IRIA News

Japan became the fifth nation to achieve a soft lunar landing as the Japanese space agency said its robotic lander had touched down and communication had been established. Despite this achievement, the spacecraft encountered solar power issues that threaten to cut short the country’s lunar mission.

“We think we have succeeded in executing a soft landing,” JAXA President Hiroshi Yamanaka told a news conference at the agency’s Sagamihara campus. “The data are continually sent to the Earth now after landing, which is evidence that our goal of a soft landing has been achieved.”

SLIM probe faces power issues

Japan’s space agency said that its robotic Smart Lander for Investigating Moon (SLIM) spacecraft successfully landed on the lunar surface on January 19 at 12:20 a.m. local time. However, a power glitch post-landing has hindered its operations, posing challenges in generating electricity from its solar cells in the harsh lunar environment.

Without functional solar panels, the probe’s battery will last only a few hours, but the space agency is actively addressing this issue to ensure the continuation of the mission.

“Communication with spacecraft has been established after the landing. However, the solar cells are currently not generating power, and priority is given to data acquisition from the SLIM on the moon,” Japan Aerospace Exploration Agency (JAXA) said in its statement.

JAXA officials shared concerns that the solar system was possibly not facing the sun and expressed hope that the panels could generate electricity once the angle of the sun changes over the coming weeks. “It takes 30 days for the solar angle to change on the moon,” Kuninaka said. “So when the solar direction changes, and the light shines from a different direction, the light could end up hitting the solar cell,” Hitoshi Kuninaka, the head of JAXA’s research center, told a press conference.

Despite the solar power issue, the space agency considers the mission a “minimum success” since the spacecraft achieved a precise and soft lunar landing using optical navigation.

Japanese Prime Minister Fumio Kishida called the lunar mission “welcoming news” and promised the government’s continued support for the space endeavors.

NASA Administrator Bill Nelson also praised SLIM’s landing, congratulating Japan “on being the historic 5th country to land successfully on the Moon!” adding that “We value our partnership in the cosmos and continued collaboration” in the U.S.-led multinational Artemis Moon exploration.

SLIM “Moon Sniper”

SLIM was launched on a Mitsubishi Heavy H2A rocket in September 2023 and initially orbited Earth and entered lunar orbit on December 25. Its parts were 3D-printed with aluminum, creating a spongelike grid that deforms when it comes in contact with the ground.

Japan’s Smart Lander for Investigating Moon (SLIM) spacecraft — dubbed “Moon Sniper” for its precision technology — was aiming to hit a very small target using “pinpoint landing” technology that promises far greater control than any previous moon landing.

While most previous probes have used landing zones about 10 kilometers wide, SLIM was aiming to land in an area of less than 100 meters (328 feet).

JAXA officials said the probe had managed a high-precision landing, but could not confirm yet if SLIM made a pinpoint landing. JAXA President Hiroshi Yamakawa said that the agency would need a month to analyze the landing and exactly what happened to the spacecraft as it reached the lunar surface.

The SLIM moon lander had two primary goals:

• The mission aims to showcase a high-precision landing system, guiding the probe to touch down within a remarkable 100 meters.
• It seeks to assess an innovative lightweight design that enables smaller spacecraft to accommodate a greater array of sensors and instruments.

What did the spacecraft carry?

SLIM was carrying two small autonomous probes — lunar excursion vehicles LEV-1 and LEV-2.

LEV-1 rover, equipped with antennas and cameras, is tasked with recording SLIM’s landing. The LEV-2 is a small ball-shaped equipped with two cameras, developed by JAXA together with Sony, toymaker Tomy and Doshisha University.

The lunar surface robot ‘SORA-Q’ looks like a metallic ball, and is slightly bigger than a tennis ball, measuring 8 centimeters in diameter and weighing 250 grams. “Sora” means universe in Japanese while the letter “Q” is named after the English words “Question” and “Quest”. SORA-Q has been built to transform, springing its two halves apart into independently controlled wheels, exposing a pair of cameras and transmitting images back to Earth.

The lander was able to release both of its lunar rovers and their data was being sent back to Earth, JAXA officials said. LEV-1 was able to communicate directly with Earth, and LEV-2 communicated via LEV-1.

Japan’s lunar ambitions

Japan is now the fifth country to achieve a soft landing on the moon, joining the U.S., China, the former Soviet Union, and India.

The touchdown on the moon, which has one-sixth of the Earth’s gravity, is a big boost for Japan’s space program. A successful pinpoint landing on the moon would raise Japan’s profile in the global space technology race.

In the last 11 years, several spacecraft headed to the moon, but less than half reached their destination. China has had a flawless record, successfully landing its robotic spacecraft on the moon in all three attempts. India succeeded last year, overcoming a 2019 crash. Attempts by Russia, Israel, and a Japanese private company all have failed.