Japan has embarked on a critical space mission as it successfully launched a rocket carrying two payloads for different tasks — a groundbreaking lunar lander and a high-powered X-ray space telescope.
At 8:42 AM, Japan Standard Time, a Japanese H-2A rocket successfully departed from the Tanegashima Space Center approximately ten days later than initially scheduled due to weather-related setbacks. This launch carried both the SLIM lunar lander and the XRISM space telescope.
Japan’s Space Odyssey
Following the liftoff, both spacecraft were deployed as planned, with the deployment sequence completed in under an hour. If things proceed according to plan, SLIM, which stands for “Smart Lander for Investigating Moon,” will, in a few months, make Japan’s first soft lunar landing. This precision touchdown represents a significant milestone, laying the foundation for even more ambitious space endeavors in the future.
According to the Japan Aerospace Exploration Agency (JAXA), SLIM has a clear mission objective. It strives to develop a compact, lightweight probe system that incorporates the essential pinpoint landing technology for forthcoming lunar missions. This initiative is driven by the desire to reduce weight, particularly in advanced observational equipment, and to enable landings on celestial bodies with limited resources. Additionally, it aligns with the long-term vision of advancing solar system research through future space probes.
SLIM, despite its relatively modest size, stands as a remarkable spacecraft, measuring 7.9 feet (2.4 meters) in height, 8.8 feet (2.7 meters) in length, and 5.6 feet (1.7 meters) in width. At launch, it had a total weight of approximately 1,540 pounds (700 kilograms), with most of that mass comprising propellant, accounting for roughly 70% of the spacecraft’s weight.
The mission plan for SLIM involves a lengthy and fuel-efficient trajectory to the moon, with an estimated arrival in lunar orbit expected within the next three to four months. Once in orbit around the moon, SLIM will dedicate about a month to surveying the lunar surface before making an audacious touchdown attempt within Shioli Crater. This crater is the chosen target, with a width of 1,000 feet (300 meters) and located at 13 degrees south latitude on the moon’s near side.
SLIM’s ambitious objective is to achieve an exact landing within 330 feet (100 meters) of its designated point within Shioli Crater. This precision landing technology aims to open up new frontiers for lunar exploration and exploration of other celestial bodies.
As stated in JAXA’s mission description, the creation of the SLIM lander represents a significant advancement in humanity’s ability to land precisely where desired, rather than simply choosing the most accessible landing sites, as has been the norm in the past. This capability will extend to planets even more resource-scarce than the moon, expanding the possibilities of space exploration.
Japan’s Moon Sniper – the SLIM module
In addition to its primary mission, SLIM carries two mini probes that will be released onto the lunar surface following its touchdown. These mini probes serve various functions, including monitoring the larger lander’s status, capturing images of the landing site, and providing an independent communication system for direct contact with Earth, as outlined in JAXA’s mission press kit.
While SLIM represents a significant endeavor, it is not Japan’s first foray into lunar exploration. The agency previously launched the OMOTENASHI craft, among the ten cubesats launched alongside NASA’s Artemis 1 moon mission in November 2022. Unfortunately, OMOTENASHI encountered communication challenges that prevented it from completing its planned landing attempt, and several other CubeSats on the same mission also faced mission failures.
Furthermore, a Japanese lander, Hakuto-R, developed by the company Ispace, reached lunar orbit, a significant achievement for a private spacecraft. However, it experienced an unsuccessful landing attempt in April of the same year.
Therefore, the success of the SLIM mission would be a historic achievement. Only four nations—the Soviet Union, the United States, China, and India—have achieved successful soft landings of probes on the moon. India recently joined this exclusive list with its Chandrayaan-3 mission, which successfully touched down near the lunar south pole just last month.
Peering into the Universe
While SLIM’s mission is exciting, it takes a backseat to the primary payload of Sunday’s launch, XRISM. XRISM, short for “X-Ray Imaging and Spectroscopy Mission,” is a collaborative effort involving the Japan Aerospace Exploration Agency (JAXA), NASA, and the European Space Agency (ESA). True to its full name, this telescope is poised to explore the universe by capturing high-energy X-ray light.
Matteo Guainazzi, ESA’s project scientist for XRISM, emphasized the significance of X-ray astronomy, stating, “X-ray astronomy enables us to study the most energetic phenomena in the universe.” This field of study holds the key to addressing critical questions in modern astrophysics, such as the evolution of the universe’s most significant structures, the distribution of the matter that constitutes our existence throughout the cosmos, and the impact of massive black holes at the centers of galaxies on their formation.
One of the observatory’s primary focus areas will be the super-hot gas enveloping galaxy clusters. As ESA officials noted, “JAXA has designed XRISM to detect X-ray light from this gas to help astronomers measure the total mass of these systems.” This will provide valuable insights into the formation and evolution of our universe.
It’s worth mentioning that XRISM won’t be alone in its mission to study the heavens using X-ray technology from Earth orbit. Currently in orbit are NASA’s Chandra X-Ray Observatory, ESA’s XMM-Newton, launched in 1999, and NASA’s NuSTAR, which began its mission in 2012. These telescopes collectively contribute to our ever-expanding understanding of the cosmos through X-ray observations.
