Giant Telescopes Of The Future 136
mindpixel writes: "Mindjack just published my article about the the future of very large telescopes, such as the VLT and the OWL which I talked about in my /. interview. In addition, I talk about a future space-based telescope that would use the Sun's gravity to 'image large surface features,' of extrasolar planets, which telescpes like the VLT can just detect, 'such as oceans, continents or ice caps, or even the impact of civilization on such features.'"
Re:Borrrrrrrrring!!!!1! (Score:4, Insightful)
The one thing they need... (Score:1)
Ah! It's so simple. All we need is money!
With the budget cuts at NASA, I don't think either one of these ideas will take off. (no pun intended)
D/\ Gooberguy
Re:The one thing they need... (Score:2)
The plan I'm working now calls for each of the 1600 OWL primary mirror segments to be financed by different visionary individuals and corporations. I'm bugging all my billionaire friends to each sponsor a segment at about $625,000 per segemnt, it's cheap and useful immortality.
As well, 62,500 people could get together (a city perhaps) and each contribute $10 to sponsor a community segement...
This fractional financing model is easier and better than trying to convince a single entity such as a govenemnt to pay the whle $1 billion.
How much bigger... (Score:2, Informative)
Re:How much bigger... (Score:1)
atmospheric distortion (Score:4, Interesting)
To me, that is simply amazing. Adjusting 1600 mirrors realtime to correct tiny air currents!
Corecting atmospheric distortion (Score:1)
This is done continously and the information is fed into a computer which caluclates how to deform the mirror, or mirrors, in order to get an undistorted light beam to the detectors in the telescope.
Using this kind of technology the European VLT will be able to create better pictures from the ground than the Hubble do from space. The current belief is that the limit for adaptive otpics will be reach with telescopes of a radius of 130-150 meter.
However space based telescope are still the only way to observe at wavelengths which are aborbed by the earths atmosphere.
Orbital Telescopes... (Score:3, Interesting)
I'm curious to know - because of the limited size (surface area) on earth (which cosmologically is a pinprick in space) what kind of performance increase would one get by placing those telescopes in space and would it be a better move in the long run?
-- Dan =)
Re:Orbital Telescopes... (Score:1)
Can't get better than that, can it?
Interferometry (Score:4, Informative)
Re:Orbital Telescopes... (Score:1)
Re:Wh00t (Score:2)
Re:Wh00t (Score:1)
Apparently, for you, that is a big achievement. Not too many times, mind you, that would be too much effort, but a few times anyway. (I think my karma is still better than yours, though, for what it is worth.)
New excuse for oil companies... (Score:2, Funny)
You think we've got global warming problems just because our ice caps are melting? Go talk to the aliens over on Alpha Centauri, they've got so much global warming that their continents are melting!
Why not just do it the Bible way ? (Score:3, Funny)
After all we know that the universe is around 6,000 years old so you don't need a very big telescope, and anything that looks older is wrong so you don't need funding.
This announcement was brought to you by the State of Kansas Research Funding Department.
:-)
Solar foci telescpoe (Score:4, Insightful)
Re:Solar foci telescpoe (Score:3, Insightful)
Today the Hubble acts as a finder scope and the VLT as a spectrometer. The Hubble's small mirror, and the fact that it is in space make it a poor spectrometer for distant or faint objects. The reason for this (other than the small primary) is that after about 20 minutes exposure in space, the CCD becomes saturated with cosmic rays. On the ground, the atmosphere filters the cosmics, allowing for much longer exposures than are possible in space.
Re:Solar foci telescpoe (Score:1)
Once you have scanned one target star/galaxy/ nebula you have to wait anther coupler of millenia to get to the next intersting spot. By that time we should have invented warp drive or some other FTL technology and visited the place...
Re:Not a good idea (Score:1, Informative)
space is that empty. In interplanetary space there are about two or three molecules per cup of vacume space.
anything without a gravitational field can be expected to last damn near forever if you keep it away from things with gravitational fields. Basically if we put it far away from the sun, comet tails, and other planets there's almost no chance it will ever be hit by anything.
