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Prototype Telescopes Complete Key Test

CowboyNeal posted more than 7 years ago | from the if-this-trend-continues dept.

Space 78

Matthew Sparkes writes "Two prototype antennas for the world's largest array of millimeter-wave telescopes have passed a key test, working to track and image Saturn for more than an hour. Ultimately, ALMA (Atacama Large Millimeter/submillimeter Array) is expected to resolve details 10 times finer than the Hubble Space Telescope when it is completed in 2012."

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Rubber baby buggy bumpers. (-1, Troll)

Anonymous Coward | more than 7 years ago | (#18300420)

Rubber baby buggy bumpers.

Cached page (1)

LotsOfPhil (982823) | more than 7 years ago | (#18300442)

Server isn't responding to me. So I ask google. cache [209.85.165.104]

Text (3, Informative)

Anonymous Coward | more than 7 years ago | (#18300476)

Two prototype antennas for the world's largest array of millimetre-wave telescopes have passed a key test, working together to track and image Saturn for more than an hour on 2 March. Ultimately, ALMA (Atacama Large Millimeter/submillimeter Array) is expected to resolve details 10 times finer than the Hubble Space Telescope when it is completed in 2012.
ALMA will use up to 64 antennas and will be located in the Atacama desert, 5 kilometres above sea level in the Chilean Andes. Designed to look through dust clouds to reveal star formation, image embryonic planets and probe the early universe, it will be the world's most sensitive telescope at wavelengths of 0.3 to 9.6 millimetres - a regime obscured at lower altitudes by atmospheric moisture.
But making all of the 12-metre dishes function like a single giant telescope will be a challenge. Fibre-optic cables will link each dish to every other dish in the array, and to a giant special-purpose electronic computer called a correlator.
"It collects the amplitude and phase information from each of the antennas, and knowing their distances from each other, it lines everything up to produce a coherent picture of the source," says Jeff Mangum, an ALMA project scientist at the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia, US.
'Fringes of the universe'
The 2 March test actually linked two prototype antennas at another observatory, the Very Large Array site in New Mexico, US, with each other and with a small-scale prototype of the correlator. But the test, called 'first fringes', bodes well for ALMA's future, Mangum told New Scientist: "It verifies that ALMA can make measurements not just as single telescopes, but as a collection of antennas, which is the primary mode of operation."
Millimetre waves are at the upper end of the radio spectrum, just below infrared radiation. They can reveal important organic molecules, but are obscured by atmospheric moisture.
Small arrays at lower elevations have probed the sky since the 1980s, but atmospheric moisture made observations difficult at wavelengths shorter than 3 millimetres. A 1990 report urged building a large array at high elevation, and the NRAO, the European Southern Observatory, and the National Astronomical Observatory of Japan later picked the Atacama site. The altitude puts the array above most of our atmosphere's water, allowing observations down to 0.3 millimetres.
Although plans call for up to 64 antennas, present funding can pay for only 50 or so dishes. The dishes will be movable, allowing baselines from 150 metres to 18 kilometres, with the longest baseline and the shortest wavelength giving resolution as fine as 0.005 arcsecond, a factor of 10 better than Hubble.
Because millimeter waves can penetrate dust that blocks visible light, ALMA's large collecting area "will make it much easier to detect very faint objects at the fringes of the universe", says Mangum.

well, (1, Funny)

Anonymous Coward | more than 7 years ago | (#18300506)

apparently, you've slashdotted Google.

---
brought to you by the CAPTCHA "flamers"

Ultimate Test (1, Funny)

Anonymous Coward | more than 7 years ago | (#18300458)

Ah, but can it image... Cassini?

That would rock.

Re:Ultimate Test (0)

Anonymous Coward | more than 7 years ago | (#18301462)

Not yet. But it will.

Obligatory joke (0)

Looce (1062620) | more than 7 years ago | (#18300488)

I, for one, welcome our new overlords from outer space.

With finer details!

Will they.. (2, Interesting)

Creepy Crawler (680178) | more than 7 years ago | (#18300490)

Censor the raw data coming from out of this too, like they have with the Hubble?

I'm a ham operator, and the signals coming from the Hubble are a jumbled mass of unintelligible garble. Further research shows they are using military hardware for secure connections.

I do understand that control codes are administered via ground, however, public key signing would allow transparency while providing a secure platform.

Why do they hide the whole data stream? What do they not want us to see?

Hubble censored? Data encrypted? (4, Insightful)

Firethorn (177587) | more than 7 years ago | (#18300550)

I have no problems believing that the control data is encrypted for the hubble. For one thing, you don't want others taking it over.

As for the data, I'd imagine that it'd be compressed, encoded, and multiplexed to the point that you'd need special equipment that no normal HAM operator* would have, much less the settings needed to sort it all out and make sense of it.

For public key stuff - that's more computationally intense than private key military encryption methods. Remember, we're talking about systems where a 386 would be considered 'high end'.

*I'm not saying that you're a 'normal' Ham operator, Crawler, but we're talking the space industry here.

Re:Hubble censored? Data encrypted? (3, Interesting)

Creepy Crawler (680178) | more than 7 years ago | (#18300756)

---I have no problems believing that the control data is encrypted for the hubble. For one thing, you don't want others taking it over.

No, of course you dont want some random joe to take Hubble over. However, they could implement in which "packets" are signed. The data would be separate from the authenticated signature. Along with that, they would want to implement a proper timecode to prevent replay attacks.

But controlling is aside the issue.

And I do hate to mince words but "normal HAM operator"... There isnt such a thing as a normal ham operator these days. Many hams specialize in one or two distinct fields of RF study. I like examining digital commms and remote communications (EME and meteor scatter).Along with my interests, I have bought that A/D board recommended by GnuRadio (normal HAM operator). All I needed was a RF front end and just to downsample to the range of the AD board (0-20 MHz).

I asked for help from some people at NASA and they said the connection was encrypted, and it does seem to be the case.

It doesnt really matter what Im required to build for receiving gear. It's all multi-purpose for us hams. And I do like the idea of splitting the transmitters from the receivers (well, you do have 2 antenna then per kit).

