ASTHROS: The Telescope That Floats
- Sharife Gacel
- 1 hour ago
- 4 min read
On a visit to the Jet Propulsion Laboratory in late September 2025, a group of us NASA/JPL Solar System Ambassadors had a chance to visit the High Bay 1 building. We walked inside the building titled Spacecraft Assembly Facility. Inside the giant clean room, was the beginnings of a spacecraft frame. This is site where I first had a chance to see the Europa Clipper prior to it being launched the next year. Exciting place where science and technology take shape. This time, the frame of a giant telescope called ASTHROS was being assembled. We were met by one of the scientists working on it, who explained what this project is all about.
ASTHROS is a giant telescope that flies under a balloon at the edge of space. Instead of being launched on a rocket, it is lifted by a huge helium balloon and floats about 24 miles above Antarctica. At that height, it is above most of Earth’s atmosphere, which normally blocks certain kinds of light from space. This lets ASTHROS see parts of the universe that ground-based telescopes cannot.
The balloon will be enormous. When it is filled with helium, it is about as wide as a football stadium, or 400 feet (150 meters) wide to be exact. Hanging underneath it is a platform that carries the telescope, cameras, computers, solar panels, and communication equipment. Altogether, the whole observatory weighs about 5,500 pounds (2,500 kilograms). The mission will stay in the air for about three to four weeks, slowly drifting around Antarctica while it collects data.
The telescope
The telescope has a dish about 8.4 feet wide. That makes it one of the biggest telescopes ever flown on a balloon. Scientists on the ground can aim it very precisely and receive data from it in real time through satellites. To work properly, the telescope’s sensors must be extremely cold, just a few degrees above absolute zero. Instead of using tanks of liquid helium that would eventually run out, ASTHROS uses an electric cooling system powered by its solar panels. That lets it stay cold for the entire mission.
What is it trying to learn?
ASTHROS is designed to study how stars affect their surroundings. When stars form, they do not just sit quietly. They heat, push, and stir the gas and dust around them. This can either help new stars form or stop star formation from happening. This process is called “stellar feedback,” and it plays a huge role in how galaxies grow and change over time.
ASTHROS will look at special kinds of light that reveal the presence of certain atoms in space, especially forms of nitrogen that are created by these star-forming processes. By measuring this light very precisely, scientists can map where gas is located, how dense it is, and how it is moving. This allows them to build three-dimensional maps of star-forming regions in our galaxy and others.
Looking at a young star system
ASTHROS will also study a young star called TW Hydrae, which is surrounded by a large disk of gas and dust. This is the kind of place where planets are born. The telescope will measure how much material is in this disk and how it is spread out. This can show where clumps of dust may be forming into new planets and help scientists understand how different kinds of planets come to exist.
How this fits with other space telescopes
ASTHROS works in the same general type of infrared wavelength range as famous space telescopes like Spitzer, Herschel, WISE, SOFIA, and Hubble. Its data will add important new details to what those missions have already discovered.
Who is running the mission?
NASA provides the balloon and launch services. The telescope, instruments, and control systems are built by teams at places like Johns Hopkins University, NASA’s Jet Propulsion Laboratory, Lockheed Martin, and Media Lario S.r.l. in Italy which makes the antenna. The launch site is managed by the U.S. Antarctic Program. The mission is led by scientists and engineers at NASA’s Jet Propulsion Laboratory, who oversee the telescope and its science goals.
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