×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

Helium Depleted, Herschel Space Telescope Mission Ends

timothy posted about a year ago | from the say-goodbye-in-a-squeaky-voice dept.

Space 204

AmiMoJo writes "The billion-euro Herschel observatory has run out of the liquid helium needed to keep its instruments and detectors at their ultra-low functioning temperature. This equipment has now warmed, meaning the telescope cannot see the sky. Its 3.5m mirror and three state-of-the-art instruments made it the most powerful observatory of its kind ever put in space, but astronomers always knew the helium store onboard would be a time-limiting factor." Reader etash points to a collection of some infrared imagery that Herschel collected.

cancel ×
This is a preview of your comment

No Comment Title Entered

Anonymous Coward 1 minute ago

No Comment Entered

204 comments

Orbital pickup truck (5, Interesting)

mabhatter654 (561290) | about a year ago | (#43589503)

If only we had a plan for recurring orbital missions... A "space pickup" that would launch on a regular basis to make pit stops for things like extra helium.

To think how many multi-decade projects like this will "rot on the vine".

Re:Orbital pickup truck (5, Informative)

Anonymous Coward | about a year ago | (#43589533)

It'd have to be more than orbital. Herschel is out at Earth-Sun L2. That's not exactly a short trek.

Re:Orbital pickup truck (5, Informative)

Anonymous Coward | about a year ago | (#43589547)

A pickup truck that can get to L2 and back. Whatever you're thinking of, it isn't the shuttle.

Re:Orbital pickup truck (5, Funny)

TWiTfan (2887093) | about a year ago | (#43589667)

Hey, Bruce Willis and James Bond taught me that the Space Shuttle can go anywhere!

Re:Orbital pickup truck (1)

MightyYar (622222) | about a year ago | (#43590649)

In "Footfall" they strap the whole fleet of shuttles to a single nuclear rocket and use them as fighters against alien invaders.

Re:Orbital pickup truck (2)

DragonTHC (208439) | about a year ago | (#43590191)

more of a sailing vessel with a significant hold.

We will also need an orbital platform capable of storing the materials.

Re:Orbital pickup truck (0)

Anonymous Coward | about a year ago | (#43590537)

But what if it runs into Klingons?

Re:Orbital pickup truck (3, Funny)

Anonymous Coward | about a year ago | (#43590603)

We'll just scrape 'em off.

.

Re:Orbital pickup truck (1)

mabhatter654 (561290) | about a year ago | (#43590629)

Ok, what about Buck Roger's Deep Space Shuttle?. We were supposed to launch that in 1999... Like 20 years after the ones we just retired.

Re:Orbital pickup truck (4, Informative)

Alex Pennace (27488) | about a year ago | (#43589587)

If only we had a plan for recurring orbital missions... A "space pickup" that would launch on a regular basis to make pit stops for things like extra helium.

To think how many multi-decade projects like this will "rot on the vine".

The Herschel Space Observatory is 1,500,000 km away at a Lagrangian point. Servicing missions of any kind are out of the question.

Re:Orbital pickup truck (5, Insightful)

mrsquid0 (1335303) | about a year ago | (#43589707)

The Earth-Sun L2 point is out of reach with the old Space Shuttle, but the original point is a good one. It is too bad that we do not have the capability to repair and restock the consumables on spacecraft in the inner Solar System. It has been nearly 45 years since we first went to the Moon. We should be able to move around in our band of the Solar System by now.

Re:Orbital pickup truck (0)

Anonymous Coward | about a year ago | (#43589921)

It has been nearly 45 years since we first went to the Moon.

The current sorry state of our space faring capabilities really makes it hard to believe that's true. Maybe the space age indeed is over.

Re:Orbital pickup truck (1, Interesting)

Anonymous Coward | about a year ago | (#43590179)

The "Ages" system refers to "cutting edge" technology - the technology used to kill each other. Given this, I don't think we ever really entered the space age. Silicon age is more descriptive of current weapons.

Re:Orbital pickup truck (4, Interesting)

MightyYar (622222) | about a year ago | (#43590693)

I have to disagree. Just last night I was marveling at how we have rovers cruising around mars, orbiters and probes strewn all over the place, and how the technology is now at hand to create "tugboats" for asteroids. Maybe manned missions have been disappointing, but robotic missions are amazing too.

