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Successful Launch of ESA's Herschel and Planck
rgarbacz writes "Today at 13:12 GMT, the ESA launched successfully new and long-awaiting spacecraft: Herschel, the infrared telescope with a 3.5m mirror, and Planck, the CMB mapper. The spacecraft were carried by the Ariane-5, which lifted off from Kourou in French Guiana. They will stay in L2 to perform the research. This launch is one of the most expensive and important missions of the European Space Agency. Planck will measure the CMB with an accuracy more than 10 times better than the previous mission, WMAP. Because of this high sensitivity, both spacecraft are cooled to temperatures close to absolute zero by on-board liquid helium; staying in L2 is very helpful to maintain this state. Both spacecraft are designed to observe the Universe at its infancy: Herschel by observing the first stars and galaxies (whichever came first), and Planck by scrutinizing the first photons that were set free, making up the cosmic microwave background radiation."
even if it is ten times more accurate than before, I think we have a long way to go.
Planck will measure CMB with accuracy below 1%
Uhm. Is this technical terminology that I simply don't understand, or just a typo? Because I can understand a '1% margin of error', and I can sort of understand 'accurate to 1%'... but something which is below 1% accurate?
If only I could get away with that in my job.
Herschel is supposed to complete its mission in three years, Planck in only 15 months. After the helium supplies have evaporated, their missions end. They won't be repaired / serviced, because they are too far away to be easily reached with a shuttle. That's what local news here say.
I hope I didn't brain my damage.
Wiki Entry for Lagrange Point
Oh god, that woman is John Romero!
Lagrange point. Location where the gravitic pulls of some objects cancel each other out. In this case, it's Earth and Moon.
It seems like the summary writer didn't understand TFA. Quoting from ESA:
The older measurements that Planck is trying to improve already are accurate to 0.1%.
It seems like someone got confused with the coincidence that the temperature of the universe, 2.7 K, is about 1% of the temperature of freezing water, 270 K.
it's all about the pretty sparkle isnt it?
If I don't get new desktops by June I will NOT be happy...
It pays to be obvious, especially if you have a reputation for being subtle.
Well, that's because the space is too hot.
Even without the sun.
They are trying to measure the CMB. If you are not colder than outer space, most of the radiation would just come from the telescope itself...
HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
Plural of "spacecraft" is "spacecraft".
But the plural should be spacecreft!
Spacecruft?
As maintainer of RTEMS, I am very proud that both spacecraft are running our free real-time operating system on at least the Spacecraft Management Unit (SMU). These are both important missions which promise to provide us with new insights.
"In order to study the coolest places in the Universe the Herschel instruments must be cooled to just above absolute zero. A large cryostat surrounds the instruments maintaining an operational temperature of 1.7 K for a nominal mission lifetime of 4 years." ESA has some great info on their site.
I hope I didn't brain my damage.
Because what they're trying to measure is, in some senses, the temperature of space itself - the ~3K CMB. So they need the detector to be colder than that.
Isn't there some way to use one or more of the three forms of heat transfer to keep the instruments cold enough to work without having to rely on a limited source of helium?
No. The radiative coolers (can't really use conduction or convection in space) will keep the craft cold enough for the low frequency instrument to work, even after the helium* runs out, but to get the 0.1K that the high frequency instrument needs, there's no (good) alternative to this active cooler.
* Well, not after the helium in its own refrigerators runs out. But it's not actively venting that, so we only have leakage to worry about there.
I am trolling
To put it another way- heat is full of microwaves (the same as are in your kitchen appliance) which heats up everything in space to a certain point (2.7 Kelvin, if it's a black something). If you simply rely on "the coldness of space" to cool you down, that's as cool as you're going to get.
That's still EXTREMELY cold, but for this particular mission it's not cold enough. This mission is to measure said background radiation, meaning that in order to do it's job it must be colder than that extremely low temperature that is "the coldness of space".
There is a huge technical problem that many of the above posters have ignored. To use "space" as a heat sink requires you to conduct that head to space. However, space is very close to vacuum and thus it is near impossible to conduct heat away. The other option is to radiate heat away this requires that you have something which is very efficient at radiating in the peak frequency for the nominal temperature of the radiator. To make a long story short you cannot use radiative cooling to cool something to near zero in space because you are being bathed by 2.7k blackbody radiation.