Any telescope that reaches the launch pad in the 2030s likely will look much different than the concepts four teams are currently studying to inform the 2020 Decadal Survey for Astrophysics, but the studies do offer a roadmap. Here's a brief overview of each:
LUVOIR, now being studied by a team at NASA's Goddard Space Flight Center in Greenbelt, Maryland, is conceived as a great observatory in the tradition of the Hubble Space Telescope. LUVOIR will tell the story of life by searching for signs of life on exoplanets and exploring the cosmic origins of life. Its specific capabilities will span exoplanetary science, general astrophysics, and solar system science. As its name implies, LUVOIR would cover wavelengths from the far ultraviolet to the near infrared and its primary mirror could be up to six times larger than Hubble's.
OST, another concept that a Goddard-led team is investigating, would be extraordinarily sensitive in the mid- to far-infrared wavelengths. Through imaging and spectroscopy, it would probe the early universe, trace the path of water through star and planet formation, and search for signs of life in the atmospheres of exoplanets. Considered a follow-on to the Spitzer Space Telescope and the Herschel Space Observatory, OST would offer 10,000 times more sensitivity than any preceding far-infrared telescope.
NASA's Jet Propulsion Laboratory in Pasadena, California, is leading the HabEx study. This observatory would directly image planetary systems around Sun-like stars. By measuring the spectra of these planets, HabEx would search for signatures of habitability, including water, oxygen, or ozone. It would also study the early universe and the lifecycle of massive stars. Like LUVOIR, HabEx would be sensitive to ultraviolet, optical, and near-infrared wavelengths.
Lynx, which the Marshall Space Flight Center in Huntsville, Alabama, is studying, would investigate the universe in X-rays. It is expected to offer a two orders-of-magnitude leap in sensitivity over Chandra and the European Space Agency's Advanced Telescope for High-Energy Astrophysics, or Athena, which is due to launch in 2028. It would detect X-rays from black holes lighting up the first galaxies and from young stars and their planetary systems.