Like two peas in a pod, the Herschel and Planck satellites, built by Thales Alenia Space as prime contractor for the European Space Agency, have arrived at the Guiana Space Center in Kourou, French Guiana, and are undergoing final preparations leading up to an Ariane 5 launch on April 16. These two space observatories, the most complex ever built in Europe, will be placed in orbit at a stable point 1.5 million kilometers from Earth, to ensure the thermal conditions needed to observe some of the coldest radiation in the Universe.
Arriving in French Guiana on February 18, the Planck spacecraft is dedicated to the study of cosmic background noise, meaning the “fossil” radiation of the very first light in the Universe, emitted some 380,000 years after the Big Bang, over 13 billion years ago. At that time, the Universe was concentrated in a volume 1,000 times smaller than today. When its temperature dropped to 3,300°C, it was barely enough to allow the formation of the first hydrogen atoms, and to liberate photons to move about freely.
Planck is equipped with a six-stage cooling system (three passive, three active) to enable the observation of this radiation, whose temperature today does not exceed 2.725 K (-270.435°C), and above all to draw up a highly precise map of its miniscule fluctuations (±0.002°). The cooling system is designed to maintain its main mirror at 60 K (-213°C), and the detectors in the payload at 20 K (-253°C), 4 K (-269°C) and even 0.1 K (-273.05°C) for the bolometers in the High Frequency Instrument (HFI). Throughout the 18 months of this mission, these will be the coldest objects in the Universe. The Planck spacecraft, which will enable to better understand the origin and evolution of large structures in our Universe, has reached the incredible temperature of 0.1K (273.05°C) as part of final thermal-cryogenic testing at the Liege Space Center.
This new record comes within a hair’s breadth of absolute zero (-273.15°C) – the equivalent of the amount of energy exchanged between two people 400 kilometers from each other.
In June 2001, ESA chose Thales Alenia Space as prime contractor for these two major scientific missions, based on a contract that is still the largest ever awarded to industry for space science.
The Herschel satellite, shipped to French Guiana on February 11, features a telescope operating in the far infrared band, and will be the first spacecraft to observe the Universe in the submillimetric part of the spectrum. It has a primary mirror 3.5 meters in diameter (versus only 2.4 meters on the Hubble space telescope), making it the largest telescope in orbit until the arrival of the James Webb Space Telescope in 2013.
A successor to ISO (Infrared Space Observatory), also built by Thales Alenia Space, which revolutionized infrared astronomical observations from 1995 to 1998, Herschel will be capable of observing the cold, dust-loaded regions of the Universe that are inaccessible to other telescopes. Its primary mission is to study the genesis of galaxies and changes to stars being formed, as well as dust and gas clouds that could give birth to stars, protoplanetary disks and complex organic molecules in comet comas.
“With the delivery of Herschel and Planck and their upcoming launch, Thales Alenia Space culminates eight years of intense teamwork with ESA, the scientific community and one of the largest industrial teams ever assembled for this type of project,” said Reynald Seznec, CEO of Thales Alenia Space. “The extremely high level of performance offered by these two satellites reflects the technical expertise and high-quality industrial facilities deployed by Thales Alenia Space for European space astronomy programs. Looking beyond Herschel and Planck, we will continue to offer our expertise and capabilities to the scientific community. In fact, we are already participating in studies for upcoming astronomy and astrophysics missions to be developed within the scope of ESA’s Cosmic Vision program.”
Thales Alenia Space has worked with ESA and the French and Italian space agencies, CNES and ASI respectively, since the beginning of European space astronomy programs at the end of the 1960s. Over the last 20 years Thales Alenia Space has become a major European manufacturer in this sector, with responsibility for major programs such as the space observatories ISO (infrared), BeppoSAX (X-ray) and Integral (gamma rays), and COROT (exoplanet “hunter”).
