Slashdot Mirror
The Billion-Dollar Telescope
dcmeserve writes "As in all science, astronomers are ever searching for better technology to aid in their task. But when it comes to telescopes, nothing beats sheer bulk of light-gathering capability. This article gives a brief overview of the top contenders for the next leap forward, including
a 100-meter behemoth that is expected to run $1 billion."
In fact, it's "The Billion-Euros Telescope" which means about 20% more.
____
nico
Nico-Live
Necessity may be the mother of invention, but when you've got a lean budget you innovate.
BTW, there's this interesting other stuff in the news about Aussies seaching the heavens for likely places to host another earth.
Obligatory filching of Galaxy Song lyrics: So remember, when you're feeling very small and insecure,
how amazingly unlikely is your birth,
Pray that there's intelligent life somewhere up in space,
because there's bugger all down here on Earth.
A feeling of having made the same mistake before: Deja Foobar
Hey hubbles lens is(or at least was a month or so ago) the smoothest man made object. We're talking about polishing a lense so that the surface bumps are smaller than transistors, and the shape is near perfect over a 10 meter or 30 meter diameter. That is where a lot of the money will go. Also, throw in a few physicists at about 80k a year, a IT guy, 60k a year, a janitor, a tour guide, a few technitians salarys for 20 years. Not to mention if something big goes wrong, your going to have to fly in experts to Chile or where ever. They aren't going to want to drop what there doing unless you pay them really well. An atomic force microscope can image at the atomic scale. It is made from a rod and a piezoelectric crystal(the same type of stuff that's in a barbeue starter). The price tag on those is about 1M, I know a lab with 3 of these guys. To get a top notch small scale lab going your looking at 1-10M. The data from the telescope will be used by hundreds of researchers.
Vacuum qualified autonomous hardware is extremely expensive. Hubble's mirror is 2.4m in diameter I think, and building/launching/running/maintaining it has cost over $2 billion. The 10m ground-based Keck observatory cost $80 million.
Astronomers want a big telescope in their lifetimes, not in the remote future when people go back to the Moon (if ever?). Its also pretty dusty and dirty up there...
Negative.
Slashdot monitor for your Mozilla sidebar or Active Desktop.
Not really. With the rise of adaptive optics, ground-based telescopes are increasingly able to achieve diffration-limited or near-diffraction-limited resolution in the optical and (in particular) the near-IR (which is of crucial importance for cosmology -- the current "Hot" area of astronomy).
Once you hit that physics-limited level of resolution (which has been the true advantage of HST), the gains come from light-gathering ability. This is where ground-based telescopes clean up. The $$/area is much lower (i.e. better) for ground-based telescopes. And the upkeep costs are much smaller as well. Space is expensive.
When you can have a telescope with near-diffraction limited resolution and 10-1000 times the light gathering ability of a space-based telescope of the same cost, astronomer's will choose that guy any day.
Note: IAAA (I am an astronomer)
Putting telescopes on mountaintops solves a quarter to a third of that problem, since a good hunk of the atmosphere is below you . Adaptive Optics solves another big hunk of the problem. And until we can fabricate the space telescope in space it will be possible to build earth based telescopes much larger for much less money.
No electrons were harmed creating this post, though some may have been subjected to electrical and/or magnetic fields.
I wonder why nobody is talking about a lunar-based telescope. It seems that would give you the best of both worlds: pretty much no atmospheric interference, but with a modicum of gravity so a human crew could be there for extended periods.
Am I just crazy to suggest such a thing?
No, you're not crazy to suggest such a thing; you're crazy for saying that nobody is talking about it, hehe.
Seriously, it does get discussed in the astrophysics community, and there are people who are enthusiastic about it. In the end, it comes down to what you want to spend your money on. Right now, high redshift optical and IR observations are not as limited by atmospheric distortion as they are by the ability to collect a lot of light, which in turn is limited by the collecting area of the telescope. Building your telescope on the Moon wouldn't appreciably change the collecting area required.
With a fixed pot of funds, and the incredible expense of safely lifting the components of a large telescope to the moon, assembling the telescope there, and then operating/maintaining it, the maximum size of your telescope just got a lot smaller. Is what you gain in image resolution by going to the moon worth what you lose in what, and how far away, you can see? Right now, so much of the interesting optical and IR observations are aperture limited, and so most observers' answer to that question is no.
You're not going to get rid of it completely, but there are steps to reduce it immensely: just covering the tops of street and park lights (i.e. no more of those white globe lights) does wonders - the intensity of the light that's reflected up into the sky from the streets' asphalt is miniscule compared to the amount of light that's emitted straight up into it if the light lacks a covered top (and as a bonus you'll get better light down on the ground where it's needed)...
There's more to the electromagnetic spectrum than visible light you know. The Hubble Space Telescope is only one of NASA's four orbiting "Grand Observatories". Here are links to info about the other telescopes.
Several people have commented that the money may be better spent on a space telescope. Here's why that may not be true:
Advantages of space:
* Extremely low light pollution and air absorption. This means you can see very dim things that may not be ever visible from the ground.
