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Herschel Space Telescope Opens For the First Time

ScuttleMonkey posted more than 5 years ago | from the hey-big-guy-open-your-eyes dept.

Space 84

davecl writes "The Herschel space telescope, the largest ever launched into space, has opened its instrument cover, allowing its three instruments to observe for the first time. BBC news has the main coverage, while there is more coverage on the SPIRE instrument team website, and on the mission blog. I'm part of the SPIRE instrument team and the excitement as we move towards our first observations is building fast. The PACS and SPIRE instruments will see first light in the next few days."

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Space Niggers (-1, Troll)

Anonymous Coward | more than 5 years ago | (#28340295)

I hope this thing doesn't discover space niggers.

The last thing we need right now is more niggers living off of welfare and crack.

Porch monkeys aren't good for anything.

Be aware (-1, Troll)

Anonymous Coward | more than 5 years ago | (#28340347)

Slashdot user BadAnalogyGuy is a scientologist.
If he offers you a free personality test, firmly refuse him.

Whale Oil (-1, Troll)

Anonymous Coward | more than 5 years ago | (#28340383)

Another story on the Slashdot front page talks about Michigan counties reverting to gravel roads instead of paved to save money. It says:

At least 50 miles of road have been reverted to gravel in Michigan the past three years. I can't wait until we revert back to whale oil lighting and can finally be rid of this electricity fad.

God damn, with all the fatasses who visit Slashdot and the tremendous reserves of blubber they contain, you really shouldn't say things like this. It probably scares them, as many of them bear a strong resemblance to whales and don't want to part with their oil! I know they're fatasses and have loser attitudes that prevent them from eating better and working out, but it's still wrong to go around scaring them like that.

Re:Whale Oil (-1, Troll)

sakdoctor (1087155) | more than 5 years ago | (#28340469)

It took you over two hours to think up this troll and it wasn't even good.
Hang your head in shame.

space telescope (5, Insightful)

spidercoz (947220) | more than 5 years ago | (#28340423)

In an effort to contribute something to the thread that isn't irrelevant, stupid, or hateful assholery, this is very cool. I'm looking forward to its first images. Maybe it'll be sensitive enough to image extrasolar planets.

Re:space telescope (1)

Normal Dan (1053064) | more than 5 years ago | (#28340599)

As am I.

Maybe it'll be sensitive enough to image extrasolar planets.

From what I understand, even Hubble was sensitive enough to get a glimps of a few. Surely this will grant us an even better view. *Holds breath*

Re:space telescope (2, Funny)

uberjack (1311219) | more than 5 years ago | (#28340673)

I was trying to come up with something useful, but all I could think of was Herschel Krustofsky [wikipedia.org]

Re:space telescope (1)

Presto Vivace (882157) | more than 5 years ago | (#28340699)

Very cool, is this the first time a mission has has a mission blog?

Re:space telescope (1)

longacre (1090157) | more than 5 years ago | (#28343931)

The Mars Phoenix Lander mission had its own blog, not sure if it was the first, though. Herschel may be the first telescope to have a blog.

Re:space telescope (2, Funny)

tverbeek (457094) | more than 5 years ago | (#28343343)

"Maybe it'll be sensitive enough to image extrasolar planets."

We don't need any extra solar planets! We have enough solar planets as it is, especially if you count all them newfangled "dwarf" planets like Pluto and Grumpy and Sneezy. When I was a boy we only had eight solar planets, and we were happy to have them... (except maybe the one name after "yer anus")...

Re:space telescope (0)

Anonymous Coward | more than 5 years ago | (#28343737)

this was a stealth firstie

it is not the "largest evel launched into space" (5, Informative)

juanergie (909157) | more than 5 years ago | (#28340551)

The entry should clarify that it is the largest infrared telescope ever launched. Actually, the adjective large should not be used. Space is not porn. To most people.

It would also be very helpful for the public to know how will Herschel and Hubble complement each-other. Otherwise, the general public may believe that humanity has launched two different things to accomplish the same task.

Re:it is not the "largest evel launched into space (1)

tc3driver (669596) | more than 5 years ago | (#28340645)

I couldn't agree more with this statement.
With the dwindling funds that space programs are receiving these days, it is a wonder that we can even send probes into space any more.