---I'm not saying that you're a 'normal' Ham operator, Crawler, but we're talking the space industry here.

Too true. No offense taken. Still, I can decode the majority of transmissions (the old freq shift Symbol cards are really neat under a scope) and can transmit on quite a few bands. I dont know if you've ever been in a Ham's shack, but the amount of gear they can have (and I too) is pretty immense. I just focus on the digital side a bit more :-) .

Re:Hubble censored? Data encrypted? (1)

Creepy Crawler (680178) | more than 7 years ago | (#18300780)

Correction: recommended by GnuRadio (normal HAM operator). All I

Damn clipboard. It was SUPPOSED TO BE (Measurement Computing PCI-DAS4020/12 A/D card).

Re:Hubble censored? Data encrypted? (1)

cheater512 (783349) | more than 7 years ago | (#18302842)

Why dont you buy a telescope and see what they are trying to hide yourself?

Re:Hubble censored? Data encrypted? (2, Insightful)

Firethorn (177587) | more than 7 years ago | (#18304892)

Hmm... My extent of satellite experience was working with 8" floppies and multiplexors at Schriever AFB years ago, and more recently training in how to configure slightly more modern multiplexors for field applications. Fun time: spending three hours troubleshooting while in chem gear only to have the instructors realize that their satellite simulator(couldn't get real sat time for the exercise) had been jarred out of position.

No, of course you dont want some random joe to take Hubble over. However, they could implement in which "packets" are signed. The data would be separate from the authenticated signature. Along with that, they would want to implement a proper timecode to prevent replay attacks.

I've learned that satellites tend to keep their control and data bands seperate, and the usage of multiplexing* is common, especially when you're talking about multiple instruments. And our demuxers run in the hundreds of thousands of dollars for our stuff, much less NASA science stuff. Remember what I said about military private-key encryption being cheaper computationally? Timing is already part of the security, and the hubble was designed back in the '80s and would have to use a system cleared for space and capable of remaining secure through decades of operation. Public key infrastructure is too new, computationally expensive, and expaning of a field. After that, it's easier to encrypt the whole channel than to worry about packets.

Are you even sure that you were trying to listen in on a data channel? From my reading it looks like the hubble stores it's data and then transmits it down in batches.

*For the uninitiated, a multiplexor takes multiple data streams and merges it into one stream, which a demultiplexor then splits back into multiple streams. For example, something like 60 voice lines, two ip networks, a crash-net(think red phone), etc... I'm sure Creepy Crawler knows this, but other readers might not

Re:Hubble censored? Data encrypted? (1)

Creepy Crawler (680178) | more than 7 years ago | (#18312024)

I hate to respond to a dead article, but you are spot on.

---Remember what I said about military private-key encryption being cheaper computationally?

I remember seeing special chips when I was with my dad at a naval reserve center (he's a retired chief).. One of the things Im interested in is TEMPEST and such technology dealing with EMP. What I saw was impressive: Ceramic CPUs. They wernt made out of silicon (or that look anyways) but instead they were pearlish white and said to be immune to EM pulses.

From what little I understand about TEMPEST and the government books, these chips could detect an 'event' at the beginning of the chip, and fail-over to ground the whole chip. Amazing piece of work.. However it was a 286, but guaranteed to work in high energy environments and low-shielded environments (Space).

I've even thought about going into Comm in the military just to access the powerful equipment. The things my dad can legally tell me about is just
amazing.

---Are you even sure that you were trying to listen in on a data channel? From my reading it looks like the hubble stores it's data and then transmits it down in batches.

You might have a point there... I'm not sure what to make of their data formats, nor do I have an idea of what mux they use, though I doubt it would be UWB-like... however it could be. GPS is already under the floor, and I dont see why Hubble couldnt be. From my eyes, I just saw a swath of data and I tried to process it. A bigger question is if my 16 bits/Hz is actually enough to extract real data...

I know there's a few people who make fun of me for doing this, but I find what the Hubble puts out as important as the numbers stations. By the time you try to triangulate them, they're already gone or moved.

Re:Hubble censored? Data encrypted? (0)

Anonymous Coward | more than 7 years ago | (#18300974)

In a related news release, scientists announced that the power of Hubble is so great that it can resolve the inanity of a ham radio operator who has spent his (definitely *his*, not her) Saturday night listening to satellites pass overhead, followed by him complaining that he isn't smart enough to understand the transmitted signals.

Re:Hubble censored? Data encrypted? (1)

Tablizer (95088) | more than 7 years ago | (#18301782)

control data is encrypted for the hubble. For one thing, you don't want others taking it over.

I am kind of curious to see what Mr. Goatse would do with it for a day. (But tell me about it instead of show me.) Cue the Uranus jokes...
                   

Re:Will they.. (-1, Flamebait)

Anonymous Coward | more than 7 years ago | (#18300554)

Your sig makes you an asshole of the highest order.
I enjoy modding you down every time I get points.

Re:Will they.. (0, Offtopic)

limecat4eva (1055464) | more than 7 years ago | (#18300580)

Sounds like someone doesn't know how to take a good prank.

Re:Will they.. (0)

Anonymous Coward | more than 7 years ago | (#18300678)

Considering his journal brags about his successes trolling, I don't think I am too far off the mark.

More embargo than censorship. (3, Informative)

jpellino (202698) | more than 7 years ago | (#18300784)

Hubble releases public images, but much of the research is just that - research - done by labs who are trying to maintain the integrity and proprietary nature of their work. Hubble data is supposed to go to the researcher first and the public second. IIRC it's a default six month delay unless overridden by the lab collecting the data. It's not censorship so much as embargo, and it's really no different from what any researcher does in order to not be scooped on the research they're doing.

Re:More embargo than censorship. (2, Interesting)

Creepy Crawler (680178) | more than 7 years ago | (#18300838)

---Hubble releases public images, but much of the research is just that - research - done by labs who are trying to maintain the integrity and proprietary nature of their work.

I want you to realize that I am a US citizen and who pays his taxes. I speak from my American view: WHY is governmental science proprietary? Above all other things, science done by the government or by government money should be either 100% public domain, or the % of profits should be returned to the people (Im thinking of public uni's here).

