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."

SuperAccurate

[wild_quinine]

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.

Re:L2?

[MozeeToby]

Also, at the L2 point, all three major heat sources (Sun, Earth, and Moon) are in the same direction. This allows them to have a single heat shield to block radiation from those sources, reducing the cooling needs. When you're trying to keep something at 1.5K, even the light shining off the moon can make a pretty big difference in how much it takes to maintain that temperature.

Re:FFS

[1u3hr]

But maybe we are being too hard on the author of this piece, who may not have english as his native language.

I don't blame the original author, but the incompetent editors who should have noticed and fixed it before publishing it.

Re:Another Job well Done

[Patch86]

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".

Re:Another Job well Done

[forand]

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.

Re:SuperAccurate

[sofar]

Most likely due to:

- funding (the launch phase costs the most because everything has to be tested & proven before it even goes up).
- other projects going up first (short-term projects slip in first etc), occupying launch events.
- feasibility (sometimes a great idea just is too risky)

in that order. it's not rocket science :)