It's only space near planets that is filled with junk. And earth is an especially bad case because we've dumped lots of additional junk in orbit ourselves.
tjw19[at]columbia.edu
Re:Not a good idea (Score:2)
Bruce Willis.
Links (Score:5, Informative)
A very readable article, but I was surprised to see no other information on the referenced large telescopes. To save others from searching as I did, take a look at:
Other similar info links. (Score:2, Informative)
For example the Terrestrial Planet Finder (TPF) [space.com] which although is currently un-funded, is targeted to launch around 2011.
More links and info. [space.com]
These kinds of advancements make me happy to be alive now, and I look forward to 'seeing' the first "earth like" plannet!
Re:Links (Score:2)
Not to mention the Square Kilometer Array ... (Score:5, Interesting)
LL
Re:Not to mention the Square Kilometer Array ... (Score:1)
There's one limitation with ground-based arrays that might be avoidable in space (or on water for that matter) - being stuck with an array covering a fixed area, once you've spent your money.
Could a space-based array be designed so that once it reaches its target location, it spreads itself out, gradually increasing the distance between its elements in a coherent manner, thereby increasing the effective size of the array over time? I would assume that a space-borne array would already be designed with plenty of fuel/rocketry for compensating for massive objects passing nearby and tugging on its corners... The same principle might be handy for adjusting/balacing the spacing between elements if an asteroid hits the jackpot, or a failure is detected.
Space-based radio telescope arrays. (Score:3, Interesting)
Yes, but you'd be trading off angular resolution against aliasing artifacts (the less of your aperture is filled, the worse aliasing artifacts will be, even when you assume constant sources and integrate over time). IMO, you'd be better off just adding more satellites
By coincidence, I recently did the calculations for the size of a metre-band radio telescope array needed to resolve features 100 km in size at a distance of 10 light-years (enough to resolve the aurorae of earth-sized planets, show thunderstorms on gas giants, and so forth). You'd need thousands of radio telescopes in solar orbits out to a radius of about 4 AU, but you could do it. Put them in eccentric polar orbits (i.e. away from most of the junk in the ecliptic), add excellent GPS-style beacons in precisely known orbits (constantly observed from Earth) to let the satellites track themselves, and you could get a very nice radio telescope for a surprisingly modest price (cheap satellites, well-known technologies and electronics, and the benefits of mass production, since you'll be making a thousand or more of them).
Such a telescope would be able to see aurorae and civilization-induced radio junk from Earth-sized planets out to around 10 light-years, map the magnetospheres of Earth-like planets and see detailed magnetic features in gas giants out to about 100 light-years, and get very detailed pictures of the outer envelopes of stars out to about 1000 light-years. It would be a very useful project.
Interesting idea but... (Score:5, Informative)
The solar foci telescope sounds like a really interesting idea but I'm not sure it's all that practical now or in the near future. 550 astronomical units is really far out there, several orders of magnitude further then any other space mission to date. Combine that with the proposed size of the mission spacecraft, again vastly larger then anything previously done, and I don't see this happening anytime soon. Still, a very interesting idea though and a logical extension of using extra-galatic objects and looking for lensed objects behind them. Just a few years back that was 'never been done before' stuff too so who knows. In any event, I have to give credit to whomever came up with this idea, they certainly think big!
More information on the solar foci idea can be found on this page from the Texas Space Grant Consortium [utexas.edu].
Re:Interesting idea but... (Score:3, Informative)
This is not correct. Pioneer 10 and Voyager 1 have both passed more than 75 AU (which you would have known, if you read the following paragraphs in the article), and that does not make 550 AU "several orders of magnitude further".
So, even if 550 AU isn't really that far away, considering that this is the inner boundary of the solar foci, this is indeed a technical challenge.
It doesn't seem to be an unsurmountable challenge as such, except for the political issues with the nuclear powered engine.
Re:Interesting idea but... (Score:1)
Not that necessarily this detracts from the possibility, new propulsion techniques such as the ion drive discused in the article will bring that time down considerably, but I didnt notice any estimates there in the article. A quick guess would indicate that even at 10x the speed, you would still be looking at a few decades of travel time!
So I would imagine this being quite a while off yet, neverless it's still a very good idea!