Hubble was paid for by US Citizens. I want their data open and in the clear. I dont want to vandalize or destroy. I wish to look.

---Hubble data is supposed to go to the researcher first and the public second. IIRC it's a default six month delay unless overridden by the lab collecting the data.

You know, these scientists could learn something from following the model the GPL uses: collaboration. Open up the output for all to see.. Most of it's probably not much anyways... But that's the point. Let us decide.

---It's not censorship so much as embargo, and it's really no different from what any researcher does in order to not be scooped on the research they're doing.

That isnt an excuse. I (in part) paid for this damned orbital telescope, and I want the output untouched by some "research group".

Re:More embargo than censorship. (2, Insightful)

Teun (17872) | more than 7 years ago | (#18301168)

It seems you forget that your tax money bought more than just the Hubble Telescope, the deal includes the scientific institutions that add value to the raw data.
Many of these institutions bring their own budget and they want Value for Money, they need, for a period of time, to have some exclusive access.

I'm sure that when you bring a juicy enough budget and the credentials for high-level research you can have a set of keys to decrypt the data first hand.

Re:More embargo than censorship. (1)

Gerzel (240421) | more than 7 years ago | (#18301620)


--I want you to realize that I am a US citizen and who pays his taxes. I speak from my American view: WHY is governmental science proprietary? Above all other things, science done by the government or by government money should be either 100% public domain, or the % of profits should be returned to the people (Im thinking of public uni's here). --Creepy Crawler

Unfortunetly being a US citizen and paying taxes does not give you the government's consideration. You didn't pay for the politician's election campaigns nor did you give any bribes/gifts/donations to them. Therefore you are not going to get the legislation you want.

Paying taxes simply gives you the base package of Civil "Rights" and other benefits of the government. It does not entitle you to have any real say in the laws or how those tax dollars are spent (weather or not it should is another point entirely).

Re:More embargo than censorship. (5, Informative)

Greg Lindahl (37568) | more than 7 years ago | (#18301792)

The astronomy community does exactly what you're asking for, you're just not listening:

* The data is made available to everyone after a short time delay

* The software to reduce the data is given away for free

* Our papers are generally available for free at http://lanl.arxiv.org/ [arxiv.org]

The point of the short delay is that the person who made the effort to write the proposal to get the telescope time deserves a reward: a short time to write the first paper about the results.

If you look at other branches of science, they aren't nearly as good. But you're flaming your friends.

Re:More embargo than censorship. (2, Interesting)

Cid Highwind (9258) | more than 7 years ago | (#18302310)

* The data is made available to everyone after a short time delay

We *assume* that the data are made available after a short time, but because of the encryption there's no way to correlate released data with observed transmissions from HST. Some people accept NASA's word on this, others don't.

Let me put it this way: Given the present theocratic leanings of the US government, if NASA found something that fundamentally challenged our notion of our place in the universe (like, say, one of the Mars rovers found fossil bacteria that predate any known life on Earth by a billion years or so) do you think we would ever hear about it through official channels? Or would NASA just "lose contact" with the vehicle and quietly shut down the program?

Is getting a shot at publishing before the other scientists really that much more important than keeping the christian fundies that control the hardware and the money honest?

Re:More embargo than censorship. (1)

Greg Lindahl (37568) | more than 7 years ago | (#18302412)

It wasn't clear that you're a nut until this posting; now it's overly clear. Shame on me, I suppose.

Re:More embargo than censorship. (1)

fifedrum (611338) | more than 7 years ago | (#18304502)

really, cripes the guy had a point until that rant exposed the tin foil wrapping his head.

Re:More embargo than censorship. (1)

Cid Highwind (9258) | more than 7 years ago | (#18307498)

Actually I just play one on the internet.

Anyway, learn to read, I'm not the same poster you were arguing with above.

Um, yeah. (1)

jpellino (202698) | more than 7 years ago | (#18303446)

They do share it. But they worked hard to be able to use it and they get to be in line ahead of you.

Scientists doing basic research do in fact collaborate, cooperate and compete, as it best serves the task at hand. That would explain the whole peer review process, not to mention the rampant cross-pollination of people between labs, projects, funding sources, large scale projects, etc.

The vast majority of the results do get back to the public, you benefit from them, and they are shared.

I pay my taxes too - and part of that is so that the astronomers who know what they're doing can sort out what comes back from the hubble and let me know when they find something I need to know about.

"That isnt an excuse. I (in part) paid for this damned orbital telescope, and I want the output untouched by some "research group"."

Yeah, I'm not sure the Yosemite Sam approach will get you very far. The "research group" is actually a vast collection of individual and collaborating scientists, research associates, assistants and pretty dedicated scientists who work their tails off in pretty impressive fashion. They're hardly a group deserving of derision, and there's no evil intent behind them.

In case you care to see it - here is the verbatim info from STSci on how data gets used. It's hardly nefarious:

XVI. PROPRIETARY RIGHTS TO DATA

General Observers (GOs) have exclusive access to their scientific data during a proprietary period. Normally this period is the 12 months following the date on which the data are made available to the investigator in a form suitable for scientific analysis. This policy also applies to data obtained during the Director's Discretionary time that is assigned to individual scientists. At the end of the proprietary period, data are placed in the HST archive where they are available for analysis by any interested Scientist.

Proprietary periods longer than 12 months may occasionally be appropriate for Long-Term programs if there is a need to have most or all of the data available before significant scientific results can be obtained. Other special circumstances requiring extensions of the proprietary periods may also arise for GO programs of any scope. NASA policy permits the ST ScI Director to lengthen the proprietary period by up to an additional 12 months, in cases where the Director concludes that an extension is justified. Such requests are subject to the Telescope Allocation Committee (TAC) review. Data-rights extensions beyond a total of two years are possible only when approved individually by the Space Telescope Institute Council upon the recommendation of TAC and the ST ScI Director.

GOs who wish to request a proprietary period shorter than one year, or to waive their proprietary rights, are welcome to specify this to ST ScI. Because of the potential benefit to the community at large, particularly in the case of large projects, GOs are asked to give this possibility serious consideration whenever they feel that such waivers would not be harmful to their programs.

