Why in news?

• India’s Moon mission Chandrayaan-3 scripted history by successfully landing on the lunar surface.
• With the Lander accomplishing a ‘soft landing’ on the Moon’s south pole, India becomes the only country to have ever done so.
• 

What’s in today’s article?

• What is a soft landing?
• Why is Chandrayaan-3 landing on the south pole?
• Why South Pole is Significant?
• What happened to Chandrayaan-2?
• What has changed since then?
• What happens after Chandrayaan-3 successfully lands on the Moon?

What is a soft landing?

• Soft landing simply means landing at a gentle, controlled speed to not sustain damage to a spacecraft.Doing so showcases a spacecraft’s technical capabilities.
• During a soft landing, the spacecraft undergoes a series of manoeuvres and braking techniques to reduce its velocity and align itself with the landing site.
  • This typically involves firing retro-rockets or thrusters to slow down the descent and make a controlled approach.
• The goal is to land the spacecraft gently without causing any significant damage.

Why is Chandrayaan-3 landing on the south pole?

• All of the previous spacecraft (landed on the Moon) have landed in the region near the Moon’s equator.
  • This is because it is easier and safer here.
  • The terrain and temperature are more conducive for a long and sustained operation of instruments.
  • Sunlight is also present, offering a regular supply of energy to solar-powered instruments.
• The polar regions of the Moon, however, are different. Many parts lie in a completely dark region without sunlight, and temperatures can go below 230 degrees Celsius.
• This creates difficulty in the operation of instruments. In addition, there are large craters all over the place.

Why South Pole is Significant?

• Water:
  • There is strong evidence that water ice is present in the permanently shadowed craters at the moon's south pole.
  • This water ice could be a valuable resource for future human exploration of the moon, as it could be used for drinking, growing food, and producing rocket fuel.
• Volatiles:
  • In addition to water ice, the moon's south pole may also contain other volatiles, such as methane and ammonia.
  • These volatiles could also be used as resources for future human exploration.
• Geological insights:
  • The moon's south pole is also a geologically interesting place. The region is home to the South Pole-Aitken basin, the largest impact basin on the moon.
  • Studying the South Pole-Aitken basin could provide insights into the Moon's formation and evolution.
• Astronomical observations:
  • The moon's south pole is also a good location for astronomical observations.
  • The permanently shadowed craters at the south pole are shielded from the Sun's radiation, which makes them ideal for observing radio waves and other forms of radiation that are blocked by the Earth's atmosphere.

What happened to Chandrayaan-2?

• Chandrayaan-2 lost control over its descent around 7.2 km from the surface of the Moon.
• Its communications system relayed data of the loss of control up to around 400 m above the surface. The Lander had slowed down to about 580 km/hr when it crashed.

What has changed since then?

• The legs of Chandrayaan-3 have been strengthened to ensure that it would be able to land, and stabilise, even at a speed of 3 m/sec, or 10.8 km/hour.
  • A Lander does not have wheels; it has stilts, or legs, which are supposed to touch down on the lunar surface.
• The prospective landing site has had its range increased.
  • Instead of trying to reach a specific 500mx500m patch for landing as targeted by Chandrayaan-2, the current mission was given instructions to land safely anywhere in a 4kmx2.4km area.
• The Chandrayaan-3 Lander is carrying more fuel than Chandrayaan-2.
  • This has been done to ensure that the Lander is able to make a last-minute change in its landing site, if it needs to.
• The Chandrayaan-3 Lander has solar panels on four sides, instead of only two in Chandrayaan-2.
  • This is to ensure that the Lander continues to draw solar power, even if it lands in a wrong direction, or tumbles over.
  • At least one or two of its sides would always be facing the Sun, and remain active.

What happens after Chandrayaan-3 successfully lands on the Moon?

• Spacecraft are often carrying certain instruments and experiments with them (called payloads) that observe and record what is happening in Space.
• This information is then relayed to Earth for scientists to analyse and study.
• The six payloads on the Vikram lander and rover Pragyan remain the same as the previous mission.
• There will be four scientific payloads on the lander to study lunar quakes, thermal properties of the lunar surface, changes in the plasma near the surface, and a passive experiment to help accurately measure the distance between Earth and the Moon.
  • The fourth payload comes from NASA.
• There are two payloads on the Rover, designed to study the chemical and mineral composition of the lunar surface and to determine the composition of elements such as magnesium, aluminium and iron in the lunar soil and rocks.