India’s Chandrayaan-3 Will Attempt Soft Lunar Landing

The Indian Space Research Organization’s Chandrayaan-3 is heading to the lunar south pole on a quest to make India the fourth country to land a spacecraft on the Moon. The nation’s last attempt at a soft landing crashed into the surface. This time, the space agency has designed the new lander, Vikram, to withstand failure.

• Mission should enter lunar transfer phase soon
• Chandrayaan-2 orbiter’s camera is slated to watch over the landing

The 6.1 billion rupee ($74 million) 3,900-kg (8,600-lb.) mission, which includes a companion 26-kg rover, is targeted to touch down near the Moon’s little-explored south pole around Aug. 23. If successful, India would join the former Soviet Union, the U.S. and China on the short list of countries that have accomplished a lunar landing. 

As many as four more Moon missions are poised to launch this year, including:

• Luna 25, which is set to be Russia’s first foray to the Moon since the 1976 Soviet-era Luna 24 returned with 170 grams (6 oz.) of lunar soil. Launch is planned for Aug. 11.

• Japan’s Smart Lander for Investigating Moon, which aims to demonstrate the pinpoint landing technology necessary for future lunar probes. Launch is targeted for Aug. 26.

• Commercially developed and operated landers owned by U.S.-based Intuitive Machines and Astrobotic, which are set to attempt missions for NASA and other customers (AW&ST July 17-30, p. 32). Launches onboard a SpaceX Falcon 9 and United Launch Alliance’s first Vulcan rocket are planned for the third and fourth quarters, respectively.

Two previous private efforts to land spacecraft on the Moon failed—one by Israel’s SpaceIL in 2019 and the other by Japan’s Ispace in April 2023.

The Indian Space Research Organization (ISRO) Launch Vehicle Mk. 3 rocket (LMV3)—previously called the Geosynchronous Satellite Launch Vehicle Mk. 3—launched the Chandrayaan-3 mission on schedule at 5:05 a.m. EDT (2:35 p.m. local time) from the Satish Dhawan Space Center in Sriharikota, India, on July 14. It was the rocket’s fourth operational mission.

“All of our spacecraft parameters are normal, including the power generation in both propulsion module and lander module,” Chandrayaan-3 Project Director P. Veeramuthuvel said after the launch.

“Wishing you safe travels to the Moon,” NASA Administrator Bill Nelson commented on X, formerly known as Twitter. “We look forward to the scientific results to come from the mission.”

The planned 40-day trip to the Moon is divided into three phases. In Phase 1, the Earth-bound maneuver phase, the spacecraft orbits Earth while periodically increasing its distance from the planet. So far, it has performed five orbit-raising maneuvers.

The first firing on July 15—the day after launch—left Chandrayaan-3 in an elliptical orbit that stretched as far as 41,762 km (26,000 mi.) and came as close as 173 km from Earth. The second, third and fourth firings occurred on July 17, 18 and 20. The fifth maneuver occurred on July 25 and was expected to place Chandrayaan-3 into a 127,609 X 236-km orbit, ISRO says. 

After the Earth-bound maneuvers are complete, the mission is to transition to Phase 2: the lunar transfer phase. The TransLunar Injection burn, scheduled for Aug. 1, is intended to send the spacecraft toward the Moon and into lunar orbit.

When Chandrayaan-3 reaches lunar orbit, targeted for Aug. 5, Phase 3 is planned to begin. The spacecraft is slated to orbit the Moon multiple times, gradually approaching the surface with each pass. Once it reaches a 100-km orbit above the lunar surface, the lander and rover are planned to detach and attempt to touch down.

Chandrayaan-3, which does not include an orbiter, is designed to use the Chandrayaan-2 orbiter as a data relay spacecraft, the ISRO said. The 2019 Chandrayaan-2 mission’s orbiter placed itself around the Moon and remains operational, surpassing its expected one-year design life. The Chandrayaan-2 program ended with its lander and rover crashing into the Moon’s surface during the final descent phase. 

