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Russia Launches Long-Delayed Deep Space Radio Telescope
Russia Launches Long-Delayed Deep Space Radio Telescope | Giant Space
Telescopes | Radio Astronomy & Deep Space Exploration | Space.com http://www.space.com/12329-russia-la...telescope.html |
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Russia Launches Long-Delayed Deep Space Radio Telescope
Yousuf Khan wrote in
: Russia Launches Long-Delayed Deep Space Radio Telescope | Giant Space Telescopes | Radio Astronomy & Deep Space Exploration | Space.com http://www.space.com/12329-russia-la...nt-radio-teles cope.html 207,000 miles to 621 miles is a bit of an orbital swing. I've never heard of this. This is neat. |
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Russia Launches Long-Delayed Deep Space Radio Telescope
On 18/07/2011 8:50 PM, eric gisse wrote:
Yousuf wrote in : Russia Launches Long-Delayed Deep Space Radio Telescope | Giant Space Telescopes | Radio Astronomy& Deep Space Exploration | Space.com http://www.space.com/12329-russia-la...nt-radio-teles cope.html 207,000 miles to 621 miles is a bit of an orbital swing. I've never heard of this. This is neat. I'm not even sure why they are doing such an elliptical orbit like that? Any advantages for viewing angles or stuff like that? Yousuf Khan |
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Russia Launches Long-Delayed Deep Space Radio Telescope
Yousuf Khan wrote in
: On 18/07/2011 8:50 PM, eric gisse wrote: Yousuf wrote in : Russia Launches Long-Delayed Deep Space Radio Telescope | Giant Space Telescopes | Radio Astronomy& Deep Space Exploration | Space.com http://www.space.com/12329-russia-la...e-giant-radio- teles cope.html 207,000 miles to 621 miles is a bit of an orbital swing. I've never heard of this. This is neat. I'm not even sure why they are doing such an elliptical orbit like that? Any advantages for viewing angles or stuff like that? Yousuf Khan No ****ing idea. The distance isn't enough to alter the view seen, but it _might_ be enough to play VLBI games but I don't believe the orbital information and transmission setup is precise enough to preserve phase/timing information down to the nanosecond. Orbits are not accidental so either they wanted it to be there, or a higher purpose was served that has putting it there as a byproduct. I just can't figure it out. |
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Russia Launches Long-Delayed Deep Space Radio Telescope
On 18/07/2011 11:39 PM, eric gisse wrote:
Yousuf wrote in I'm not even sure why they are doing such an elliptical orbit like that? Any advantages for viewing angles or stuff like that? Yousuf Khan No ****ing idea. The distance isn't enough to alter the view seen, but it _might_ be enough to play VLBI games but I don't believe the orbital information and transmission setup is precise enough to preserve phase/timing information down to the nanosecond. I was thinking maybe the orbit would allow it to avoid the day side of the planet and avoid being blocked by the planet as it looks at distant stars. Also avoid it'll the radio noise of the planet. Earth is supposedly much brighter than the Sun when it comes to radio. Orbits are not accidental so either they wanted it to be there, or a higher purpose was served that has putting it there as a byproduct. I just can't figure it out. Maybe they don't have a strong enough booster to put it in a circular orbit that far up? That's almost as far as the Moon. Yousuf Khan |
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Russia Launches Long-Delayed Deep Space Radio Telescope
On 19/07/2011 03:43, Yousuf Khan wrote:
On 18/07/2011 8:50 PM, eric gisse wrote: Yousuf wrote in : Russia Launches Long-Delayed Deep Space Radio Telescope | Giant Space Telescopes | Radio Astronomy& Deep Space Exploration | Space.com http://www.space.com/12329-russia-la...nt-radio-teles cope.html 207,000 miles to 621 miles is a bit of an orbital swing. I've never heard of this. This is neat. I'm not even sure why they are doing such an elliptical orbit like that? Any advantages for viewing angles or stuff like that? Allows it to cover a decent range of baselines relative to ground based scopes when operated as an interferometer (assuming that their orbit determination is precise enough to get the correlators to lock-in). The ground based VLBI network is stuck with the pattern formed by where the various big steerable dishes happen to have been built. Regards, Martin Brown |
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Russia Launches Long-Delayed Deep Space Radio Telescope