Re:Orbital pickup truck (1)

Anonymous Coward | about a year ago | (#43590091)

Soon we may. There are multiple organizations working to solve this problem.

http://www.darpa.mil/Our_Work/TTO/Programs/Phoenix.aspx

http://ssco.gsfc.nasa.gov/

Re:Orbital pickup truck (5, Interesting)

Megane (129182) | about a year ago | (#43590137)

It has been nearly 45 years since we first went to the Moon.

We only went there because of a super stretch effort that went to the limits of our technology and budgets. It was an anomaly in the progression of space exploration, and the extreme effort involved probably even set us back by a couple of decades. We are currently on a more normal progression of space exploration, with the possible exception that we (the western world, as opposed to the Chinese) may bypass the moon this time around because we've already been there and it's not really very interesting.

Actually, I'm surprised that we've sent hardly any robotic missions to the moon in the past 45 years. There's a lot less need for humans when communication delays are only a few seconds, and maybe we could find out something interesting enough to want to go back there.

Re:Orbital pickup truck (1)

Runaway1956 (1322357) | about a year ago | (#43590493)

Just send a super model. Hundreds of thousands of men will start searching for ways to get there.

Better yet - get Avon to hint to the world that moon dust is the new wonder ingredient in the fight against aging. Instead of the men, millions of women will be racing to the moon!

Re:Orbital pickup truck (1)

wagnerrp (1305589) | about a year ago | (#43590589)

So the scientists are telling me that rubbing myself down with moon dust was a bad idea... and that I now have cancer...

Re:Orbital pickup truck (1)

Runaway1956 (1322357) | about a year ago | (#43590719)

That reminds me of a story -

Some woman had joint pains. Someone told her that WD-40 would help to ease the joint pains. Instead of asking "how much", or doing any research, the woman supposedly BATHED in a tub of WD-40.

I really don't know how true the story is. My wife told it to me, she swears it's true, yada yada yada . . .

Anyway, please, when you get your moon dust cosmetics, follow the guidelines that Avon and Maybelline publish and distribure with every 3 gram bottle they sell.

Re:Orbital pickup truck (1)

FrankSchwab (675585) | about a year ago | (#43590343)

Unfortunately, despite decades of wishful thinking, the laws of physics haven't changed much in the decades since we went to the moon.

Re:Orbital pickup truck (2, Interesting)

Runaway1956 (1322357) | about a year ago | (#43590469)

We pissed away more than two decades with that stupid ass "space plane" thing. It's like America said, "Well, we were the first on the moon - we'll never beat that, so we'll just give up now. Oh - launch that space plane thingy occasionally, to give lip service to exploration and research."

Re:Orbital pickup truck (2)

jekewa (751500) | about a year ago | (#43589997)

Robots? I'm sure the limiting factor is that no one considered sending unmanned missions with supplies. Surely something akin to refueling USAF planes in flight could have been considered and a giant "put it here" port could have been exposed for injecting more Helium as needed.

To be fair, unmanned drones weren't as good as they are now when the telescope was launched, so it probably seemed much more impossible than I think it might seem today.

Re:Orbital pickup truck (1)

xhrit (915936) | about a year ago | (#43590057)

I am pretty sure the telescope itself fits the definition of an unmanned drone.

Re:Orbital pickup truck (0)

Anonymous Coward | about a year ago | (#43590383)

I am pretty sure the telescope itself fits the definition of an unmanned drone.

I'm pretty sure the phrase "unmanned drone" is redundant.

Re:Orbital pickup truck (2)

MBGMorden (803437) | about a year ago | (#43590699)

Any robot that could go out that far is going to have to be pretty sophisticated - to the point that its probably cheaper to just build and launch another telescope (and then we get to benefit by replacing it with a better one).

Re:Orbital pickup truck (0)

Anonymous Coward | about a year ago | (#43589607)

Nice try, but the space shuttle does not fly to Lagrange points. It take a tiny wee bit more fuel to get there.... and back...

Now if you had a one way vehicle it would be much cheaper....... :)

Re:Orbital pickup truck (4, Funny)

Virtucon (127420) | about a year ago | (#43589715)

space shuttle does not fly to Lagrange points

Rumour spreadin' a-'round in that Texas town
'bout that shack outside La Grange
And you know what I'm talkin' about.
Just let me know if you wanna go
To that home out on the range.
They gotta lotta nice girls ah.