Chandrayaan-1—the first Indian lunar mission, launched by a Polar Satellite Launch Vehicle in October 2008—completed more than 3,400 orbits around the Moon until communications were lost in August 2009. That orbiter made the first discovery of water molecules on the lunar surface, specifically in the polar regions.

Building upon its predecessors’ capabilities, the new Vikram lander has a higher landing velocity tolerance, ISRO Chairman S. Somanath told The Times of India in a June 29 interview. This means it should not break or crash at a vertical velocity of 3 m/sec. (10 ft./sec.)—an increase from Chandrayaan-2, which was designed for a 2-m/sec. touchdown velocity.

Since the lander’s mass was increased by around 200 kg, it requires a minimum of two engines to land, Somanath said in the interview. Vikram also carries more fuel this time, he said.

The lander is equipped with improved technology as well, such as a laser doppler velocimeter sensor, which examines lunar terrain and provides three velocity vector components, and lander horizontal velocity cameras to hedge against failures.

“Instead of a success-based design, the ISRO has this time opted for a failure-based design,” Somanath said at the ​​Space Economy Leaders Meeting in Bengaluru, India, in early July. “We looked at sensor failure, engine failure, algorithm failure, calculation failure. There are different failure scenarios calculated and programmed inside.”

ISRO is targeting a larger landing ellipse this time, aiming for a 4.2 X 2.5-km region near the Moon’s south pole. The agency expects to have a clear view of the landing site ahead of touchdown via Chandrayaan-2’s camera, so it will not rely solely on pictures from the lander itself, Somanath said. 

The lander and rover are designed to last for one lunar day, the equivalent of about 14 Earth days. They carry an array of scientific payloads that are to perform experiments on the lunar surface.

Vikram carries Chandra’s Surface Thermophysical Experiment, designed to measure the thermal properties of the lunar surface near the polar region; the Radio Anatomy of Moon-Bound Hypersensitive Ionosphere and Atmosphere Langmuir probe to measure changes in the near-surface plasma ions and electron density over time; and the Instrument for Lunar Seismic Activity to measure seismic activity in the area surrounding the landing site as well as analyze the lunar crust and mantle structures.

In addition to the ISRO payloads, the lander carries a NASA-provided Laser Retroreflector Array. This passive instrument can provide lunar ranging by reflecting laser light from other spacecraft, enabling it to measure the distance between the two.

On the rover, Pragyan, an Alpha Particle X-Ray Spectrometer is planned to infer the mineral and chemical composition of the lunar surface and a Laser-Induced Breakdown Spectroscope is slated to determine the elemental composition of the lunar soil and rocks near the landing site.

The propulsion module has an experimental payload of its own, the Spectro-Polarimetry of Habitable Planet Earth, intended to study the signatures of the polarization of light on Earth in the near-infrared range.

Standing 43.5 m (140 ft.) tall, the LMV3 is a three-stage rocket that includes a pair of solid S200 strap-on motors. With 204 tons of solid propellant, the S200s are among the largest solid boosters in the world.

The rocket’s L110 liquid-fuel core stage is powered by two Vikas engines fueled by 115 tons of unsymmetrical dimethylhydrazine and water. The rocket is designed to take off with the simultaneous ignition of the S200 boosters. The core stage ignites at 113 sec. after liftoff, and booster burnout occurs 21 sec. later. The L110 is designed to continue firing until 313 sec., at which point it separates, leaving the rest of the ascent to a high-thrust C25 upper stage fueled by 28 tons of liquid oxygen and liquid hydrogen.

The LMV3 can carry up to 4,000 kg to geostationary transfer orbit and 8,000 kg into low Earth orbit. In March, an LMV3 launched 36 OneWeb satellites. ISRO is developing a human-rated version of the rocket to carry astronauts. “We are in the process of increasing the launch frequency of this vehicle, considering national requirements as well as satellite demand,” noted Chandrayaan-3 Mission Director S. Mohan Kumar.

—With Irene Klotz in Cape Canaveral