Japan launches X-ray satellite, Moon Sniper lunar lander. Details here

Japan's Smart Lander for Investigating Moon (SLIM) is taking a uniquely long route to the Moon and is scheduled to make a landing in four to six months

Japan launches 'moon sniper' lunar lander

(Photo: Reuters)

Nandini Singh New Delhi
On Thursday morning in Japan, a bus-sized telescope with X-ray vision was launched into space.

It wasn't alone. A robotic moon lander called "Moon Sniper", around the size of a small food truck, was also on board. The two missions, XRISM and SLIM, would soon separate ways, with one-off to spy on some of our universe's hottest spots and the other to assist Japan's space agency, JAXA, in testing technology that will be employed in larger-scale lunar landings in the future.

The liftoff from the shores of Tanegashima, an island in the southern part of the Japanese archipelago, was picturesque, with the Japanese H-IIA rocket soaring over the remote launch site and disappearing into the blue skies that were punctuated by a few clouds. The $100-million mission is expected to reach the Moon by February.

A live video stream showed launch officials celebrating in the mission control centre about 47 minutes after the flight began, as the XRISM and SLIM spacecraft sped towards their diverging cosmic destinations.

What is XRISM?

The X-Ray Imaging and Spectroscopy Mission, XRISM for short (and pronounced like "chrism"), is the launch's primary passenger.

From an orbit 350 miles above Earth, XRISM will explore exotic environments that emit X-ray radiation, including the accretion of material whirling around black holes, the searing plasma permeating galaxy clusters, and the remnants of exploding massive stars.

Data from the telescope will shed light on the motion and chemistry of these cosmic places using a technique called spectroscopy, which relies on changes in the brightness of objects at different wavelengths to derive information about their composition.

The technique provides scientists with insight into some of the cosmos's greatest energy occurrences and will contribute to astronomers' comprehensive, multiwavelength picture of the universe.

XRISM's spectroscopy will "reveal energy flows among the celestial objects in different scales" with unprecedented resolution, Makoto Tashiro, the telescope's principal investigator and an astrophysicist at JAXA, was quoted as saying by The New York Times (NYT).

Who else is contributing to Japan's space mission?

The mission is led by the Japanese space agency along with the National Aeronautics and Space Administration (Nasa). The European Space Agency (ESA) contributed to the telescope's construction, which implies that European astronomers will be granted a portion of the telescope's observing time.

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XRISM is a rebuild of the Hitomi mission, a JAXA spacecraft that launched in 2016. The Hitomi telescope spun out of control several weeks into its mission, and Japan lost touch with the spacecraft.

"It was a devastating loss," said Brian J Williams, a Nasa Goddard Space Flight Centre astrophysicist on the Hitomi team and now an XRISM project scientist.

The limited information gathered from Hitomi was a tantalising sample of what a mission like this may bring, he was quoted as saying by NYT.

"We realised we needed to rebuild this mission because this is the future of X-ray astronomy," Dr Williams remarked.

How is Japan's mission different from others?

Unlike other wavelengths of light, cosmic X-rays can only be detected from above the Earth's atmosphere, which protects us from damaging radiation. XRISM will join a bevvy of other X-ray telescopes already in space, including Nasa's Chandra X-ray Observatory, which launched in 1999, and Nasa's Imaging X-ray Polarimetry Explorer, which joined the party in 2021.

What distinguishes XRISM from earlier missions is a tool called Resolve, which must be cooled to just a fraction above absolute zero so that the instrument can monitor minuscule changes in temperature when X-rays hit its surface. The mission team anticipates that Resolve's spectroscopic data will be 30 times sharper than those of Chandra's instruments.

Next step in X-ray observations

Lia Corrales, an astronomer at the University of Michigan who was chosen as a participating scientist on the mission, sees XRISM as "a pioneer vehicle" that symbolises "the next step in X-ray observations."

Dr Corrales will use cutting-edge spectroscopy to study the composition of interstellar dust in order to get insight into the chemical evolution of our universe.

Jan-Uwe Ness, an astronomer at the European Space Agency who will manage the proposal selection process for Europe's allotted observing time, stated that the superior quality of data obtained by XRISM's spectroscopy may feel nearly like visiting these extreme environments themselves.

"I'm looking forward to the spectral revolution," he said, adding that it will pave the way for even more ambitious X-ray telescopes in the future.