Have mercy.
A pow, pow, pow, pow, a pow.
A pow, pow, pow.

- ZZ Top...

Re:Orbital pickup truck (1, Funny)

Anonymous Coward | about a year ago | (#43590215)

A pow, pow, pow, pow, a pow.
A pow, pow, pow.

Ah, their lyrics were like poetry. So intelligent.

Re:Orbital pickup truck (2)

Electricity Likes Me (1098643) | about a year ago | (#43589979)

You could launch an ion-drive craft from the ISS which would take a long slow orbit to the telescope, refill the liquid helium, then orbit back to the ISS for resupply.

Re:Orbital pickup truck (1)

Megane (129182) | about a year ago | (#43590155)

Why would you even need it to return unless there are humans aboard? Especially to the ISS, of all places, where a mistake in approach or docking could trash the station. Too much focus on "reuse" is what made the Shuttle so flawed.

Re:Orbital pickup truck (1)

Runaway1956 (1322357) | about a year ago | (#43590517)

It returns for more helium? As for those humans - just tell them to get the docking procedure right the first time. I mean, you don't have to hand off the final approach to a computer, do you?

Re:Orbital pickup truck (0)

Anonymous Coward | about a year ago | (#43590413)

You could launch an ion-drive craft from the ISS which would take a long slow orbit to the telescope, refill the liquid helium, then orbit back to the ISS for resupply.

Ion drives aren't very useful for start-stop type operations, they work best as a continuous thrust drive where you don't ever plan on slowing down.

Re:Orbital pickup truck (1)

Anonymous Coward | about a year ago | (#43589787)

Why not have the cooling system in a closed loop and use solar power to chill the helium back down - keeping the satellite dormant until it could operate again? It seems like a waste of $billions to not think of such a system. Even if it could only operate 10% of the time, it could provide decades of additional science.

Re:Orbital pickup truck (0)

Anonymous Coward | about a year ago | (#43589961)

They must just not have thought of that. Too bad you weren't on the team.

Re:Orbital pickup truck (5, Informative)

MrMickS (568778) | about a year ago | (#43590239)

Why not have the cooling system in a closed loop and use solar power to chill the helium back down - keeping the satellite dormant until it could operate again? It seems like a waste of $billions to not think of such a system. Even if it could only operate 10% of the time, it could provide decades of additional science.

If you read one of the linked articles it explains that they did think of this but at the time it was too risky so went for a simpler solution with a known maximum operational life. A new telescope is being designed that will incorporate mechanical cooling and be able to operate for longer.

"You were made as well as we could make you."

"But not to last."

"The light that burns twice as bright burns for half as long - and you have burned so very, very brightly"

Re:Orbital pickup truck (2, Insightful)

Anonymous Coward | about a year ago | (#43590319)

Yeah, but just remember, then he crushed his head. :)

Re:Orbital pickup truck (1)

Golddess (1361003) | about a year ago | (#43590307)

Because the mechanics of cooling something in space are not the same as cooling them on earth.

On earth, in your typical home AC unit, the freon or whatever runs in a sealed, continuous loop, with one end of the loop being where heat is absorbed, and the other end being where the heat is expelled. This works because at that other end, a fan is blowing air across the radiator, ensuring a fresh supply of cool air to absorb the heat from the AC unit.

But in space, there is no air. So instead, as I understand it, they just dump the hot liquid out into space.

Re:Orbital pickup truck (1)

Pinky's Brain (1158667) | about a year ago | (#43590531)

If you make the radiator hot enough it can dissipate whatever wattage you want ... that said, there might be some practical problems with that.

If cooling the system at peak power consumption isn't an option you might be able to store the gaseous helium for a while in a balloon before cooling. So at the start you just vent like they did now, once the helium almost runs out you go into a low duty cycle operation where you dump expanded helium in the balloon during operation and then slowly recover it ... this way the cooling system can work at much lower wattage.

Re:Orbital pickup truck (0)

Anonymous Coward | about a year ago | (#43590477)

Why not have the cooling system in a closed loop

What do you plan on doing with the excess heat?

and use solar power to chill the helium back down

WHAT????

