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As the first American lunar landing mission in decades ends without reaching its goal, a spacecraft launched by Japan approaches the moon and prepares for a historic landing attempt.
The Japan Aerospace Exploration Agency’s Lunar Exploration Intelligent Lander, or SLIM, is expected to touch down on the lunar surface at 10:20 a.m. EDT on Friday, or 12:20 a.m. Saturday JST. If successful, the SLIM landing will be the first time Japan has placed a robotic explorer on the surface of the Moon — and will make it the third country to achieve such a feat in the 21st century, and the fifth country to land a spacecraft on the Moon since the Soviet Luna 9 mission in 1966.
The spacecraft, also nicknamed the “Moon Sniper” for its precision technology, will begin descending toward the lunar surface at 10 a.m. ET. The landing will be broadcast live on YouTube in Japanese and English.
“The onset of lunar landing deceleration is expected to be a breathless, numbing terror for 20 minutes,” Kenji Koshiki, SLIM mission subproject manager, said in a statement.
The small-scale exploratory lander is designed to demonstrate a “pointed” landing at a specific location.
Other lunar landings, including NASA’s Apollo missions, have achieved pinpoint accuracy in reaching a specific area, but SLIM aims to bring precision to low-cost, lightweight robotic probes. The hope, according to the Japan Aerospace Exploration Agency, is that this technology will allow the small lander to target specific locations on the moon, allowing SLIM to land even among treacherous rocky terrain.
If successful, this technology could allow future missions to “land on planets that are more resource-scarce than the Moon,” according to the space agency.
“Nowadays, there is an increase in the knowledge of target astronomical objects, and the details that should be studied have become more defined, such that a high-precision landing near the study target has become necessary,” according to the Japan Aerospace Exploration Agency.
The SLIM lander will target a landing site extending just 100 meters (328 feet) Defeat. By comparison, Astrobotic Technology’s Peregrine lunar lander — which became the first American lander to be launched in more than 50 years — was targeting a landing zone that extended a few kilometers before a fuel leak forced the spacecraft to abandon its mission.
If SLIM misses this window to attempt a landing, it will have another chance on February 16.
The Japan Aerospace Exploration Agency’s SLIM lunar lander lifted off aboard the H-IIA launch vehicle on September 7, 2023, from Tanegashima Space Center.
The SLIM lander was launched in September alongside the XRISM (pronounced “crisis”) satellite, also called the X-ray Imaging and Spectroscopy mission, a joint mission between JAXA and NASA. After launch, SLIM used its propulsion system to head toward the Moon. The spacecraft successfully entered an elliptical lunar orbit on Christmas Day.
Since entering an orbit that passes the north and south poles of the moon, the spacecraft has been getting closer and closer to the lunar surface.
If the spacecraft lands successfully, it will briefly study the lunar surface south of a dark spot on the moon called the Sea of Tranquility, the area where Apollo 11 landed in 1969.
1) Sea of tranquility 2) Apollo 11 landing site 3) Shiuli crater targeted by the SLIM moon sniper 4) Chandrayaan-3 moon landing site
Unlike other robotic missions targeting the Moon’s south pole, SLIM targets a site near a small impact crater on the Moon’s surface called Shiule, within a plain known as the Nectar Sea, which scientists suspect was formed by ancient volcanic activity. There, you will investigate the composition of rocks that may help scientists discover the origins of the Moon.
“A closer look at such minerals could reveal information about the moon’s internal structure and composition,” according to the Japan Aerospace Exploration Agency. “However, crater ejection sites are usually avoided due to the difficulty of landing within a small, ejecta-scattered area on the sloped sides surrounding the crater.”
The SLIM probe has vision-based navigation technology, which the Japan Aerospace Exploration Agency refers to as “smart eyes.” The spacecraft will take images of the lunar surface as it approaches, quickly locate the rover on maps previously plotted by lunar satellites, and independently adjust its course as it swoops in for landing.
In those final moments, the SLIM lander will be constantly pulled toward the lunar surface by the moon’s gravity, requiring the spacecraft’s engines to be constantly running, Koshiki said.
He added, “Relegation is a one-shot game and cannot be undone.”
The SLIM mission comes amid a renewed international campaign to explore the moon.
After the United States, the former Soviet Union and China, India became the fourth country to carry out a controlled landing on the moon when its Chandrayaan-3 mission in August reached near the moon’s south pole.
But other recent missions have highlighted how difficult it is to land safely on the moon. Last year, Japanese company Ispace’s Hakuto-R lunar lander fell 3 miles (4.8 kilometers) before crashing into the moon during a landing attempt in April. A Russian mission, dubbed Luna-25, also landed in August during the country’s first attempt to return to the moon since the fall of the Soviet Union.
Likewise, the Peregrine mission, which launched on January 8, marked the first lunar landing mission launched from the United States in decades, but a critical fuel leak forced the lander to abandon its targets just hours later. The spacecraft is expected to burn up as it reenters Earth’s atmosphere.
A private company called Astrobotic developed Peregrine for NASA. Another American commercial lander, built by a company called Intuitive Machines for the space agency, could take off in mid-February.
Each of these latest robotic missions has targeted a different region of the Moon, although most of the focus of this renewed lunar race is centered around the South Pole. Scientists suspect that the area, parts of which remain permanently shaded, may be home to water ice deposits. These resources can be filtered and turned into drinking water for astronauts on future manned missions or even turned into rocket fuel to explore the depths of the universe.
The Lunar South Pole also presents a number of subsidence hazards due to craters and rocks. Future missions will need to be able to land in a narrow area to avoid these features, which is one reason the JAXA hopes SLIM’s precision landing technology will prove effective.
SLIM also has a lightweight design that could be convenient as agencies plan more frequent missions and explore moons around other planets like Mars. The Japan Aerospace Exploration Agency asserts that if the SLIM project succeeds, it will shift missions from “landing where we can to landing where we want.”