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Herschel space telescope to become biggest space telescope
Bigger than Hubble, until the James Webb telescope is launched. Also it
seems to be the first telescope being put into one of the Earth-Sun Lagrange points, Lagrange point 2 to be exact. James Webb is supposed to into this Lagrange point too. Yousuf Khan BBC NEWS | Science & Environment | 'Silver sensation' seeks cold cosmos "It is enchanting, spectacular and - at 3.5m in diameter - it will soon become the biggest telescope mirror in space, surpassing that of Hubble." http://news.bbc.co.uk/1/hi/sci/tech/7864087.stm |
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Herschel space telescope to become biggest space telescope
On Feb 9, 10:02*am, Yousuf Khan wrote:
Bigger than Hubble, until the James Webb telescope is launched. Also it seems to be the first telescope being put into one of the Earth-Sun Lagrange points, Lagrange point 2 to be exact. James Webb is supposed to into this Lagrange point too. * * * * Yousuf Khan BBC NEWS | Science & Environment | 'Silver sensation' seeks cold cosmos "It is enchanting, spectacular and - at 3.5m in diameter - it will soon become the biggest telescope mirror in space, surpassing that of Hubble."http://news.bbc.co.uk/1/hi/sci/tech/7864087.stm Are they going to firmware/software lock-out the Sirius star/solar system? ~ BG |
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Herschel space telescope to become biggest space telescope
In article ,
Yousuf Khan writes: Bigger than Hubble, until the James Webb telescope is launched. Presumably referring to _Herschel_, which is supposed to be launched later this year. Herschel is a far infrared mission; the shortest wavelength it will observe is something like 60 microns. More information at http://sci.esa.int/science-e/www/are...cfm?fareaid=16 (I see the planned launch date is Apr 16.) The same rocket (Ariane ECA, which I think must be some form of Ariane 5) will launch _Planck_, a cosmic background mission. Also it seems to be the first telescope being put into one of the Earth-Sun Lagrange points, Lagrange point 2 to be exact. I think WMAP is in an L2 orbit, and it wouldn't surprise me if other satellites are there too. James Webb is supposed to into this Lagrange point too. Yep. L2 is a pretty good orbit, though as always there are tradeoffs. L2 is fairly far from Earth and Moon so those bodies don't contribute much heat input nor block the solar panels from a full-time view of the Sun. Compared to a solar orbit (as Spitzer), L2 takes more energy to get to, and station keeping is required, but pointing restrictions are simpler and don't change over the mission. Downlink rate is lower from L2 at mission start (for the same transmitter power and directional antenna), but the rate is constant rather than deteriorating during the mission. There are probably other considerations as well, but it's not surprising to see L2 used. -- Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA (Please email your reply if you want to be sure I see it; include a valid Reply-To address to receive an acknowledgement. Commercial email may be sent to your ISP.) |
#4
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Herschel space telescope to become biggest space telescope
On Feb 10, 1:52*pm, (Steve Willner) wrote:
In article , *Yousuf Khan writes: Bigger than Hubble, until the James Webb telescope is launched. Presumably referring to _Herschel_, which is supposed to be launched later this year. *Herschel is a far infrared mission; the shortest wavelength it will observe is something like 60 microns. *More information athttp://sci.esa.int/science-e/www/area/index.cfm?fareaid=16 (I see the planned launch date is Apr 16.) The same rocket (Ariane ECA, which I think must be some form of Ariane 5) will launch _Planck_, a cosmic background mission. Also it seems to be the first telescope being put into one of the Earth-Sun Lagrange points, Lagrange point 2 to be exact. I think WMAP is in an L2 orbit, and it wouldn't surprise me if other satellites are there too. James Webb is supposed to into this Lagrange point too. Yep. *L2 is a pretty good orbit, though as always there are tradeoffs. *L2 is fairly far from Earth and Moon so those bodies don't contribute much heat input nor block the solar panels from a full-time view of the Sun. *Compared to a solar orbit (as Spitzer), L2 takes more energy to get to, and station keeping is required, but pointing restrictions are simpler and don't change over the mission. Downlink rate is lower from L2 at mission start (for the same transmitter power and directional antenna), but the rate is constant rather than deteriorating during the mission. *There are probably other considerations as well, but it's not surprising to see L2 used. -- Steve Willner * * * * * *Phone 617-495-7123 * * Cambridge, MA 02138 USA * * * * * * * * (Please email your reply if you want to be sure I see it; include a valid Reply-To address to receive an acknowledgement. *Commercial email may be sent to your ISP.) Selene L1 is nearly ideal, second only to Selene L2. ~ BG |
