Chandrayaan-3: Everything you need to know about the mission and what happens after its successful moon landing (2023)

...... and so it isChandrayaan-3 Rover descended from the lander to the lunar surface.pic.twitter.com/nEU8s1At0W

-ISRO(@isro)25. August 2023

WhenChandrayaan-3 launched to the moon on July 14, we explain the mission basics: How does a mission launch into space, huh?Chandrayaan-1 againChandrayaan-2 missions went, etc. He canClick here to read this. Here we explain in more detail why a “soft landing” was crucial to the mission, what makes the South Pole landing such a difficult task, and what will happen after landing.

What is a soft landing and why did Chandrayaan-3 land at the South Pole?

AccordinglyISROThe mission's three objectives were to demonstrate a safe and smooth landing on the lunar surface, demonstrate a roving rover on the moon, and conduct on-site science experiments.

Soft landing simply means landing at a steady, controlled speed so as not to damage the spacecraft. Amitabha Ghosh, NASA Mars Rover Mission Scientist,He explained it in the Indian Express as follows:“Imagine a spacecraft flying through space at ten times the speed of an airplane, almost having to stop to make a smooth landing on Earth, all in a matter of minutes, and most importantly, without human intervention. . All in all, this is a smooth landing.”

This shows the engineering capabilities of a spacecraft. The landing site is near the south pole of the moon, at the 70th degree of latitude.

All spacecraft that have ever reached the moon have done so near the lunar equator, primarily because it is easier and safer here. Terrain and temperature are best conducive to long and sustained instrument operation. Sunlight is also present and regularly supplies energy to solar-powered instruments.

However, the polar regions of the moon are different. Many areas are completely dark with no sunlight, and temperatures can drop below 230 degrees Celsius. This leads to difficulties in operating the instruments. Also, there are big craters everywhere.

This is how Chandrayaan-3 reached lunar orbit and plans to descend to the lunar surface.

As a result, the moon's polar regions remained unexplored. Extremely low temperatures could cause whatever is trapped in the region to remain frozen over time with little major change. Therefore, the rocks and soil at the moon's north and south poles could provide clues to the early solar system.

Above all,Chandrayaan-2 also planned to land in this region in 2019, but failed to make a smooth landing and lost contact after landing.

Why couldn't Chandrayaan-2 land properly and what has changed since then?

A subsequent review found that there were software and hardware issues in 2019.Chandrayaan-2.isroPresident S. Somanath recently said that changes to the current mission were "based on failure." He said, "Rather than success-based design."Chandrayaan-2, we are doing a crash based designChandrayaan-3: We check what could go wrong and how we can fix it.”Some of the changes made are:

*Chandrayaan-2 lost control of its descent to a distance of about 7.2 km from the lunar surface. Its communication system transmitted loss of control data up to a distance of about 400 m. The lander was slowed down to about 580 km/h when it crashed.

A lander has no wheels; has stilts or legs meant to touch the lunar surface, the legs ofChandrayaan-3 have been reinforced to ensure they can land and stabilize even at speeds of 3m/s or 10.8km/h.

*This time the range of possible landing pad has been increased. Instead of trying to hit a specific 500x500m zone to land when aimingChandrayaan-2, the current mission has been instructed to land safely anywhere within a 4km x 2.4km area.

*IsChandrayaan-3 The lander carried more fuel thanChandrayaan-two. This was done to ensure that the lander could change its landing location at the last minute if necessary.

*IsChandrayaan-3 Lander has solar panels on four sides instead of just twoChandrayaan-two. The goal was to ensure that the lander would continue to use solar energy even if it lands the wrong way or flips over. At least one or two of its sides would always face the sun and remain active.

What had to happen for Chandrayaan-3 to land successfully?

The decisive technical maneuver that theChandrayaan-3 on Aug 23, as it entered the final 15 minutes of its attempt at a soft landing on the Moon, had to convert its high-speed horizontal position to a vertical position to allow for a smooth descent. to the surface.

AfterChandrayaan-2 failed on its soft landing mission, K Sivan, then President ofISRO, referred to this process as “15 minutes of terror”. It includes four phases:

1. The hard braking phase involves reducing the lander's horizontal speed from a range of 1.68 km/s (more than 6,000 km/h) at an altitude of 30 km above the lunar surface to almost zero in order to achieve a smooth landing at the designated point aim to ensure location. . This must be done precisely and within specific timeframes.Read this explainer for a more detailed explanation..

2. At an altitude of 7.42 km above the surface, the lander enters an approximately 10-second “attitude hold” phase during which it transitions from a horizontal to a vertical position over a distance of 3.48 km.

3. The "fine braking phase" lasts about 175 seconds, during which the lander must move completely to the vertical. To cover the last 28.52 km to the landing site, the altitude drops to 800-1000 m and reaches a nominal speed of 0 m/s. It was between the "posture maintenance phase" and the "fine braking phase".Chandrayaan-2 lost control and fell.

4. "Terminal Descent" is the final phase in which the spacecraft must descend completely perpendicular to the surface.

And finally: what will happen after the successful landing of Chandrayaan-3 on the moon?

Spacecraft often carry specific instruments and experiments (called payloads) that observe and record what is happening in space. This information is then sent back to Earth for scientists to analyze and study.

The six payloads of the Vikram lander and the Pragyan rover remain the same as in the previous mission. The probe will carry four science payloads to study moonquakes, thermal properties of the lunar surface, changes in near-surface plasma and a passive experiment to accurately measure the distance between Earth and the moon. The fourth payload is from NASA.

The rover carries two payloads to study the chemical and mineral composition of the lunar surface and to determine the composition of elements such as magnesium, aluminum and iron in the lunar soil and rocks.

For a detailed analysis of these experiments and how they build on the results of previous studiesChandrayaanThe mission (Chandrayaan-1 againChandrayaan-2),Read our statement here.