A Telescope The Size Of The Earth 66
Neil Blender writes "From this article: "Astronomers have fashioned an Earth-sized virtual radio telescope that can distinguish celestial features 3,000 times smaller than the those observed by the Hubble Space Telescope. The device, which uses atomic clocks and a custom supercomputer to link together radio dishes on three continents, is the most powerful radio observatory ever, according to scientists." Some parts of the custom supercomputer use linux and IDE RAID."
Resolution and limits? (Score:2, Interesting)
I'd love to take a geography class in an astronomy major, discussing the geography of Betelgese-124
Re:Resolution and limits? (Score:2, Informative)
Re:Resolution and limits? (Score:2)
Thats what I was thinking (Score:2)
Re:Thats what I was thinking (Score:1)
Re:Resolution and limits? (Score:1)
They'll be nice to look at, say, jets coming off neutron stars and such at higher resolution, or things that are major radio sources already. I doubt that they can pick up faint radio sources (powerwise) because the antennas they're using are definitely not earth-sized.
This is also why some large ground telescopes can see farther than hubble because they have a larger light collecting area.
Yes, but (Score:4, Funny)
While I don't doubt the value a radio telescope might have for planetary research, I'm willing to bet you're thinking about something akin to being able to see the individual cells on Pathfinder's solar-array on the surface of Mars from a telescope mounted here on Earth.
Anyone know the _optical_ resolution for maximum "zoom" on Hubble...?
Re:Yes, but (Score:2, Informative)
Note that this will be the maximum theoretical resolution, Hubble is probably less. (and that I could be wrong, but I'm pretty sure about the aperture to resolution relation).
Re:Yes, but (Score:1)
http://hubblesite.org/sci.d.tech/nuts_.and._bol
Re:Yes, but (Score:2, Interesting)
Or the Mars Polar Lander debri field. I am curious to know what happend to the bugger, not just speculation.
Hubble and radio telescope resolutions. (Score:5, Informative)
Anyone know the _optical_ resolution for maximum "zoom" on Hubble...?
A really good telescope will usually be limited by diffraction effects (the fact that the telescope is of finite size causes light being focused to blur out a bit as it passes through the telescope aperture).
A back of the envelope calculation suggests that the diffraction-limited resolution of the Hubble (at 2.5m) for 500 nm light is about 0.2 microradians (letting it resolve features ten million kilometres wide at Alpha Centauri, five light-years away [give or take], or letting you read a typewritten letter at 5 km).
A radio telescope typically operates on wavelengths on the order of a tenth of a metre (as a gross approximation; it's really an order of magnitude in either direction from there, if I understand correctly). The largest radio telescope dish on the planet is about 300m wide, giving a diffraction-limited resolution of about 0.3 milliradians, or about three times sharper than the unaided human eye is at optical wavelengths (the equivalent of reading a typewritten letter at about 10 feet).
An interferometric radio telescope with an aperture the size of the planet would have a resolution of about 10 nanoradians, letting it resolve features about 0.5 million kilometres wide at Alpha Centauri [slightly smaller than our sun] (the equivalent of reading a typewritten letter at a distance of 100 km, or the title on a paperback book from low Earth orbit).
If we had a radio telescope with an atomic clock on the moon (about 400,000 km away), we could resolve objects the size of Jupiter in the Alpha Centauri system. If we had a space-based radio telescopes in the Earth-Sun L4 or L5 points (each 150 million km from Earth), we could resolve individual cities on an Earth-like planet.
This is cheap enough to do that we're probably going to put radio telescopes there within the next couple of decades. Any planet with a magnetosphere within 50-200 light years would be detectable, and we'd have detailed maps of magnetic effects on the surfaces of every star within a thousand light-years.
Re:Yes, but (Score:2)
Anyone know the _optical_ resolution for maximum "zoon" on Hubble...?
