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SLIM Smart Lander for Investigating Moon

Japan on 07 September 2023 launched a lunar mission after overcoming multiple delays due to unfavorable weather conditions. Several lunar landing attempts by Japan had failed, including last year when it sent a probe called Omotenashi as part of the US Artemis program.

While the order from various countries in moon landing accuracy is in units of kilometers, SLIM aims to answer to an order of 100 meters. Moon Sniper is the nickname for a small and light spacecraft that was designed as a "pinpoint" lander called SLIM. SLIM stands for Smart Lander for Investigating Moon. And scientists call it the sniper because of its precision. Japanese officials say the idea is to go from an era of "landing where we can" to "landing where we want" on a celestial body with gravity, such as the moon. The moon's gravity is about one-sixth of Earth's gravity — its pull is weaker — which is why you can jump about six times as high on the moon as you can on Earth. And that has an impact on how spacecraft land on the moon's surface.

Since the beginning of human moon exploration in the 1960s, and the advent of advanced satellites and telescopes and other camera technology, researchers have gathered masses of high-definition images and other data, such as information about the moon's atmosphere. So we know more about the moon's constitution, including where we are likely to find water. And scientists want to land exactly where there is water, such as the south pole. Or, if they are interested in a specific rock on the moon, it's important that a spacecraft can land very close by on a flat piece of land.

The landing precision of conventional landers can be anywhere between "several and a dozen" kilometers (1 kilometer = 0.62 miles). That's according to the Japanese space agency, JAXA, and its Institute of Space and Astronautical Science. Pinpoint landers aim to bring that range down to about 100 meters (330 feet).

SLIM has a dry weight of 200 kilograms (440 pounds) and a boxlike shape and dimensions of 2.4 meters by 1.7 meters by 2.7 meters. The objective is to test lightweight vehicles to facilitate more frequent missions moons and planets. SLIM has radar and a laser range finder to measure the altitude above the lunar surface before landing, and a navigation camera. SLIM uses this "vision-based navigation" technology to measure and correct its position for pinpoint landing.

On the moon's surface, a multiband spectral camera will investigate the composition of rocks. To further investigate the land, a probe called a Lunar Exploration Vehicle can separate, including a Transformable Lunar Robot, nicknamed SORA-Q, which is the shape of a large egg and fits in the palm of a hand.

SLIM's scheduled launch is 28 August 2023 at 9:26:22 a.m. Japan time (0026 a.m. UTC). It will aim to arrive in a lunar orbit about three to four months after its launch. It will remain in lunar orbit for a month, and then begin its descent to land on the lunar surface about six months after launch. The biggest highlight of the landing process will probably be after SLIM begins its final descent, when it approaches its target point by verifying the images, and finally landing while avoiding obstacles. We expect this process to take about 20 minutes, more or less.

Once SLIM safely succeeds with its pinpoint landing, it is also scheduled to perform scientific observations of the lunar surface. The probe will be loaded with an equipment called the multiband camera, which will be used to observe and analyze the components of the rocks that are believed to originate from the moon's mantle.