Advanced Technology Large-Aperture Space Telescope (ATLAST)
What is ATLAST?
The greatest leaps in our understanding of the universe typically follow the introduction of radically new observational capabilities that bring previously unobserved phenomena into view. Some, such as the unambiguous detection of life on an Earth-like planet orbiting another star, will be profound yet conceivable. Others are entirely beyond our imagination. All forever change our view of our place in the universe. Astronomers and engineers are now developing a conceptual design for a space-based observatory that is designed to address one of the most compelling questions of our time: Is there life elsewhere in our galaxy? The concept mission, currently dubbed the Advanced Technology Large Aperture Space Telescope (ATLAST), will accomplish this by detecting "biosignatures" (such as molecular oxygen, ozone, water, and methane) in the spectra of terrestrial exoplanets orbiting other stars.
But ATLAST is more than just a "life-finder." ATLAST will have the performance required to reveal the underlying physics that drives star formation and to trace the complex interactions between dark matter, galaxies, and the intergalactic medium. Because of the large leap in observing capabilities that ATLAST will provide, we cannot fully anticipate the diversity or direction of the investigations that will dominate its use – just as the creators of Hubble did not foresee its pioneering roles in characterizing the atmospheres of Jupiter-mass exoplanets or measuring the acceleration of cosmic expansion using distant supernovae. ATLAST will have the versatility to far outlast the scientific vision of current-day astronomers.
Why build ATLAST?
ATLAST will need to have a primary mirror diameter in the 8m to 16m range in order to accomplish its ambitious scientific goals. This large and precise mirror will allow us to perform some of the most challenging observations in order to answer some of our most compelling astrophysical questions. Two different telescope architectures are being studied for ATLAST but both have similar overall optical designs. The two architectures span the range in viable technologies for building very large optical telescopes in space. The architectures are a telescope with a monolithic primary mirror, like Hubble, and a telescope with a large segmented primary mirror, like the James Webb Space Telescope (JWST). The concepts invoke heritage from Hubble and JWST design, but also take significant departures from these designs to minimize complexity, observatory mass, or both. ATLAST will have an angular resolution that is 5-10 times better than JWST and a sensitivity limit that is up to 2,000 times better than Hubble.