X-Ray Imaging and Spectroscopy Mission

The X-Ray Imaging and Spectroscopy Mission (XRISM, pronounced "crism"), formerly the X-ray Astronomy Recovery Mission (XARM), is an X-ray astronomy satellite of the Japan Aerospace Exploration Agency (JAXA) to provide breakthroughs in the study of structure formation of the universe, outflows from galaxy nuclei, and dark matter.[3][4] As the only international X-ray observatory project of its period, XRISM will function as a next generation space telescope in the X-ray astronomy field, similar to how the James Webb Space Telescope, Fermi Space Telescope, and the ALMA Observatory are placed in their respective fields.[2][5] The mission is a stopgap for avoiding a potential observation period gap between X-ray telescopes of the present (Chandra, XMM-Newton) and that of the future (ATHENA, Lynx X-ray Observatory). Without XRISM, a blank period in X-ray astronomy may arise in the early 2020s due to the loss of Hitomi.[2][5] During its formulation, XRISM/XARM was also known as the "ASTRO-H Successor", "ASTRO-H2".

X-Ray Imaging and Spectroscopy Mission (X線分光撮像衛星)
NamesXARM, ASTRO-H Successor, ASTRO-H2
Mission typeX-ray astronomy
OperatorJAXA
Start of mission
Launch dateJanuary 2022[1]
RocketH-IIA 202
Launch siteTanegashima Space Center, Japan
ContractorMitsubishi Heavy Industries
Orbital parameters
Reference systemGeocentric
RegimeLow Earth
Main
NameSoft X-ray Telescope
Diameter45 cm (18 in)[2]
Focal length5.6 m (18 ft)[2]
 

Overview
XRISM will be based on the ASTRO-H mission

With the retirement of Suzaku in August 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 will have a 12-year blank period in soft X-ray observation, until the launch of ATHENA in 2028.[Note 1][2][5][6] This may result in a major setback for the international community,[7] as during the early 2020s, in other wavelengths studies performed by large scale observatories such as the James Webb Space Telescope and the Thirty Meter Telescope will commence, while there may be no telescope to cover the most important part of X-ray astronomy.[2][5] A lack of new missions could also deprive young astronomers a chance to gain hands-on experience from participating in a project.[2][5] 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.[5][8]

With a planned launch in January 2022,[1] XRISM will recover 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.[4] The space telescope will also serve as a technology demonstrator for the European ATHENA (Advanced Telescope for High Energy Astrophysics) telescope.[6][9][10] Multiple space agencies, including NASA and the European Space Agency (ESA)[11] 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.[12][13]

Changes from Hitomi

The X-ray Imaging and Spectroscopy Mission will be one of the first projects for ISAS to place a separate Project Manager (PM) and a Primary Investigator (PI). This measure was taken as part of ISAS's reform in project management to prevent the recurrence of the Hitomi accident.[5] In traditional ISAS missions, the PM was also responsible for tasks that would typically be allocated to PI's in a NASA mission.

A team of astronomers from GSFC suggests pairing the XRISM satellite with a source satellite containing radioactive sources. XRISM will observe the source sat to conduct absolute calibration of its telescopes, thus functioning as an in-orbit X-ray "standard candle". With its broad effective area, the telescope could potentially establish several standard candles in the sky by observing constant celestial sources. If this concept proves successful, later missions such as ATHENA and Lynx may have their own source sats.[14]

While Hitomi had an array of instruments spanning from soft X-ray to soft gamma ray, XRISM will focus around the Resolve instrument (equivalent to Hitomi's SXS),[15] as well as Xtend (SXI), which has a high affinity to Resolve.[16] The elimination of a hard X-ray telescope is based on the launch of NASA's NuSTAR satellite, a development that was not put to consideration when the NeXT proposal was initially formulated.[17][Note 2] NuSTAR's spatial and energy resolution is analogous to Hitomi's hard X-ray instruments.[17] Once XRISM's operation starts, collaborative observations with NuSTAR will likely be essential.[4] Meanwhile, the scientific value of the soft and hard X-ray band width boundary has been noted; therefore the option of upgrading XRISM's instruments to be partially capable of hard X-ray observation is under consideration.[16][17] Furthermore, a hard X-ray telescope proposal with abilities surpassing Hitomi has also been proposed.[18] 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 is to be launched after the mid 2020s, with an eye towards conducting simultaneous observations with ATHENA.[18][4]

History

Following the premature termination of the Hitomi mission, on 14 June 2016 JAXA announced their proposal to rebuild the satellite.[19] The XARM pre-project preparation team was formed in October 2016.[20] In the U.S. side, formulation began in the summer of 2017.[3] In June 2017, ESA announced that they will participate in XRISM as a mission of opportunity.[11]

Instruments

XRISM will carry two instruments for studying the soft X-ray energy range, Resolve and Xtend. The satellite will have telescopes for each of the instruments, SXT-I (Soft X-ray Telescope for Imager) and SXT-S (Soft X-ray Telescope for Spectrometer).[5] The pair of telescopes will have a focal length of 5.6 m (18 ft).[2]