Re:Orbital pickup truck (0)

Anonymous Coward | about a year ago | (#43590043)

If only it weren't cheaper just to build more disposable rockets and telescopes. Technology moves forward you know, what's the point in maintaining a twenty year old space telescope?

Re:Orbital pickup truck (1)

The Grim Reefer (1162755) | about a year ago | (#43590321)

If only it weren't cheaper just to build more disposable rockets and telescopes. Technology moves forward you know, what's the point in maintaining a twenty year old space telescope?

Except it isn't. Hubble has been in operation since 1990 and will not be replaced for at least another 5 years. Hopefully it will stay operational until then. There have been 4 or 5 missions to repair/upgrade it since its launch. Don't you think they would have simply replaced it if it would have been cheaper?

Re:Orbital pickup truck (2)

Grizzley9 (1407005) | about a year ago | (#43590053)

If only we had a plan for recurring orbital missions... A "space pickup" that would launch on a regular basis to make pit stops for things like extra helium.

To think how many multi-decade projects like this will "rot on the vine".

I'm going to assume due diligence was done and that with it being so far away, a refillable port and a small, single-use robotic craft to accomplish that would be more expensive than just creating a newer satellite to replace it.

How hard can it be to send up some more? (1, Funny)

michelcolman (1208008) | about a year ago | (#43589561)

Come on, even school kids can send balloons filled with helium up into space. Surely that can't be the problem?

It doesn't look at the sky... (3)

gblackwo (1087063) | about a year ago | (#43589583)

That's my nitpick of the day.

Re:It doesn't look at the sky... (0)

Anonymous Coward | about a year ago | (#43589647)

I'm looking at the sky, and it's looking at what I'm looking at...

Worked for 4 years. (1, Insightful)

140Mandak262Jamuna (970587) | about a year ago | (#43589595)

They knew at some point helium will be gone and the telescope will become useless. It ran for four years more or less. Not as bad as the summary made it sound like.

They are in deep space, so they have an infinite sink at nearly zero deg kelvin. It should be possible to design a closed circuit cooling system that just uses energy from solar panels to pump the refrigerant. But in space applications the weight of such a system of compressors, radiators and pumps might prove to be prohibitive. Still feel sad such a fine piece of machinery is rotting away. Well, may be a better design next time.

Re:Worked for 4 years. (1)

140Mandak262Jamuna (970587) | about a year ago | (#43589653)

Looks like the reliability concerns were the reasons why they did not use an active cooling system, not weight.

Re:Worked for 4 years. (1)

DarthVain (724186) | about a year ago | (#43590141)

Still, might fail, seems better than, will fail. I guess the risk/reward is: "What are the odds of it failing within the first 4 years?"

I would have to think part of the problem is having to insulate electronic components against hard radiation, while at the same time trying to cool them.

You would think the best method would be simply to use a peltier with a big ass heat sink protruding into vacuum. Zero moving parts, no liquid coolants. Then again, ultra low temperature might be hard to hit this way, depending what ultra low is. Or the wattage required for such a device might exceed what is realistically gathered from solar. Then again something like a RTG, though expensive might provide perhaps enough power.

Though looking a terrestrial CPU overclocking, if you want to hit those ultra low temperatures, you have to use a compressor based system, or LN2. Which is more or less the only options being discussed.

Re:Worked for 4 years. (2)

Megane (129182) | about a year ago | (#43590163)

I'm sure that an active cooling system wouldn't have been vibration-free either. Telescopes don't work so well when you keep bumping them around.

Re:Worked for 4 years. (4, Informative)

kav2k (1545689) | about a year ago | (#43589659)

It's not exactly an efficient sink, is it? Your only option for heat transfer "outside" is infrared radiation, since vacuum does not exactly support conduction/convection.

Re:Worked for 4 years. (3, Insightful)

mmcxii (1707574) | about a year ago | (#43589671)

Another problem with the system you mention is that heat doesn't radiate away efficiently in space. While such a system may be possible I'm sure that the up-time of the scope would suffer greatly from it.

Do we have any thermal dynamic geeks here with something a bit more insightful?

Re:Worked for 4 years. (1)

140Mandak262Jamuna (970587) | about a year ago | (#43589799)

Thanks, I did not realize things are different in space. So how would one design an active cooling system to dissipate heat in space?