There was a relevant picture [nasa.gov] at The Astronomy Picture of the Day [nasa.gov] a few months ago that mentioned this issue:
(and so it can't make out the lunar modules that are there)How about doing the same with multiple Hubbles... (Score:2)
Kind of reminiscent of the question, "How about a Beowulf cluster of these?" only applied to telescopes.
Re:How about doing the same with multiple Hubbles. (Score:2)
Re:How about doing the same with multiple Hubbles. (Score:1)
Re:How about doing the same with multiple Hubbles. (Score:1)
Light Versus Radio Waves (Score:3, Interesting)
It is theoretically possible IIRC, but just much tougher than radio waves. The timing is very important to putting the signals back together properly in the computer. Radio waves are less dense than light-waves, and thus you have more tolerence of timing errors.
Thus, someday we may be able to do such with light, but for now it is beyond our technology (except at close range).
Re:Light Versus Radio Waves (Score:2)
For radio this is difficult enough - radio is measured in the MHz to GHz range - so you have to sample at a GHz frequency and record time to the billionth of a second. For light you are talking wavelengths in the 400nm range - which is a frequency of c/400nm=749 terrahertz. I don't know of anything which samples in quite that range (that would be HIGH!!!). Also, you need to record time in the trillionth of a second range (picoseconds). That probably isn't all that easy either (I don't know much about atomic clocks, but I think that is feasible, though you have to sync the time recording to the data recording, which isn't easy).
Light is a whole lot tougher to record than radio as the frequency is outside the range of modern electronics to handle.
Re:Light Versus Radio Waves (Score:2)
At two samples per cycle, you need better than femtosecond (10^-15 second) resolution.
Atomic clocks are stable to one part in 10^14+, but that doesn't mean we can measure time in femtoseconds. Just that drift between two clocks will be less than ten femtoseconds per second.
You can make a strong circumstantial case for direct waveform sampling of visible light being outright impossible with machines built from normal matter, as the relaxation time of most electron state transitions is longer than the required sampling rate, meaning that there would be no way for any possible device to switch fast enough Various forms of exotic matter have faster state transitions, but making measurements from the surface of a white dwarf or a neutron star is difficult
OTOH, I can believe direct sampling of far-infrared, which would at least give many orders of magnitude better resolution than radio telescopes, with baselines longer than are practical for optical interferometers.
Re:How about doing the same with multiple Hubbles. (Score:1)
Re:How about doing the same with multiple Hubbles. (Score:1)
Re:How about doing the same with multiple Hubbles. (Score:2, Informative)
Re:How about doing the same with multiple Hubbles. (Score:2, Informative)
Its called an interferrometer (Score:1)
And interferrometer takes two images at a wide distace apart and then one image is used to cancel the other. The remaining image is a result of the slight angle difference, allowing you to see very dim objects next to bright ones. The same could be used for radio waves.
In any case this would be tough, but not impossible job, for actually seeing a planet. I remember one scientist literally describing it as trying to see a firefly with a nuclear explosion as a backdrop.
Alternative reading (Score:2, Informative)
Tiny Elvis (Score:1)
Re:Tiny Elvis (-1 offtopic) (Score:1)
SETI already does something like this (Score:2)
Re:SETI already does something like this (Score:2, Insightful)
Pulling the data together after the fact and then analyzing it shouldn't result in a different conclusion of facts based on the data.
Re:SETI already does something like this (Score:1)
Re:And immediatly they discovered (Score:3, Interesting)
Jupiter does. Some amatures can even detect Jupiter's radio emmissions from home-built radio scopes.
I have read that Jupiter broadcasts more radio noise than the Sun, but don't quote me on this.
BTW, it has no beat and you can't dance to it.
Planetary radio sources. (Score:2)
Jupiter does. Some amatures can even detect Jupiter's radio emmissions from home-built radio scopes
Any planet with a magnetosphere should produce substantial radio emissions from both trapped particles in their equivalent of the van Allen belts, and from diverted solar wind crashing down near the poles (the aurorae come from _somewhere_
In practice, this means anything Earth-sized or larger (i.e. something with a molten nickel-iron core, or [for gas giants] with a metallic hydrogen ocean). In principle, ice moons with mantles of saltwater deep beneath the surface might have magnetospheres too, but in practice they won't have much, as you need a powerful heat source to drive the dynamo.