GOs should be aware of the great public information potential of HST data. Cases may arise in which it would be appropriate to release HST data, for public-affairs purposes only, during the proprietary period. In such cases, it is hoped that GOs will cooperate with the ST ScI Office of Public Outreach in meeting the public's right to information. In no case, however, will proprietary HST data be released for such purposes without concurrence of the Principal Investigator. All PIs whose data are released for public-affairs purposes will receive full acknowledgment.

The principal investigator will endeavor in good faith to inform NASA and ST ScI of any planned press release at the earliest practical time and shall consider seriously and in good faith any comments made by NASA and ST ScI prior to the press release.

Except for images and animations produced under this Grant for which copyright shall not be asserted and except if otherwise provided in the terms and conditions of the Grant Award document, the author or recipient grantee is free to assert its copyright in any books, publications, or other copyrightable materials developed as a result of the analysis of HST data. The recipient grants to the ST ScI and the Federal Government, a royalty-free, nonexclusive and irrevocable license to use, reproduce, distribute (including distribution by transmission) to the public, perform publicly, prepare derivative works, and display publicly, data in whole or in part and in any manner for ST ScI and Federal purposes and to have or permit others to do so for ST ScI and Federal purposes only. ST ScI and Federal purposes include competitive procurement but do not include the right to have or permit others to use data for commercial purposes. In order that the Federal Government may exercise its license rights in data, the ST ScI and the Federal Government, upon request to the recipient, shall have the right to review and/or obtain delivery of data resulting from the performance of work under this grant, and authorize others to receive data to use for ST ScI and Federal purposes. In addition, the following sentence shall be placed on any images or animations before distribution with the appropriate acknowledgement filled in: "No copyright is claimed in this work and is considered in the public domain. However, any use of this work should acknowledge as its creator(s) and NASA's support under the Hubble Space Telescope Project."

Re:Will they.. (1)

doubletruncation (939847) | more than 7 years ago | (#18302262)

I don't know the reasons why hst uses an encrypted data stream, but it is in line with their policy regarding the public release of data. The principal investigator for the observations has a 1 year proprietary period on the data. This is because it represents a lot of work to plan in detail how the observations should be carried out and to justify the observations to the time allocation committee - so if you do the work of figuring out how the observations are to be done and why they should be done, you get a one year head-start on analyzing the data. After the one year period is up, the raw data is released to the public - anyone else can access it at http://archive.stsci.edu/ [stsci.edu]

Re:Will they.. (0)

Anonymous Coward | more than 7 years ago | (#18302522)

Why do they hide the whole data stream? What do they not want us to see?
The aliens, of course.

On a marginally more serious note, why don't you buy the HST when NASA is done with it? You could run whatever software you wanted on it.

OTOH, if slashdot collectively raised money to buy it, I suspect there would be an immidiate surge in requests/attempts to point the HST at nude beaches :)

Re:Will they.. (0)

Anonymous Coward | more than 7 years ago | (#18303180)

Hubble uses a lot of recycled spy-satellite hardware, just aimed in the other direction. It's possible that its exact operational parameters are/were classified, for the same reasons ("Paranoia is Our Profession") that apply to the NRO's communications with traditional recon birds. I don't think I would read any more into Hubble's use of downlink encryption than this, without a specific reason.

Re:Will they.. (1)

Chris6502 (857915) | more than 7 years ago | (#18304044)

You are comparing apples with oranges here. The entire "data stream" is available to anyone with a suitable dish and receiver. Unless of course the targets decide to encrypt their natural RF emissions.

Once the data has been captured it will become available after a proprietary period during which the principal investigator will have exclusive access to it. I believe this period will be one year.

Ow, cool. (1)

clawoo (945374) | more than 7 years ago | (#18300498)

Call me back when they complete the Turing test.

Re:Ow, cool. (5, Funny)

Tablizer (95088) | more than 7 years ago | (#18300664)

Call me back when they complete the Turing test.

It would call you by itself
           

But... (0, Flamebait)

DemoFish (1051816) | more than 7 years ago | (#18300524)

Does it run Linux?

Re:But... (1)

Falladir (1026636) | more than 7 years ago | (#18300574)

Some of the ACT ( Atacama Cosmology Telescope [princeton.edu] ) computers run an old version of Red Hat.

Re:But... (1)

TransEurope (889206) | more than 7 years ago | (#18300820)

1st: These damn terrorists.

2nd: Where is that information? The only text on the Software/Hardwaresites is "Under construction.".
Or contains that phrase the information of running older RedHat versions ;-)

Re:But... (0)

Anonymous Coward | more than 7 years ago | (#18304286)

Sure it run Linux everywhere.

Apples and oranges (4, Insightful)

$RANDOMLUSER (804576) | more than 7 years ago | (#18300556)

Ultimately, ALMA (Atacama Large Millimeter/submillimeter Array) is expected to resolve details 10 times finer than the Hubble Space Telescope when it is completed in 2012.
Except that one is a radio telescope and one is an optical telescope.

Re:Apples and oranges (2, Informative)

jcorno (889560) | more than 7 years ago | (#18301076)

Except that one is a radio telescope and one is an optical telescope.

So what? Stars and other black bodies radiate in both visible and microwave. If you're trying to resolve nearby objects (like binary stars or planetary systems), either one will work. Resolution is resolution. And besides, the angle resolved by a telescope is proportional to wavelength, so that just makes it MORE impressive. This telescope has a better resolution than the Hubble, even though it's working with 1000 times the wavelength.

Re:Apples and oranges (0, Flamebait)

Anonymous Coward | more than 7 years ago | (#18301296)

Come back when you understand the issue and don't get things bassackwards.

Re:Apples and oranges (0)

Anonymous Coward | more than 7 years ago | (#18301360)

Why don't you share with us what exactly you think is backwards in that post?

