SpaDeX first of many as ISRO prepares for Chandrayaan-4

ISRO Chairman S. Somanath with senior ISRO scientists and the administrators of assorted centres throughout a press convention after efficiently launching the primary SpaDeX mission, Sriharikota, December 30, 2024.
| Picture Credit score: PTI

There will likely be a sequence of house docking experiments earlier than the Indian House Analysis Organisation embarks on its Chandrayaan-4 mission to carry soil samples from the moon to the earth, ISRO has mentioned.

On December 30, 2024, the C60 mission of the Polar Satellite tv for pc Launch Automobile (PSLV) positioned two satellites, every weighing 220 kg, in orbit. They are going to rendezvous and dock with one another as a part of ISRO’s first House Docking Experiment (SpaDeX).

ISRO Chairman S. Somanath mentioned “the nominal time” for the docking “will likely be roughly January 7.”  He added, “The 2 SpaDeX satellites have moved one behind the opposite, so over a time frame, they may decide up additional distance. The gap will enhance by 20 km over the following few days after which the rendezvous and docking course of will begin.”

For Chandrayaan-4, ISRO will launch the mission’s modules in two Launch Automobile Mark-3 (LVM-3) rockets. At numerous factors throughout the mission, the modules will endure a sequence of docking and undocking manoeuvres earlier than lastly transporting a canister of lunar soil safely again to the earth.

A vital know-how

Mr. Somanath had mentioned on December 31, “2025 will likely be an thrilling yr as ISRO will launch 4 GSLV rockets, three PSLV launches in addition to an SSLV launch.” (GSLV is brief for Geosynchronous Satellite tv for pc Launch Automobile and SSLV for Small Satellite tv for pc Launch Automobile).

Docking is an important know-how for India to grasp for Chandrayaan-4 in addition to its forthcoming orbital Bharatiya Antariksh Station (BAS), anticipated to be prepared by 2035, and for its objective to ship an Indian astronaut to the moon.

Chandrayaan-4 research director P. Veeramuthuvel mentioned, “Docking is essential for all future missions of ISRO since you can not launch the whole lot in a single go. So that you want docking of modules in house. … There will likely be 5 modules in BAS, all of which require docking. This know-how is essential for bringing again the lunar soil samples and for India’s fixed presence in house.”

The 2 satellites within the present SpaDeX mission are in a round orbit 475 km above the earth. “At that top, the 2 satellites will likely be transferring at a velocity of 28,000 km an hour,” mentioned former ISRO affiliate director B.R. Guruprasad. “You need to set up the orbit of each the satellites. To carry them collectively, it’s a must to match their speeds. It’s not straightforward to match and alter their speeds exactly, make them come shut to one another after which dock. There lies the problem.”

Chandrayaan-4 mission profile

Mr. Veeramuthuvel mentioned on the Worldwide Astronautical Congress at Milan, Italy, in October 2024 one LVM-3 would carry the switch and reentry modules and the opposite would carry the descend and ascend modules. The 4 modules collectively would weigh about 9.2 tonnes.

The pairs will dock within the geosynchronous switch orbit and journey to lunar orbit.  Right here, the switch and reentry modules will stay in orbit whereas the descent and ascent modules will attain the moon’s floor. The descent module will undock from the ascent module and deploy a robotic scoop to acquire a 3 kg pattern of the lunar floor and subsurface, and place it in a cartridge. The ascent module will then elevate off from the moon with the sealed cartridge.

“The descent module will likely be useless after the ascent module lifts off,” Mr. Veeramuthuvel mentioned.

The ascent module will dock with the switch module, switch the cartridge, and undock to remain in a low lunar orbit. The reentry and switch modules will then collectively journey in direction of the earth. Within the closing step, the switch module will eject the reentry module, which can descend to the bottom for retrieval.