Re:Interesting idea but... (Score:1)
I think it's important to keep in mind that neither Voyager 1 nor Pioneer 10 were ever intended to last as long as they have. Its a tribute to the engineers and technicians that designed and built these spacecraft that they continue to do useful science long after their primary missions ended. What the solar foci mission proposes to do though is really quite different from any previous mission and comparing the Voyager or Pioneer missions to it is, in some respects, like comparing apples to oranges. Sending a spacecraft out to 550 AU before it actually starts its primary mission is an entirely different proposition and a very much harder technical feat to achieve. Consider that the round trip light-time to 550 AU is on the order of 6 days and you start to realize how far out we're talking about here. Not that I think it's impossible to accomplish this type of mission but I don't expect to see it happen in my lifetime. I'll leave out the discussion of costs for another time but suffice it to say that considering all the hassles that the NASA and the Pluto Express folks have run into I wouldn't hold my breath.
I'll give you the point as to the 'orders of magnitude' question. I tend to use the astronomical definition, i.e. approx. 2.5 times, and not the 10 times definition. So sue me.
Re:Interesting idea but... (Score:2)
That's the astronomical definition of "magnitude", not "orders of magnitude".
No need to sue. Just back to school
Definition of "order of magnitude" (Score:1)
On the other hand, a factor of two seems not to be big enough. If a is twice as big as b, they seem still to be in the same ballpark. The b quantity is a significant portion of a, such that subtracting b would completely change the character of a.
So, I came to the conclusion that e, the base of the natural logarithm, should also be the base for "orders of magnitude". To me it seemed like about the right ratio to raise one number into a whole different category from another.
However, since most of us still count on our fingers, ten it is.
Re:Interesting idea but... (Score:1)
I wondered about this too. I figured that the plan would involve slowing down, upon arrival, so the telescope stayed near the 550 AU sphere. Even so steering the telescope so it was looking at some other part of the sky would take decades.
I wondered about a couple of other things. How much power would be required to send a signal from this telescope back to Earth? How big would the receiving antennae have to be?
550 AU, let's see, that is 4,400 light minutes, or
about one light month.
Maybe this is more practical (Score:1)
Re:Interesting idea but... (Score:1)
Much higher top speeds, supposedly even relativistic speeds, can be reached by this method. Thus, the trip length may be vastly shorter than the rocket thruster+slingshot method that these older satellites use.
However, IANARS, so please correct me if I'm wrong.
Re:Interesting idea but... (Score:1)
Make Your Own Telescope (Score:4, Interesting)
You can get books telling how to make telescopes from Willman-Bell [willbell.com] and ask for help on the Amateur Telescope Maker's mailing list [jacksonville.net]. Dan Cassaro [jacksonville.net] can sell you a reasonably priced mirror grinding kit.
You can find many products for amateur astronomers at the Astronomy Mall [astronomy-mall.com].
Clear Skies!
Scary... (Score:1)
$title =~ s/Telescopes/Robots/; :)
Sweet (Score:1)
World-wide radio telescope. (Score:3, Interesting)
If that's possible, maybe when people are not using their satellite antennas for TV they could be combined to create a world-wide radio telescope.
I'm thinking of something along the ideas of SETI@home. There, the unused computer time of many people is combined for the SETI program. Maybe unused satellite TV antenna time could be combined in a similar way.
To create a large and powerful telescope you combine several smaller telescopes. There is an enormous amount of unused TV antenna time. If ordinary satellite dishes are suitable for this purpose, you'd get an extremely powerful telescope.
Give a man a fish and he eats for one day. Teach him how to fish, and though he'll eat for a lifetime, he'll call you a miser for not giving him your fish.
Re:World-wide radio telescope. (Score:1)
I wonder why people aren't trying this.
Give a man a fish and he eats for one day. Teach him how to fish, and though he'll eat for a lifetime, he'll call you a miser for not giving him your fish.
Re:World-wide radio telescope. (Score:1)
It's possible, but not happening now!
Re:World-wide radio telescope. (Score:1)
Wouldn't it be possible to record first and combine the signals later? For synchronization, instead of having a perfect clock you would look for known periodic signals from stars etc. Would that make sense?