Re:it is not the "largest evel launched into space (2, Informative)

Tablizer (95088) | more than 5 years ago | (#28340745)

With the dwindling funds that space programs are receiving these days, it is a wonder that we can even send probes into space any more.

I'm not sure who "we" is here, but note that it is mostly a European project, not a US one. It's good to see more international missions because it means more science and different ways of approaching designs and management. Russia's Keep-It-Simple and incremental improvement approach to manned-mission designs have been a fine lesson for NASA, for example. Hopefully NASA will learn new tricks from others' unmanned missions also, as they are learning from our stuff. Plus, more science.
       

Re:it is not the "largest evel launched into space (2, Insightful)

Amazing Quantum Man (458715) | more than 5 years ago | (#28341411)

Now who's being ethnocentric?

I assumed GP meant "we" as in "humanity". Of course, now some asshat will accuse me of speciesism.

Re:it is not the "largest evel launched into space (1)

Tablizer (95088) | more than 5 years ago | (#28341465)

Or singularists accusing you of pro-pluralist bias. Can't win :-)

Re:it is not the "largest evel launched into space (2, Funny)

bertoelcon (1557907) | more than 5 years ago | (#28341695)

Being speciesist isn't bad, you just have to know which species to not like, and no humanity is not a good choice.

Re:it is not the "largest evel launched into space (0)

Anonymous Coward | more than 5 years ago | (#28358907)

Of course, now some asshat will accuse me of speciesism.

Silence, you insensitive clod -- I'm an asshat.

Re:it is not the "largest evel launched into space (0)

Anonymous Coward | more than 5 years ago | (#28349251)

I couldn't agree more with this statement.

With the dwindling funds that space programs are receiving these days, it is a wonder that we can even send probes into space any more.

Just FYI: http://www.nasa.gov/home/hqnews/2009/may/HQ_09-102_FY2010Budget.html

That's a 5% increase for those not interested in link clicking.

Re:it is not the "largest evel launched into space (1)

T Murphy (1054674) | more than 5 years ago | (#28340713)

Why do they make Hubble and Herschel sensitive to infrared light? I would think it most important to pick a spectrum that will provide the best information (i.e. instruments should be sentitive to gamma rays if you are looking for gamma ray bursts from supernovae); if that is their criteria, how does infrared help them see what they are looking for?

Re:it is not the "largest evel launched into space (4, Interesting)

spidercoz (947220) | more than 5 years ago | (#28340881)

Infrared can pass through dust, such as that which composes nebulae, that would block other wavelengths.

Re:it is not the "largest evel launched into space (5, Informative)

Bemopolis (698691) | more than 5 years ago | (#28340895)

There are several good reasons to concentrate on infrared radiation. A few, off the top of my head, are: the relative transparency of the interstellar medium in the infrared compared to optical and UV; the optical design of infrared telescopes is closer to that of the familiar optical types compared to X-ray and gamma-ray telescopes; the presence of strong emission lines in the infrared from ionization species unavailable in the optical; the fact that UV and optical emission from distant objects is seen in the infrared due to their high redshifts; and that the thermal emission of circumstellar dust peaks in the infrared. Similar lists exist for the other bandpasses, but screw them :)

Good reasons for placing infrared telescopes into space include the high opacity of the Earth's atmosphere in the infrared, the high thermal emissivity of the Earth and atmosphere in the infrared, and the low temperatures at which the detectors need to be kept.

Re:it is not the "largest evel launched into space (1)

Shatrat (855151) | more than 5 years ago | (#28341009)

You make good points but you are using "optical" as a synonym for "visible" which makes me wince a bit.

It's all optical, from 200 nm to 2000 nm.

Re:it is not the "largest evel launched into space (3, Interesting)

Anonymous Coward | more than 5 years ago | (#28340919)

Why do they make Hubble and Herschel sensitive to infrared light? I would think it most important to pick a spectrum that will provide the best information...

Exactly. What spectrum you pick depends on what information you want to get.

Infrared is good for a lot of things. Dust clouds are mostly transparent to infrared, for example, so the infrared is good if you want to look, say, at the nuclei of galaxies (such as our own galaxy) which are surrounded by dust. And if you want to look at galaxies at high redshifts, which is to say, far away (and hence far back in time), infrared is good because the light is shifted into the infrared. Infrared is good at looking for planets, since they emit in the thermal infrared. And many other things.

