Yesterday, Sept. 6 at 23:42 UTC, JAXA successfully launched two historic missions on board an H-IIA rocket. The Japanese launcher lifted off from the Tanegashima Space Center, carrying the SLIM lunar lander and the X-Ray Imaging and Spectroscopy Mission (XRISM).
#XRISM update: XRISM was launched successfully on Thursday, 7 September 2023, at 0:42 BST/01:42 CEST on an H-IIA rocket from Japan’s Tanegashima Space Center (pic: @JAXA_en/@MHI_LS) pic.twitter.com/D2y27eiO1y
— ESA (@esa) September 7, 2023
SLIM will now take a long, fuel-efficient route toward the Moon. The lander will reach the lunar orbit between three and four months from now, and will then study the surface for another month before attempting the landing. XRISM was successfully deployed on a LEO orbit at an altitude of 550km.
The launch of the two missions was originally planned for 2021, but a series of delays on the development of XRISM postponed the launch to August 2023, a series of weather issues then pushed the liftoff to September.
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SLIM: JAXA’s first Moon landing?
After the recent success of Chandrayaan-3, Japan will try to become the fifth country to soft-land on the lunar surface. Certainly less ambitious than the previously mentioned, SLIM could however turn out to be a historic success for Japan and the beginning of a new space era for the Asian country. The lander will touchdown inside the Shioli Crater.
SLIM’s main objective will be to demonstrate accurate lunar landing techniques using a small explorer, the landing accuracy range will be less than 100 m. In particular, the lander will test a pinpoint landing. At 3 meters from the ground, the engines will be shut off, and SLIM will be released to fall. A series of shock-absorbing legs, made of crushable aluminum, will arrest the vehicle that will finally settle on its side.
The Japanese probe, at full load, weighs 590 kg with a volume of 11 m³. It’s equipped with thin-film solar cells, a radar to analyze the soil during landing phases, a multiband camera for mineralogical exploration, and a small laser retroreflector array. All engines and thrusters are powered with N2H4 and nitrogen tetroxide (NTO-MON-3) stored in a common tank.
The mission will also include the deployment of two rovers: a small probe called Lunar Exploration Vehicle (LEV) which will take photos of the Moon’s surface, and the TOMY’s Sora-Q mini moon explorer of only eight centimeters in diameter and 250 grams.
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XRISM: a new eye on galaxy clusters
Alongside SLIM the mission carried XRISM, an X-Ray space telescope resulting from a collaboration between JAXA, ESA and NASA. This new telescope is the successor of the ASTRO-H satellite, launched in 2017, and will be the bridge with the future ESA’s X-Ray observatory, Athena.
This mission will have as its main objective the study of the galaxy clusters, the flow of matter around accreting supermassive black holes (AGN), and the chemical enrichment of the Universe. The telescope will have a lifetime of three years until the Helium cooler runs out.
In particular, XRISM will analyze the Universe’s biggest building blocks: galaxy clusters. Those large structures of hot gas emit X-Ray light. By collecting it, the telescope will determine their velocity and energy level. Thanks to this data, scientists will discover more about the evolution of the Universe.
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