March 1, 2024

Lukmaan IAS

A Blog for IAS Examination




THE CONTEXT: Recently, Japan’s Smart Lander for Investigating Moon (SLIM) spacecraft entered into orbit around the moon after a months-long journey, and ahead of its planned moon-landing attempt on January 19.


  • Japan’s Smart Lander for Investigating Moon (SLIM) spacecraft represents a significant advancement in lunar exploration.
  • It entered the moon’s orbit, marking Japan’s endeavour to soft-land a robotic craft on the lunar surface.
  • SLIM’s success or failure is poised to impact not only Japan’s lunar exploration initiatives but also India’s Chandrayaan missions, notably Chandrayaan-4.

Factors Contributing to SLIM’s Lower Weight and Impact on Mission Objectives

  • SLIM’s remarkable attribute lies in its significantly lower weight compared to other lunar exploration missions.
  • Weighing a mere 590 kg at launch, approximately one-seventh of the Chandrayaan-3 mission’s weight, SLIM’s lighter design stems from carrying much less fuel.
  • This weight reduction allows SLIM to follow a more fuel-efficient trajectory, taking four months to reach the moon compared to Chandrayaan-3’s quicker journey.
  • The spacecraft’s fuel-thrifty route, based on weak-stability boundary theory, involved swinging around Earth multiple times to build kinetic energy before shooting toward the moon’s orbit.
  • Upon nearing the moon, instead of slowing down to be captured by lunar gravity, SLIM allowed itself to be deflected by the combined forces of Earth and the moon, resulting in an elongated trajectory.

SLIM’s Lunar Objectives and Precision Landing

  • SLIM’s distinctive feature, termed the “moon sniper,” is its planned landing attempt on January 19, aiming to land within a remarkably tight limit of 100 meters from its chosen site near the Shioli Crater.
  • This precision far exceeds previous moon-landing missions’ accuracy. SLIM’s maneuverability, owing to its lower mass of 120 kg (excluding fuel), and small size will be tested during this endeavour.
  • Additionally, two small rovers, LEV-1 and LEV-2, will be deployed to study the lunar surface, collect data on temperature, radiation, and explore the moon’s mantle.

Impact on Chandrayaan-4 and India-Japan Lunar Exploration

  • SLIM’s success or failure holds implications for India’s Chandrayaan missions.
  • Chandrayaan-4, part of the Indian Space Research Organisation’s (ISRO) lunar exploration program, is slated as an Indian-Japan joint enterprise, although India’s final approval is pending.
  • Scheduled for a potential launch in 2026, Chandrayaan-4 aims to explore the moon’s South Pole region, focusing on areas perpetually shadowed that likely contain water-ice deposits.
  • The technologies tested by JAXA through SLIM, particularly the feature-matching algorithm and navigation systems, will be critical for Chandrayaan-4’s success.
  • This joint mission will involve Japan providing the launch vehicle and lunar rover, while India contributes the lander module.
  • The mission’s landing site, potentially closer to the moon’s South Pole, poses challenges due to rocky terrain and steep slopes, demanding precision in landing.
  • SLIM’s pioneering precision landing attempt influences the design and approach of Chandrayaan-4, shaping the future of India-Japan lunar exploration.


  • SLIM’s innovative approach to lunar landings and its precision-oriented mission signify a significant leap in space exploration.
  • Its success not only expands Japan’s achievements in lunar missions but also impacts the trajectory and technological advancements in India-Japan collaborative lunar exploration, notably influencing the forthcoming Chandrayaan-4 mission’s strategies and objectives.


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