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UK Moon mission gets
green light

...the UK-led MoonLITE mission that will see penetrator darts embedded into the lunar surface has entered into a ‘Phase-A’ study period...

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Students discover planet orbiting rapidly rotating hot star

...three undergraduate students from Leiden University have discovered the first extrasolar planet orbiting a fast-rotating hot star...

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Spitzer paints portrait of gaseous rivers flowing around stars

...a new image from NASA's Spitzer Space Telescope shows a turbulent star-forming region where rivers of gas and stellar winds are blowing out cavities in the dusty Swan nebula....

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Video archive

STS-120 day 2 highlights

Flight Day 2 of Discovery's mission focused on heat shield inspections. This movie shows the day's highlights.


STS-120 day 1 highlights

The highlights from shuttle Discovery's launch day are packaged into this movie.


STS-118: Highlights

The STS-118 crew, including Barbara Morgan, narrates its mission highlights film and answers questions in this post-flight presentation.

 Full presentation
 Mission film

STS-120: Rollout to pad

Space shuttle Discovery rolls out of the Vehicle Assembly Building and travels to launch pad 39A for its STS-120 mission.


Dawn leaves Earth

NASA's Dawn space probe launches aboard a Delta 2-Heavy rocket from Cape Canaveral to explore two worlds in the asteroid belt.

 Full coverage

Dawn: Launch preview

These briefings preview the launch and science objectives of NASA's Dawn asteroid orbiter.

 Launch | Science

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Hubble finds carbon dioxide on exoplanet

Posted: 10 December, 2008

NASA's Hubble Space Telescope has discovered carbon dioxide in the atmosphere of a hot jupiter planet, a crucial step towards finding the chemical tracers of extraterrestrial life in other solar systems.

"In the terrestrial planets of our Solar System, carbon dioxide plays a crucial role for the stability of climate, says Giovanna Tinetti from University College London. “On Earth, carbon dioxide is one of the ingredients of the photosynthesis and a key element for the carbon cycle. Our observations represent a great opportunity to understand the role of carbon dioxide in the atmospheres of hot Jupiter-type planets."

Although the Jupiter-sized planet HD 189733b is far too hot for life, the Hubble observations demonstrate that the basic chemistry for life can be measured on planets orbiting other stars. Previous observations of HD 189733b by Hubble and the Spitzer Space Telescope identified water vapour and methane in the planet's atmosphere. "This is exciting because Hubble is allowing us to see molecules that probe the conditions, chemistry, and composition of atmospheres on other planets," says team leader Mark Swain of NASA's Jet Propulsion Laboratory. "Thanks to Hubble we're entering an era where we are rapidly going to expand the number of molecules we know about on other planets."

Artist impression of HD 189733b, which lies 63 light years away. Astronomers have now detected carbon dioxide and carbon monoxide in the planet’s atmosphere, in addition to methane and water vapour. Image: NASA, ESA, and A. Feild (STScI).

Swain and colleagues used Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) to study infrared light emitted from the planet as it routinely passed in front of and behind its parent star once every 2.2 days. This afforded the astronomers the opportunity to subtract the light of the star alone (when the planet is blocked) from that of the star and planet together prior to eclipse, therefore isolating the emission of the planet alone and arriving at a chemical analysis of its ‘day-side’ atmosphere. "In this way, we are using the eclipse of the planet behind the star to probe the planet's day side, which contains the hottest portions of its atmosphere," says team member Guatam Vasisht of JPL. "We are starting to find the molecules and to figure out how many there are to see the changes between the day side and the night side."

The observations revealed the spectral fingerprints of not only carbon dioxide, but also carbon monoxide. This is the first time a near-infrared emission spectrum has been obtained for an exoplanet. "The carbon dioxide is kind of the main focus of the excitement, because that is a molecule that under the right circumstances could have a connection to biological activity as it does on Earth," says Swain. "The very fact that we're able to detect it, and estimate its abundance, is significant for the long-term effort of characterising planets both to find out what they're made of and to find out if they could be a possible host for life."

This successful demonstration of looking at near-infrared light
emitted from a planet is very encouraging for astronomers planning to use NASA's James Webb Space Telescope (JWST) when it is launched in 2013, since these biomarkers are best seen at near-infrared wavelengths and furthermore, astronomers hope to detect and study Earthlike planets with it. Meanwhile, the international research team plans to search for more bio-molecules in the atmospheres of other exoplanets, as well as trying to increase the number of molecules detected in exoplanet atmospheres, which could yield new information regarding the weather on these distant worlds.