A Jammed Door Is Locking Astronomers Out Of The X-Ray Universe

A jammed door is locking astronomers out of the X-ray universe. With Chandra’s fate uncertain, XRISM carries the hopes of X-ray astronomers across the globe — but a technical issue is holding it back from achieving its full potential. Just outside Hiroya Yamaguchi’s office is a blackboard crowded with exploded stars, spaceship schematics, and spectral lines. Yamaguchi, an associate professor at Japan’s Institute of Space and Astronautical Science, stands in front of it, explaining XRISM.

XRISM, a partnership between NASA, JAXA, and ESA, was launched on September 6, 2023, with high expectations. JAXA’s previous X-ray telescopes, Suzaku and Hitomi, faced issues after launch. Suzaku’s spectrometer malfunctioned, while Hitomi broke apart after its first light image. Despite this, XRISM has been performing well, providing unexpected discoveries since first light in January.

However, a problem persists. The telescope’s main instrument, Resolve, is functioning, but its aperture door remains jammed. Multiple attempts to open the door have failed. NASA and JAXA are considering operating the spacecraft as is for 18 months before another attempt.

The jammed door presents a dilemma. The spacecraft is delivering exciting data, but opening the door could reveal even more about the universe. X-rays allow astronomers to study energetic phenomena, but Earth’s atmosphere blocks them, necessitating space-based telescopes.

“We’re unraveling the composition of the universe,” says Aurora Simionescu, an astrophysicist at the Netherlands Institute for Space Research. XRISM’s Resolve is a microcalorimeter spectrometer, converting X-rays to heat and measuring minute temperature changes. It needs to be extremely cold, achieved by chemical and mechanical means.

Chandra uses a different X-ray detector with CCDs. Resolve can measure higher energies with greater resolution, allowing detailed studies of atomic physics and X-ray sources. Chandra excels in imaging quality due to its high-quality X-ray mirrors.

The jammed door blocks low-energy X-rays, but XRISM continues to explore high-energy X-rays effectively. Scientists must weigh the risk of trying to open the door. Despite the setback, XRISM is collecting valuable data. Simionescu is particularly interested in studying galactic atmospheres, currently inaccessible due to the closed gate valve.

The situation is a tough break for Simionescu and others, but the field of X-ray astronomy remains hopeful. “The most beautiful thing is when you look at the data, and it looks nothing like what you expected,” she says.

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