JAXA and NASA have a problem with the XRISM telescope

The X-ray Imaging and Spectroscopy Mission (XRISM) marks a new era in X-ray astronomy. Launched on September 6, 2023, the space telescope is a collaboration between NASA, the Japan Aerospace Exploration Agency (JAXA), and the European Space Agency (ESA). XRISM is equipped with Resolve, an instrument designed to provide X-ray spectra with unprecedented precision. Unfortunately, a hatch that won’t open prevents it from operating.

A past of challenges and hopes

Suzaku was launched by the Japan Aerospace Exploration Agency (JAXA) in July 2005. This X-ray telescope was designed to study energetic phenomena in the Universe, such as black holes, supernovae and galaxy clusters. Suzaku had unfortunately encountered technical issues shortly after its launch. Its spectrometer had indeed stopped working due to a cooling system failure, which had then considerably limited its initial capabilities. Despite this loss, Suzaku had been able to continue its mission thanks to its other functional instruments, thus contributing to a better understanding of the extreme phenomena of the universe.
Hitomilaunched in February 2016, represented another leap forward in X-ray telescope technology. Equipped with a high-resolution X-ray spectrometer and other advanced instruments, Hitomi promised to provide unprecedented details about the energetic processes in the Universe. The mission aimed to study galactic winds, galaxy clusters, and high-energy X-ray sources with unprecedented precision. However, soon after its launch, Hitomi itself suffered a series of setbacks. catastrophic failures. In March 2016, a series of errors in the attitude control system caused the satellite to spin rapidly and uncontrollably. Attempts to stabilize Hitomi failed, and the spacecraft eventually disintegrated in orbit. Suzaku and Hitomi’s experiments, however, were crucial. for the development of XRISM. Lessons learned from the failures and successes of these missions have indeed helped improve the design and reliability of the X-ray instruments on this telescope. Unfortunately, here again, it seems that not everything is going as planned.

A trap problem encountered by the XRISM telescope

Resolve is the lead instrument of XRISM, launching in 2023. It is a high-precision soft X-ray spectrometer designed to measure the properties of X-rays emitted by celestial objects with unprecedented energy resolution. To operate, Resolve uses an advanced spectrometry technology called microcalorimetry. Unlike traditional X-ray detectors that convert X-ray photons into electrical charges, this instrument measures X-rays by converting their energy into heat. This heat is then detected and measured with extreme precision, making it possible to determine the exact energy of the observed X-ray photons. The main current concern of this mission is the opening hatch of Resolve. This hatch, initially designed to protect the spectrometer during the terrestrial phases of the mission, was in fact not not open as planned once the telescope is in orbitThe other instruments are operating as expected, allowing JAXA and NASA to collect valuable data.
The galaxy cluster Abell 2319 captured in X-rays (shown in purple) by the XRISM space telescope. Credits: JAXA/NASA/XRISM Xtend; background, DSS

A real risk

The two space agencies now plan to continue operating XRISM as is for another 18 months in order to collect as much data as possible before attempting to open it again. However, such a maneuver carries several serious risks that could damage the telescope. First, opening the hatch could require the application of a significant mechanical force. Such force could then damage the actuators or other mechanical components of the telescope. The actions required to dislodge the hatch, such as shaking the telescope, could also introduce vibrations or jolts that would affect other sensitive components. Another risk is that of temperature change. In order to try to dislodge the trap, it may indeed be necessary to warm up the telescope. However, Resolve’s cryostat must be kept at extremely low temperatures to ensure proper operation of the spectrometer. Warming up could compromise this condition and potentially damage the instrument. Finally, if the trap is opened in an uncontrolled manner, this could result in a rapid depressurizationwhich would disrupt the cryostat’s operation and affect the entire cooling system. Ultimately, space agencies JAXA and NASA will have to carefully weigh the risks and benefits before attempting to open Resolve’s hatch again.