Does this just lower the quality of the signal or is it impossible to receive a useful signal in the desired frequencies?
If instead we tried on the frequencies that they are built for, would that be meaningless? Could such frequencies reach us?
Interesting! Maybe it'll happen some day then!
Give a man a fish and he eats for one day. Teach him how to fish, and though he'll eat for a lifetime, he'll call you a miser for not giving him your fish.Re:World-wide radio telescope. (Score:1)
Of course! Now I understand why nobody is trying this!
Once we had our world-wide collaborative antenna tuned to our nearest neighbor civilization's TV frequencies, we'd have endless world-wide conflicts about which programs to watch.
Give a man a fish and he eats for one day. Teach him how to fish, and though he'll eat for a lifetime, he'll call you a miser for not giving him your fish.
"Yes, but" for satellite-TV distributed telescopes (Score:3, Interesting)
If that's possible, maybe when people are not using their satellite antennas for TV they could be combined to create a world-wide radio telescope.
You could in principle do this, but in practice there are problems.
The main problem is that the electronics in the detector used with the dish are completely unsuited to radio astronomy. To use a radio telescope as a part of the array, you need a high-fidelity sample of the radio signal being received, timestamped to atomic-clock accuracy. A satellite TV pickup doesn't have a sub-nanosecond-accurate clock, and won't give you a digitization of the raw signal. Instead, it looks for strong signals in specific, narrow bands and blindly decodes them through combined analog and digital means (i.e. it treats everything it hears as a TV signal).
A secondary problem is that your satellite dish is pointed directly at a strong source of radio noise in the frequencies it's tuned to detect (the satellite).
The idea is a great one, but because you'd need to completely replace the electronics rig with something far more expensive, a better approach might be to sell radio telescope array "kits" built from stock parts and forget about using peoples' TV dishes.
This would probably be quite practical from an engineering standpoint, as most of the parts (including timestamping radio sampling boxes) can be bought off-the-shelf. I have no idea if enough amateur astronomers would buy these for them to be marketable (they wouldn't be cheap - tens of thousands of dollars per kit).
Idea Already Floated (Score:1)
The home satellite dish idea is in the closing graph.
Earth Begins To Fade From Galactic View
By CHRISTIAN LARKIN (Special to SPACE.com)
Mountain View, CA, November 16, 2001. You can watch "Aliens" on DirecTV, but as a result fewer aliens will be watching you. At a time when the sphere of radiation carrying "I Love Lucy" has reached a radius of 50 light years, stray emissions from Earth into outer space are plummeting as communications technology moves away from the big broadcast antenna or yore into new delivery systems.
Like a ship deliberately eluding detection, we may slip into global radio silence.
In other words, for extraterrestrial civilizations scouting weak radio frequencies for signs of intelligent life in our neighborhood in future millennia may miss Earth because for practical purposes our beacon will have winked out.
Astronomer Frank Drake, SETI (Search for Extraterrestrial Intelligence) Institute chief and author of the famous "Drake Equation" for calculating the number of civilizations beyond Earth, expressed his dismay in the book "Here be Dragons," by David Koerner and Simon LeVay.
"The thing that's ringing alarm bells for me," says Drake, "is that we see our civilization going very rapidly toward the use of fiber-optic systems, and direct to home satellites. A typical TV station radiates a million watts, but a typical satellite transmits at 100 watts, and of that only about 10 watts leak out into space. So we're rapidly losing visibility--by a factor of 100,000. Is that typical or quirky? We don't know, but it's a warning signal."
But while Drake fears the Earth will become a wallflower at the galactic dance, other express relief.
"Earth is dimming, and that may just save our civilization," according to researcher who requested the he remain anonymous. "I am certain that extraterrestrials exist, though I can't tell you why. All I can say is that we're not ready for our coming out party."
The fear of premature detection is one UFO enthusiasts have debated for years.
Experts say that one solution for those want to be spotted is to actively send transmissions in strong and steady streams in the frequency that matches quantum transitions of hydrogen, the most common element in the universe. Radio astronomers use the hydrogen band as a benchmark, much as videotape cameramen "white balance" their instruments.