Yousuf Khan wrote:
On 18/07/2011 11:39 PM, eric gisse wrote: Yousuf wrote in I'm not even sure why they are doing such an elliptical orbit like that? Any advantages for viewing angles or stuff like that? Yousuf Khan No ****ing idea. The distance isn't enough to alter the view seen, but it _might_ be enough to play VLBI games but I don't believe the orbital information and transmission setup is precise enough to preserve phase/timing information down to the nanosecond. I was thinking maybe the orbit would allow it to avoid the day side of the planet and avoid being blocked by the planet as it looks at distant stars. Also avoid it'll the radio noise of the planet. Earth is supposedly much brighter than the Sun when it comes to radio. Orbits are not accidental so either they wanted it to be there, or a higher purpose was served that has putting it there as a byproduct. I just can't figure it out. Maybe they don't have a strong enough booster to put it in a circular orbit that far up? That's almost as far as the Moon. Yousuf Khan It always helps to read the articles about which you post links. It is stated that the orbit is designed to allow the telescope to work with the interferometric network of radio telescopes on Earth to provided higher resolution than can be obttained from the ground. From this I assume that the ground stations can track the position of the telescope accurately enough to permit good interferometry to be done. A high-eccentricity orbit costs less than a low-eccentricity distant orbit in terms of thrust required, yet it allows the radio telescope to be at a large distance from Earth about 80-90% of the time (near apogee) in accord with Kepler's 2nd law of planetary motion. -- Mike Dworetsky (Remove pants sp*mbl*ck to reply) |
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Russia Launches Long-Delayed Deep Space Radio Telescope
"Mike Dworetsky" wrote in
: Yousuf Khan wrote: On 18/07/2011 11:39 PM, eric gisse wrote: Yousuf wrote in I'm not even sure why they are doing such an elliptical orbit like that? Any advantages for viewing angles or stuff like that? Yousuf Khan No ****ing idea. The distance isn't enough to alter the view seen, but it _might_ be enough to play VLBI games but I don't believe the orbital information and transmission setup is precise enough to preserve phase/timing information down to the nanosecond. I was thinking maybe the orbit would allow it to avoid the day side of the planet and avoid being blocked by the planet as it looks at distant stars. Also avoid it'll the radio noise of the planet. Earth is supposedly much brighter than the Sun when it comes to radio. Orbits are not accidental so either they wanted it to be there, or a higher purpose was served that has putting it there as a byproduct. I just can't figure it out. Maybe they don't have a strong enough booster to put it in a circular orbit that far up? That's almost as far as the Moon. Yousuf Khan It always helps to read the articles about which you post links. It is stated that the orbit is designed to allow the telescope to work with the interferometric network of radio telescopes on Earth to provided higher resolution than can be obttained from the ground. From this I assume that the ground stations can track the position of the telescope accurately enough to permit good interferometry to be done. http://space.skyrocket.de/doc_sdat/spektr-r.htm I only noticed the VLBI link _after_ I read this, and revisited the original link. Somehow it escaped notice on the first read. I'm truly impressed that they can do space-ground interferometry with a radio telescope. This will be very valuable. A high-eccentricity orbit costs less than a low-eccentricity distant orbit in terms of thrust required, yet it allows the radio telescope to be at a large distance from Earth about 80-90% of the time (near apogee) in accord with Kepler's 2nd law of planetary motion. A subtlety that doesn't appear until you think about it. |
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Russia Launches Long-Delayed Deep Space Radio Telescope
In article ,
Yousuf Khan writes: I'm not even sure why they are doing such an elliptical orbit like that? As others have mentioned, variable baseline for VLBI and lots of time spent far from Earth. This isn't the first VLBI satellite. Halca, sometimes called VSOP, was launched by Japan in 1997. More details at: http://www.sciencedirect.com/science...94576501001710 -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
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