But if you want to look at gamma-ray bursts from supernovae, no, probably infrared isn't the right way to look. You might want to try the Fermi [nasa.gov] telescope instead.

Re:it is not the "largest evel launched into space (5, Informative)

Tablizer (95088) | more than 5 years ago | (#28340937)

Why do they make Hubble and Herschel sensitive to infrared light? I would think it most important to pick a spectrum that will provide the best information (i.e. instruments should be sentitive to gamma rays if you are looking for gamma ray bursts from supernovae); if that is their criteria, how does infrared help them see what they are looking for?

There is no one "right" spectrum frequency. They each offer different information; different clues. For example, an animal that can see 3 colors has more potential information than an animal that can only see 1 or 2.

And while Hubble and Herschel may be able to overlap somewhat, they are specialized (optimized) for different frequencies. It's difficult to make a single scope that can see every frequency well, so they send up different scopes for different spectrum ranges. Different materials make for better reflectors, conduits, and sensors for different frequencies. That's just life on the Spectrum Highway.

Think how AM radios need a long wire (coiled in practice) for an antenna. FM radios and traditional TV need about a meter-long antenna(s), and cell-phones have about a 3-inch antenna. No single antenna works best for all. Same with light-based scopes.
       

Re:it is not the "largest evel launched into space (1)

JoCat (1291368) | more than 5 years ago | (#28343969)

"Same with light-based scopes."

Not to be pedantic, but all electromagnetic radiation is light, just not the way we're use to hearing it used.

Infra-red light is still light. 802.11 radiation is still electromagnetic radiation. Whether it's an AM radio in an old car, a $400 cell phone, or a telescope in the sky, it's all the same medium.

Re:it is not the "largest evel launched into space (1)

Tablizer (95088) | more than 5 years ago | (#28352701)

Not to be pedantic, but all electromagnetic radiation is light, just not the way we're use to hearing it used.

I am not sure if "light" has a technical definition. Generally when one says "light", they mean either the visible spectrum (to humans), or frequencies close to it. That's what common usage dictates.
     

Re:it is not the "largest evel launched into space (4, Insightful)

vlm (69642) | more than 5 years ago | (#28341117)

The atmosphere is a lovely IR absorber. So, if you're gonna launch a telescope into space, why not look at a band of frequencies you can't see thru the atmosphere? Whatever you see, it'll be something you can't see from the ground (more or less).

So that works pretty well, if the criteria is to see whats never been seen before, discover new things, etc.

http://en.wikipedia.org/wiki/Infrared_astronomy [wikipedia.org]

Re:it is not the "largest evel launched into space (0)

Anonymous Coward | more than 5 years ago | (#28343583)

to boldly look where... no... man... has looked... before!

Re:it is not the "largest evel launched into space (0)

Anonymous Coward | more than 5 years ago | (#28344595)

if that is their criteria, how does infrared help them see what they are looking for?

Night vision, you clod. Astronomers sleep during the day. Why do you think the astronomical Julian day begins at noon?

Re:it is not the "largest evel launched into space (1)

Tablizer (95088) | more than 5 years ago | (#28341055)

The entry should clarify that it is the largest infrared telescope ever launched. Actually, the adjective large should not be used.

"Largest" is simply poorly qualified. There's lots of different metrics that they could be referencing, such as weight (of the whole probe), aperture of light-gathering reflector/lens, and total energy of light/radiation it's able to collect and/or process per unit of time from a typical or reference target. Dollars/Euros spent also, for that matter.
     

Re:it is not the "largest evel launched into space (0)

Anonymous Coward | more than 5 years ago | (#28341771)

Space is not porn. To most people.

I beg to differ, maybe you just don't hang out with those people because they wants tentacles?

Re:it is not the "largest evel launched into space (1)

rlseaman (1420667) | more than 5 years ago | (#28341893)

The entry should clarify that it is the largest infrared telescope ever launched.

...and perhaps also that there may well be larger telescopes looking down than up.

Re:it is not the "largest evel launched into space (0)

Anonymous Coward | more than 5 years ago | (#28341975)

*gets out his tinfoil hat*

Launched by us as in earthlings?

