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Aug 18, 2009 | 5
A NASA probe that ferried material from a comet to Earth appears to have brought back an amino acid from that encounter, bolstering a theory that life's precursors may have arrived on our planet from outer space.
The Stardust spacecraft, launched in 1999, passed through Comet Wild 2 in 2004, soaking up particulates and gas with a unique, lightweight capture material known as aerogel. The sample-return portion of the spacecraft dropped safely to Earth during a flyby of our planet two years later.
Early analysis of the samples revealed the presence of biological building blocks such as amino acids, but terrestrial contamination remained a possible explanation for their occurrence.
Jun 1, 2009 | 1
To find out what water might look like on alien worlds, a group of researchers decided to see how Earth's oceans would appear from afar, as if from another planet.
Using the Deep Impact/EPOXI spacecraft, currently headed for a rendezvous next year with Comet Hartley 2, they peered back at Earth from more than 30 million miles (50 million kilometers) away, tracking the way reflected light changes as oceans rotate in and out of view.
From that distance, Earth's surface features were blurred [see photo at left], but the presence of water passing through the spacecraft's view increased the planet's blueness. Landmasses, on the other hand, lent a reddish hue. The team of researchers was able to assemble from those color variations a rough map of the liquid and land boundaries on Earth, presented in a paper set to be published in the Astrophysical Journal.
Feb 3, 2009 | 1
Titan, Saturn's largest moon, has a curious abundance of methane, both in its atmosphere and in massive liquid pools on the surface. As with Mars, the presence of the relatively short-lived compound on Titan raises questions about its origin. (Methane comes largely from biological processes on Earth, but other celestial bodies might have different primary sources for the hydrocarbon, such as subsurface geologic activity—Titan appears to be something of a long shot for sustaining life.)
Satellite data from NASA's Cassini mission continue to provide clues as to the workings of Titan's methane cycle. A new paper in Geophysical Research Letters details the latest findings from Cassini, including a vast system of hydrocarbon (methane and ethane) lakes near the poles that appear to be replenished by seasonal precipitation from storm clouds. One of the lakes, whose discovery was announced last summer, is comparable in surface area to Lake Ontario.
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