#5
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Herschel space telescope to become biggest space telescope
On Feb 10, 4:52*pm, (Steve Willner) wrote:
Presumably referring to _Herschel_, which is supposed to be launched later this year. *Herschel is a far infrared mission; the shortest wavelength it will observe is something like 60 microns. *More information athttp://sci.esa.int/science-e/www/area/index.cfm?fareaid=16 (I see the planned launch date is Apr 16.) Yeah, seems to show the growing importance of the infrared band these days. Even James Webb will be mostly in the infrared band. Hubble's small footprint in the infrared seems to be its most useful. The same rocket (Ariane ECA, which I think must be some form of Ariane 5) will launch _Planck_, a cosmic background mission. Yes, the article just barely mentioned the Planck telescope. Very little detail about it, I don't even know if it's attached physically to the Herschel, or if it'll separate upon arrival at the L2. Don't even know what band it's going to be observing. Also it seems to be the first telescope being put into one of the Earth-Sun Lagrange points, Lagrange point 2 to be exact. I think WMAP is in an L2 orbit, and it wouldn't surprise me if other satellites are there too. Interesting. I wonder how crowded it's getting up there? Will we be having space junk problems there soon? James Webb is supposed to into this Lagrange point too. Yep. *L2 is a pretty good orbit, though as always there are tradeoffs. *L2 is fairly far from Earth and Moon so those bodies don't contribute much heat input nor block the solar panels from a full-time view of the Sun. *Compared to a solar orbit (as Spitzer), L2 takes more energy to get to, and station keeping is required, but pointing restrictions are simpler and don't change over the mission. Downlink rate is lower from L2 at mission start (for the same transmitter power and directional antenna), but the rate is constant rather than deteriorating during the mission. *There are probably other considerations as well, but it's not surprising to see L2 used. What do you mean Spitzer is in a Solar orbit? Is it in the same Solar orbit as Earth (just a little bit further ahead or behind)? Or is it a little larger or smaller solar orbit? Yousuf Khan |
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Herschel space telescope to become biggest space telescope
On Feb 10, 6:01*pm, YKhan wrote:
On Feb 10, 4:52*pm, (Steve Willner) wrote: Presumably referring to _Herschel_, which is supposed to be launched later this year. *Herschel is a far infrared mission; the shortest wavelength it will observe is something like 60 microns. *More information athttp://sci.esa.int/science-e/www/area/index.cfm?fareaid=16 (I see the planned launch date is Apr 16.) Yeah, seems to show the growing importance of the infrared band these days. Even James Webb will be mostly in the infrared band. Hubble's small footprint in the infrared seems to be its most useful. The same rocket (Ariane ECA, which I think must be some form of Ariane 5) will launch _Planck_, a cosmic background mission. Yes, the article just barely mentioned the Planck telescope. Very little detail about it, I don't even know if it's attached physically to the Herschel, or if it'll separate upon arrival at the L2. Don't even know what band it's going to be observing. Also it seems to be the first telescope being put into one of the Earth-Sun Lagrange points, Lagrange point 2 to be exact. I think WMAP is in an L2 orbit, and it wouldn't surprise me if other satellites are there too. Interesting. I wonder how crowded it's getting up there? Will we be having space junk problems there soon? Earth L2 is a very large volume of space, room for safely accommodating dozens to hundreds of large satellites. James Webb is supposed to into this Lagrange point too. Yep. *L2 is a pretty good orbit, though as always there are tradeoffs. *L2 is fairly far from Earth and Moon so those bodies don't contribute much heat input nor block the solar panels from a full-time view of the Sun. *Compared to a solar orbit (as Spitzer), L2 takes more energy to get to, and station keeping is required, but pointing restrictions are simpler and don't change over the mission. Downlink rate is lower from L2 at mission start (for the same transmitter power and directional antenna), but the rate is constant rather than deteriorating during the mission. *There are probably other considerations as well, but it's not surprising to see L2 used. What do you mean Spitzer is in a Solar orbit? Is it in the same Solar orbit as Earth (just a little bit further ahead or behind)? Or is it a little larger or smaller solar orbit? * Yousuf Khan It should get parked within the Selene/moon L1, but that would be asking too much, and extremely hot much of the time. Otherwise, the Selene/moon L2 would require a couple of transponders. ~ BG |
