Propulsion module successfully transferred from Moon to Earth
Indian Space Research Organization, ISRO has successfully transferred Chandrayaan Orbiter, also known as Propulsion Module, from the Moon to Earth. ISRO had successfully achieved the historic landing of Vikram lander and landing of Pragyan rover on the lunar surface near the south pole on August 23.
After more than a month of operation in lunar orbit, the propulsion module contained more than 100 kg of fuel. ISRO decided to use the available fuel to obtain additional information for future lunar missions and successfully brought the module into Earth orbit. The SHAPE payload on the module will now be used for Earth observations.
Chandrayaan-3 mission was launched on 14 July 2023. It had three parts – propulsion module, lander and rover. The propulsion module was placed in lunar orbit. The lander and rover had landed on the South Pole of the Moon on August 23. The propulsion module carries the SHAPE payload which is designed to study the Earth.
The primary objective of the Chandrayaan-3 mission was to demonstrate a soft landing near the south polar region of the Moon using Vikram and Pragyan. At the same time, the main objective of the Propulsion Module was to transport the lander module from the Geostationary Transfer Orbit (GTO) to the final lunar polar circular orbit and to separate the lander. After separation, the Spectro-Polarimetry of the Habitable Planet Earth (SHAPE) payload was also conducted in the PM.
The propulsion module propelled the lander and rover configuration to a 100 kilometers (62 mi) lunar orbit. It was a box-like structure with a large solar panel mounted on one side and a cylindrical mounting structure for the lander (Intermodular Adapter Cone) on top. A few months after the conclusion of the lander portion of the mission, ISRO officials said that the propulsion module is equipped with two radioisotope heating units (RHU) generating one watt each designed and developed by BARC (Bhabha Atomic Research Centre) .
RHUs keep spacecraft at their operating temperatures by decaying radioactive materials, which also produce electricity to power heaters using solar energy or battery power. Chandrayaan 3 project director P Veeramuthuvel said ISRO may soon use nuclear resources to maintain instruments in future rovers. ISRO officials later said that the RHU could not be installed on Chandrayaan 3's Vikram lander and Pragyan rover as it would have increased their mass, which would unfortunately have reduced their maximum lifetime to 14 Earth days or 1 lunar day.
The propulsion module is currently orbiting the Earth with a perigee and apogee altitude that varies during its trajectory and an estimated minimum apogee altitude of 1.15 lakh km and an orbital period of approximately 13 days with 27° inclination. According to the plan, the SHAPE payload is operated whenever Earth is in its field of view. Additionally, a special operation of the SHAPE payload was conducted during the solar eclipse on October 28, 2023. SHAPE payload operations will continue.