Re:Worked for 4 years. (4, Informative)

fuzzyfuzzyfungus (1223518) | about a year ago | (#43590103)

Thanks, I did not realize things are different in space. So how would one design an active cooling system to dissipate heat in space?

I am not a rocket scientist; but my understanding is that the space-equivalent of a 'heatsink' is a fin, with a surface that approximates a black body as closely as engineering constraints allow, aligned so that as much surface area as possible(the flat faces) receives as little incoming light as possible, with as little as possible exposed to the sun(so, in practice, the alignment is pretty much the opposite of a solar panel, where you want as much surface area getting sunlight as you can and as little being wasted by facing into deep space as you can). Depending on the orbit, and whether your thermal load is constant or can accept variations, this may or may not require the fins to move.

If you need active cooling(as you probably would here, since ultrasensitive IR hardware generates some heat on its own and works less well for every additional kelvin) you use a heat pump of some sort, just as on earth; but your 'sink' is thermal radiation from the fins, rather than conduction from the fins into the atmosphere or coolant water.

The real problem(in addition to the fact that solid-state heat pumps are miserably inefficient, and ones with moving parts have mechanical levels of reliability in an area where you can't just schedule a tech visit), is that thermal radiation alone is miserable compared to conduction/convection into air, which is weak compared to conduction into forced air.

If you have a large enough payload budget, it isn't necessarily insurmountable, all it takes is more surface area radiating heat; but the engineering challenges of having a cryogenic heat pump capable of keeping the instruments at liquid helium temperatures and enough fin surface area to dump the waste heat from both the instruments and the heat pump's own inefficiencies are significant.

Liquid helium isn't cheap, and relying on a consumable cuts mission lifespan; but "just let the helium boil off where you need things to be colder" simplifies the engineering considerably.

Re:Worked for 4 years. (0)

Anonymous Coward | about a year ago | (#43590391)

Put the cooling apparatus in a separate vehicle. No vibration.

Re:Worked for 4 years. (2, Informative)

Anonymous Coward | about a year ago | (#43590701)

Well, put, but one other major killer ... There are no "good" ways to get rid of vibrations on a spacecraft. There's no atmospheric drag (see the mythbusters on the flag on the moon). You basically have to have a damper attached to a mass that kind of sort of slowly adsorbs the energy, re-radiating it as heat. However, most materials are very linear in compression and tension at their minimum range, so it just doesn't work well. Bad enough trying to point a terestrial comms satellite. Absolutely mission killer for aiming a telescope.

Re:Worked for 4 years. (1)

camperdave (969942) | about a year ago | (#43590203)

Thanks, I did not realize things are different in space. So how would one design an active cooling system to dissipate heat in space?

Well, if you have a big ol' tank of liquid helium, you could slowly boil that off...

Re:Worked for 4 years. (3, Informative)

Overzeetop (214511) | about a year ago | (#43590455)

You're limited to radiation, and the cosmic background temp, but that's the only limit. Although inefficient, peltier coolers can be used - the advantage is there is no fluid. Heat pipes are the most common form of heat transport, allowing the evaporation of a liquid in a sealed tube to migrate to the radiator end.

One challenge is the temperatures you're trying to work with. Remember that the temperature of the universe isn't actually 0K, but more like 3K. Liquid helium needs to be 4K or less. That's a slim margin, and at those temps the heat transfer rate is very, very low.

I clicked on the story because I was an engineer involved in the Superfluid Helium On Orbit Transfer (http://istd.gsfc.nasa.gov/cryo/SHOOT/shoot.html) research project back in the early 90s. If you get Helium just above absolute zero, it loses it's viscosity (like a superconductor loses it's resistance). That makes it far easier to transfer the fluid from a storage container/refueling dewar to a spacecraft in service.

I actually like radiative heat transfer - it's very straight forward, much like conduction. Convection problems make me cry.

Re:Worked for 4 years. (0)

Anonymous Coward | about a year ago | (#43589853)

What? Heat radiates just as efficiently in space as it does anywhere else.

It doesn't convect away, of course.

Re:Worked for 4 years. (1)

Anonymous Coward | about a year ago | (#43589945)

What you guys are talking about is a Cryocooler. http://en.wikipedia.org/wiki/Cryocooler

These have been used in space since the mid 70s. JWST will be using a cryocooler to cool the MIRI instrument to near 7K.

