The James Webb space telescope has launched into space
After several setbacks, it is now done: On December 25th, the James Webb Space Telescope (JWST), the largest telescope in the history of space travel, was launched. The launch vehicle was a European Ariane 5 rocket used by JWST from the Guiana Space Center near Kourou in French Guiana.
Telescope of superlatives
It will take a total of one month for the telescope to reach its target position at Lagrange point L2, 1.5 million kilometers from Earth. On the way there, the JWST will initially unfold its sun shields and solar cells in order to then be able to open the 6.5 meter main mirror, which consists of a total of 18 gold-coated segments, by mid-January. Should it reach its final position unscathed, the space telescope, which emerged from a cooperation between NASA, ESA and the Canadian space agency CSA, will be the largest of its kind that has ever been in use.
Look back to the Big Bang
The James Webb Space Telescope is a direct predecessor of the Hubble Space Telescope. In comparison, the JWST absorbs ten times as much light and is a hundred times more efficient. Technically, it is more comparable to the Spitzer infrared space telescope – only a thousand times more sensitive. Like Spitzer, the JWST absorbs longer-wave infrared radiation and can therefore look particularly far into the universe. This continuously expands, which means that the ultraviolet and visible light, which was emitted by distant stars, is shifted into the infrared spectrum and can thus be recorded by space telescopes such as the Spitzer and now also the James Webb.
Academic expectations of the JWST are relatively high. The researchers hope to gain insights into a previously very dark zone. Hubble’s range was a maximum of 13.4 billion light years. To be able to look back to the times of the Big Bang, another hundred million years would be needed. Then it might be possible to look back with the JWST in times when the first, possibly differently composed stars and galaxies arose.
JWST observes cosmic clouds
But other areas of space are also to be opened up by the JWST. For example, the astronomers want to observe cosmic clouds in which new stars and planets are formed. The telescope’s infrared eye can see through the gas and dust in the clouds and observe black holes, quasars and the movements of previously unknown galaxies. Even previously undiscovered exoplanets can be found through the telescope.
German institutions were also involved in the development of the telescope. MIRI, a camera and a spectograph for long-wave infrared, was developed at the Max Planck Institute for Astronomy (MPIA) in Heidelberg. “Our filter and grid wheel is a crucial component in detecting different gases in the spectral lines of exoplanet atmospheres“, Says Oliver Krause, who works at the MPIA. The camera can detect oxygen and ozone, among other things, so that the JWST can provide valuable information for the search for life in space: “The search for life or even a ‘second earth’ is not the aim of the mission. We will first have to understand the chemical and physical parameters of exoplanet atmospheres, something that was previously not possible without the JWST“, Continues Krause.
Precise technology with challenges
From a technical point of view, the JWST presents one or the other challenge. Its measuring instruments have to be operated extremely cool, since radiated heat (which is also infrared radiation) would interfere with the telescope’s images. Therefore, you have to wait before operating the JWST until all residual heat has escaped from the instruments into space. This will take about six months.
The telescope is in a fixed orbit and is directed outwards, i.e. away from the earth. On the inside is the sun shield, which takes up about the area of a tennis court and protects the JWST from light and heat radiation from the sun, moon and earth. The antenna is also located there. Since the telescope itself always looks outwards, it takes a full year, i.e. one orbit of the sun, to cover the entire sky.
The original launch was scheduled for 2007
The scientists will use the time until the final commissioning in summer to calibrate the instruments and align the 18 mirror segments of the 6.5 meter main mirror. A total of 40 million working hours with the participation of highly specialized personnel from 14 different countries went into the construction of the telescope. The planning phase goes back to 1989 – even before the start of the Hubble space telescope. At the end of the 1990s, there was talk of a start in 2007, which then obviously didn’t work out. The date was postponed several times while project costs increased to a total of $ 9.7 billion. Rescheduling and quality defects that had to be corrected contributed to the increased costs. However, scientists continue to believe that the telescope’s potential more than justifies the cost.