Re:Apples and oranges (1)

strider44 (650833) | more than 7 years ago | (#18302710)

The difference is that radio telescopes don't have to be a mirror - they can even just be a mesh. Radio telescopes are relatively really easy to make - there's no real precision to them, an interferometer is easy to make so resolution is usually not a problem. Optical telescopes on the other hand, do require mirrors and they must be almost perfectly flat. To complicate things, you can't just get a mirror like those in your bathroom because glass is a liquid and this means that if you make it out of glass then it won't stay a parabola for very long. You also can't put it anywhere near "fresh" air because the dust that settles on the telescope would severely disrupt the picture.

So in other words, we already have telescopes (or rather telescope arrays) with larger resolutions than hubble, and the level of technology in building large.

Re:Apples and oranges (1)

strider44 (650833) | more than 7 years ago | (#18302736)

Apologies in clicking reply too soon. The last line should read:

So in other words, we already have radio telescopes (or rather telescope arrays) with larger resolutions than hubble, and the level of technology required in building large optical telescopes is simply miles ahead of the radio telescopes.

Re:Apples and oranges (0)

Anonymous Coward | more than 7 years ago | (#18306140)

please stop perpetuating the myth that glass is a liquid. it is not. i imagine you heard about 'old' glass being thicker at the base than at the top. this is an artifact of medieval manufacturing process, not a result of the glass flowing while installed in a window frame. just google on the topic and enlighten yourself.

Re:Apples and oranges (1)

strider44 (650833) | more than 7 years ago | (#18306664)

Apologies for deeply offending you. All we talked about when I was studying the subject was that optical reflectors that are too large fail and distort, so they have to split them up into tiny flat mirrors. I suppose I never considered the topic too much!

Re:Apples and oranges (2, Interesting)

spaceyhackerlady (462530) | more than 7 years ago | (#18303156)

Except that one is a radio telescope and one is an optical telescope.

So? ALMA images the universe in different wavelengths than Hubble/Spitzer at al, but can do so at very high resolution. What really matters is how many wavelengths your aperture is. An 18 km baseline at a 1 mm wavelength is more wavelengths across than a 2.2 meter mirror at 600 nm. A lot of the highest resolution imaging is done with aperture synthesis nowadays, whether it's astronomers doing long-baseline interferometry, or using synthetic aperture radar to take pictures of the Earth.

Some day we'll be able to optical interferometry across multi-kilometer baselines. I look forward to the results.

...laura

the use of space-telescopes? (4, Interesting)

N3wsByt3 (758224) | more than 7 years ago | (#18300568)

I'm actually beginning to wonder if space-telescopes still have their use (in regard to costs/benefits). I mean, thanks to interferometry one can get the resolution (equal or better) with earth based telescopes for a fraction of the price of space-telescopes like hubble and consorts. And thanks to adaptive optics there is hardly any atmospheric blurring which smears out the pictures anymore, neither. And, since the mirrors can be bigger then those send into space, the light-gathering power is way superior for earth-based telescopes.

The only advantages left are for specific wavelengths (like near-infrared), because the atmosphere absorbs most of that, but even that is more and more debatable, now that new instruments and detectors are becomming so sensitive that they can detect and use it on Earth too. I'm wondering, with the multi-billion costs of space-telescopes, if it's really worth the money? With the same amount of money, one could make a huge interferometer-telescope with a diameter of the Earth (though it would need to consist out of many 10-meter telescopes for light-gathering purposes). I'm all for space-exploration, but what still justifies the expense of a space-telescope, if earth-bound ones can do as well for a fraction of the price?

Re:the use of space-telescopes? (3, Insightful)

Falladir (1026636) | more than 7 years ago | (#18300616)

The people who design and build these telescopes don't have unlimited budgets. If they use up their grant money sending a telescope into space, they can't hire as many graduate students, for instance. While saving money isn't the primary concern for the principal investigator, it's certainly a priority.

The reason WMAP was a space telescope was, as you said, so that it wouldn't have to look through the water-vapor in the atmosphere. ACT [princeton.edu] and ALMA will be earth-based because it's impractical to send telescopes as big as those into space.

In summation, don't worry: astronomy funds are not being wasted!

Re:the use of space-telescopes? (5, Insightful)

Tablizer (95088) | more than 7 years ago | (#18300632)

I'm actually beginning to wonder if space-telescopes still have their use

It is hard to separate hype from reality. Hubble is used as the benchmark in many claims because of its popularity. But as you partially pointed out, there are some rough-spots in Earth-based techniques:

* Spectrum coverage: some important frequencies are blocked by the atmosphere.
* Ecology: Earth scopes are accused of messing up mountain peaks and views and "sacred lands".
* Guide-stars: Some earth-bound techniques require bright guide-stars near a scene to compensate for atmospheric distortion. This limits their use in dim portions of the sky.
* Southern hemisphere: It is hard to see all portions of the sky well from any given point on Earth.
* Newness: Many of the hi-res earth-scope techniques are new and complicated. Without a reference point, such as Hubble images, they may be collecting unintended artifacts of the technology.

But it is an interesting issue to consider.
       

Damn budgets. (0)

Anonymous Coward | more than 7 years ago | (#18301254)

In an ideal world we could just say "why argue about it?" and build both. But of course this is not that ideal world so we have to fight each other for morsels.

For instance, I'm based at a new observatory in the southern hemisphere, so I'm biased towards ground-based systems and can reel off a string of reasons why ground-based telescopes are superior (or at the very least worthy of further investment).

A friend works with the Hubble and he's completely dismissive of ground-based instruments, and can prove beyond all reasonable doubt that space-based instruments are the only way to go.

Yet another friend and colleague does much of his work from Antarctica and, as far as he is concerned, no new instruments should be built outside that continent, and all funding should go to his pet projects.

Meanwhile, guys working at other sites, often on venerable gear at places like Kitt Peak or Mt Wilson, fight just to keep their observatories open against claims by everybody else that their facilities are obsolete and a waste of funding.

The cost of allthese observatories is high. Going into space is hideously expensive and fraught with risk. Building and working in Antarctica is barely less so. Transporting components to high, remote mountaintops elsewhere is slightly easier but still difficult and costly.

But the alternative is to put all our eggs in one basket, and suffer the inevitable consequences, so we don't do that. Or even worse, we can fall victim to the ignorant who claim astronomy (in fact, all science) is worthless and a waste of money, and so have nothing.