Obviously the Herschel mission made some system level trades to choose a cryostat over a cryocooler, such as mass, cost and schedule.

Re:Worked for 4 years. (3, Informative)

Anonymous Coward | about a year ago | (#43589703)

Actually, strangely the inverse is true.

In space, there are very few particles, which means that heat transfer is almost non-existant when away from the atmosphere. This causes a problem in that if you generate any heat, it dissipates extremely slowly, which was why the Helium was important. If this piece of equipment was in the sun, it would have been even worse.

Re:Worked for 4 years. (5, Informative)

IndustrialComplex (975015) | about a year ago | (#43589775)

They are in deep space, so they have an infinite sink at nearly zero deg kelvin.

What exactly could it 'sink' that heat into? While we consider space to be 'cold' the reality is that it is less 'cold' and more 'generally won't make things warm.'

The vacuum is both a benefit and a problem. When you want to keep things a certain temperature, the vacuum is great as you don't have to sorry about convection/conduction altering the temperature. But when you want to cool things off, that vacuum is a problem because you can't use convection/conduction to remove that heat from your system. You can certainly move the heat from one part of your system to another part of your system, but it takes a long time to take that heat OUT of your system.

You would have to move the heat to a massive radiator and wait a long time for it to cool due to radiation. Whatever you are using to move that heat will have to work the entire time, (and may have to be cooled as well!). Even then, the temperatures involved mean that such a process would take a very long time to get as low as they needed to conduct the experiments.

Don't think of space as cold, think of space as very effective insulation.

Re:Worked for 4 years. (1)

Twanfox (185252) | about a year ago | (#43590229)

What, you mean there's a reason we sometimes use vacuum insulation in our hot/cold thermoses? Scandalous ;).

Re:Worked for 4 years. (2)

xiox (66483) | about a year ago | (#43589823)

The forthcoming ASTRO-H [isas.jaxa.jp] X-ray observatory mission will have a cooling system that will be able to run without coolent. The X-ray microcalorimeter detectors must be cooled down to 50 mK in temperature. ASTRO-H should be launched in 2014.

Re:Worked for 4 years. (2)

grimJester (890090) | about a year ago | (#43590193)

According to NASA [nasa.gov] it will still last just three years.

"The instrument utilizes a multi-stage cooling system that will maintain the ultra-low temperature of the calorimeter array for more than 3 years in space."

Re:Worked for 4 years. (1)

xiox (66483) | about a year ago | (#43590253)

The minimum design lifetime isn't the actual lifetime of the mission. I believe there is enough helium for three years, but the multistage cooler is designed to be able to run in the event of coolant loss. ASTRO-H replaces ASTRO-E2 which suffered a catastrophic coolant loss. There are more details here [harvard.edu], but it's behind a paywall.

Re:Worked for 4 years. (4, Informative)

tgd (2822) | about a year ago | (#43589843)

They knew at some point helium will be gone and the telescope will become useless. It ran for four years more or less. Not as bad as the summary made it sound like.

They are in deep space, so they have an infinite sink at nearly zero deg kelvin. It should be possible to design a closed circuit cooling system that just uses energy from solar panels to pump the refrigerant. But in space applications the weight of such a system of compressors, radiators and pumps might prove to be prohibitive.
Still feel sad such a fine piece of machinery is rotting away. Well, may be a better design next time.

No, they have near perfect insulation. The only heat they can get rid of has to happen by radiating it away.

Go step outside.

Notice how warm it is in the sun?

There's no way you can radiate much heat if you're in direct sunlight -- that's why the space shuttle flew upside down in orbit. It kept the heat shield towards the sun, so it had a chance to radiate heat away from the other side.

"So, put a big sun shade and block the sun", you might say... well that's easier said than done, the solar wind would apply a lot of pressure to it, and (for that matter) the solar wind itself is well above the operating temperature of the telescope.

But by all means, I'm sure you're smarter than the experts to designed it.

Re:Worked for 4 years. (1)

chihowa (366380) | about a year ago | (#43590675)

There's no way you can radiate much heat if you're in direct sunlight -- that's why the space shuttle flew upside down in orbit. It kept the heat shield towards the sun, so it had a chance to radiate heat away from the other side.

