Chandrayaan 3's giant leap: Nuclear energy fuels propulsion module orbiting moon

Chandrayaan 3, the moon exploration mission that soft landed near the lunar south pole few weeks back, successfully demonstrated tests use of nuclear energy in power generation in one of its components.

The propulsion module of Chandrayaan 3, which is still orbiting the Moon, has been powered by a Radioisotope Heating Unit (RHU), reported Times of India.

The propulsion module of Chandrayaan 3 includes two RHUs, each generating one watt, designed and developed by BARC. Project director P. Veeramuthuvel has expressed the possibility of using nuclear resources to maintain instruments in future rovers.

However, the RHUs were not installed on Chandrayaan 3's Vikram lander and Pragyan rover due to increased mass, the report said.

Instead, they were placed in the propulsion module for experimental and demonstration purposes.

About the Chandrayaan 3 mission:

The Chandrayaan 3 mission included a rover, Pragyan, carried inside the Vikram lander through a propulsion module. Unlike its predecessor, Chandrayaan 2, it did not include a lunar orbiter, as the earlier one continues to operate as intended.

While the Vikram lander with the Pragyan Rover successfully landed on the moon on August 23, it entered sleep mode after completing 10 days of lunar exploration. Meanwhile, the propulsion module is still orbiting the moon after separating from the lander.

The successful landing marked India as the fourth country to achieve a controlled landing on the lunar surface and the very first to achieve a landing near the south pole.

What is the purpose of a radioisotope heating unit?

Despite being engineered for moon travel, modern spacecraft electronics and mechanical systems sometimes require assistance in maintaining optimal temperatures.

When placed aboard a spacecraft or inside a rover, the heat energy from RHUs serves to keep a mission’s hardware at proper operating temperatures.

"Like a steady campfire that warms intrepid hikers in a remote forest, radioisotope heater units help bring dependable heat to wherever it’s needed for missions bound for the coldest corners of the solar system," says National Aeronautics and Space Administration (NASA).

How do radioisotope heater units work?

Each RHU generates approximately one watt of heat through the natural radioactive decay of a small pellet primarily composed of plutonium dioxide, particularly plutonium-238, says NASA.

This heat can be directly transferred to spacecraft structures, systems, and instruments, eliminating the need for moving parts or intervening electronic components.

Is India the first to take nuclear technology to space?

RHUs have a rich history of use in space missions. They were first used with the science experiments that were left on the surface of the Moon in 1969 by the Apollo 11 astronauts. According to NASA, they have been used in missions that have carried them to Jupiter, Saturn, and Mars.