Re:it is not the "largest evel launched into space (1)

Muad'Dave (255648) | more than 5 years ago | (#28346567)

Yes, to look for things like missile launches and %$^%@#$# CARRIER LOST

Re:it is not the "largest evel launched into space (2, Informative)

KatTran (122906) | more than 5 years ago | (#28341947)

It is actually the largest telescope every launched into space. It has a larger mirror than Hubble. It is also true that it is the largest infrared telescope launched into space, but then a square is also a rectangle.

Re:it is not the "largest evel launched into space (1)

budgenator (254554) | more than 5 years ago | (#28356273)

Actually measuring the aperture in wavelengths of light observed by the instrument might be even more meaning full; an instrument like Herschel that observes in the deep infrared need a larger aperture than Hubble to get the same resolution.

Re:it is not the "largest evel launched into space (1)

waveformwafflehouse (1221950) | more than 5 years ago | (#28342319)

Unfortunately competition has been the primary funding motive for space programs world wide.

Re:it is not the "largest evel launched into space (1)

jonnat (1168035) | more than 5 years ago | (#28343315)

According to Wikipedia [wikipedia.org] :

At 3.5 meters wide, its telescope incorporates the largest mirror ever deployed in space.

It's also important to note that there are fields other than porn in which size matters. In this case, the size of the mirrors in a telescope is proportional to the quantity of light it can focus to its sensors, and thus proportional to its sensitivity.

Re:it is not the "largest evel launched into space (1, Funny)

Anonymous Coward | more than 5 years ago | (#28343407)

The entry should clarify that it is the largest infrared telescope ever launched. Actually, the adjective large should not be used. Space is not porn. To most people.

The kid's never seen an an open elliptical galaxy. Heh.

Repair? (4, Interesting)

Tablizer (95088) | more than 5 years ago | (#28340623)

I wonder if they designed any of it to be repaired in space, learning from Hubble. (It's not a direct competitor to Hubble because it "sees" in longer wavelengths.)

I wonder if it would have been cheaper to build *multiple* Hubbles rather than repair them in space, which costs about a half-billion per mission. However, they'd have to decide that path in advanced to take advantage of bulk assembly procedures. Or build them to be remotely serviceable thru a repair-bot? But that's mostly untried technology, which usually means expensive or unpredictable overrun risk.
     

Re:Repair? (3, Informative)

Anonymous Coward | more than 5 years ago | (#28340721)

It's not repairable. It'll orbit around L2 and is placed 1.5 millions km away from earth. We cannot currently send humans at that distance. As for repairbots, I don't know.

Re:Repair? (1)

Tablizer (95088) | more than 5 years ago | (#28341399)

It's not repairable. It'll orbit around L2 and is placed 1.5 millions km away from earth. We cannot currently send humans at that distance.

Such may be a good test-run for a Mars mission, killing 2 birds with one stone (for lack of a nicer saying). After all, before Apollo 11 actually landed, earlier missions went around the back of the moon in a partial test run.
     

Re:Repair? (5, Informative)

Mal-2 (675116) | more than 5 years ago | (#28342017)

The upside of it being in orbit around L2 is that it never has to face either the earth or the sun, so every second of every day is useful observation time. Hubble is in LEO which makes it accessible, but also shielded by the bulk of the planet almost half of every day for any given target. This is fine for scheduled observations, but not so good for staring at one point or homing in on something in progress. Also, some time is inevitably lost making sure it doesn't stare into something bright as it swings around the planet, which is not an issue at L2.

Even if it does not live as long as Hubble (and it probably won't if there is no servicing), it has the potential to produce more data per unit of time. Also, with the bigger reflector, exposures should not take as long, also freeing it up to do more science. This also has the nice side effect of reducing the effects of thermal noise and cosmic rays, since they just don't have as much time to do their damage to any given picture.

Mal-2

Re:Repair? (2, Informative)

jhol13 (1087781) | more than 5 years ago | (#28344135)

It will live three to five years, so it will not outlive Hubble. After that it has run out of the coolant (helium).
By that time it has scanned the whole space a couple of times.

Re:Repair? (3, Funny)

tnk1 (899206) | more than 5 years ago | (#28340763)

I agree. We should also have manned missions be one way as well.