I have read that Jupiter broadcasts more radio noise than the Sun, but don't quote me on this.
I'd have to look that up. It sounds more like a mangling of another quote (that Jupiter emits more energy than it receives from the sun), but the Jupiter/Io flux tube does emit a lot of crud.
It's just that switchback currents in solar flares do too
nomenclature (Score:2)
Bay Wof (Score:1)
Yes but... (Score:2)
All I care about is can it see the pornography on the nearest planet inhabited by intelligent perverts like us?
Resolving Golf Balls (Score:4, Funny)
"The resolution achieved by this telescope is the equivalent of sitting in New York and being able to see the dimples on a golf ball in Los Angeles," astronomer Sheperd Doeleman said this week. "
I'm surprised an astronomer would say that. Most of them know that the earth is round. Seeing the L.A. golf ball would be really tough. I don't believe they can see through dirt, and even Tiger Woods couldn't hit it high enough. I felt the bodies of a thousand astronomers flinching in their graves.
Re:Resolving Golf Balls (Score:1)
contentless article, nothing new (Score:2, Informative)
array of radio telescopes scattered around the whole earch can act like a single telescope if we combine the signal coherently. this can be done by connecting them together in real time (e.g. VLA in New Mexico) or offline (e.g. VLBA). Both VLA and VLBA are run by NRAO [nrao.edu]. if you want to do offline, you need to preserve amplitude, phase and timing information. atomic clocks are used for time stamping and supercomputers are used to combine signal. this simulates a large telescope whose lens is mostly opaque, save for few dots! the technique is really old (originated in late 60s, early 70s) and has been well mastered for more than 20 years. so there is absolutely nothing new in the article. depending upon the scientific relevance, many global telescopes participate in these experiments. in some cases, only US telescopes (VLBA which is scattered from hawaii to virgin islands) participate, which creates somewhat smaller effective telescope size. some experiments have beed done using space based radio telescopes which increases effective size even further (by the time, the space telescope became operational in late 90s, i left astronomy, so don't know the results).
the supercomputer which combines signal is made up of custom chips and uses custom OS. linux part is quite small and it comes into picture well after the data has been pre-processed (raw data sizes could be few terrabytes a day while processed data is only few gigabytes).
Re:contentless article, nothing new (Score:2, Informative)
radiation (as opposed to VLBI which has a maximum
of about 2cm). So we've pushed the resolution up by
a factor of ten (with admitedly poor baseline coverage) and as a result the hardware has to sample
10x as fast.
The `new' is in the hardware, not the technique. Lets not forget that the first sub-mm (0.3-1.3mm)
interferometers are fairly new instruments, indeed
they are the `last' wavelength to "discover" interferometry.
ali
Earth-Sun baseline? (Score:1)
Wow! How did they get the RAID to actually work? (Score:1)
I'm impressed! I just spent a couple hours setting up an Adaptec 1200A IDE RAID 0, only to find out that it runs as fast as the individual drives did, about 40MB/s.
Re:Wow! How did they get the RAID to actually work (Score:1)
I have a raid 5 that runs 500MB/s
Excuse me but... (Score:1)
Re:Excuse me but... (Score:1)
Re:Excuse me but... (Score:2)
Why don't you think so? Try looking at a globe, and you'll see that those locations have a decent overlap in their fields of view. Alternatively, think of their time zones -6, +1, +2, -8. The maximum difference is 10, and half the earth is 12. Hence they are on the same hemisphere.
Re:Excuse me but... (Score:1)
Re:Excuse me but... (Score:1)
quoting: (Score:1)
For millions of light-years - yes that *is* a long time....
Just like 10 kg is indeed very fast.
MIsleading headline (Score:2, Informative)