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Occulter for a space telescope: what about effects of the Sun ?
I was wondering if it is actually feasible to use an occulter with a
space telescope to watch extrasolar planets by dimming their star. I think the occulter will be close enough to our Sun so that the sunlight, dispersed from the edges of the occulter, would completely drown the faint planets. Am I correct ? Is an occulter even feasible without moving the telescope / occulter pair many billions kilometers from the Sun (which is beyond our current propulsion technologies) ? |
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Occulter for a space telescope: what about effects of the Sun ?
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Occulter for a space telescope: what about effects of the Sun ?
Thanks Dan for your kind reply. But I don't think that hiding the
telescope + occulter behind the Earth shadow will be an option for the future space telescope missions, because they will be orbiting too far from the Earth. Also, placing a sunshade behind the telescope won't work either, because the occulter has to be placed very far from the telescope (probably millions of telescope mirror's raidii away). Am I correct ? On Oct 6, 4:08*am, Dan Birchall wrote: (ivk) wrote: *I was wondering if it is actually feasible to use an occulter with a *space telescope to watch extrasolar planets by dimming their star. I *think the occulter will be close enough to our Sun so that the *sunlight, dispersed from the edges of the occulter, would completely *drown the faint planets. Am I correct ? Is an occulter even feasible *without moving the telescope / occulter pair many billions kilometers *from the Sun (which is beyond our current propulsion technologies) ? Sure! *This technique is already used on terrestrial telescopes - for example, here at Subaru, we have HiCIAO, a coronographic imager that sits behind our 188-element AO system. *During _commissioning_ last year, it found exoplanet GJ 758 B, and there's an ongoing project (SEEDS - Strategic Exploration of Exoplanets and Disks) to check for planets around some big number of nearby stars. *Other 8-10 meter class telescopes have similar instruments, or will soon, complementing the other existing means of finding exoplanets. Keeping the sun out of your space telescope is pretty much just a matter of either putting it on the dark side of the Earth or Moon, or building a nice big sunshade for it. -- djb@ | Dan Birchall - Observation System Associate - Subaru Telescope. naoj | Views I express are my own, obviously not those of my employer. .org | I only wear black so much because I can't find anything darker. |
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Occulter for a space telescope: what about effects of the Sun ?
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Occulter for a space telescope: what about effects of the Sun ?
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Occulter for a space telescope: what about effects of the Sun ?
On 11 Okt, 13:39, "Androcles" wrote:
"Dan Birchall" wrote in message ...| (Androcles) wrote: | | *"Dan Birchall" wrote in message | ... | | (ivk) wrote: | | *placing a sunshade behind the telescope won't work either, because | | *the occulter has to be placed very far from the telescope (probably | | *millions of telescope mirror's raidii away). Am I correct ? | | | | I suppose you could do it that way, but most just make the occulter a | | lot smaller in diameter than one that you would use for doing | | coronographic observations of something nearby like the sun. | | *As in hold a penny at arm's length... | | Precisely. *Instead of holding a penny, hold a pinhead[1], or whatever. |
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Occulter for a space telescope: what about effects of the Sun ?
On 11 Okt, 13:39, "Androcles" wrote:
"Dan Birchall" wrote in message ...| (Androcles) wrote: | | *"Dan Birchall" wrote in message | ... | | (ivk) wrote: | | *placing a sunshade behind the telescope won't work either, because | | *the occulter has to be placed very far from the telescope (probably | | *millions of telescope mirror's raidii away). Am I correct ? | | | | I suppose you could do it that way, but most just make the occulter a | | lot smaller in diameter than one that you would use for doing | | coronographic observations of something nearby like the sun. | | *As in hold a penny at arm's length... | | Precisely. *Instead of holding a penny, hold a pinhead[1], or whatever. |
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Occulter for a space telescope: what about effects of the Sun ?
On 11 Okt, 13:39, "Androcles" wrote:
"Dan Birchall" wrote in message ...| (Androcles) wrote: | | *"Dan Birchall" wrote in message | ... | | (ivk) wrote: | | *placing a sunshade behind the telescope won't work either, because | | *the occulter has to be placed very far from the telescope (probably | | *millions of telescope mirror's raidii away). Am I correct ? | | | | I suppose you could do it that way, but most just make the occulter a | | lot smaller in diameter than one that you would use for doing | | coronographic observations of something nearby like the sun. | | *As in hold a penny at arm's length... | | Precisely. *Instead of holding a penny, hold a pinhead[1], or whatever. |
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Occulter for a space telescope: what about effects of the Sun ?
On 11 Okt, 13:39, "Androcles" wrote:
"Dan Birchall" wrote in message ...| (Androcles) wrote: | | *"Dan Birchall" wrote in message | ... | | (ivk) wrote: | | *placing a sunshade behind the telescope won't work either, because | | *the occulter has to be placed very far from the telescope (probably | | *millions of telescope mirror's raidii away). Am I correct ? | | | | I suppose you could do it that way, but most just make the occulter a | | lot smaller in diameter than one that you would use for doing | | coronographic observations of something nearby like the sun. | | *As in hold a penny at arm's length... | | Precisely. *Instead of holding a penny, hold a pinhead[1], or whatever. |
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