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NASA's Giant Pinhole Camera
Cecil writes "The University of Colorado at Boulder has come up with an interesting proposal, and NASA has decided it has enough merit to give it funding. They're developing what is in essence a pinhole camera where the pinhole is 30 feet wide, and the "film" is tens of thousands of miles away. The "New Worlds Imager" as it is called, may eventually have enough resolution to get visual images of extrasolar planets as small as Earth's moon around stars 100 light years away, and would be able to search them for the key signs of life-as-we-know-it, like oxygen, water, and ozone. Other ideas that NASA will be developing include a lunar space elevator and magnetized beam plasma propulsion."
The dark box isn't necessary if you can restrict the light getting to the film some other way. The article mentioned that the detector would be attached to a telescope, so that would prevent light entering from any place other than the pinhole lens.
e scope-lr.gif or at http://www.apo.nmsu.edu/Site/3.5m_Images/telescope 06.JPEG
Most large telescopes don't have tubes either, since they aren't strictly needed, and they weigh a lot. See the photo of the scope at: http://gemini.physics.ox.ac.uk/photos/geminin-tel
Fascism trolls keeping me up every night. When I starts a preachin', he HITS ME WITH HIS REICH!
Onc can do similar observations with inverse optics using asteroid occultations. I suppose one could create an artificial asteroid and watch as it passes in front of stars as it orbits or create a detector satellite with an ion engine that visits occultation zones between selected stars and satellites.
Two wrongs don't make a right, but three lefts do.
Magnification of a telescope is figured by dividing the focal length of the objective by the focal length of the eyepiece. The type of objective doesn't matter, just it's focal length.
So here, we've got a focal length of 10,000 miles. At the eyepiece end, the article talks about a telescope being mounted there. That telescope would be for all intents and purposes an eyepiece. Don't know what the focal length of that would be, but it would be a very small fraction of the 10,000 miles, making the final magnification of the telescope very large.
Fascism trolls keeping me up every night. When I starts a preachin', he HITS ME WITH HIS REICH!
You hold the film and go stand back.
Farther.
Farther.
Farther!
Farther!!
Farther!!!
There's no way this is going to work. I mean, how the hell are they going to lift into space a pin big enough to poke a 30-foot hole. Where are they even going to *find* a pin that big?
Gotta be the most hare-brained scheme ever. Sheesh.
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Diffraction is how this thing works, and why the telescope is so far back from the shade.
The purpose of the shade is to null out the light from the star without affecting the light from the planet. The shade is extremely effective at doing this, and doing it in a way that is insensitive to wavelength.
I'm not sure they need a hole; using the edge of a large disk should also work.