The mission of the Spitzer space telescope comes to an end after a period of more than 16 years. Space agency NASA says that the telescope has now received and sent some of the latest data.
NASA showed on Twitter on Wednesday that the dishes of the California Goldstone complex, part of NASA’s Deep Space Network, were still receiving and sending data to and from Spitzer. At the time of writing, that has ended. On Thursday, the mission of the Spitzer Space Telescope will come to an end and the observatory, launched in August 2003, will no longer be used.
Perhaps one of Spitzer’s most important discoveries is the confirmation that a total of seven planets orbit the star Trappist-1, discovered in 2017. In addition, the observatory was able to detect molecules in the atmospheres of exoplanets and the telescope formed the basis for the first measurements of temperature variations and the wind in the atmosphere of an exoplanet.
On the left is an image of the Tarantula Nebula in the Large Magellanic Cloud, where the different colors represent different wavelengths of infrared light. Also included is a photo of star formation in the Rho Ophiuchi Nebula about 407 light-years from Earth.
According to Paul Hertz of NASA, Spitzer has taught scientists the importance of infrared light for understanding our universe, both for our immediate cosmic environment and for the most distant galaxies. According to Hertz, Spitzer was designed to investigate ‘the cold, old, and dusty’, which can be studied particularly well with infrared light. This part of the spectrum ranges from 700nm to about 1mm. Using different wavelengths, Spitzer was able to observe different features of the universe.
The cold mainly applies to objects that are too cold to emit much visible light, such as exoplanets, brown dwarfs and the cold matter in the space between stars. The old refers to very distant galaxies. The light from these systems takes billions of years to reach Earth. Spitzer, in collaboration with the Hubble Telescope, has found the most distant galaxy discovered by humans, called GN-z11. Light from this galaxy takes 13.4 billion years to reach us. We see this galaxy as it was 13.4 billion years ago; only 400 million years after the Big Bang. Thanks to the two observatories, scientists now know that such early galaxies are more massive than previously believed.
In addition, Spitzer also focused on interstellar dust, which is present in most galaxies. This dust can mix with gas in huge clouds and condense there to form stars, after which the remnants can also form the basis of planet formation. By using a spectroscope, Spitzer was able to analyze the chemical composition of the dust and thus contribute to more knowledge about which ingredients make up planets and stars. Spitzer was also able to see through the dust with certain wavelengths, which is not possible with visible light. This allowed the telescope to detect objects, nebulae and gas clouds that would otherwise not be visible.
Spitzer orbits the sun and is a great distance from Earth, which helps keep it cool. This is important in order not to disturb observations with infrared light. To that end, the observatory is designed to keep cool and operate in temperatures of -267 degrees Celsius. The helium needed for cooling ran out in 2009, but its distance from Earth allowed Spitzer to continue observing at -244 degrees Celsius in two infrared wavelengths. This ‘warm’ mission lasted more than ten years, significantly longer than the ‘cold’ mission. The James Webb telescope is due to go into space in 2021 and can partly be regarded as the successor to Spitzer, partly because this telescope will also focus on the infrared part of the spectrum.