The Mitsubishi Heavy Industries H-IIA launch vehicle, as its profession is being wound down in favor of the H3, is preparing to fly the Smart Lander for Investigating Moon (SLIM) robotic lunar lander and the X-Ray Imaging and Spectroscopy Mission (XRISM) X-ray telescope on its forty seventh flight. After this flight, the second of 2023 for the H-IIA, the H-IIA can have three flights left before retirement.
The H-IIA vehicle F47 is scheduled to launch from the LA-Y1 launch pad at Tanegashima Space Center, Japan, on Monday, Aug. 28, at 00:26 UTC. The launch window for this mission lasts until Sept. 15.
Immediately after liftoff, the H-IIA will fly an eastward trajectory over the Pacific. The H-IIA’s two solid rocket boosters are to be released near the T+1:48 mark, while the core and its LE-7A engine, using liquid hydrogen and liquid oxygen as propellants, will operate until around T+6:35.
After stage separation, the second stage, equipped with a LE-5B engine and using the identical propellant combination because the LE-7A, would burn until roughly quarter-hour after launch. The 2 payloads shall be separated sometime after the stage shuts down its engine.
The XRISM X-ray observatory is to be placed right into a 550-kilometer circular low-Earth orbit inclined 31 degrees to the Equator. The SLIM lunar lander can even be placed in the identical orbit but will use its own engines to get to the Moon.
XRISM
This flight’s most important payload is the XRISM — the observatory is a alternative mission began in 2016 after the failure of the Hitomi X-ray observatory weeks after reaching orbit. Hitomi was in its commissioning phase, having made some test observations when false information from a sensor and software issues caused the spacecraft to spin in orbit and break apart.
Hitomi’s failure could have left the scientific community without an orbiting X-ray observatory for an extended time frame from the early 2020s to the late 2030s. JAXA began the XRISM project in June 2016, three months after Hitomi’s failure. NASA, ESA, and major universities on three continents are collaborating on the project.
X-ray astronomy has only been performed inside the last sixty years, as X-rays from deep space are attenuated by the Earth’s atmosphere. Humanity has observed the heavens in visible light with its own eyes for millennia and with optical means for hundreds of years. The arrival of spaceflight has enabled observations of stars, galaxies, and the background of the universe in wavelengths inaccessible to astronomers prior to the Sixties.
The primary Japanese X-ray observatory, Cygnus X-1, was launched in 1979, and Japan has successfully flown a variety of X-ray telescopes. XRISM will join other space-based observatories equivalent to the Chandra X-ray Observatory, XMM-Newton, NuSTAR, and IXPE in orbit. These spacecraft all observe the universe within the X-ray spectrum but accomplish that in alternative ways which counterpoint one another.
X-rays are generated by objects like exploding stars, black holes, radio galaxies, pulsars, and other high-energy phenomena. XRISM’s science objectives are to check clusters of galaxies, how the structure of the Universe evolves, how matter spreads through interstellar space, how energy is transported through the Universe, and the way matter behaves under strong gravitational and magnetic fields that can’t be created on Earth.
To perform these objectives, XRISM is supplied with two instruments, each attached to a dedicated X-ray mirror assembly. The Resolve spectrometer is designed to make highly detailed measurements of an X-ray emitting object’s temperature and composition, and may make detailed Doppler measurements to find out how objects within the Universe move.
Resolve must be cooled to -273.1 degrees Celsius, which is just barely above absolute zero, to make its observations. This is completed with a dewar crammed with superfluid helium. The instrument observes “soft” X-rays, which have longer wavelengths than “hard” X-rays which spacecraft like IXPE are designed to look at.
The Xtend X-ray imager, like Resolve, is designed to look at soft X-rays. Xtend has a field of view that may capture the total Moon, and may image larger celestial objects. The instrument is analogous to 1 that was used on Hitomi.
The XRISM spacecraft masses 2,300 kilograms and is eight meters long and three meters in diameter. As well as, the 2 solar panels will extend nine meters from tip to tip. After the spacecraft reaches orbit, there shall be a critical operation phase where XRISM’s attitude control ability shall be tested.
A commissioning phase will test the spacecraft’s subsystems, and a seven-month performance verification phase will evaluate the science instruments. Once that is finished, science observations will start. The first mission is scheduled to last for 2 years, and a mission extension shall be evaluated.
SLIM
On the heels of the successful Chandrayaan-3 landing, Japan will seek to affix the USA, the Soviet Union, China, and India within the club of countries which have landed probes successfully on the Moon. The SLIM lander will try to succeed where earlier Japanese landing attempts with the Hakuto-R and OMOTENASHI missions failed.
