Smart Lander for Investigating Moon (SLIM) Mission

Smart Lander for Investigating Moon (SLIM) Mission

Context:

• Recently, Japan’s Smart Lander for Investigating Moon (SLIM) spacecraft entered into orbit around the moon after nearly months­long journey.
• It entered into the orbit ahead of its planned moon­landing attempt which will be on January 19, 2024.
• If the landing turns to be successful then Japan will become only the fifth country in the world to soft­land a robotic craft on the moon
• India succeeded in the soft landing mission with its Chandrayaan­3 mission in August.

What is SLIM Mission?

• SLIM (Smart Lander for Investigating Moon) is a spacecraft which was built and launched by the JAXA (Japan Aerospace Exploration Agency) on September 7, 2023, from the Tanegashima spaceport.
• Compared to the Chandrayaan-3 mission, the SLIM spacecraft weighs only around 590 kg at launch, which is almost one­seventh of Chandrayaan­3, which weighed 3,900 kg at launch.
• Along with SLIM spacecraft XRISM was also launched. XRISM is a next­generation X­ray space telescope.
• Initially, JAXA had planned to launch SLIM and XRISM together but delays in making XRISM pushed back SLIM’s launch date from 2021 to 2023.
• On December 25, SLIM entered into an elliptical orbit around the natural satellite of Earth over three minutes or so.
• Its apogee which means farthest point in this orbit is 4,000 km and perigee (closest point) is 600 km above the lunar surface.
• SLIM mission will also mark the second attempt of Japan this year to soft­land on the moon.
• The HAKUTO­R M1 lander which was built by Japanese company ispace was the first attempt.
• It crashed in late April when its engines shut down too soon during the landing.

How did SLIM get to the moon and comparison with Chandrayaan-3:

• SLIM is lighter because it carried way too much less fuel.
• But in Chandrayaan­3 mission, out of 3.9 tonnes, the propulsion module alone weighed around 2.1 tonnes.
• This is the reason that why the mission could reach the moon less than a month and it followed a route called the Hohmann transfer orbit.
• On the other side, SLIM spacecraft took nearly four months because it followed a longer but more fuel­thrifty route based on weak­stability boundary theory.
• Once it went close to the moon, Chandrayaan­3 applied its brakes which led to consumption of fuel in space.
• The application of brakes made sure that it could slow down enough to be captured by the moon’s weaker gravity.
• But the SLIM when got near the moon, instead of slowing down like chandrayaan-3 and being captured by the moon’s gravity, it allowed itself to be deflected in the moon’s direction.
• This deflection is due to the result of the combined forces exerted by both i.e., the earth and the moon.

Purpose of SLIM on Moon:

• SLIM is prepared to soft­land with the smallest ever area tolerance on the moon.
• The chosen site for this mission is near the Shioli Crater, at 13.3o S and 25.2o E.
• Similar to the ‘Vikram’ lander of the Chandrayaan­3 mission which used data from the Chandrayaan 2 orbiter to help guide its descent likewise SLIM will use data from JAXA’s SELENE orbiter that was ended in 2009.
• Its lower mass is only 120 kg (which excludes fuel) will help in this task by rendering it more manoeuvrable while the small size will be a test of its economical design.
• SLIM will have two small rovers names as Lunar Excursion Vehicle (LEV) 1 and 2.
• LEV­1, LEV­2, and SLIM will together study the surface of the moon near the landing point, collect the temperature of the site and radiation readings, and also attempt to study the moon’s mantle.

How will SLIM mission affect Chandrayaan­4 mission?

• Scientists are particularly interested in the moon’s South Pole region at large due to the fact that parts of some of the craters in the South Pole are always in shadow.
• So, they allow the temperature there to drop very low as well as escaping them from the effects of sunlight and diurnal temperature variations.
• India’s first mission of its third phase is the Lunar Polar Exploration (LUPEX) mission which is also called as Chandrayaan 4.
• LUPEX will be a joint enterprise between India and Japan, with an earliest expected launch date in 2026.
• The LUPEX mission will try to explore an area which is closer to the moon’s South Pole than Chandrayaan­3.