A combination of space-based and ground-based telescopes is still the best way to go, and we'll just have to keep fighting over funds to do it that way. One decade may be excellent for space telescopes, at the expense of ground-based ones, but the following decade can be just the opposite, and that's how it's been, and probably will be in the decades to come. At least I hope so.

Re:Damn budgets. (1)

Tablizer (95088) | more than 7 years ago | (#18301762)

build both. But of course this is not that ideal world so we have to fight each other for morsels...I'm based at a new observatory in the southern hemisphere, so I'm biased towards ground-based systems...A friend works with the Hubble and he's completely dismissive of ground-based instruments...guys working at other sites, often on venerable gear at places like Kitt Peak or Mt Wilson, fight just to keep their observatories open against claims by everybody else that their facilities are obsolete and a waste of funding...

Just don't ask them whether vi or emacs is better...
       

Re:Damn budgets. (1)

zippthorne (748122) | more than 7 years ago | (#18304196)

Bah, vi and emacs are great...for losers who make mistakes.

All you need is cat if you get it right the first time. It's got all the keyboard shortcuts you need. ^D means done.

Re:Damn budgets. (1)

RobertLTux (260313) | more than 7 years ago | (#18311474)

IANARocketScientist but the big thing about space based scopes is that you could in an emergency move the ground station for a scope but with a ground based scope it #randomwhacko wants to take out your scope "all" he has to do is drive up with a big enough bomb and boom your scope goes buh-bye.

Re:the use of space-telescopes? (1)

SeaDour (704727) | more than 7 years ago | (#18301698)

Not to mention the increasing prevalence of light pollution and radio wave interference. Aside from asking everyone to turn everything off, space-based observatories are the only way to counter this problem.

Not necessarily. (0)

Anonymous Coward | more than 7 years ago | (#18301796)

Some sites on Earth will always remain unaffected by light pollution, and it'll still be cheaper and easier to build and work there than in space; at least in the foreseeable future. We can build the really huge instruments on remote mountaintops, and send smaller telescopes into space to explore the spectrum unavailable to the large ground-based ones.

Re:the use of space-telescopes? (1)

Tablizer (95088) | more than 7 years ago | (#18301808)

Not to mention the increasing prevalence of light pollution and radio wave interference. Aside from asking everyone to turn everything off, space-based observatories are the only way to counter this problem.

But "floating" space junk has been pelting Hubble, so space is polluted also.
     

Re:the use of space-telescopes? (4, Insightful)

Gil-galad55 (707960) | more than 7 years ago | (#18300682)

Land-based telescopes are gaining much ground, especially when it comes to data volume. The dataset for the LSST (Large Synoptic Survey Telescope) will most likely be measured in exabytes when all is said and done, and it simply isn't possible to send that volume of data home via telemetry. However, space-based telescopes most definitely have their place.

Two exciting ones are Planck, which will make extremely precise measurements of the CMB (Cosmic Microwave Background) and--if we're lucky--LISA, a gravity wave telescope that will open a completely new part of the universe to us. The science prospects for LISA are staggering, and it is simply impossible to build an interferometer with a 5 million km arm length on the ground!

Re:the use of space-telescopes? (1, Interesting)

Anonymous Coward | more than 7 years ago | (#18300748)

One point to consider. Radio-frequency and ligth polution. If you look at a map from the earth at nigth
you see almost no free spot in the northern hemisphere for an optical telescope. Also, radio-frequency polution
will give the VLA and similar a hard time in years to come. This could be justification to go to space
(maybe the moon?). So far, Chile is the best place to put a telescope.

Re:the use of space-telescopes? (1)

Original Replica (908688) | more than 7 years ago | (#18300806)

The science prospects for LISA are staggering, and it is simply impossible to build an interferometer with a 5 million km arm length on the ground!

Um, the circumference of the earth at the equator is 40,076 km. The average distance to the Moon is 382,500 km. I'm not sure this LISA can be built, in space or not. I know it supposed to be three probes hovering 5 million km apart with no physical connection, but keeping their positions reletive to each other accurate over those kind of distances would be no mean feat.

Re:the use of space-telescopes? (1)

Gil-galad55 (707960) | more than 7 years ago | (#18300882)

It's absolutely non-trivial to do, but well within current capabilities. Just to blow your mind a bit, LISA must be sensitive to changes in arm length on the order of picometers... when the spacecraft are so far apart that round trip time for the light is 33 seconds! The only really tricky part in all of it is eliminating systematic errors from interactions with the LISA test masses and the spacecraft, but there has already been some testing done on test mass/spacecraft interaction, and they show the noise floor is low enough for good results. Now, it's just a matter of whether NASA and ESA can keep it together long enough to get her up.

space-telescopes allow a 258 Million km Baseline (0)

Anonymous Coward | more than 7 years ago | (#18337435)

i think this is indeed the path to pursue. since the most bang for the buck is achieved by maximizing the separation, not the scale or scope of technology at each point, one could insert relatively small and relatively inexpensive twin observation platforms into the L4 & L5 Lagrange Nodes via a S.T.E.R.E.O.-like lunar loop trajectories. these two 'outrigger' platforms on either side of the 'mother-ship' earth would provide a baseline separation of ~1.7 AU, 258 million km or almost 15 light minutes. That aught to allow for a handsome degree of angular resolution. The wavelength of observation would need to be long enough to not overtax the ground based processing speed for combination of the signals, so optical might be off the table for a decade or two, but there are plenty of very bright objects we could learn tons about in the longer wavelengths, like black holes for starters.

Re:the use of space-telescopes? (2, Interesting)

ajpr (921401) | more than 7 years ago | (#18300856)

In a lot of bands you can't see anything through the atmosphere.

Also if you are looking for chemical signitures (oxygen, methane) etc then you will have problems with the atmosphere again.

Space also gives you 24 hour observation, obviously not possible on the earth during the day. Apart from that you get a free vaccuum which will help in keeping the instrument cool. This is useful for all observations, not just infra red (although it is particularly good for that). Ground based telescopes are more suited to microwave/radio astronomy.

And don't forget about UV, which is impossible to see through the atmosphere (if it wasn't for the atmosphere absorption of UV we'd be having a bad case of sunburn).