#7
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Herschel space telescope to become biggest space telescope
In article ,
YKhan writes: Yeah, seems to show the growing importance of the infrared band these days. Even James Webb will be mostly in the infrared band. Hubble's small footprint in the infrared seems to be its most useful. As a career infrared astronomer, I certainly won't argue with the first two sentences. :-) That last one about Hubble seems a bit dubious, though. NICMOS is nice but has a tiny field of view and doesn't get very much of Hubble's observing time. Are you confusing it with Spitzer? Yes, the article just barely mentioned the Planck telescope. Very little detail about it, The Planck home page was hard to find, but it seems to be at http://sci.esa.int/science-e/www/obj...objectid=33333 I don't even know if it's attached physically to the Herschel, or if it'll separate upon arrival at the L2. See http://sci.esa.int/science-e/www/obj...objectid=34727 Separation will be "shortly after launch." I wonder how crowded it's getting [in L2]? Will we be having space junk problems there soon? Not likely ever to be a problem. See http://sci.esa.int/science-e/www/obj...objectid=34728 (and note especially "not to scale" on the figure). The "Lissajous orbit" is something like 10^5 km in radius IIRC around L2 itself. What do you mean Spitzer is in a Solar orbit? Is it in the same Solar orbit as Earth (just a little bit further ahead or behind)? Or is it a little larger or smaller solar orbit? Very slightly larger; orbit period is about 363 days. See http://www.spitzer.caltech.edu/about/now.shtml I couldn't find a good illustration of the orbit, but there may be one somewhere on that site. This is a low-launch-energy orbit with good telecom at the start of mission, but keeping the high data rate now requires the 70-m DSN antennas. -- Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA (Please email your reply if you want to be sure I see it; include a valid Reply-To address to receive an acknowledgement. Commercial email may be sent to your ISP.) |
#8
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Herschel space telescope to become biggest space telescope
On Feb 11, 4:52*pm, I wrote:
In article , [Spitzer Space Telescope orbit is] Very slightly larger [than Earth's]; orbit period is about 363 days. Either I can't type, can't add, or think a year is 355 days -- or maybe more than one of the above. :-) Spitzer's orbit is about 8 days longer than a year; that _might_ work out to 373 days or so. |
#9
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Herschel space telescope to become biggest space telescope
On Feb 11, 5:52*pm, Steve Willner wrote:
On Feb 11, 4:52*pm, I wrote: In article , [Spitzer Space Telescope orbit is] Very slightly larger [than Earth's]; orbit period is about 363 days. Either I can't type, can't add, or think a year is 355 days -- or maybe more than one of the above. :-) *Spitzer's orbit is about 8 days longer than a year; that _might_ work out to 373 days or so. Why can't Spitzer look for Sirius C? ~ BG |
#10
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Herschel space telescope to become biggest space telescope
On Feb 11, 4:52*pm, (Steve Willner) wrote:
As a career infrared astronomer, I certainly won't argue with the first two sentences. :-) That last one about Hubble seems a bit dubious, though. *NICMOS is nice but has a tiny field of view and doesn't get very much of Hubble's observing time. *Are you confusing it with Spitzer? I was just observing that a lot of really far away galactic images from Hubble tend to be false-color images, which would indicate to me that they've been enhanced to allow our visual range to perceive it. That indicates that perhaps most of them are in the infrared range. Yes, the article just barely mentioned the Planck telescope. Very little detail about it, The Planck home page was hard to find, but it seems to be athttp://sci.esa.int/science-e/www/object/index.cfm?fobjectid=33333 Ah, I see, so it's a successor to the COBE and WMAP Cosmic Microwave Background mapping satellites. I wonder how crowded it's getting [in L2]? Will we be having space junk problems there soon? Not likely ever to be a problem. *Seehttp://sci.esa.int/science-e/www/object/index.cfm?fobjectid=34728 (and note especially "not to scale" on the figure). *The "Lissajous orbit" is something like 10^5 km in radius IIRC around L2 itself. Are these stable orbits, i.e. doesn't require thrusters to keep them going? Yousuf Khan |
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