Why pay a few million extra to bring them down again when we have 6 billion cheaply made replacements already available?

I hear the Chinese are itching to get to the moon, they could use the same plan. They could even pretend that they retrieved the astronaut. All they have to do is threaten to run over anyone who said differently with a tank.

Re:Repair? (1)

Tablizer (95088) | more than 5 years ago | (#28340975)

We should also have manned missions be one way as well.

There's a handful of ex-politicians I'd like to volunteer :-)
   

Re:Repair? (1)

Amazing Quantum Man (458715) | more than 5 years ago | (#28341443)

ex-politicians??

I have more than a handful of current ones I'd like to volunteer... from multiple countries, including my own.

Re:Repair? (0)

Anonymous Coward | more than 5 years ago | (#28341623)

Only a handful?

Re:Repair? (1)

Tablizer (95088) | more than 5 years ago | (#28353071)

Too many and they may start a new colony and reproduce.

Re:Repair? (1)

Sir_Dill (218371) | more than 5 years ago | (#28342045)

I would guess that the optics make up the majority of the cost of these devices both in actual dollars and manhours.

The detectors, cameras and other instrumentation would come in a close second while the structure, power, navigation, and communications systems are probably largely built of off the shelf stuff.

Cameras and instruments get better and more sensitive, other systems require periodic maintenance and repair while good optics generally stay good provided they aren't physically damaged.

I would think the smartest use of cash is build the most expensive and accurate optics system and make all other parts field replaceable.

in short I don't think that 'disposable' space telescopes would be viable from the optics perspective alone.

Perhaps someone who knows more about the cost breakdowns work out.

Re:Repair? (1)

Jeff DeMaagd (2015) | more than 5 years ago | (#28342055)

There is a risk of premature breakdown, but the cost of the Hubble is such that they've launched several groundbreaking, science advancing telescopes since Hubble, each did their intended job for less than the cost of a servicing mission via the manned shuttle.

Developing robotic servicing capabilities would be interesting, but that may be a ways off yet, and it's hard to design for something that hasn't been established yet, and designing for serviceability might also lead to compromises to the capabilities of the telescope.

Re:Repair? (3, Interesting)

FleaPlus (6935) | more than 5 years ago | (#28343665)

I wonder if it would have been cheaper to build *multiple* Hubbles rather than repair them in space, which costs about a half-billion per mission.

The Hubble repair cost was actually well over $1 billion. Even ignoring mass-production, it would have been cheaper to just replace the Hubble instead of repairing it. Let me dig up an old comment of mine from 4 years ago:

http://science.slashdot.org/comments.pl?sid=141507&cid=11856177 [slashdot.org]

An international team led by Johns Hopkins University astronomers have proposed an alternative [spaceref.com] to sending a robotic or manned repair mission to the ailing Hubble Space Telescope [wikipedia.org]. Their proposal is to build a new Hubble Origins Probe [jhu.edu], reusing the Hubble design but using lighter and more cost-effective technologies. The probe would include instruments currently waiting to be installed on Hubble, as well as a Japanese-built imager which 'will allow scientists to map the heavens more than 20 times faster than even a refurbished Hubble Space Telescope could.' It would take an estimated 65 months and $1 billion to build and launch, approximately the same cost as a robotic service mission.

Here's the official web site, with slideshows and posters explaining the planned scientific instruments:

http://www.pha.jhu.edu/hop/ [jhu.edu]

Lid Release Video (2, Informative)

Anonymous Coward | more than 5 years ago | (#28340641)

While not completely obvious from the wording, the slow motion video [youtube.com] that most sites seem to be using of the lid opening is actually from a test on an identical cover after it had been sealed for 2 years and not from the actual telescope in space. On the actual telescope, opening was only initially confirmed via gyro sensors and temperature changes afterwards. It won't be fully confirmed until they do light tests.

Except it has mysteriously stopped responding (1)

davester666 (731373) | more than 5 years ago | (#28340681)

Just as the Hubble happened to be flying by...

Re:Except it has mysteriously stopped responding (1, Insightful)

Anonymous Coward | more than 5 years ago | (#28341077)

Hubble is in low earth orbit. Herschel is en route to L2. They will be no flyby.

