The James Webb Space Telescope may get most of the attention this summer but look for the Astrophysics Stratospheric Telescope for High Spectral Resolution Observations at Submillimeter Wavelengths (ASTROS) next year.
ASTROS is not a space or terrestrial telescope but something in between, floating in the stratosphere. NASA intends to fly the instrument up to 130,000 feet (40,000 meters) in a balloon more prominent than a football field and deploy it over Antarctica for up to four weeks. The advantage of flying the telescope at this altitude is that it dramatically reduces interference from the Earth’s atmosphere – an aspect critical to the ASTROS mission.
The telescope will study an unusual phenomenon called stellar feedback, the process by which living and dying stars stir up clouds of gas and dust around each other. Usually, this creates an environment that favors the birth of stars. But in some extreme cases, too much stellar feedback can prevent new leads from being born. ASTROS will scan star-forming regions in the Milky Way and create 3D maps cataloging the movement of gas inside those regions, NASA officials said in a statement.
To do this, the instrument needs to observe light in far-infrared wavelengths. Ground-based telescopes cannot see this light because it is blocked by the densest part of the atmosphere, the troposphere. But at an altitude of nearly 25 miles (40 kilometers), ASTROS will be in a less dense stratosphere, allowing it to take sharp images in the far infrared.
Engineers face a unique set of design challenges for this device. The entire telescope must be extremely light for the balloon to carry. But it also has to be stiff enough so that the shape of the 8.2-foot-long (2.5 m) nine-piece mirror doesn’t twist or move more than 0.0001 inches (2.5 micrometers), less than the width of a human hair. If the mirrors were to deviate even this minute, they would not be able to produce a clear image.
NASA tapped Italian optical company Media Lario to design ASTROS; the company previously developed the lightweight telescope mirrors used in the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile.
“I think it’s probably the most complex telescope ever built for a high-altitude balloon mission,” Jose Siles, ASTROS project manager at NASA’s Jet Propulsion Laboratory, which manages the mission, said in a statement. “We had specifications similar to a space telescope, but with a tighter budget, schedule and weight. We had to combine techniques from ground-based telescopes that observe at similar wavelengths with advanced manufacturing techniques used for professional racing sailboats. It’s quite unique.”
ASTROS is currently under construction and will launch from NASA’s Long Duration Balloon Facility in Antarctica in December 2023.