X-Ray Imaging And Spectroscopy Mission

The X-Ray Imaging and Spectroscopy Mission (XRISM, pronounced 'crism' or 'krizz-em', as if the X was a chi), is an X-ray space telescope. It is a mission of the Japan Aerospace Exploration Agency (JAXA) in partnership with NASA and ESA, intended to study galaxy clusters, outflows from galaxy nuclei, and dark matter.

XRISM is a next generation X-ray astronomy spacecraft, succeeding the Chandra X-ray Observatory and XMM-Newton. XRISM is intended to fill a gap in observational capabilities between the anticipated retirement of those older X-ray telescopes and the future launch of the planned Advanced Telescope for High Energy Astrophysics (ATHENA). The Hitomi X-ray telescope was intended to fill that gap, but destroyed itself a few weeks after launch in 2016. XRISM replaces Hitomi's role of filling the expected observational gap.

During its early design phase, XRISM was known as the "ASTRO-H Successor" or "ASTRO-H2". After the loss of Hitomi, the name X-ray Astronomy Recovery Mission (XARM) was used, the R in the acronym referring to recovering Hitomi's capabilities. The name was changed to XRISM in 2018 when JAXA formally initiated the project team.

Overview

With the retirement of ''Suzaku'' in September 2015, and the detectors onboard Chandra X-ray Observatory and XMM-Newton operating for more than 15 years and gradually aging, the failure of ''Hitomi'' meant that X-ray astronomers would have a 13-year blank period in soft X-ray observation, until the launch of ATHENA in 2035.Saku Tsuneta, director general of ISAS describes ATHENA as being a "super ASTRO-H" This would result in a major setback for the international community, as studies performed by large scale observatories in other wavelengths, such as the James Webb Space Telescope and the Thirty Meter Telescope will commence in the early 2020s, while there would be no telescope to cover the most important part of X-ray astronomy. A lack of new missions could also deprive young astronomers a chance to gain hands-on experience from participating in a project. Along with these reasons, motivation to recover science that was expected as results from ''Hitomi'', became the rationale to initiate the ''XRISM'' project. ''XRISM'' has been recommended by ISAS's Advisory Council for Research and Management, the High Energy AstroPhysics Association in Japan, NASA Astrophysics Subcommittee, NASA Science Committee, NASA Advisory Council.

With its successful launch in September 2023, ''XRISM'' is expected to cover the science that was lost with ''Hitomi'', such as the structure formation of the universe, feedback from galaxies/active galaxy nuclei, and the history of material circulation from stars to galaxy clusters. The space telescope will also take over ''Hitomi'' role as a technology demonstrator for the European Advanced Telescope for High Energy Astrophysics (ATHENA) telescope. Multiple space agencies, including NASA and the European Space Agency (ESA) are participating in the mission. In Japan, the project is led by JAXA's Institute of Space and Astronautical Science (ISAS) division, and U.S. participation is led by NASA's Goddard Space Flight Center (GSFC). The U.S. contribution is expected to cost around US$80 million, which is about the same amount as the contribution to ''Hitomi''.

Changes from ''Hitomi''

The X-ray Imaging and Spectroscopy Mission is one of the first projects for ISAS to have a separate project manager (PM) and primary investigator (PI). This is part of ISAS's reform in project management to prevent the recurrence of the ''Hitomi'' accident. In traditional ISAS missions, the PM was also responsible for tasks that would typically be allocated to PIs in a NASA mission.

While ''Hitomi'' had an array of instruments spanning from soft X-ray to soft gamma ray, ''XRISM'' focuses around the Resolve instrument (equivalent to ''Hitomi'' soft X-ray spectrometer), as well as Xtend (SXI), which has a high affinity to Resolve. The elimination of a hard X-ray telescope was justified by the 2012 launch of NASA's NuSTAR satellite, which did not exist when ''Hitomi'' (then known as the New X-Ray Telescope, NeXT) was initially formulated.Hitomi/ASTRO-H was known as New X-ray Telescope (NeXT) during its proposal stage NuSTAR's spatial and energy resolution is analogous to ''Hitomi'' hard X-ray instruments. Once ''XRISM'' operation starts, collaborative observations with NuSTAR will likely be essential. Meanwhile, the scientific value of the soft and hard X-ray band width boundary has been noted; therefore the option of upgrading ''XRISM'' instruments to be partially capable of hard X-ray observation is under consideration.

A hard X-ray telescope with abilities surpassing ''Hitomi'' was proposed in 2017. The ''FORCE'' (Focusing On Relativistic universe and Cosmic Evolution) space telescope is a candidate for the next ISAS competitive medium class mission. If selected, ''FORCE'' would be launched after the mid-2020s, with an eye towards conducting simultaneous observations with ATHENA.

History

Following the premature termination of the ''Hitomi'' mission, on 14 June 2016 JAXA announced their proposal to rebuild the satellite. The XARM pre-project preparation team was formed in October 2016. In the U.S. side, formulation began in the summer of 2017. In June 2017, ESA announced that they would participate in XARM as a mission of opportunity.

Instruments

XRISM carries two instruments for studying the soft X-ray energy range, Resolve and Xtend. The satellite has separate telescopes for each of the instruments, SXT-I (Soft X-ray Telescope for Imager) and SXT-S (Soft X-ray Telescope for Spectrometer). Both telescopes have a focal length of .

Resolve

Resolve is an X-ray micro calorimeter developed by NASA and the Goddard Space Flight Center. The instrument is a duplicate version of its ''Hitomi'' predecessor. It used some space-qualified hardware left from the manufacture of ''Hitomi'' SXS.

Xtend

Xtend is an X-ray CCD camera. Xtend improves on the energy resolution of ''Hitomi'' SXI.

Launch

JAXA launched XRISM on 6 September 2023 at 23:42 UTC (7 September 08:42 Japan Standard Time) using an H-IIA rocket from Tanegashima Space Center. XRISM was successfully inserted into orbit on the same day, and the accompanying launch payload, SLIM, began its multi-month journey to the Moon.

A protective shutter over the Resolve instrument's detector has failed to open. This does not prevent the instrument from operating, but limits it to observing X-rays of energy and above, as opposed to the planned . A similar shutter over Xtend has opened normally.

See also

* Suzaku
* List of X-ray space telescopes
* X-ray astronomy

Notes

References

External links

XRISM
official website

X-Ray Imaging and Spectroscopy Mission (XRISM)
at JAXA

X-ray Imaging and Spectroscopy Mission
at NASA Goddard Space Flight Center

Beyond the loss of ''Hitomi''

{{Orbital launches in 2023

Space telescopes
Satellites of Japan
X-ray telescopes
Spacecraft launched in 2023
Explorers Program
Satellites orbiting Earth
2023 in Japan