BRIDGEPORT, WV (S-M) - ESA officials announced Monday that scientists are using a novel technique to study the atmospheres of Earth, Mars and Venus.


The technique involves using a spectroscope mounted on a satellite to watch stars as they set behind a planet. Just before the star sets, it can be seen through the planet's atmosphere, and molecules in the atmosphere change the starlight in ways which tell scientists about the chemical makeup of the atmospheric gasses.


"Scientists have used these so-called occultations to indirectly study the properties of objects like the Moon for years," said Senior Editor Glen Ward. "But this technique of using satellites to watch occultations by a planet being orbited is really exciting."


The ESA said scientists using the Envisat satellite recently noticed a buildup of nitrogen dioxide high in the Earth's atmosphere. Over the next two months, scientist watched as the chemical descended through the atmosphere, destroying ozone along the way. "It’s still too early to say whether the ozone is recovering or not," Jean-Loup Bertaux of the French Service d'Aeronomie said in a release.


Meanwhile, at Mars, the Mars Express probe is using a spectroscope to watch stars being occulted by the red planet. "Atmospheric profiles of Mars are important for designing parachutes for landing craft," said Bertaux. Scientists have discovered that the Martian atmosphere sometimes develops long-lasting haze layers.


Bertaux was the first to suggest the occultation technique to the ESA, and he is pleased with the results. "I think the stellar occultation technique is now ‘combat proven’ and should be useful for further long-term studies," he said. - GW

Copyright 2007 Starry Mirror and Glen Ward

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