Today holds immense significance for India’s lunar endeavour, the Chandrayaan-3 mission. The mission is on the brink of its culminating and pivotal phase, a delicate lunar landing at approximately 6:04 pm. The Indian Space Research Organisation (ISRO) has given assurance that all elements are progressing as scheduled as of August 22. The public can witness the event through a live broadcast at 5:20 pm today.
Interestingly, India will become the first country to achieve this feat if the spacecraft can gently land on the Moon’s south pole. Once this successful landing occurs, a rover (a small vehicle for moving on the Moon) will emerge from the spacecraft.
In this context, let’s delve deeper into why achieving a ‘soft landing’ is essential for the mission. Moreover, let’s explore the challenges of landing on the south pole and what unfolds once India accomplishes this feat.
As per ISRO’s plans, the mission has three main goals: firstly, to show the safe and soft landing of the spacecraft on the Moon’s surface. Secondly, to demonstrate a rover moving around on the Moon. Finally, to carry out scientific experiments right there on the Moon.
Why Choose the Challenging Polar Region for Moon Landing?
To explain the idea of a soft landing, imagine a spacecraft moving faster in space than an airplane. Now, imagine that this spacecraft needs to slow down a lot and land gently on the Earth’s surface, all in just a few minutes. And the remarkable part is all of this needs to happen without any direct help from humans. That’s what a soft landing means.
Amitabha Ghosh, a scientist on NASA’s Mars rover mission, used a simple example to describe this concept. It’s like a spacecraft racing through space ten times faster than an airplane. But then, it must almost stop completely to land very softly on Earth. And all of this has to happen quickly, without humans stepping in to control everything. That’s the essence of a soft landing.
Demonstrating a spacecraft’s abilities is the purpose here. The chosen landing spot is close to the Moon’s south pole at a latitude of 70 degrees. Until now, all the previous spacecraft that have landed on the Moon picked spots around the equator. This was mainly because it’s easier and safer. The conditions like the terrain and temperature there are better for keeping instruments working well for a long time. Also, there’s consistent sunlight, which helps power instruments using solar energy.
However, the polar areas of the Moon are a different story. Many parts of these regions are in complete darkness, and the temperatures can drop low, even reaching -230 degrees Celsius. This makes it challenging for instruments to function correctly. On top of that, there are many big craters scattered around.
Exploring the Uncharted Lunar Poles: Chandrayaan-3’s Lessons from the Past
Consequently, the frigid polar areas of the Moon have remained untouched by exploration. The intensely cold temperatures suggest that any objects ensnared in this region would remain cryogenically preserved, undergoing minimal alteration over time. The lunar terrain and soil at the north and south poles potentially hold vital clues about the formative stages of the Solar System.
It’s worth noting that even Chandrayaan-2, India’s lunar probe mission, intended to touch down in this enigmatic region in 2019. However, it encountered difficulties during its attempted soft landing and lost communication shortly after contacting the lunar surface.
Further investigations revealed that the 2019’s Chandrayaan-2 mission encountered issues from software and hardware complications. S Somanath, the chairperson of ISRO, recently explained that the modifications made for the ongoing mission were founded on lessons from past failures. He elaborated, stating, “Instead of a success-based design in Chandrayaan-2, we are doing a failure-based design in Chandrayaan-3 —we are looking at what can go wrong and how to deal with it.”
What Are the Notable Enhancements in the Design of the Chandrayaan-3 Lunar Lander?
Some of the changes that have been made include, “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 power up to around 400 m above the surface. When it crashed, the Lander had slowed to about 580 km/hr.”
A lunar lander doesn’t possess wheels; instead, it’s equipped with stilts or legs that are designed to make contact with the surface of the Moon. For the upcoming Chandrayaan-3 mission, these legs have been reinforced to guarantee a stable landing even at a velocity of 3 meters per second, which is equivalent to 10.8 kilometres per hour.
The Chandrayaan-3 Lander carries a larger fuel supply compared to Chandrayaan-2. This enhancement is intended to allow the Lander to adjust its landing site at the last moment, if necessary.
Unlike Chandrayaan-2, the Chandrayaan-3 Lander has solar panels on all four sides. This design alteration ensures that the Lander can continuously harness solar power, even if it touches down in an incorrect orientation or ends up tumbling. This way, one or two sides of the Lander will always face the Sun, allowing it to remain operational.
Chandrayaan-3 Moon Landing Process Simplified
- Rough Braking Phase: The Lander starts by slowing down its sideways speed, going from super fast (over 6,000 km/h) to nearly stopped. Imagine a car slowing down before parking, but this is happening way up in the sky, about 30 km above the Moon’s surface.
- Attitude Hold Phase: When the Lander is about 7.42 km above the Moon, it makes a particular move. It tilts from lying down to standing up, like a plane tilts before landing. This takes about 10 seconds and covers a distance similar to three and a half football fields.
- Delicate Braking Phase: The Lander moves into a fully standing position, high above the Moon. It’s like a rocket switching from going sideways to going straight down. This part takes about 175 seconds, and during this time, it gets closer to the landing spot while slowing down a lot.
- Terminal Descent: This is the grand finale. The Lander comes down almost straight from the sky, like a feather falling gently. It’s the last part of the journey and must be precise for a soft landing on the Moon.
Spacecraft often carry instruments and experiments, known as payloads, that observe and gather information in space. This data is sent back to Earth for analysis by scientists.
The Vikram lander and rover Pragyan have the identical six payloads as before. The Lander has four scientific loads: one for studying lunar quakes, one for analyzing the Moon’s thermal properties, one for observing changes in nearby plasma, and a passive experiment to measure Earth-Moon distance accurately. NASA provides the fourth payload.