Re:Except it has mysteriously stopped responding (1)

youn (1516637) | more than 5 years ago | (#28341207)

Two telescopes in space... they needed a little privacy :)

Re:Except it has mysteriously stopped responding (0)

Anonymous Coward | more than 5 years ago | (#28345111)

Two telescopes in space... they needed a little privacy :)

They should hook 'em up like a pair of binoculars, then they'd be able to see twice as far.

Congrats to ESA and all involved! (1)

Ponga (934481) | more than 5 years ago | (#28340711)

I was really bummed when the Beagle rover went MIA years ago... so good for ESA, this is a great accomplishment!

Re:Congrats to ESA and all involved! (3, Interesting)

Tablizer (95088) | more than 5 years ago | (#28341125)

I was really bummed when the Beagle rover went MIA years ago... so good for ESA, this is a great accomplishment!

It was a static lander, not a rover. And it likely failed because they tried to do it on the cheap. Based on NASA's expenditure-versus-failure history, the amount they spent on it would result in very roughly a 70% chance of failure using the NASA scale. They got what they paid for, I hate to say. They should have scaled it down in my opinion. They got a little carried away with the features, having a small budget. They could have had both more funds and margin for landing reliability if they cut back on weight and instrument-related cost.
         

Re:Congrats to ESA and all involved! (1)

smoker2 (750216) | more than 5 years ago | (#28346071)

I'm sorry but that's crap. Many people die because their parachutes don't open or get tangled. They don't redesign the parachute every time. And the cost is irrelevant. How much more can you spend on a chute to make sure it deploys correctly ? For all we know the chute didn't deploy correctly or tangled, or the gas bags didn't inflate before landing. To say it failed because they spent too much on instrumentation is just ridiculous. And you realise that the Beagle2 used US suppliers (who later pulled out) for airbags and chutes ? Due mainly to their existing reliability record. And that US regulations regarding IP rights and arms shipments prevented the Beagle2 team from knowing the full technical details of the descent systems ? Sure you can throw money at a problem, but you can never ever guarantee success, even on earth let alone on another planet, on a first time mission. There are at least 16 different possibilities as to why the mission failed, ranging from abnormally low atmospheric pressure, to failure of the antenna once the probe was down. Even NASA has had data showing "surprisingly low atmospheric pressure" during the Spirit and Opportunity landings.

Try reading the mission report [le.ac.uk] .(pdf)

Re:Congrats to ESA and all involved! (1)

Tablizer (95088) | more than 5 years ago | (#28355891)

The Beagle team knowingly skipped some landing-related tests to cut costs. Britain's own post analysis agreed with that. And my analysis is generally a statistical one. I agree the problem may have been related to something else: statistics only estimate probabilities, not guarantee them. If you plot failure-rate per expenditure for NASA probes, with some fudging for mission type and instrument count, it will generally point to what I said. (But I do agree its a small sample size one is using.)

Damn, pictures will be only tomorrow (1)

dvh.tosomja (1235032) | more than 5 years ago | (#28340761)

Perhaps we should ask some Japanese to get some because today, it is tomorrow there.

How far out is 1.5 million miles? (1)

DJRumpy (1345787) | more than 5 years ago | (#28340843)

Questions question questions. Hopefully someone who's been keeping up with event is reading. This is exciting stuff!

I'm curious how far out this will be in comparison to Hubble. Is this in a Lagrange Point? The articles I'm finding via Google just note the distance but don't say much else about it.

Also, will the longer wavelengths give it a better chance of imaging through dust? What effect will it have on the images produced as opposed to Hubble?

Finally, given it's about a meter larger in diameter for the mirror, do they expect that this one will be able to actually image exoplanets? I seem to recall a blip of a story that Hubble 'may' have been able to actually image an exoplanet, but from what I recall, it was almost like a pimple on the edge of a solar disc. Exciting to people in the field, but visually it left something to be desired ;)

Thanks

Re:How far out is 1.5 million miles? (0)

Anonymous Coward | more than 5 years ago | (#28341277)

1.5 million kilometres (not miles) - L2.

