Planet shine 'to aid life search' (BBC) {extrasolar planets}

[eppur_se_muova]

By Jonathan Amos
BBC News science reporter, in Baltimore

Earth-like planets around distant stars may be too far away to be reached by spacecraft but scientists could still investigate whether they harbour life.

Telescope technologies are being developed that will probe the very faint light from these objects for tell-tale signs of biology.
***
They include signatures for water, and gases such as oxygen and methane.

"This gives you some information on habitability," said Wesley Traub, chief scientist on the US space agency's (Nasa) Navigator Program which specialises in the search for far-off worlds.

"These are only signs of life; they are only indicators. You can't actually detect the life itself crawling or sliming around on the surface of the planet," he told the American Geophysical Union Joint Assembly here in Baltimore, US.
***
http://news.bbc.co.uk/2/hi/science/nature/5010936.stm

This would require more funding for NASA. Maybe after the impeachment. Or we could just watch the Euros beat us to it.

[electron_blue]

1. very cool!

This is the one of the most exciting fields in astronomy.

[xchrom]

2. they could detect me

in some of my disco get-ups.

[Canuckistanian]

3. I don't understand this

They didn't detect these planets by looking at the light reflected from planets, they detected them by the planets blocking light from a star.

So now they have the capability to detect faint reflected light?

If so, that's astounding.

[eppur_se_muova]

5. They can't resolve an image of the planet, but they can detect the light.

Specifically, what they're doing is splitting the light from a telescope image of the star (and planet(s)) into a spectrum and then looking for absorption bands of things like oxygen, ozone and methane, and then assuming those must have arisen by reflection from a planetary atmosphere. Since these substances are really unlikely to be found elsewhere, that's a good clue to their presence in a planetary atmosphere, and after a couple more steps of deductive logic, the *possible* presence of life.

In principle, this has always been possible, but there have been certain *ahem* technical details to work out. As with most things in astronomy, it's basically a question of catching enough light, which means building bigger mirrors and/or hoisting them above Earth's atmosphere. (Since Earth's atmosphere contains gobs of the things they're looking for, the TPF just about has to go into space.) Of course, once you decide that there are planets there to look at, then it's worth the extra effort to try doing the spectroscopy. But until you reach that point, it's faster/easier/cheaper to carry out the search for the 'mere'(!) presence of planets by looking for occulation or precession with more conventional telescopic methods.

[Canuckistanian]

8. So they're just looking at spectrograms of the stars, then?

And then trying to see diferences over time? I agree, that'll take a lot of light gathering power.

It might have to wait for the next generation of space-based telescopes.

[Dudley_DUright]

4. NASA funding for this type of space science is very tight right now

due to the Decider's emphasis on manned missions to the moon and mars. Here is the NASA site describing the terrestrial planet finder missions.

http://planetquest.jpl.nasa.gov/TPF/tpf_index.cfm

[eppur_se_muova]

6. ESA is planning a project called "Darwin" ... very ambitious. (link)

http://www.esa.int/esaSC/120382_index_0_m.html

Darwin consists of four separate spacecraft. Three of the spacecraft will carry 3-4 metre 'space telescopes', or more accurately light collectors, based on the Herschel design. These will redirect light to the central hub spacecraft.
***
In 'imaging' mode, Darwin will work like a single large telescope, with a diameter of up to several 100 metres, providing images of many types of celestial object in detail.

For Darwin to work, the telescopes and the hub must stay in formation with millimetre precision. ESA is confident of achieving this aim using a variation of the highly successful Global Positioning System (GPS) that provides so much of the satellite-based navigation on Earth.

But this is not enough, when the light collected by the telescopes is recombined it has to be done at very high precision. A deviation of more than just 100 thousandths of a millimetre will ruin the observation.

Although this sounds an impossible feat of accuracy, ESA has already together with European industry made pre-developments of the necessary metrology and optical equipment that would allow such precision.

[Dudley_DUright]

7. They need the positional accuracy since they will be using interferometry

(destructive interference) to cancel out the light from the star, leaving reflected light from the planet. Very clever technology.