ISRO’s lunar spacecraft, Chandrayaan-3, launched at 2.35 pm local time on Friday, commences its mission to cover the 384,000-kilometer journey from Earth to Moon.

The voyage is expected to last around 40 days, culminating with a planned soft landing at 5.47 pm Indian time on August 23. This landing timeline was unveiled by ISRO Chairman, Dr S Somanath, who underscored that the landing time was targeted and depended on the mission’s smooth progression.

Designed to function for a lunar day, equivalent to 14 Earth days, Chandrayaan-3 intends to touch down near the lunar south pole, approximately at an 80-degree latitude. The beginning of the lunar day is a crucial landing period for the ‘Vikram’ lander. This is to maximize the available sunlight for its solar panels and batteries, enabling the operation of its scientific equipment, data collection, and communication back to Earth.

ISRO’s lunar vehicle is targeting an area several hundred kilometers from the Moon’s south pole, a largely uncharted region due to its near-zero sunlight illumination. In-situ probing of this region might unlock several lunar secrets.

The Indian space agency also has a contingency plan in place, should any unexpected delays occur. This plan would involve allowing the spacecraft to orbit the Moon and attempt the landing at the following lunar dawn, potentially almost a month later than the intended date. The landing process is complex, given the Moon’s gravity is just one-sixth that of Earth’s, causing a 60kg object on Earth to weigh only 10kg on the Moon.

Due to the inability to communicate real-time decisions from Earth, the lunar landing relies heavily on the spacecraft’s onboard programming and decision-making. Difficulties such as uneven terrain, rocks, mountains, and boulders on the lunar surface also pose significant challenges for smooth landings.

Building upon the lessons from the Chandrayaan-2 mission, ISRO has conducted numerous tests on Chandrayaan-3 to ensure it is more robust and failure-tolerant. According to M Sanakaran, the Director of ISRO’s UR Rao Satellite Centre, the spacecraft’s four landing legs have been designed to withstand landing impacts up to 3 meters/second. ISRO has also introduced numerous modifications to the software, hardware, and sensors to maximize the probability of a successful lunar landing.

To date, only the US, Russia, and China have managed to soft-land their spacecraft on the Moon. The US has also conducted multiple manned lunar missions and plans to relaunch its manned program under the Artemis Program.

  Artemis program, Chandrayaan-3, India, ISRO, Moon, S Somanath