Ironically, the plethora of home satellite dishes currently forcing the demise of broadcast television and radio could also be a boon for SETI. Eventually, linking volunteers with such hardware in an effort to scan the skies could propel the hunt for alien messages more economically than building large telescopes like the Arecibo Observatory in Puerto Rico. The effort to process radio waves from outer space has already gotten a boost from volunteers donating time on home machines for a parallel computing program called SETI@home.
Copyright 2001 by Space.com, Inc
Re:World-wide radio telescope. (Score:1)
There was a science fiction movie, starring Charlie Sheen, that used this idea, half a dozen years ago. In addition to the excellent objections to this idea that have been raised already let me add one more. Steerable satellite antennae intended to be used with geosynchronous telecommunications satellites all point to locations above the equator. You can change the longitude they point at, but not the latitude.
So, it's only a matter of time... (Score:2, Funny)
Optics (Score:1)
just my misguided two cents.
NASA's still in the game though ... (Score:2, Interesting)
cost? (Score:1)
Let's see: 400 tons is 800,000 lbs and at NASA's goal by 2025 of $100/lb that is $80,000,000. That's just launch costs alone. Ouch.
550 AU (Score:1)
A 100+ redundant system would be cheap over a self fixing system. Let's go! A B.F.A.A (Big Fuckin' Ass Array) would solve many philosophical questions. Artificial light on a far away planet? Bring it on!!!
Moon-Based Telescope...? (Score:1)
The moon, however, has neither of these problems. It doesn't have any seismic activity that I know of, and there is no atmosphere to hinder a telescope.
From what I gather (I don't know nearly enough about this stuff) you don't actually need to build a giant telescope on the moon for this to work. You can build an array of smaller scopes and link them together to see a giant field. Since the moon has no seismic activity all of the small scopes effectivly function as one giant one, that we can focus onto anything we'd like, including extrasolar planets.
Since these are smaller telescopes (not tiny, but smaller than some of the giant things we've got on earth), we can use traditional spacecraft to get them to the moon. Of course it'll cost a lot, but would make the Hubble look like a child's toy when it's finished. The question is, are we willing to head back to the moon, and do we really feel that the search for life is this valuable?
Robert Zubrin wrote a good book about this, "Entering Space", which is where I got most of this moon-telescope information. My copy is back at my dorm in Arizona, so I can't quote exactly, but I think I've given the basics. A site that may also be helpful is Here [google.com] (A little to much math for my tastes, but maybe some of you guys can figure it out)
Charlie
Re:Moon-Based Telescope...? (Score:1)
And LEO has another advantage: No gravity which means you don't have to take care about mirrors bending because of their own weight.
Oh, BTW there are quite often (and sometimes quite large) moonquakes as the seismometers installed by the Apollo crews showed.
Moonquakes? (Score:1)
Why not use Earth as the lens? (Score:1)
What is the focal length for the earth anyway?
Re:Why not use Earth as the lens? (Score:3, Insightful)
No idea, but given that the earth is much lighter and thus much less "light bending" as the sun I guess it's much, much, much larger... (a few light years?)
Satellite roast? (Score:1)
Don't you think it'd be a bad idea to place a multi-billion dollar satellite in an area of space where the sun "...focuses all electromagnetic radiation passing it to a resolution beyond anything possible with human engineering." ? In order to be useful (i.e. have an electromagnetic image in focus) the 'scope would have to be near the focal point where DC-gamma radiation levels would be unbelievably high.
Also, is a 76 hour one-way light travel time going to cause problems? We have enough angst waiting for stuff from mars.
Going out to 550 AU (Score:2, Interesting)
To start, our most distant Pioneer probe won't be at 550 AU for 180 years. Pluto, remember, is just at 39 AU. Radically increase speed and you'll have a probe there in what, 80 years?
Once there, where will you point it? You'd have to spend hundreds or thousands or years arcing the telescope into different positions to see a broad sweep of space. And we don't have that kind of fuel technology, including nuclear.
I was in love with the 550 AU idea (I've read that 763 AU might be ideal), but the reality check dampened that more than a bit.
I hope this helps.
Erik Baard
Re:Let the McKinstry bashing begin... (Score:1)