Slashdot Mirror
First Exoplanet Atmospheres Analyzed
deblau writes "NASA's Spitzer Space Telescope has captured for the first time enough light from planets outside our solar system, known as exoplanets, to identify signatures of individual molecules in their atmospheres. The landmark achievement is a significant step toward being able to detect possible life on rocky exoplanets and comes years before astronomers had anticipated."
All the extra solar planets that have been found so far are large gas giant type planets.
Our telescopes aren't good enough (yet) to detect small earth size rocky planets.
While spectographic analysis of these planets atmosphere is interesting, it does not give us information about the possiblity of life (as we know it, Jim) since these aren't the places we would find life in this solar system either. Maybe these other planetary systems do include rocky planets, or moons (like titan and europa ) that could be candidates for some form of life, but we wouldn't find that out by looking at the atmospheres of JUpiter and Saturn
I'm sorry, but they are not detecting the signatures of INDIVIDUAL MOLECULES. Try "individual compounds".
I figured somebody better follow the joke up with some clarification. The optics on Spitzer, like Hubble, aren't focused that close. Plus it's infrared. Skin complexion would look like crap.
Also, they aren't directly seeing the planet. I don't know if Spitzer's cameras could theoretically resolve it, but I do know it can't pick it out of the glare from its star. The method is to use a spectrograph and note really carefully the spectra of light received from the observation. When the planet, which is emitting light at different wavelengths depending on the molecules present, goes behind the star, this spectra changes ever so slightly. From this you know which portions of the spectra are from the star and which are from the planet, and you can deduce the molecules based on characteristic spectral lines.
This is very much like colors on an LCD monitor. Let's say you have a switch that will let you turn off one pixel of a triad (the triad being the red, green, and blue pixels that make up a visible pixel), but you don't know what color it is. If you see a yellow pixel, you know there is actually a red pixel and green pixel turned on right next to each other, even though your eye can't resolve them. You flip the switch and the visible pixel turns red, so you know the pixel you control is green. The colors of the pixels are analogous to the molecules on the planet versus the star. The pixel you can control is like the planet, but instead of a switch it goes behind the star.
Since the article apparently likes big numbers over useful units, the 370 and 904 trillion mile figures for the distances to the two observed targets are equal to 63 and 153 light years respectively.
The more distant system is 150 lightyears away. Since that is also how much time it takes to light reach here, the data is "only" 150 years out of date.
These data were taken in the mid-infrared, where the contrast between the star and the planet is not as great --- only about 200--300:1, instead of 10^6--10^10 to 1 in the optical/near-IR.
This is great research and all, but I would think that the people at Spitzer would be a lot more cognizant and courteous to their colleagues and not inflate their claims of priority. A team already analyzed the atmosphere of a transiting exoplanet using STIS on Hubble. It's a different situation (most exoplanets don't transit, after all), but they HST team did this around five YEARS ago. I remember hearing talks about it at the time, it was a big deal. Surely the Spitzer team should have known about this?
Never mind - from a bit of online searching of some old archives, it would appear that Hubble's limit of focus is about 10000km -> infinity without adjustment. The range of adjustment needed to make in-focus observations of the ground is pretty small however (12mm or so), so it's quite possible that it could be done.
But why you would do that when there are no doubt perfectly good spysats out there with better resolution, I don't know.
You are in a twisty maze of processor lines, all alike.
There is a lot of hype here.
Here are the informations missing from TFS :
Two extrasolar gas giant upper atmospheres were observed by the Spitzer infrared sprectrometer. It revealed mainly silicate dust and no water. That bewildered scientists who take for granted that such planets contain a high quantity of water. They extrapolate that it must be present under the dust layer.
The Wise adapts himself to the world. The Fool adapts the world to himself. Therefore, all progress depends on the Fool.
Well, not necessarily. Oxygen (and thus ozone) can be produced in macroscopic scales abiotically. Some classes of water worlds should do this, for example. They don't have a surface that wants to oxidize, and if they're massive enough, they'll hold onto an oxygen atmosphere produced through photochemical means. Some moons in our solar system, like Europa, have tenuous oxygen atmospheres.
Likewise, other chemicals that we're not used to would probably still scream out "life" to us. What if you saw an atmosphere rich in fluorine? That's even more reactive than oxygen. Might seem reasonable to consider that a marker of life -- just not LAWKI. Might not mean anything; there's a lot of potential inorganic that we don't know about.
What about surface features instead of atmospheric ones? Leaves tend to reflect strongly in the 700-750 nm range. What if we have a surface that has sharp spectral features in that range? Could be an indicator. Might not be. What if there were sharp spectral signatures in other ranges that don't correspond to minerals that we'd expect to be on the surface? Perhaps there are lifeforms with different biochemistry. Perhaps it's just deposits of a mineral that we don't expect to be there.
There are plenty of other potential biosignatures, and it's basically going to take having multiple biosignatures to make a compelling case for life.
"Who the hell is Nietzche? It's a question stupid people are asking." -- Newscaster, "Jesus Christ Supercop"