I doubt that's the main reason why the shuttle flies upside down. The bottom of the shuttle is also black, while the top is white. From a simple light-absorption-radiation point of view, this configuration would lead to heating of the shuttle as a whole. The heat shield is designed to shield from heat conduction due to superheated compressed air in contact with the shuttle during reentry. Shielding from radiative heating makes use of reflective surfaces like what satellites are coated in.

It seems the shuttle would fly upside down to aid in radio communication with the earth, allow viewing of the earth through the windows (a human concern, but still an important one), and to protect the shuttle from earthbound debris (though I'd think the heat shield is the last thing you'd want to damage before attempting reentry).

Re:Worked for 4 years. (3, Informative)

Anonymous Coward | about a year ago | (#43589919)

Some parts of Herschel's detectors had to be chilled to 0.3 K, others to 1.7 K. There's no way to get that low with radiative cooling; indeed, it's below the temperature of the cosmic microwave background. Virtually all known materials except for helium freeze solid at those temperatures; no standard refrigerant can do it.

The only technologies we have that can get that cold are all based on liquid helium, and they inevitably lose trace amounts of it over time. They could have given it a bigger dewar vessel, but that would have been heavier, and therefore needing a bigger rocket, and therefore more expensive.

(Ref: http://herschel.esac.esa.int/Docs/Herschel/html/ch02.html )

Re:Worked for 4 years. (3, Informative)

delt0r (999393) | about a year ago | (#43590005)

Radiating heat goes to the 4th power. So at 273K (0C) a panel in space radiates 314 watts per m2. However at 4K we radiate a mere 14.5 micro watts. So to radiate 1 watt we would need a square panel 262 meters a side (69000m2). Even worse space is radiating the same amount of heat back at you. So you in fact would not get rid of any heat. In fact i think this particular system needed to be colder than 4K. So no passive system can do it.

Re:Worked for 4 years. (1)

arkhan_jg (618674) | about a year ago | (#43590119)

The problem is also the heat sink. Without convection and conduction, you're left with heat radiation, which is pretty damn slow. Worse, any such heat sink would actually pick up more heat due to being in direct sunlight - the existing solar shield on it to protect the instruments was at 400k! Would depend on the design, but I imagine it would be tricky to even break even against solar heating - that's a lot of energy headed your way all the time (and solar panels only convert a small part of it). So if you packed some kind of big folding heatsink to get it in the launch vehicle, you'd also need a folding shield to protect that too. Complex and heavy, and that's before you even start on the active heat pump system, which is a nightmare engineering job in space in and of itself - you really can't afford it to fail.

Frankly carrying your own dump tank of coolant (which eventually gets effectively depleted) seems like it probably was the sensible option. We got 4 years of unique data gathering, and it will take a lot longer before we finish processing it. Space is a really harsh environment, even for machines.

Condensers in vacuum would just create heat (2)

dfm3 (830843) | about a year ago | (#43590127)

There are two problems with your approach: one, the near vacuum of space does not allow for effective cooling via convection. Two, compressors only displace heat, and in doing so they actually generate more heat overall. A good example of this is the coils on the back of your refrigerator, which get quite warm during operation. Your kitchen warms up slightly while the interior of the fridge cools. In space, this heat does not dissipate readily and would build up until the system overheats.

Re:Worked for 4 years. (0)

Anonymous Coward | about a year ago | (#43590165)

Actually, empty space radiates at almost 3 K, well above the 0.3 K those at which those instruments are kept. So you're asking for a compressor with a compression ratio of well above 10, where the working fluid is liquid hydrogen (not any gas) and with enough thermal insulation between its hot and cold ends to maintain a temperature ratio well above the ratio of room temperature vs. molten iron.
I'm afraid this might be harder than it looks.

Re:Worked for 4 years. (0)

Anonymous Coward | about a year ago | (#43590287)

For Helium nothing is airtight.

Re:Worked for 4 years. (1)

The Grim Reefer (1162755) | about a year ago | (#43590655)

They are in deep space, so they have an infinite sink at nearly zero deg kelvin.

I don't think it's in "deep space" by most definitions as that's generally considered to be outside of the solar system. Also, L2 is not around the 2.75K that is estimated to be the average temperature of space. The temperature of space around Pluto's orbit is estimated at 35 to 40 K. [wisegeek.org] This site states that Herschel passively cools to 80K [caltech.edu] So I would guess that the temperature at L2 is 80K and they are in fact using the He to cool to ambient as you already suggested.

