Chandrayaan-3: India's New Lunar Mission Explained | ISRO's Second Moon Landing Attempt

Chandrayaan 3

With the successful launch of Chandrayaan-3 today (July 14), the Indian Space Research Organisation (Isro) is set to make its second attempt to land a spacecraft on the moon.
Earlier in 2019, due to problems that had emerged during the last stage of the descent, Chandrayaan-2’s lander and rover crashed on the moon’s surface.

Any space mission as two parts :
- Rocket, or the carrier
- Spacecraft, which could be a satellite or any other payload.
The rocket transports the spacecraft into space. In most missions, the rockets get destroyed after completing their job.
The rocket is powered by a propellant, which is a mix of fuel and oxidisers (that allow for burning to happen), all meant to generate enough energy to help the spacecraft lift-off.
Once that happens, this powered flight continues and ends only when the rocket’s last stage burns out and the spacecraft separates.
The payload should have been, ideally, placed into the orbit of the planetary body that it is supposed to reach by this time.

Aimed at lunar exploration
Began with Chandrayaan-1 that launched on October 22, 2008.
Objective: To prepare a three dimensional atlas of both near and far side of the Moon and to conduct chemical and mineralogical mapping of the entire lunar surface with high spatial resolution.
In 2008, a payload named MIP (Moon Impact Probe) carried by the spacecraft was separated and it struck the lunar South Pole in a controlled manner.
India was then able to make discoveries related to the detection of water (H2O) and hydroxyl (OH) on the lunar surface.
The data also revealed their enhanced abundance towards the polar region.
It further found ice in the North polar region of the Moon.

Brought together an Orbiter , Lander and Rover to explore the south pole of the Moon.
Launched in July 2019 and was only a partial success, because on September 7 that year, its lander, Vikram, and rover, Pragyaan, crashed on the Moon’s surface.
However, its Orbiter functioned well and was able to gather data.
It found signatures of water at all latitudes.
The Large Area Soft X-Ray Spectrometer (CLASS) found the minor elements chromium and manganese for the first time through remote sensing.

The payloads on the lander and rover remain the same as the last mission.
Payloads on the lander: 4 payloads to study lunar quakes, thermal properties of the lunar surface, changes in the plasma near the surface.
- The fourth payload comes from NASA.
2 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.
The landing site of the latest mission is more or less the same as the Chandrayaan-2: near the south pole of the moon at 70 degrees latitude.

The south pole of the moon was chosen by the Indian Space Research Organisation (ISRO) as the lunar surface area that remains in shadow there is much larger than that at the north pole.
There is a possibility of presence of water in permanently shadowed areas around it.
The south pole region also has craters that are cold traps and contain a fossil record of the early Solar System.

The term “launch window” refers to the window of opportunity that exists for a specific mission to get off the ground.
The launch of the spacecraft must be precisely timed in order for their orbits to overlap at some point in the distant future if the spacecraft intends to get in close proximity to another spacecraft, a planet, or some other point in space.
In the event that a malfunction occurs or the weather is unfavorable during a launch window, the mission will need to be delayed until the subsequent launch window that is suitable for the flight.
The Earth and other planetary bodies are also not stationary and their constant movement needs to be calculated to devise the shortest, most fuel-efficient path for the spacecraft.

This whole process is likely to take around 42 days, with the landing slated for August 23 at the lunar dawn.
Launched into space by the Launch Vehicle Mark-III, (LVM-III).
After launching into an orbit around the Earth at an altitude of 179 km, the spacecraft will gradually increase its orbit in a series of manoeuvres to escape the Earth’s gravity and slingshot towards the moon.
After reaching close to the moon, the spacecraft will need to be captured by its gravity.
Once that happens, another series of manoeuvres will reduce the orbit of the spacecraft to a 100×100 km circular one.
Thereafter, the lander, which carries the rover inside it, will separate from the propulsion module and start its powered descent towards the moon’s surface.
The craft lander and rover have a mission life of one Lunar day.
Each Lunar day lasts for 14 earth days, as does each Lunar night, as it takes around one month (close to 28 earth days) for the moon to complete one rotation on its axis (and one revolution around the earth).
The rover and lander cannot survive the extreme drop in temperatures during lunar nights, which is why they are being landed right at dawn.