Hubble Space Telescope longer wavelengths than Hubble or JWST, was the European Space Agency's Herschel Space Observatory, launched on May 14, 2009. Like JWST, Herschel was not designed to be serviced after launch, and had a mirror substantially larger than Hubble's, but observed only in the far infrared and submillimeter. It needed helium coolant, of which it ran out on April 29, 2013. Further concepts for advanced 21st-century space telescopes include the Advanced Technology Large-Aperture Space Telescope, a conceptualized optical space telescope that if realized could be a more direct successor to HST, with the ability to observe and photograph astronomical objects in
Spitzer Space Telescope located in the habitable zone, which means they are capable of supporting liquid water given sufficient parameters. Using the transit method, "Spitzer" helped measure the sizes of the seven planets and estimate the mass and density of the inner six. Further observations will help determine if there is liquid water on any of the planets. Spitzer Space Telescope The Spitzer Space Telescope (SST), formerly the Space Infrared Telescope Facility (SIRTF), is an infrared space telescope launched in 2003 and still operating as of 2018. It is the fourth and final of the NASA Great Observatories program. The planned mission period