Resolve

Resolve is an X-ray micro calorimeter developed by NASA and the Goddard Space Flight Center.[1] The instrument will likely not be a complete remanufacture of Hitomi's SXS, as there are some space-qualified hardware left from developing SXS, and these spare parts may be utilized to build Resolve.[21]

Xtend

Xtend is an X-ray CCD camera. Unlike Resolve, which will be a "built-to-print" version of its predecessor, Xtend differs in that its energy resolution will be improved from Hitomi's SXI.[22]

See also

Notes
  1. Saku Tsuneta, director general of ISAS describes ATHENA as being a "super ASTRO-H"
  2. Hitomi/ASTRO-H was known as New X-ray Telescope (NeXT) during its proposal stage

References
  1. "Missions of Opportunity (MO) in Development – X-Ray Imaging and Spectroscopy Mission (XRISM) – Resolve". NASA. Retrieved 9 July 2019.
  2. Tsuneta, Saku (July 14, 2016). "Ｘ線天文衛星ASTRO‐H「ひとみ」の後継機の検討について" (PDF) (Press release) (in Japanese). JAXA. Retrieved July 1, 2017.
  3. Hertz, Paul (22 June 2017). "Astrophysics" (PDF). NASA. Retrieved 2017-07-01.
  4. Fujimoto, Ryuichi; Tashiro, Makoto (5 January 2017). "ASTRO-Hに対する高エネルギーコミュニティの総括と今後の方向性について" (PDF) (in Japanese). JAXA. Retrieved 2017-07-01.
  5. "Ｘ線天文衛星代替機の検討状況について" (PDF) (in Japanese). MEXT. 29 September 2016. Retrieved 2017-07-01.
  6. "ISASニュース 2017.1 No.430" (PDF) (in Japanese). Institute of Space and Astronautical Science. 22 January 2017. Retrieved 2016-03-23.
  7. "Ｘ線天文衛星「ひとみ」の異常事象への対応と代替機の開発について" (PDF) (in Japanese). Committee on National Space Policy of Japan. 18 August 2016. Retrieved 2017-07-01.
  8. Craft, R; Bautz, M; Tomsick, J (29 January 2017). "Probing the Hot and Energetic Universe: X-rays and Astrophysics" (PDF). NASA. Retrieved 2017-06-28.
  9. Takahashi, Tadayuki (27 November 2015). "X線天文衛星 ASTRO-Hの衛星概要" (PDF) (in Japanese). JAXA. Retrieved 2017-07-13.
  10. Dotani, Tadayasu (15 June 2011). "The 1st Athena Science Workshop JAXA Contribution" (PDF). ISAS. Retrieved 2017-06-24.
  11. "GRAVITATIONAL WAVE MISSION SELECTED, PLANET-HUNTING MISSION MOVES FORWARD". ESA. 20 June 2017. Retrieved 2017-06-24.
  12. Foust, Jeff (July 21, 2016). "NASA may build replacement instrument for Japanese astronomy mission". SpaceNews. Retrieved 2017-06-30.
  13. "第９回 宇宙科学・探査小委員会 議事要旨" (PDF) (in Japanese). Committee on National Space Policy of Japan. 1 November 2016. Retrieved 2017-06-30.
  14. Markevitch, M; Jahoda, K; Hill, J (29 March 2017). "Cal X-1: an in-orbit X-ray standard candle" (PDF). MIT. Retrieved 2017-06-30.
  15. Tashiro, Makoto; Kelley, Richard (8 June 2017). "X‐ray Astronomy Recovery Mission XARM" (PDF). ESA. Retrieved 2017-10-05.
  16. "宇宙開発利用部会（第30回） 議事録" (in Japanese). MEXT. 29 September 2016. Retrieved 2017-07-01.
  17. "宇宙開発利用部会（第29回） 議事録" (in Japanese). MEXT. 14 July 2016. Retrieved 2017-07-01.
  18. Nakazawa, Kazuhiro; Mori, Koji (6 January 2017). "軟Ｘ線から硬Ｘ線の広帯域を高感度で撮像分光する小型衛星計画 FORCE - Focusing On Relativistic universe and Cosmic Evolution -" (PDF) (in Japanese). JAXA. Retrieved 2017-07-01.
  19. "Astrophysics Implementation Plan: 2016 Update" (PDF). NASA. 15 December 2017. Retrieved 2017-07-01.
  20. "ISASニュース 2017.6 No.435" (PDF) (in Japanese). Institute of Space and Astronautical Science. 23 June 2017. Retrieved 2017-07-04.
  21. Foust, Jeff (June 13, 2016). "NASA and JAXA begin discussions on aftermath of Hitomi failure". SpaceNews. Retrieved 2017-06-28.
  22. "X線天文衛星ASTRO-Hのプロジェクト終了について" (PDF) (in Japanese). MEXT. 30 May 2017. Retrieved 2017-07-01.
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