shine brightly at visible as well as ultraviolet wavelengths. The existence of similar aurorae is well known on the giant planets of the Solar System. They occur wherever a planet's magnetic field channels electrically charged particles into the atmosphere. In all of these planets, the magnetic fields are large-scale structures generated deep in the interior of the planet. Mars lacks such a large-scale internal mechanism. Instead, it just generates small pockets of magnetism where areas of rocks in the crust of Mars are themselves magnetic. This results in many magnetic pole-type regions all over Mars. The aurorae are caused by charged particles, in this case most probably electrons, colliding with molecules in the atmosphere. The electrons almost certainly come from the Sun, which constantly blows out electrically charged particles into space. Known as the solar wind, this constant stream of particles provides the source of electrons to generate the aurorae, as suggested by MARSIS and ASPERA. But how the electrons are accelerated to sufficiently high energies to spark aurorae on Mars remains a mystery. "It may be that magnetic fields on Mars connect with the solar wind, providing a road for the electrons to travel along," says Leblanc. Any future astronauts expecting a spectacular light show, similar to aurorae on Earth, may be in for a disappointment. "We're not sure whether the aurorae will be bright enough to be observed at visible wavelengths," says Leblanc. This is because the molecules responsible for the visible light show on Earth - molecular and atomic oxygen and molecular nitrogen - are not abundant enough in the martian atmosphere. SPICAM is designed to work at ultraviolet wavelengths and cannot see whether visible light is being emitted as well. Nevertheless, there is plenty of work for the scientists to do. "There's now a large domain of physics that we have to explore in order to understand the aurorae on Mars. Thanks to Mars Express we have a lot of very good measurements to work with," says Leblanc. European Space Agency |
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| Related Mars Express Current Events and Mars Express News Articles Mars, methane and mysteries 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. Mountain on Mars may answer big question The Martian volcano Olympus Mons is about three times the height of Mount Everest, but it's the small details that Rice University professors Patrick McGovern and Julia Morgan are looking at in thinking about whether the Red Planet ever had - or still supports - life. Important role of groundwater springs in shaping Mars Data and images from Mars Express suggest that several Light Toned Deposits, some of the least understood features on Mars, were formed when large amounts of groundwater burst on to the surface. Mars Express mission controllers ready for NASA Phoenix landing ESA's Mars Express mission control team are ready to monitor Phoenix's critical entry, descent and landing onto the Martian surface on 26 May 2008. Artificial intelligence boosts science from Mars Artificial intelligence (AI) being used at the European Space Operations Centre is giving a powerful boost to ESA's Mars Express as it searches for signs of past or present life on the Red Planet. Plan to identify watery Earth-like planets develops Astronomers are looking to identify Earth-like watery worlds circling distant stars from a glint of light seen through an optical space telescope and a mathematical method developed by researchers at Penn State and the University of Hawaii. Mars Express reveals the Red Planet's volcanic past A new analysis of impact cratering data from Mars reveals that the planet has undergone a series of global volcanic upheavals. These violent episodes spewed lava and water onto the surface, sculpting the landscape that ESA's Mars Express looks down on today. Mars and Venus are surprisingly similar Using two ESA spacecraft, planetary scientists are watching the atmospheres of Mars and Venus being stripped away into space. The simultaneous observations by Mars Express and Venus Express give scientists the data they need to investigate the evolution of the two planets' atmospheres. Ice clouds put Mars in the shade Until now, Mars has generally been regarded as a desert world, where a visiting astronaut would be surprised to see clouds scudding across the orange sky. However, new results show that the arid planet possesses high-level clouds that are sufficiently dense to cast a shadow on the surface. Setting stars reveal planetary secrets Watching the stars set from the surface of the Earth may be a romantic pastime but when a spacecraft does it from orbit, it can reveal hidden details about a planet's atmosphere. More Mars Express Current Events and Mars Express News Articles |
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