Four months after its launch from the Tanegashima Space Center, SLIM, led by the Japan Aerospace Exploration Agency (JAXA), landed near Shioli, and affected the crater within the larger Mare Nectaris (“Nectar Sea”) at 23:20 JST on January 19, 2024 (15:20 UTC).
SLIM went on an exclusive adventure involving two close approaches to the Moon and orbits that took it into deep space, traveling for 110 days before performing a lunar insertion on Christmas Day in a lunar orbit of 15 x 600 kilometers. Other burns slowly descended and circulated the eye socket. The long circular trajectory was designed to save fuel and mass important for the landing phase, giving the spacecraft the most productive possibility imaginable for a comfortable landing.
The Länder have landed, they have communications, but the solar mobile does not produce electricity. It is battery operated. Trying to maximize the science.
LEV was separated as planned, but JAXA wants more time to collect data. https://t. co/4Wct726bum
– Chris Bergin – NSF (@NASASpaceflight) January 19, 2024
Omotenashi, a small 6u cubesat from Artemis 1, which suffered from solar cell orientation disorders and was lost. Hakuto-R, an advertising lander designed by the Japanese company iSpace. This lander crashed into the Moon on April 25, 2023, following a mix-up between the other navigation systems resulting in a fuel shortage.
Earlier in 2019, Israel’s Beresheet lander suffered another failure, crashing into the Moon’s surface after a gyroscope failed, resulting in a loss of control of the spacecraft. More recently, the Astrobotic Peregrine One lunar lander was unable to attempt a moon landing as a result of an anomaly in the propulsion formula, which, in turn, caused disruptions that kept the spacecraft in a sun-facing orientation. A leak of the formula booster added to the disruption, ruling out any landing attempt. The leak slowed down as the days went by, allowing controllers to focus on Peregrine to conduct as many clinical studies as possible. Astrobotic was able to maintain transparent and informative communication with the public during the mission. Controllers directed the lander conscientiously and responsibly to avoid creating debris in the area. taking it on a trajectory to intercept Earth’s atmosphere, where it burned safely over the Pacific on January 18, 2024.
SLIM’s first project was to demonstrate that complex navigation and radar systems can allow an accurate landing within a hundred meters of a given target. To achieve this particularly improved accuracy, the spacecraft carried several complex instruments, in addition to a laser rangefinder and landing radar. During its descent to the lunar surface, the lander was able to compare terrain with high-resolution symbols collected from Japan’s previous lunar orbiter, Kaguya, and NASA’s Lunar Reconnaissance Orbiter, to make autonomous decisions in time. Genuine in terms of its speed and trajectory, symbol processing algorithms evolved through JAXA. Precisely targeted touchdowns are considered imperative to achieving optimal results in long-term landings, but the final location of this landing may not be known for a few weeks, according to JAXA officials.
The target for landing, the Shioli crater, is an impact crater about 300 meters wide and has important scientific potential, not least for the suspected presence of the mineral olivine, which is conjectured to comprise part of the Moon’s mantle. The near-infrared Multi-Band Camera aboard SLIM will determine the composition of olivine by analyzing the spectra of sunlight reflected off the lunar surface. The data will further inform scientists about the early formation of the Moon.
The main current goal of this project is the “realization of a lightweight lunar and planetary probe formula to enable more common lunar and planetary exploration projects. “To this end, SLIM has carried out considerable weight reduction, modern framing techniques and a chemical-based tough propellant formula.
The structural core of the spacecraft is the integrated fuel tank, a cylinder that holds fuel and oxidizer in a common dome to save mass. The oxidizing component has a specially evolved form of polytetrafluoroethylene coating to prevent any reaction.
There are two main engines, manufactured through Mitsubishi Heavy Industries, Ltd. These feature ceramic combustion chambers, a very wide thrust diversity and can fire using complex pulsation techniques to facilitate accurate positioning. Each of the engines supplies approximately 500 newtons of thrust and are used for the main insertion operations, transit to the Moon, and descent/lunar landing. The thrusters used to supply attitude control were built through IHI AEROSPACE Co. Ltd. There are 12 such thrusters, each with a nominal thrust of around 20 newtons. They use the same fuel/oxidizer as the main engines to facilitate lightweight design avoiding the need for additional fuel tanks.
The solar panels for SLIM are built through SHARP Corporation and are made of a thin, lightweight, and flexible film. They are designed to bend around some of the curved surfaces of the contraption and only have Velcro in places.
SLIM has been designed to land on a slope of about 15 degrees from the horizontal. As the spacecraft neared landing with the main engines pointing downward to slow the rate of descent, the thrusters had to tilt the craft about forty-five degrees, so that the main landing legs landed first, and then the craft finished its rotation to horizontal mode with the auxiliary legs placed at the end. All legs feature a 3D-printed aluminum alloy weight platform to absorb the full effect on stresses during landing.
Just before landing, SLIM ejected two small lunar excursion vehicles (LEV) automatons, LEV-1 and LEV-2. They will explore and photograph the surroundings and the lander, each using new experimental propulsion techniques. LEV-1 is designed to leap like a frog around the lunar surface, not only taking pictures, but also measuring the slope, elevation, temperature, and radiation of the local lunar environment. This rover is also capable of establishing direct communication with Earth.
LEV-2 has been developed by JAXA in collaboration with Tomy, Sony, and Doshisha University, Japan. Weighing a mere 250 grams and only eight centimeters in diameter, this baseball-shaped vehicle has been inspired by co-developer Tomy’s Transformers toys. The initial design concept had to be reduced in size and weight to meet the limitations imposed by the mission’s lightweight ideals. On landing, the ball split apart to form two wheels and reveal pop-out cameras and a stabilizer. The method of forward movement, a waggling motion was inspired by that of the sea turtle. This collaboration with Tomy is intended to inspire children to dream big, and indeed a toy version of SORA-Q as LEV-2 is also known, is being sold in Japan.
There has been renewed interest in landing on the Moon, and several more attempts are planned in the near future. NASA’s Commercial Lunar Payload Services (CLPS) offers incentives to business partners to demonstrate reliable shipment delivery functions to the Artemis mission. CLPS has already produced the Peregrine One mission, which has generated information, expertise and public interest despite not having landed.
Intuitive Machines hopes to succeed in its first lunar landing attempt when its Nova-C lander launches in February 2024 on a SpaceX Falcon 9. Nova-C is described as the length of a phone booth and carries 130 kilograms of payload, most commonly tools for NASA, but also a cubesat and a deployable camera called EagleCAM. Intuitive Machines has three assignments for Nova-C as part of the CLPS contract.
Japan has planned a second Hakuto-R project for the fourth quarter of 2024. This project, called Resilience, will be featured on a SpaceX Falcon nine and will come with a microrover.
(Main image: Rendering of the SLIM lander on the Moon. Credit: JAXA)
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