Context:
Japan’s Smart Lander for Investigating Moon (SLIM) successfully entered lunar orbit on December 25, marking a crucial step before its planned moon landing on January 19. This development positions Japan to potentially become the fifth country to achieve a soft landing on the moon, following India’s success with Chandrayaan 3 in August. The outcome of SLIM’s mission carries significance, as it may impact the upcoming Chandrayaan 4 mission.
Relevance:
GS III: Science and Technology
Dimensions of the Article:
- SLIM: Japan’s Lunar Mission
- SLIM’s Lunar Mission Objectives
- SLIM’s Impact on Chandrayaan 4 Mission
SLIM: Japan’s Lunar Mission
Overview of SLIM
- Developed and launched by the Japan Aerospace Exploration Agency (JAXA) on September 7, 2023.
- Weighs 590 kg at launch, significantly lighter than Chandrayaan 3.
- Launched alongside XRISM, a next-gen X-ray space telescope, onboard an H-2A rocket.
- Entered an elliptical orbit around the moon on December 25.
Comparison with Chandrayaan 3
- SLIM’s launch closely follows the success of Chandrayaan 3’s surface component and Luna 25’s failure.
- SLIM marks Japan’s second attempt in 2023 for a lunar soft landing.
Journey to the Moon
- SLIM’s lighter weight is attributed to carrying less fuel.
- Utilized a longer but fuel-thrifty route based on weak-stability boundary theory.
- Built up kinetic energy around Earth through multiple swings, allowing for a more fuel-efficient journey.
- Sacrificed time for fuel efficiency, reaching lunar orbit after four months.
- December 25 marked SLIM’s orbital capture around the moon.
Innovative Approach
- SLIM’s deflection toward the moon, rather than slowing down, utilized the combined forces of Earth and lunar gravity.
- Physicists developed this approach in the late 1980s during the ‘Hiten’ mission.
- SLIM’s unique trajectory prioritized fuel efficiency over a faster journey to the moon.
A diagram illustrating SLIM’s path from the earth to the moon, spanning four months. | Photo Credit: JAXA
SLIM’s Lunar Mission Objectives
Precision in Lunar Landing
- SLIM is known as the “moon sniper” for its remarkable precision in landing.
- Scheduled to attempt a landing within 100 meters of its chosen site on the moon.
Historical Context
- Past moon-landing missions had more lenient area tolerances for landing spots.
- For example, the Vikram lander of Chandrayaan 3 had a 4 km x 2.5 km area tolerance.
- China’s Chang’e 3 holds the record for the most precise moon landing, 89 meters away from its chosen spot within a 6 km x 6 km ellipse.
Landing Site and Data Utilization
- SLIM’s landing site is near the Shioli Crater at 13.3º S and 25.2º E.
- Similar to Chandrayaan 3, SLIM will use data from JAXA’s SELENE orbiter to guide its descent.
Technical Specifications
- SLIM’s lower mass, only 120 kg excluding fuel, contributes to its maneuverability.
- Its small size tests the efficiency of its design.
Additional Exploration
- Before landing, SLIM will deploy two small rovers, Lunar Excursion Vehicle (LEV) 1 and 2.
- LEV-1, LEV-2, and SLIM will collectively study the lunar surface, gather temperature and radiation readings, and attempt to explore the moon’s mantle.
SLIM’s Impact on Chandrayaan 4 Mission
Targeting Moon’s South Pole
- Scientists aim for the moon’s south pole region due to perpetually shadowed craters containing water-ice.
- Chandrayaan 3’s success marked the conclusion of the second phase of India’s lunar exploration program.
Lunar Polar Exploration (LUPEX) Mission
- LUPEX, or Chandrayaan 4, is the first mission of the third phase.
- Joint venture with Japan (pending Indian approval) and scheduled for a potential launch in 2026.
- LUPEX will explore an area closer to the moon’s south pole compared to Chandrayaan 3.
Challenges and Technologies
- Moon’s polar terrain is rocky with craters and steep slopes, requiring precise landing.
- Downrange and cross-range limits for LUPEX will be lower, demanding advanced navigation systems.
- SLIM’s tested technologies, including a feature-matching algorithm, are crucial for LUPEX’s success.
Collaboration Details
- JAXA expected to provide the launch vehicle and lunar rover; India contributes the lander module.
- The landing site for LUPEX is yet to be determined.
JAXA’s SLIM Mission Timing
- SLIM’s mission launch closely follows Chandrayaan 3’s success and precedes Russia’s Luna 25 spacecraft failure.
- SLIM’s success on January 19 sets a record for the smallest-ever area tolerance in a moon landing.
-Source: The Hindu