Re:the use of space-telescopes? (2, Informative)

Nyeerrmm (940927) | more than 7 years ago | (#18300972)

The idea of using interferometry is really interesting. The idea of an earth sized telescope is great. In fact, in Texas there is an attempt to build a Texas-sized interferometer with amplitude interferometer based on the Hanbury-Brown-Twiss effect. Basically the goal is to have universities or other entities across the state erect their own telescopes (we're using 16-inchers) which they will own and operate on their own, and then have a network set up where anyone can take over and run them. Hopefully we'll get the first two up soon.

For those that don't know, the method we're using, amplitude interferometry has a number of advantages. Compared to amplitude interferometer, it is easy to set up on long distances, since it doesn't require micrometer precise spacing and direct optical links. It also has better signal-to-noise qualities than a heterodyne interferometer, because those are dominated by Heisenburg effects. Finally, one of the really nice things (although we're not taking advantage of it) is that it doesn't require optical quality telescopes and good CCDs, all it requires is light collectors and good quality photodetectors., a data connection, and some voodoo math. This makes it relatively cheap, even if you have to go into space to do the observing. A 15-meter telescope in orbit is an impossibility right now, but a 15-m light collector, deployed as an inflatable foil structure has a lot of promise.

Re:the use of space-telescopes? (2, Insightful)

thrawn_aj (1073100) | more than 7 years ago | (#18301030)

You forget light pollution, which is a major problem for ground-based telescopes. That's precisely why LISA and LIGO can work on the ground - they're not measuring light, they're trying to measure gravity waves, which (we hope) are strong enough to show up in the interferometer. Space is better for another important reason, especially for new telescopes: it is VERY cold in space (~2.7K). This means you can use superconducting wires with impunity and without the need for a coolant. That itself should be a significant advantage. I do hope they make use of this =D.

Re:the use of space-telescopes? (0)

Anonymous Coward | more than 7 years ago | (#18302044)

While I understand how you might come to this conclusion, it's actually completely wrong. You demonstrate enough knowledge to intelligently question the case for space (which is relatively rare actually, but probably common here on /.), but not enough to answer it. I can't let these ideas go unchallenged because the only way new missions will be funded is if lay people continue to support them.

All of the points you made are easily refuted (see below), but the main point is that we simply must go to space to do most of the _new_ exciting science, primarily in new wavelength regimes and at high resolution.

1) "thanks to interferometry one can get the resolution (equal or better) with earth based telescopes for a fraction of the price of space-telescopes like hubble"

- ALMA is also a $1B telescope. Just because it's on the Earth doesn't make it cheap! ALMA is a good example of a great ground-based telescope, in that it can do cutting edge science more cheaply than in space. Trust me, from the NASA perspective we're very aware that you have to PROVE that your idea can't be done from the ground before you get anywhere in designing a space mission. The problem with ALMA and all interferometers is that you can only get high resolution imaging over a *tiny* area, usually just one galaxy at a time. It's great for learning about that galaxy, but useless of wide-field science like cosmic shear measurements (eg. http://www.physorg.com/news87400827.html [physorg.com] ).

2) "And thanks to adaptive optics there is hardly any atmospheric blurring which smears out the pictures anymore"

- Again, this is only true over a tiny area, typically less than 40", with a strong gradient of image correction leading to data which is very hard to work with and photometer. Useful to get the shape of 1 galaxy at a time, but that's it. And even the maximum AO correction, on axis, is inferior to what's possible from space. The sky background is also vastly lower from space, allowing us to peer much deeper into the Universe for the same exposure time. Here's some info on the limitations of AO http://www.aura-astronomy.org/nv/hst_vs_ao_2.pdf [aura-astronomy.org] .

3) "And, since the mirrors can be bigger then those send into space, the light-gathering power is way superior for earth-based telescopes."

- Potentially true. That's why 3 groups are proposing to build a massive 30-m telescope here on Earth do adaptive optics imaging and spectroscopy. It will assume with the upcoming James Webb Space Telescope (JWST) the role the Keck 10-m telescopes currently play with the Hubble Space Telescope (HST). It will be a big light bucket allowing us to spectroscopically observe objects detected by JWST. Oh, and it will also cost $1B or more.

4) "The only advantages left are for specific wavelengths (like near-infrared), because the atmosphere absorbs most of that, but even that is more and more debatable, now that new instruments and detectors are becomming so sensitive that they can detect and use it on Earth too"

- The atmosphere actually absorbs most wavelengths, though we've been so optically-oriented for so long it might not seem like it. On the blue side, we need to go to space to study objects in gamma rays, X-rays, the far and near UV. On the red side, from about 3um to 300um we must also go to space. At longer wavelengths (eg. submm) we can work from the ground, but it's very, very hard until we get to the radio.

The atmosphere is opaque on the blue side, so no new instrumentation will not help. On the red side the are atmospheric windows we can peer through, but the issue is that everything (the telescope, the dome, the earth!) radiates thermally at precisely the wavelengths we're trying to observe. And they're thousands of times brighter, so even if we cool the IR detectors it still doesn't work very well. As an example, before the Spitzer space telescope was launched, the 10-m Keck had the best mid-IR (5-10um) imaging capability on Earth. The 0.85-m Spitzer telescope in its own Earth-trailing, Sun-centered orbit (to get away from the Earth's thermal emission) is *10,000* times more efficient than the vastly larger Keck telescope. I personally have been using it to find distant galaxy clusters 10 Billion light years away with 90 second exposures.

In summary, note that people are building $1B-class ground AND space missions. No space mission whose science can be done from the ground has a prayer of getting past the chat-over-beers stage. But the majority of exciting science missions can *only* be done from space. One of the next big competitions will be pick between 3 missions concepts: LISA, which would directly detect gravitational radiation for the first time ever; Constellation X, an array of X-ray telescopes that would study the physics of black holes; and a JDEM (joint dark energy mission) like SNAP which would measure the properties of the dark energy which form 70% of the total energy density of the Universe. It would do so using multiple techniques, including Supernova Ia and weak shear lensing. All 3 of these missions must be done from space, all would cost ~$700M, but only one will happen (if we're lucky!). If anything we need more congressional support for space missions.

space...the final...something. (1)

N3wsByt3 (758224) | more than 7 years ago | (#18317141)

"While I understand how you might come to this conclusion, it's actually completely wrong."