Re:How far out is 1.5 million miles? (0)

Anonymous Coward | more than 5 years ago | (#28341327)

MMM, resolution is proportional aperture/lambda
(don't remember the constant but close to 1)

So let's suppose we want to image a Earth sized planet orbiting centauri proxima. The angular size of such planet would be 12000/(4*9.461e12)
radians. Meaning in the visible we need
D=500e-9/12000*4*9.461e12=1500m just for a single pixel of resolution.

With 3m, it's not possible.

Re:How far out is 1.5 million miles? (5, Informative)

superluminique (1567063) | more than 5 years ago | (#28341897)

Hubble and Herschel's orbits are not even comparable to each other.

As pointed out earlier in a separated thread, Hubble is in a low, circular orbit about 560 km above the Earth. It has has a low inclination -- about 28 degrees with respect to the equator. You can actually see the orbital details and where it is in the sky on Heavens Above [heavens-above.com] . The low Earth orbit was chosen so that the space shuttles could service it as they can't reach very far orbits basically due to limitation i how much fuel they can carry (bear in mind that at launch the shuttle engines are powered by the huge orange tank attached to it). It would have to be double checked but I think that the low orbital inclination was decided because it's was easier to launch -- Hubble is one of the most massive payloads ever carried by a space shuttle -- since you benefit from the fact that the Earth rotates so it effectively adds up to your velocity whereas for a polar orbit the contribution is basically null.

On the other hand, Herschel is orbiting 1.5 million km away from the Earth at the L2 point, in a direction opposite to the Sun -- the Sun - Earth - Herschel system forms a straight line. To give you an idea of the scale, the Earth-Moon distance is about 385 000 km so Herschel is located 3.9 times further. Therefore it's easy to understand why the mission is a one-hit wonder because there is no way someone is gonna go there fix it. To be more precise, Herschel is actually "orbiting" about the L2 point (see this diagram [wikipedia.org] on Wikipedia) otherwise its orbit around the Sun-Earth-Moon system would be too unstable. The main reason for sending Herschel so far away from Earth is to optimize its infrared performances. Herschel observe at very long infrared wavelengths compared to, say, the the infrared camera of Hubble and near the Earth, even though you are in space, there is still a lot of thermal radiation coming from the Earth as well as the radiation belts that add up on top of what you want to detect. By being further away, passive cooling helps you and the liquid helium that keeps you cryostat cold heats up slower so your instrument has a longer life time. Also, "temperature" fluctuations are much smaller out there whereas they can be quite large near the Earth depending if your in the Earth shadow, crossing a radiation belt, etc. More stable environment means smaller systematics, which, in turns, imply better telescope sensitivity.

Finally, note that Hubble's successor, JWST will also hang out around L2 for similar reasons.

Re:How far out is 1.5 million miles? (1)

DJRumpy (1345787) | more than 5 years ago | (#28342037)

I would mod this up as informative but I have already commented here. Exactly the information I was hoping for.

Thank you ;)

Re:How far out is 1.5 million miles? (1)

tkjtkj (577219) | more than 5 years ago | (#28345797)

Contrary to your statements about the temperature stability at such long distances from earth, we must consider the pictured 'anatomy' of the instrument: Eg, its cryostat runs at about -272 C. , and yes, there's little heat content in space at such distances .. BUT notice that the solar panels are quite close to the mirror and experience much higher temps. Also, the 'control module', at the end of the instrument farthest from the mirror, runs at an ambient of 20 C !!!!! These 'extra-cryostat' temperatures a remarkeably higher than the cryostat and such heat radiative gradients would belie your point. But im just an amature .. what do *i* know! j. a. , md tkjtkj@gmail.com

wickid cool (0)

Anonymous Coward | more than 5 years ago | (#28341183)

I was tired of looking for water on Mars. Now we can finally see the Herschel factory!

Outgassing... (2, Interesting)

msauve (701917) | more than 5 years ago | (#28341691)

The article mentions the long delay for opening the hatch to wait for outgassing to occur, so the sensors won't get contaminated.

But, don't the pyrotechnic bolts which held the hatch closed (which the article also mentions) outgas, and perhaps even send metallic fragments flying? There is obviously some explosive process involved.

I understand they're more reliable than mechanical latches, but given the need, wouldn't a solenoid operated latch have been better? The hatch would have held closed on its own until in space (since it contained a vacuum), and there's presumably not a lot of force needed to release the hatch once in space.