Advantages of ground:
* Initial cost is about 100-1000 times cheaper for same-sized primary
* Repairs and routine maintenance are possible without a $250 million shuttle launch
* Newer technology is possible, since it's less risky. Hubble uses a lot of electronics from the early 1980s.
Hubble cost $1.5 billion initially plus $0.25 billion per year (http://hubble.nasa.gov/faq.html) for a 2.5-meter telescope.
Since light-collecting power goes as the square of the diameter, a 100-meter telescope has 1600 times the light collecting ability of Hubble. So, if the celestial objects of interest are not background-limited, you can get the same quality image in 1 minute that would take Hubble a whole day to acquire.
Here is a link that mentions it.
You can make a cluster of telescopes, the technique is called interferometry. However, combining the results from individual dishes requires painstaking detail. The lengths of the signal paths must be matched to a degree less than the wavelength of the signals. For radio astronomy this has been done for a long time, because the wavelengths are quite manageable. The optical equivalents are only quite recent and not that widely deployed, but here is one example that I know of.
Escher was the first MC and Giger invented the HR department.
the mirror are so large and focused on such long distance objects, all the supports and equipment do is reduce the photons by a very slight amount. to compare, hold the end of a paperclip as close to your eye as you're comfortable with, and look off into the distance. You'll hardly notice its there.
-
You can't get rid of it completely, true. However light pollution can certainly be curtailed. Proper full-cutoff light fixtures ensure that more light is directed downward on to the street--where it does some good--rather than up to the sky--where it annoys astronomers.
Hawaii is not exactly uninhabited, but they make regular and concerted efforts to limit light pollution because of the observatories on Mauna Kea. As an added bonus, reducing light pollution saves energy--those expensive photons end up directed mostly where they are needed, rather than being lost.
~Idarubicin
oy.
The big bang was not an explosion of stuff out into a pre-existing space. It was an explosion of space itself.
See This link: http://www.astro.ucla.edu/~wright/balloon0.html
The important point in this case is that there is no "center" where the big bang happened. Any direction you look, you are looking back to the big bang... which happened EVERYwhere.
The best description I've read of this is in "Wrinkles In Time" by George Smoot, which tells the story of the COBE mission.
"Fifty million Americans can't be wrong," said Rep. Billy Tauzin. Gore - 50,999,897 Bush - 50,456,002
Short answer: yes.
As others have pointed out, there are lots of wide-open spaces in North America. I've seen black night skies in many remote parts of Canada, and the desert southwest U.S. One fascinating trip last year was to an outfit out in the middle of nowhere in New Mexico that had cool telescopes you could use and dark skies. A blast, in other words.
A couple of other points on location:
Too far north and you lose dark skies in the summer. Midnight twilight north of 49 degrees, midnight sun in the Arctic. I spent my teens at 53 north and never saw real darkness in the summer.
South is good if you like looking at our galaxy. The center of the Milky Way is in the direction of Sagittarius, low in the sky from here (Vancouver, 49 north), but overhead from Australia or Chile. This also gets you the Centaurus/Vela/Carina segment of the Milky Way, which is stunning to look at and full of goodies. As an added bonus you get two satellite galaxies, the Magellanic Clouds.
...laura
In particular, there seems to have been an agreement made some years ago between whatever entity handles the summit for astronomy (probably the University of Hawaii Institute for Astronomy) and some native groups (mountaintops are sacred places) under which the astronomy folks got permission to build a certain number (int) of telescopes.
That many have now been built. The astronomy folks would like to build more. And... various folks (natives and others) are noting that um, no, that's not what they agreed to. So there's been a lot of paperwork, environmental impact statements, and so on.
In some cases, things are a little grey-area-ish. They want to build "outriggers" on the sides of the Keck scopes, for example. And the Smithsonian-Sinica.tw-Harvard submillimetre array - does that count as 8 scopes, since there are 8 dishes, or 1, since it's an interferometer?
As it now stands, though, Mauna Kea wins lots of astronomy pissing matches. :) It has the 2 largest optical scopes in the world (Keck and Keck II), plus the 4th largest (Subaru) and another in the top 10 (Gemini North), the largest single submillimeter telescope (James Clerk Maxwell) and I think the largest dedicated infrared telescope (UKIRT).
If someone wanted to build a truly monster scope on Mauna Kea, they could simply remove one of the small ones, it would seem. University of Hawaii has an 0.6-metre one and a 2.2-metre one. (Yes, those are "small," all you backyard astronomers who are now drooling. ;) Take out the 0.6 and replace it with a 30-metre one, and you haven't changed the number of telescopes, right?
Cutting down light pollution is practical, any light going up and is no use to anyone. Putting a simple reflectors on top of street lights a) cuts the light pollution b) gives more light for people to see where there going and/or c) reduces the amount of power you need to provide a given lighting level (reducing CO2 production). Would you really miss thoes trendy spherical street lights that send 50% of their light straight up?
No need to say again the reasons why this isn't feasible (yet) the way you say. Just wanted to show a link to another interferometer: the VLTI
That machine is so delicate that we weren't allowed to walk near the tunnels (you see them on the picture) when I was visiting the site.
Cheers...