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Massive Radio Telescope Starts Observing the Skies
New submitter cyachallenge writes with this excerpt from New Scientist: "RadioAstron, effectively the largest radio telescope ever built, is up and running. The telescope's main component, a 10-metre radio dish aboard the spacecraft Spectr-R, launched in July to an oblong orbit that extends between 10,000 and more than 300,000 kilometres from Earth. By coordinating observations with radio telescopes on Earth in a technique called interferometry, the telescope can make observations as sharp as a single dish spanning the entire distance between the two farthest dishes. When Spectr-R is at its farthest from Earth, the system acts like one enormous telescope about 30 times as wide as our planet, boasting about 10,000 times the resolution of the Hubble Space Telescope."
it's too big to fail.
Anons need not reply. Questions end with a question mark.
Is that a word (still) ?
Not in reference to a (highly) flattened eliptical orbit surely.
Why wouldn't it be? Oblong is a perfectly cromulent word.
I always thought Oblong was more rectangular than elliptical. Of course the rectangle with rounded corners was invented by apple.
.. it still "only" has 10m of aperture (+ the aperture from radio telescopes on Earth) so it will have a hard time detecting faint objects near its maximum resolution. It will be excellent at detecting small details of bright objects though.
It's all photons, so it's quite comparable.
And given the nature of redshifting, simply observing things near the surface of last scattering in the radio presents what would've originally been visible light images.
Wrong! Some incredibly amazing images have come from radio telescopes such as the VLA. You can find some of those pics on the National Radio Astronomy Observatory (NRAO) Image Gallery website.
Unlike the Chinese, that seem to do a lot of "me, too" stuff (which is very impressive, of course), the Russians do work that is nicely complementing the US, European (ESA) and Japanese efforts. The Spektr-R (and RadioAstron) is something novel and unique, and will provide insights in the astrophysics and astronomy beyond the Milky Way with high angular resolution.
Another example is ill-fated Phobos Grunt. It would have been another interesting and unique experiment.
"The agriculture ministry is not in charge of Gundam" - Japanese ministry official.
http://www.asc.rssi.ru/radioastron/index.html
That's one hell of a shift.
Astronomy isn't exactly about pretty pictures, you know! But even then, you can make pretty pictures out of data from other bands of the EM spectrum, like the AC mentioned earlier.
Actually, in radio astronomy you can't really say it's photons. The wavelengths are centimeters to meters (a pretty large photon), and you get wave-effects everywhere.
It's not true that this or other radio telescopes are no match for Hubble. This satellite links up with ground-based telescopes and does VLBI. The baseline of VLBI -- equivalent to the aperture diameter for optical telescope -- is the distance between the linked telescopes. If you want to have a telescope as powerful as Hubble, you need to compare diameter/wavelength (Hubble example: 2.4m/440nm = 5e6). So for radio (e.g. 21 cm), you need a baseline of 1050 km. Ground-based VLBI networks, like the Australian LBA (3300km Perth-Sydney, 5500km Perth-Auckland) or the European EVN, the VLBA (8000km) reach these lengths. This brings you down to milliarcsecond resolutions, incidentally similar to the optical VLT interferometer.
RadioAstron will be on an "orbit that extends between 10,000 and more than 300,000 kilometres from Earth".
So yes, it will be a match for Hubble by a factor of 100. However, this comparison is not really helpful, as optical and radio telescopes see different things and probe different physical processes. To understand the universe, information from all wavelengths is relevant.
NB: The message above might reflect my opinion right now, but not necessarily tomorrow or next year.
But what is the curvature error of the TerreStar-1 dish? And of the RadioAstron? You have to compare _that_, not just dish diameter, to understand why they did not/could not make it bigger... Besides, a larger dish means more orbital interference from solar wind, etc.
Forget "oblong", how about "massive"? Massive has to do with, well, mass. Seems that Aricebo might have the best claim for that (using the Earth itself as part of the structure).
The world is made by those who show up for the job.
Despite the shortcomings (perceived and real) that many will discuss regarding this particular telescope, it is still a very good thing that the U.S. and other countries continue to spend the money to develop, build, and implement new 'scopes. Considering how tight money is (worldwide) it can't be easy to find the funding for these projects.
http://www.busyweather.com/
Well if it's not photons carrying that electromagnetic energy then what is is it? You get wave effects with solid matter too... in fact you get wave effects with everything... so?
As Feynman said in one of his Auckland lectures, to the best of my recollection (so throw in some salt) - "We may talk about [it] as waves because that's convenient for certain problems but never forget it's really a particle."
The tyrant will always find a pretext for his tyranny - Aesop
Optical interferometry is done, so there's nothing to stop someone setting up an array of optical telescopes in which Hubble was one of the telescopes involved. Ideally, since large optical telescopes are very difficult to launch, future optical space telescopes should be designed to be used in interferometry arrays. The problem is one of synchronizing, since you can't use interference when the signals aren't in phase and relativistic time matters if they're not on a common orbit, but if you record the signal and timestamp points along it, it should be possible to do the interference offline rather than live.
The other thing to remember is that telescope diameter is only one variable. Another is collecting area. You could park two radio telescopes in geostationary orbit such that they were at opposite ends. This would give you a gigantic telescope diameter, but almost no collecting area. SKA, when it is finally built, will have a superb collecting area, vastly greater than what's described here, but a much smaller effective dish diameter than the telescope described in TFA. As such, it'll be far more sensitive but have lower resolution. Combining the two would be awesome.
(Dotting a SKA across the entire length of Earth's orbit would be even more awesome, but I don't see that happening for a while.)
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
One of the more fundamental problems is that we don't have phase-sensitive detectors for visible light.