Re:Outgassing... (4, Informative)

criptic08 (1255326) | more than 5 years ago | (#28342305)

NASA uses a variety of explosive bolts [wikipedia.org] .
Manganese/barium chromate/lead chromate: time delay mix, used for sequencing. Gasless burning.
Zirconium/potassium perchlorate: NASA standard initiator (NSI). Rapid pressure rise, little gas but emits hot particles, thermally stable, vacuum stable, long shelf life. Sensitive to static electricity.

Which doesn't address the issue... (1)

msauve (701917) | more than 5 years ago | (#28342639)

Gaseous or not, an explosion produces residue. A solenoid produces none.

Re:Which doesn't address the issue... (1)

JeffSh (71237) | more than 5 years ago | (#28342847)

I'm sure there's some good reason pal, you can find it out when you join the JPL. I do not know but it's a good question nonetheless.

I suppose that since this is /. (1)

msauve (701917) | more than 5 years ago | (#28343003)

I shouldn't expect people to actually read the articles before commenting.

The Herschel was designed and built by the ESA [esa.int] , not NASA and the JPL. JPL had nothing to do with it. [esa.int]

Re:I suppose that since this is /. (1)

JeffSh (71237) | more than 5 years ago | (#28355669)

Why in the world are you being so aggressive? I merely said the JPL because they are experts and would know the answer to your question. I read the damned article, I know Herschel is an ESA project, but guess who else uses explosive bolts?

Quit being a know it all, jackass. you don't.

Re:Which doesn't address the issue... (1)

criptic08 (1255326) | more than 5 years ago | (#28342961)

I'm fairly sure it's easy to direct very small and precise explosives away from the instruments in space. Not much to alter a trajectory there...

Re:Which doesn't address the issue... (0)

Anonymous Coward | more than 5 years ago | (#28345895)

Good question. No fragments from the explosive bolts are jetisoned, they're designed so that all the parts of the bolt and explosive are retained in the housing.

Explosives are used because they're much, much more reliable than and other method.

source:
Masters degree in spacecraft engineering
& Currently researching for my PhD thesis.

Re:Outgassing... (0)

Anonymous Coward | more than 5 years ago | (#28342989)

Quick!! You better let those scientists know before they destroy their expensive experiment! Just to think, so much money and intelligent minds gone into one project and they can't even replicate their previous success...

Re:Outgassing... (1)

ae1294 (1547521) | more than 5 years ago | (#28344637)

I understand they're more reliable than mechanical latches, but given the need, wouldn't a solenoid operated latch have been better?

That depends on if you want to be pretty damn sure it's going to open. The vast temperature differences tends to mock up most other methods. I think they where more worried about the thing not opening rather than some slight smear that might happen in bazzaro world which if it did occur could still be corrected for in software unlike the hatch being stuck shut forever.

Re:Outgassing... (1)

smoker2 (750216) | more than 5 years ago | (#28345953)

Presumably the bolts are on the outside, so any gasses or fragments are blown* away from the vehicle before the lid actually gets open. This is taking place in space, so the velocity of the gas and particles would mean they depart the area pretty quickly never to return. they don't hang around and then dive back in. It would be silly to put explosives anywhere near the sensors. Like you would think it was silly to use explosive bolts to separate the SRBs from the space shuttle, considering they are right next to a huge tank of fuel. But they do use them and it doesn't detonate the tank. Funny that, almost like they know what they're doing !

* And that's blown as in explosively, not by the wind !

Re:Outgassing... (1)

budgenator (254554) | more than 5 years ago | (#28356413)

If you watch the video you'll notice a pronounced delay from when the bolts fire and the hatch opening, one fragment visible in the video leaves the area before the even begins to open.

isn't 1st light a traditional publicity point (1)

cinnamon colbert (732724) | more than 5 years ago | (#28346351)

am i the only curmudgeon who thinks telescope PR should start with 1st light ?
Cover opening doesn't actually mean anything is working - when they have images that are within spec being sent to earth on a regular basis, they have a working scope

Re:isn't 1st light a traditional publicity point (1)

Muad'Dave (255648) | more than 5 years ago | (#28346727)

I'm with you. I was going to post a "Pics or it didn't happen" comment, but there really aren't any pics! Yawn.
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