Launched with Herschel, this other deep space observatory is going to draw up the most accurate portrait ever made of the beginning of the Cosmos.
The Planck satellite dedicated to the study of relic radiation (illustration). It was launched with Herschel on 14 May 2009 to Lagrange point L2, 1.5 million km from Earth. Both European Space Agency space observatories will go into orbit around this point in July 2009. Credit: ESA/D. Ducros
Planck pays homage to the memory of German physician Max Planck (1858-1947) and, just like its namesake, intends to help humanity get a better understanding of the Universe. To achieve this, it is targeting further into the electromagnetic spectrum than its launch partner, Herschel (read this Enjoy Space feature) as it goes beyond far infrared and enters the realm of microwave wavelengths. Exactly the same ones that heat up our meals! But before we eat, let’s take a closer look at Planck’s recipe.
Go back even further in time In the Herschel feature, we saw that, due to the expansion of the Universe, the visible light given out by the galaxies tended towards the red, and the more they are distant, the more this is true. Moreover, to look a long way away in astronomy, means looking a long time ago as light does not travel instantaneously, but at 300,000 km/s which is 9,461 billion km per year (a distance that we very logically call a light year). Now, imagine yourself in the process of observing an object 13 billion light years away. You’ve got it, you see this object as it was 13 billion years ago and in this case the light discrepancy goes blithely beyond the red, the infrared and the far infrared and “falls” right in the microwave range. Your eyes, obviously, cannot see anything, but Planck’s instruments can! Consequently, they will examine the “first light” of the Cosmos as, a little more than 13 billion years ago, 380,000 years after the Big Bang to be exact, the temperature dropped below 3,000°C (it was higher than a billion degrees before that...) and matter was starting to become organised which made it possible for light to get through. Due to the expansion of the Universe and the distance travelled, this light reaches us in a considerably weakened state and all that is left of the initial 3,000°C is a weak signal that only exceeds absolute zero by 2.7°C (we therefore talk about -270°C).
Relic radiation map charted by the WMAP satellite (currently the most accurate). The differences in colour demonstrate infinitesimal temperature variations. “Imperfections” around which matter will increasingly congregate, thus enabling stars and galaxies to emerge. Credit: NASA/WMAP Science Team
To “see”, what is at the end of the day, a snapshot of the Universe coming into being, both Planck’s instruments (LFI and HFI — further details in Find out more) have to be at an even lower temperature to work or else they only measure their own warmth... A partnership between CNRS, the French National Centre for Scientific Research, and CNES, the French Space Agency, resulted in the design of the HFI which beats all records by being chilled to the extreme. Scarcely 0.1°C above absolute zero. A first on a satellite.
Lumps in the soup “Refrigerated” in this way, Planck will scan the sky by turning on itself and will gradually draw up a world map of this famous first light; also known as relic radiation or cosmic microwave background radiation. In relation to its two American space predecessors, satellites COBE and then WMAP, the European Space Agency observatory will multiply the resolution by 3 and the accuracy of the temperature differences by 10 (to the nearest millionth of a degree!) This is because relic radiation is only uniform in appearance and has infinitesimal variations which are like “lumps” in the primordial soup but which are, in fact, the actual beginnings of the large structures of our Universe such as stars, galaxies and clusters of galaxies. We therefore understand that the accurate drawing up of a map of these irregularities (scientists talk about anisotropies) is going to put restrictions on the cosmological models which are going to have to be brought into line.
This video shows how, by turning on itself, Planck will scan the entire sky to draw up a complete survey of the cosmic microwave background radiation and its infinitesimal irregularities. Credit: ESA
Consequently, Planck will settle several ongoing debates, for example, the nature of dark matter (matter that we cannot see but whose gravitational effects can be measured) and that of dark energy (which speeds up the expansion of the Universe and about which we know almost nothing). Finally, by measuring the polarisation of the cosmic microwave background radiation, this time machine might be able to reveal traces left by the gravitational wavelengths proposed by Einstein’s general theory of relativity which still elude scientists; “waves” that will not only have an effect on space-time, but also on physics as we understand it today. It is possible, therefore, that there will be a before and an after Planck and we will, perhaps, no longer see the Universe in the same way....
This is the mythical rocket par excellence, the one that launched Sputnik, the first satellite and Gagarin, the first man in space. The CSG, Guiana Space Centre, is now one of its launch bases: a historic achievement.
The first episode of this famous science-fiction series was broadcast in September 1966. NASA has often made references to these programmes, as in the case of the space shuttle Enterprise, which had the same name as the spaceship in the series.
50 years ago on 5 May 1961, a few weeks after Gagarin, American Alan Shepard reached space. Several years later, he was to walk on the Moon, summarising as it were the race in which the Soviet Union and the United States were competing.
