Planck (spacecraft)
(Also known as Planck Surveyor ) Planck is an ESA spacecraft for the exploration of the cosmic background radiation.
Mission
The 1921 kg heavy Planck telescope was brought together with the infrared telescope Herschel by an Ariane 5 ECA into space. The launch took place after several postponements on 14 May 2009 at 13:12 UTC clock from the Guiana Space Centre at Kourou. After the firing circuit of the upper stage of the Planck satellite at 13:40 UTC few minutes after the Herschel telescope on a highly elliptical orbit 270-1197080 km altitude, which is 5.99 ° inclined to the equator have been exposed. From this orbit, the satellite 's Lissajous train reached after several train maneuvers around the Lagrange point L2 of the Sun-Earth system.
On 14 August 2013, the telescope was removed from the operation L2 point after 1554 days and formed into a sheet, which ensures that it is not captured for the next 300 years through the earth. On October 23, 2013 Planck was finally shut down.
Payload
To observe the radiation of the satellite has two different instruments, the "High Frequency Instrument " ( HFI ) for the higher and the "Low Frequency Instrument " (LFI ) for the lower frequency range. These instruments form with the two levels of the satellite, a telescope, which is assembled on a carbon fiber structure.
Below the telescope is essentially composed of three aluminum sandwich shields and fiberglass props Kryostruktur ( " Cryo Structure" ). It is used to optimize the heat dissipation and protection of the telescope in front of the satellite body warm. A passive temperature of about 45 K is reached. LFI is cooled to 20 K using a sorption cooler in a closed hydrogen circuit. The HFI is additionally cooled by a closed - cycle helium to 4K. Mixing of liquid helium -4 and helium - 3, finally, the detectors of the HFI are cooled to only 0.1 K in order to suppress the noise. This cooling mechanism of the coldest part of Planck is open, ie the refrigerant is lost with time.
Specifications
- Height: 4.2 m
- Diameter: max. 4.2 m
- Take off weight: 1,921 t
- Primary mirror diameter: 1.75 m
- Telescope mass: 28 kg
- Coolant: 1500 l helium
- Service life: 21 months (planned), at 29 months ( HFI ), partial operation for a further seven months
- Railway: Lissajous path, 0.28 million km x 0.28 million km to the Earth-Sun L2, now sun orbit
- Total cost: 600 million euros
Scientific Work
History
The project of a satellite for the accurate study of the cosmic background radiation was established in 1996 and was developed in cooperation of 40 European and 10 American institutions with the ESA. The satellite is to determine the temperature fluctuations of the background radiation in the range of a millionth of a degree. He was initially evaluated under the name COBRAS / SAMBA and later renamed in honor of Max Planck.
Measurement and evaluation
On August 13, 2009 marked the beginning of the regular monitoring. The first complete recording of the sky was completed in June 2010, but in order to achieve full accuracy, a post-processing was necessary. First results were published in January 2011. The necessary cooling for the HFI coolant went 16 January 2012 to the end, the LFI can still be operated for months on what particular allows better calibration of the high- frequency data. Instead of the planned two- Planck even made five complete sky surveys. The evaluation of the data is estimated participant According take at least a year.
Goal of Planck is a mapping of the cosmic background radiation in parallel at nine frequencies 30-857 GHz. The angular resolution of Planck is much better than in the comparable previous projects COBE and WMAP with values between 4 arcmin for the highest and 33 minutes of arc for the lowest frequencies.
At the same time observations of the foreground emission of the Milky Way and galaxies are obtained. These interference effects have to be very well known for the determination of background radiation on the one hand, but also of its own scientific interest, for example, to a deeper understanding of stellar evolution.
According to simulations by Gary Shiu and Bret Underwood of the University of Wisconsin -Madison, the measurements of the Planck satellite could be suitable to check the string theory.
Results
On March 21, 2013, the first results of the Planck collaboration in 24 publications were published at the same time. Thus, for example, the age of the universe is increased slightly from 13.7 billion years ago to 13.82 billion years. The new data on the composition of the universe ( dark matter, etc.) have been changed quantitatively. Striking, however, is a slight asymmetry in the matter distribution.
Cosmological parameters of the Planck measurements
The cosmological parameters of the measurements of the telescope are shown in the table.
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