SLIM is the secondary payload on this flight. The project is an outgrowth of the SELENE-B lander proposed on the turn of the century, and SLIM was proposed in 2012. The spacecraft’s critical design review was done in 2019, and its launch date kept moving together with the XRISM payload’s flight.
The SLIM lander masses around 700 kilograms after it’s fueled, and it’s built around a cylindrical fuel tank over two meters long containing hypergolic propellants. The spacecraft is supplied with two most important engines able to 500 Newtons of thrust together with 12 thrusters able to around 20 Newtons of thrust.
The spacecraft requires a slow, fuel-efficient trajectory that will take SLIM to the Moon in around 4 months. This is analogous to the HAKUTO-R lander, and in contrast to larger landers just like the Chang’e or Chandrayaan spacecraft which took less time to achieve the Moon.
Once SLIM reaches lunar orbit, it is going to spend around a month there before its landing attempt. Unlike the Chandrayaan-3 mission, SLIM just isn’t targeted for the south polar region. The landing site is in Mare Nectaris, and is at 13.3 degrees South latitude, 25.2 degrees East longitude, on the slopes by Shioli crater.
When SLIM’s deorbit burn is complete, it is going to use a system based on face recognition technology to autonomously navigate to its landing site. The spacecraft has an onboard map with observational data from the SELENE orbiter. Using that data, it is going to compare the terrain features it sees, and it is supplied with a landing radar, laser range finder, and a navigation camera to supply critical information to the integrated computer.
A significant objective of SLIM is to reveal a precision landing to inside 100 meters of its goal. This capability, if achieved, would enable future landers to achieve sites currently not in a position to be visited by spacecraft. Current lunar landing capabilities are on the order of at the very least several kilometers because the landing ellipse.
SLIM will transition to a horizontal position just before landing, and can use five fixed landing legs with crushable aluminum shock absorbers to the touch down on the lunar surface. Thin film solar panels mounted on the side opposite the landing legs provide power, while an S-band communication system connects SLIM with Earth.
The spacecraft is supplied with a multi-band spectral camera that’s designed to measure the composition of rocks surrounding the landing site. It’s hoped that mineralogy measurements might help scientists piece together how the Moon formed.
A small probe referred to as the Lunar Exploration Vehicle-1 is to separate from SLIM just before landing and image the positioning. SLIM can be carrying the ball-shaped SORA-Q mini-rover, also referred to as Lunar Exploration Vehicle-2, that was designed by Tomy, the Japanese toy maker who invented the transformers toys.
As well as, NASA has provided a mirror reflector to enable precise measurement of the gap between Earth and the landing site, much like those aboard Chandrayaan-3 and the Apollo missions.
A stretch goal for SLIM is to conduct operations until lunar sunset. Lunar daylight at a given location lasts around 14 Earth days, and once the sun sets the lunar surface can reach a temperature of minus 130 degrees Celsius.
H-IIA retirement
The H-II family has been Japan’s workhorse launch vehicle for nearly 30 years. The H-II’s first flight was in 1994, while the H-IIA first flew in 2001 after the H-II was retired following a launch failure in 1999.
The H-IIB first flew in 2009 for HTV cargo ships to ISS and last flew in 2020 . The H-II family overall has launched communications and weather satellites, lunar and interplanetary probes, and military reconnaissance satellites together with other payloads.
The H-IIA is the one vehicle still lively within the H-II family of rockets, and the H3 is on account of replace it. Nonetheless, the H3’s first flight in March of this 12 months led to failure, and the second stage was implicated within the failure. The H3 second stage could be very much like the H-IIA’s, so common failure modes needed to be cleared before the XRISM/SLIM launch could fly.
After this flight, the H-IIA is slated to fly the GOSAT-GW greenhouse gas monitoring satellite no sooner than December 2023 and the Japanese military IGS-Optical 8 and IGS-Radar 8 reconnaissance spacecraft no sooner than April 2024. If all goes well, the H-IIA would end its profession with 49 successful launches in 50 attempts, with the one failure being in 2003 on account of the lack of an SRB separation system.
The H-IIA joins the Ariane 5 amongst the key launch vehicles being retired in 2023. JAXA is working to return the H3 to flight and the timetable for this just isn’t currently known. Once the H3’s issues are resolved, it is about to change into Japan’s most important launcher for vital missions to ISS, civilian and military weather, communications, and statement satellites, and future lunar and interplanetary flights.
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