Well...*actually*... I didn't make any conclusion, I asked an open question. :-)

It surprises me that the most interesting answer comes from an anonymous coward with score 0; if I had mod points, I'd mod you up. UYou should really post such things with your nick, you know :-). I thought you made a very good rebutal, and it makes it clear there is still use for space-telescopes (and as you say, those that can be done on Earth never get to space, I suppose).

"You demonstrate enough knowledge to intelligently question the case for space (which is relatively rare actually, but probably common here on /.),..."

No, not at all. I'm rather the exeption to the rule, also on slashdot. ;-p

"...but not enough to answer it."

Heh. You mean I also have to answer my own question in the same post? :-) As I said earlier, it was actually an open question, to see if any interesting debate could come from it. The question is quite complex, since it involves costs versus benefits.

"I can't let these ideas go unchallenged because the only way new missions will be funded is if lay people continue to support them."

Lay people, huh? *me coughs* Well, anyway, you might have had the impression I'm making a case against space-exploration/colonisation/etc., but actually I'm not. I'm rather pro-space (that's why I'm a member of the planetary society too). But it's a valid question to ask, just like the old human exploration versus robotic exploration.

That said, I doubt many space missions are funded because of the support of lay people, especially if it's about some exotic telescope to measure the background-radiation of the universe. I mean, really: how many people even know anything about what is send up there? I doubt 2% of the populace can name 3 current and ongoing space-projects or missions. Nah...it has more to do with politics and the perceived economic benefits it will bring. John Doe has really little influence on it. (Though, focused lobbying might help some missions, as TPS has already demonstrated.)

As for your exellent points, one small remark, though:

You claim a few times that those big earth-based telescopes could also cost 1 billion. Well, that may be true, but for that price what do you get? Both 10-meter keck-telescopes, which in conjuction can work as a 85 meter telescope (at least in respect to resolution), have costed $140 million; the HST, with a mirror of 2.4 m, has quite a different price-tag, and I quote from the wikipedia:

'From its original total cost estimate of about 400 million dollars, the telescope had by now cost over US$2.5 billion to construct. Hubble's cumulative costs up to this day are estimated to be several times higher still, with U.S. expenditure estimated at between 4.5 and 6 billion USD and Europe's financial contribution at 593 million Euros (1999 estimate).'

Now, you made very good points why space-telescopes are still useful in some specific area's, but my question (not conclusion) was more related to the cost/benefits.

I mean, looking at the real price-tags, for the amount of the HST, one could have built 25-30 keck-telescopes (with god knows what resolution with interferometry). Certainly, with such an earth-bound system, the amount of usefull data would have been staggering as well, and may have surpassed that of the HST in many aspects.

RFB Space-based arrays (1)

bill_mcgonigle (4333) | more than 7 years ago | (#18312162)

I'm all for space-exploration, but what still justifies the expense of a space-telescope, if earth-bound ones can do as well for a fraction of the price?

I'd like to see an array of space based telescopes set out in a pattern much bigger than the Earth, perhaps at the L2 LaGrange point. That should allow us to see planets in other solar systems quite well.

I don't see how you can do that on Earth.

well (1)

mastershake_phd (1050150) | more than 7 years ago | (#18301006)

Why not put a bunch of little telescopes in space. Best of both worlds.

Re: tiny space-based observation platforms (0)

Anonymous Coward | more than 7 years ago | (#18337281)

i think this is indeed the path to pursue. since the most bang for the buck is achieved by maximizing the separation, not the scale or scope of technology at each point, one could insert relatively small and relatively inexpensive twin observation platforms into the L4 & L5 Lagrange Nodes via a S.T.E.R.E.O.-like lunar loop trajectories. these two 'outriger' platforms on either side of the 'mothership' earth would provide a baseline seperation of ~1.7 AU or almost 15 light minutes. That aught to allow for a handsome degree of angular resolution. The wavelength of observation would need to be long enough to not overtax the ground based processesing speed for combination of the signals, so optical might be off the table for a decade or two, but there are plenty of very bright objects we could learn tons about in the longer wavelengths, like black holes for starters.

Just in time for the digital TV conversion! (1)

r_jensen11 (598210) | more than 7 years ago | (#18302610)

Here's the real question: Which will roll out first, the completion of all US television broadcasts in high definition or this thing being launched, orbiting, and operating?

sex w1th a gOat (-1, Troll)

Anonymous Coward | more than 7 years ago | (#18302796)

FIRsTO POST (-1, Flamebait)

Anonymous Coward | more than 7 years ago | (#18302888)

as 7ittingly are inherently

End of the world as we know it (1)

Rich Klein (699591) | more than 7 years ago | (#18308218)

Ultimately, ALMA (Atacama Large Millimeter/submillimeter Array) is expected to resolve details 10 times finer than the Hubble Space Telescope when it is completed in 2012.
Great. It'll be completed just in time for the end of the world [wikipedia.org] !

Distributed telescopes - question (1)

OfNoAccount (906368) | more than 7 years ago | (#18309462)

How cheap/easy would it be to make a distributed radio telescope if we had lots of small systems scattered around?

I was envisioning a small unit that plugs into a PC and has GPS location ability so we know where it is in the array, and the software reports data and location back to the central system. If everyone interested in astronomy picked one up we'd soon have a big array, and it would be reasonably low cost too if everyone paid to cover some of the cost of their antenna.

I suspect if we have enough bases then localized "noise" should be easily enough filtered.

Is radio astronomy doable with thousands of small devices?

Re:Distributed telescopes - question (0)

Anonymous Coward | more than 7 years ago | (#18322481)

Yes it is and no it isn't. Interferometric astronomy requires synchronizing the collection timebases to tight tolerances (on the order of the period of the waves). I haven't seen a "generic" computer synchronize its time better than 1 ms over the Internet for any significant period of time. This would limit the frequency of such a distributed system to roughly 1 kHz.
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