The legacy of Spitzer
Yesterday, we said goodbye to the Spitzer space telescope, deployed all the way back in 2003. With over 16 years of mission time hunting planets and other cosmic objects in infrared light, the Spitzer telescope has helped us make major discoveries in and beyond our solar system. It is one of the 4 Great Observatories launched by NASA, the other 3 being the Hubble Telescope, the Chandra X-Ray telescope and the Compton Gamma Ray Observatory.
Originally deployed for 2 and a half years, the decade long extension to the Spitzer’s mission was thanks to the excellent engineers at NASA. Exoplanet discovery was not one of the agendas of the Spitzer telescope but some clever thinking revealed that it could afterall be used in a way that would allow for detection and observation of exoplanets. Since the telescope is equipped with infrared vision, it can see things that are too cold, that are otherwise invisible to the naked eye due to the limited amount of light they emit.
Observation of far away galaxies has given valuable insight to scientists about the formation of galaxies and how the formation process has changed as our universe aged. Another thing that Spitzer was cleverly used to analyse was interstellar dust, which gathers in huge clouds of dust and gas, eventually birthing planets and stars. The chemical composition of these clouds tell us a lot of planet formation, and it wouldn’t be possible to analyse these dust clouds without the Great Observatory’s infrared vision.
Scientists used a method dubbed the transit method (link to first article) to hunt down exoplanets and other solar systems. A transit is when a planet comes in front of a star in its respective solar system and causes a dip in the star’s brightness. This method can be reliably used for single star systems but the difficulty and reliability increases for binary systems.
Spitzer’s most notable discovery has to be the TRAPPIST-1 system, which houses 5 earth sized planets, 3 of which are in the habitable zone (a zone where a planet is roughly optimal distance away from its star to be able to host life).
“When Spitzer was being designed, scientists had not yet found a single transiting exoplanet, and by the time Spitzer launched, we still knew about only a handful,” said Sean Carey, manager of the Spitzer Science Center at IPAC at Caltech in Pasadena, California. “The fact that Spitzer became such a powerful exoplanet tool, when that wasn’t something the original planners could have possibly prepared for, is really profound. And we generated some results that absolutely knocked our socks off.”
How and why the mission got extended
Though the telescope is designed to be able to detect very faint traces of infrared light, our own planet is a massive source of infrared radiation which heavily interferes with Spitzer’s observations. To overcome this, it is positioned in quite a distance away from Earth.
This also serves another purpose – to help the Spitzer stay cool, since it was originally deployed for a series of cool missions. These missions required an operating temperature of negative 267 degrees Celsius (450 Fahrenheit) and this was maintained using a limited supply of helium coolant. After exhausting coolant supplies in 2009, Spitzer was repurposed for a series of warm missions that were possible due to the telescope not heating up too much as a result of its ingenious positioning with respect to our planet.
This Great Infrared Observatory was proposed to be decommissioned in 2018, but was given a final extension due to its successor not being ready for launch – the James Webb Space Telescope.
For a short overview of the original mission, check out the video linked below –
Discover the Spitzer Telescope’s legacy in the video below –