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Raising Our Sights

After Kurzweil reported yesterday that we now have the first photograph of an exoplanet (a planet outside the solar system), Phil and I had an email conversation about the future of spotting planets visually.

The problem is that planets, particularly earth-sized planets, are very dim bulbs located on astronomical scales right next to a very bright star.

The planet that was photographed is very large and is in a wide orbit around a relatively dim star. Astronomer Gael Chauvin managed to take this picture with an earth-based telescope employing "adaptive optics" to compensate for the blurring of our atmosphere. The telescope that was used was part of the "Very Large Telescope array at the Paranal Observatory in Chile."

Chauvin's team now plan to make more detailed observations to confirm whether the object is indeed a planet in orbit around 2M1207. "Our discovery represents a first step towards opening a new field in astrophysics: the imaging and spectroscopic study of planetary systems," says team member Anne-Marie Lagrange from the Grenoble Observatory in France. "Such studies will enable astronomers to characterise the physical structure and chemical composition of giant and, eventually, terrestrial-like planets."

Instead of having to compensate for our atmosphere, wouldn't it be great to have an array in space? What I suggested yesterday to Phil was an array in the configuration of a toy jack.


Or, to be more scientific, in the xyz cartesian axes configuration. At the end of each leg would be a 3 axes movable "eye." These 6 eyes could work separately or be coordinated together. This could give you monoscopic vision in up to 6 directions at once, stereoscopic vision in up to 3 directions at once, or, if a scientist needed to take a really good look at something, up to 6 eyes could be trained on an object.

Phil had a better idea. Instead of having these space telescopes physically connected together, why not separate them further? Much further.

The thing to do would be to launch one of these jack telescopes way, way out there. Say, 100 AU. The signals would take a long time to get back to Earth, but think of what we would see! Going with the stereoscope idea, what if we put two single lenses out in space on opposite sides of the sun, again each about 100 AU from the Sun or about 200 AU from each other. With that kind of distance between the two lenses, I wonder what kind of leverage you would get towards resolving distant objects? 200 AU seems huge to us, but it's still pretty miniscule in interstellar terms. Maybe we should be thinking in terms af 1000 AUs.

We need some cool nanotech way to make the lenses realy enormous, too. Say 1/100th the diamter of the moon or so. Now that would be a pair of binoculars!

No rescue missions for those Hubbles. You would need nanotech not just to build them, but to maintain them.


I remember about 20 years or so ago when the first brown dwarfs were imaged. At that time, it took an enormous effort to get a picture of a brown dwarf, and even then nobody was sure whether we really had one or not. But it was exciting. Brown dwarfs weren't planets, but they were small and dim. And if we could see them it was possible that maybe, someday, we might see planets.

Now the brown dwarf is just the big blob in the picture, and we're looking at a planet that orbits it. Amazing.

Hubble isn't the correct frequency here. That telescope is specialized to visible and near UV light. Rather you'd be more interested in the James Webb Space Telescope which observes in infrared. Planets near stars radiate most of their energy in that frequency.

Second, a baseline of 200AU is vast, vast overkill at this stage. The baseline of the above telescope array is 130 meters. I'm not sure what the resolving power of your 200 AU interferometer (accurate distance to within a few hundred nanometers, a small fraction of the wavelength!) would be at 230 lightyears, but I suspect license plates wouldn't be that hard to resolve (and perhaps the detailed anatomy of bugs splattered on the windshield too though the bugs would have to be pretty bright at those frequencies for the telescope to see them). You might be easily resolving planets in nearby galaxies! But if you can do it, it would be cool.

A nicer feature of putting something that far out is that you don't have to worry about the Sun as a heat source. You're very close to background temperature. For a closer place to observe from, the Moon is pretty nice. The far side of the Moon during the night can get pretty cold. You would have great two week observing sessions. But these are more mundane and pretty routine speculation. ;-)

The ultimate place for observatories would be in the voids between the superclusters of galaxies. Some of these are several hundred million lightyears across.

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