XRISM also carries a second instrument called Xtend, which will work in tandem with Resolve. While Resolve zooms in, Xtend zooms out, giving scientists different viewpoints on the same X-ray sources over an expanded region.

According to Dr Williams, Xtend is less powerful than the imager on the older Chandra telescope, which generated some of the most stunning pictures of the X-ray universe to date. Xtend, on the other hand, will picture the cosmos at a resolution equivalent to what our eyes would see if we had X-ray vision.

Japan shoots for the Moon

The Smart Lander for Investigating Moon, or SLIM, is the next robotic spacecraft on its way to the Moon, but it may not be the next one to land.

SLIM will take a long, circuitous route that will use less propellant for at least four months. The lander will take several months to reach lunar orbit, then circle the Moon for a month before attempting to land on the Moon's near side near the Shioli crater.

That means two American spacecraft, built by Astrobotic Technology in Pittsburgh and Intuitive Machines in Houston, could beat SLIM to the Moon's surface later this year.

Although SLIM has a camera that can identify the composition of rocks around the landing site, the mission's primary goals are not scientific. Rather, it is to demonstrate a pinpoint navigation system, aiming to set down within about the length of a football field of the targeted site.

Currently, lunar landers can attempt to land within several miles of a designated landing spot. For example, the landing zone for India's Chandrayaan-3 spacecraft, which became the first to successfully land in the Moon's south pole region last month, was seven miles wide and 34 miles long.

For SLIM, JAXA also developed image-processing algorithms that can run quickly on the slower space chips. As SLIM approaches its landing, a camera will help direct the spacecraft's descent to the lunar surface, while radar and a laser will detect the spacecraft's altitude and downward velocity.

Because of the risks of a crash with present technology, lunar landers are often directed to flatter, less interesting terrain. A more precise navigation system might allow future spacecraft to land closer to rough terrain of scientific significance, such as craters containing frozen water near the Moon's south pole.

Race to the Moon

Following the successful launches of India's and Japan's space missions, here is an overview of the upcoming lunar exploration programmes slated to launch in the following years, according to Nasa:

1. Peregrine Mission 1 - Nasa CLPS Lunar Lander

2. IM-1 - Nasa CLPS Lunar Lander

3. Lunar Trailblazer - Nasa Lunar Orbiting Small Satellite

4. Prime 1 - Nasa CLPS Lunar Lander

5. Griffin Mission 1 - VIPER - Nasa Lunar South Pole Rover

6. Intuitive Machines 3 - Nasa Lunar Lander and Rovers

7. Blue Ghost 1 - Nasa Lunar Lander

8. Chang'e 6 - CNSA (China) Lunar Sample Return Mission

What is the current status of Chandrayaan-3?

With the Chandrayaan-3 Lander and Rover being put to sleep on the Moon following the Indian Space Research Organisation's (Isro) successful landing mission, experts say the mission's purpose has been met and even beyond expectations.

"Our scientific objective is completely met and in fact, it exceeded our expectations and this is why we are all very happy. Our director of URSC and chairman Isro and all centre directors who have been guiding us are all very satisfied," the project director for the Chandrayaan-3 mission, P Veeramuthuvel, said.

Isro said on September 3 that it put the Vikram lander and the Pragyan rover in hibernation mode since daylight time was ending on the Moon. The Chandrayaan-3 mission was only designed to operate on the lunar surface for about one lunar day or roughly 14 days on Earth.

"We are going to start the process of making them [lander and the rover] sleep in the next couple of days so that they can withstand the night. Currently, the battery [on the rover] is fully charged. The solar panel is oriented to receive the light at the next sunrise expected on September 22, 2023. The receiver is kept on," said Isro chairman S Somnath while announcing that the rover and lander were being placed in hibernation mode.

While the mission may only have been designed for one lunar day's worth of functioning, the Indian space agency is holding out hope that it will survive for longer. In order to do that, the instruments of the rover and the lander will have to survive the cold lunar day, which will bring about temperatures as low as minus 120 degrees Celsius.

If the instruments do survive the extreme temperatures and radiation on the Moon through the lunar night, which also lasts about 14 days, there is a good chance that they could spring back to life as the Sun rises on the Moon.

First Published: Sep 07 2023 | 4:12 PM IST

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