Kinda like in HS (0)

Anonymous Coward | about a year ago | (#43589597)

When the helium runs out, the party ends.

Salvage Rights (5, Interesting)

jdigriz (676802) | about a year ago | (#43589713)

SpaceX should go after it and salvage it robotically for use as a solar thermal concentrator. 3.5M mirrors that are already in space don't exactly grow on trees. A simple high-efficiency Ion engine (Dawn-class)and a robonaut should be able to handle the job. They can then lease the asset to Planetary Resources or whoever wants to do industrial experiments. Doesn't have to be quick. Cheap and slow is the way to go here.

and get off his lawn (4, Funny)

Thud457 (234763) | about a year ago | (#43589855)

Andy Griffith says "finders keepers".

Re:and get off his lawn (0)

Anonymous Coward | about a year ago | (#43590489)

Don't you mean Harry Broderick?

http://www.youtube.com/watch?v=xHUWlEB6N1s

Re:Salvage Rights (1)

kaizendojo (956951) | about a year ago | (#43589909)

+ 1 for a great idea (never have mod points when i need them!!)

Seriously; you should approach them on this.

Re:Salvage Rights (1)

jdigriz (676802) | about a year ago | (#43590087)

WIki says that there are no plans for the Robonaut 2 prototype already on ISS to be returned to Earth. I smell stone soup space mission. Thanks taxpayers!

Re:Salvage Rights (0)

Anonymous Coward | about a year ago | (#43589977)

I think Ernst Stavro Blofeld might have a use for 3.5M mirrors in space too.

Or the villain of any one of the other 3 Bond films with the exact same fucking plot.

Re:Salvage Rights (0, Insightful)

Anonymous Coward | about a year ago | (#43590211)

Oh you're so adorable. Keep chomping away at the sci-fi. "robonaut"! So Cute!

Re:Salvage Rights (1)

GameboyRMH (1153867) | about a year ago | (#43590509)

It won't be easy to disassemble it and pull the big mirror out of its guts, and then replace the smaller mirror at the focal point with whatever energy collection device you want to use. I'd say you'd need a robot that's as dextrous as a human before attempting this. And then you would have launched that thing to go to the telescope, disassemble the satellite, collect the big mirror and possibly take it to where it's needed, instead of just launching a big mirror...

Re:Salvage Rights (0)

Anonymous Coward | about a year ago | (#43590647)

This is many many orders of magnitude beyond what SpaceX can do presently. But keep dreaming.

Duh? (1)

sociocapitalist (2471722) | about a year ago | (#43589773)

Bit of a shame no one thought to make this a rechargable system.

Re:Duh? (2, Insightful)

Anonymous Coward | about a year ago | (#43589941)

They did think about that.

But it's a million and a half kilometres away. A robotic service ship to catch and refill it after four years would cost more than just sending up a second, newer-generation telescope.

Re:Duh? (0)

Anonymous Coward | about a year ago | (#43590571)

But but but SpaceX and robonauts? Technology and stuff?

Re:Duh? (0)

Anonymous Coward | about a year ago | (#43590217)

Damn, where were you when they were designing it, they really could have used your help.

Even better if you were helping the team design the STS. You could have told them, "oh, and make it so it doesn't assplode in de air."

No Helium (0)

Anonymous Coward | about a year ago | (#43589881)

So, it's out of gas!

Re:No Helium (0)

Anonymous Coward | about a year ago | (#43590201)

Why can't we switch to liquid nitrogen? doesn't it go cold enough for it? or is it too cold?

Can the sensor be replaced... (0)

Anonymous Coward | about a year ago | (#43590259)

...to make this a visible (and UV) light telescope?

Load More Comments
Slashdot Account

Need an Account?

Forgot your password?

Don't worry, we never post anything without your permission.

Submission Text Formatting Tips

We support a small subset of HTML, namely these tags:

  • b
  • i
  • p
  • br
  • a
  • ol
  • ul
  • li
  • dl
  • dt
  • dd
  • em
  • strong
  • tt
  • blockquote
  • div
  • quote
  • ecode

"ecode" can be used for code snippets, for example:

<ecode>    while(1) { do_something(); } </ecode>
Sign up for Slashdot Newsletters
Create a Slashdot Account

Loading...