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India’s third lunar reconnaissance mission, Chandrayaan-3, has begun its historic and circuitous journey to the moon.
Chandrayaan-3, which consists of a propulsion unit and a robotic lander and rover, launched early Friday morning (July 14) from India’s Satish Dhawan Space Center. The mission will land on the moon on August 23 or 24, if all goes according to plan.
The success would be huge for India, making it the fourth nation – after the Soviet Union, the United States and China – to soft-land a probe on the moon.
According to the operators of Chandrayaan-3, the Indian Space Research Organization (ISRO), the three main objectives of the approximately $77 million USD mission are to make a safe soft landing near the moon’s south pole, deploy a rover and its operation. demonstrate and conduct in-situ science experiments during a single lunar day of operation (equivalent to approximately 14 Earth days).
But there’s a lot to do before Chandrayaan-3 reaches the moon. Here’s a brief overview of those next steps.
Related: Chandrayaan-3: A Guide to India’s Third Mission to the Moon
Chandrayaan-3’s 6-week journey from Earth to the Moon
ISRO divides Chandrayaan-3’s approximately 40-day journey to the Moon into three distinct segments: the Earth-centric phase, the Moon-transfer phase, and the Moon-centric phase.
Phase 1 is now partially over, with the prelaunch and launch and ascent periods completed by the launch and separation of Chandrayaan-3 from its rocket. The mission is now in the Earthbound Maneuver phase, which is part of Phase 1.
During this chapter, Chandrayaan-3 will make five orbits around the Earth. Each time it swings past Earth, the spacecraft will increase its distance from our planet. The final sweep will help place Chandrayaan-3 on a lunar transfer trajectory and send it to the moon during the lunar transfer phase (phase 2).
Chandrayaan-3 will then place itself in orbit around the moon, a move that will start the mooncentric phase (phase 3). The mission will then orbit the moon four times, gradually getting closer to the lunar surface with each successive loop.
Chandrayaan-3 cannot just land directly from Earth orbit to the Moon.
When spacecraft return to Earth from space, our planet’s atmosphere is pulled on them and their descent is slowed down. But the moon has an incredibly wispy atmosphere, so to make a moon landing, spacecraft have to slow themselves down and make a much more gradual approach.
Related: Missions to the Moon: Past, Present, and Future
Chandrayaan-3 will perform an engine burn that will launch the craft into a circular orbit about 62 miles (100 kilometers) above the lunar surface.
The lander and rover elements of the mission will then detach from the propulsion module.
The lander will land in the moon’s south polar region, traveling at less than 5 mph (8 km/h). Chandrayaan-3’s propulsion module remains in lunar orbit and continues to communicate with the rover and lander.
The Chandrayaan-3 vehicles will also use the Chandrayaan-2 mission’s orbiter, which arrived on the moon in 2019, as a backup communications relay. Chandrayaan-2 also had a lander-rover duo, but they crashed during their attempted moon landing in September 2019.
What’s next on the moon?
ISRO Chairman Sreedhara Panicker Somanath explained to the Times of India why Chandrayaan-3’s solar-powered lander and rover will land at the end of August.
“The landing will be on August 23 or 24, because we want the landing to happen when the sun rises on the moon, so we get 14 to 15 days to work,” he said. “If the landing cannot take place on these two dates, we will wait another month and land in September.”
The Chandrayaan-3 lander has its own thruster system, navigation and guidance controls, and hazard detection and avoidance systems.
ISRO has made several changes since the Chandrayaan-2 crash. Somanath told the Times of India that these improvements include strengthening the lander’s legs, increases in landing speed tolerance and the addition of new sensors to measure approach speed.
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Once a safe landing is achieved, it will be time for the Chandrayaan-3 rover to roll out.
The rover is equipped with its own scientific payloads to survey the moon, including the LASER Induced Breakdown Spectroscope (LIBS), which can analyze the chemical composition of the lunar surface; and the Alpha Particle X-ray Spectrometer (APXS), which will do the same for lunar rocks and soil around Chandrayaan-3’s landing site.
While the rover does its job, the lander that brought it to the surface will do its own scientific work. The lander will use the Radio Anatomy of Moon Bound Hypersensitive Ionosphere and Atmosphere (RAMBHA) instrument to measure plasma — a gas of electrons and ions — at the lunar surface and how it changes over time.
Meanwhile, the lander’s Chandra’s Surface Thermophysical Experiment (ChaSTE) will measure the thermal properties of the south polar region, and the
Instrument for Lunar Seismic Activity (ILSA) will measure the moon’s seismicity to help work out the structure of the lunar crust and mantle.
While all this is taking place, a passive experiment called the LASER Retroreflector Array (LRA), contributed by NASA, will run in the background on the lander, collecting data that could help scientists better understand the dynamics of the lunar system.
