ISRO postpones SpaDeX docking again after unexpected satellite drift
The ISRO has once again postponed its ambitious Space Docking Experiment (SpaDex) Mission — which was scheduled for Thursday morning — after the satellites drifted more than expected during a manoeuvre to bring them at a distance of 225m from each other, the space agency said in a statement.
“While making a manoeuvre to reach 225 m between satellites the drift was found to be more than expected, post non-visibility period (the period when the satellites cannot be tracked by the ground stations),” the ISRO said in a statement, adding that the two satellites remain safe.
Earlier on Wednesday, the space agency said it had initiated a drift on the Chaser satellite to bring it closer in preparation for joining with the Target satellite. The aim was to reduce the distance between the two satellites from 500m to 225m. After this, there are at least two more halts for the satellites at 15m and then 3m from each other before the docking takes place.
For docking, the extended rings on both satellites will come together, before joining, and rigidization to secure the connection between the two. Then electrical power will be shared, with researchers also experimenting with giving commands to both the satellites as one.
ISRO had initially planned the docking for January 7 forenoon, but postponed it to January 9 as according to officials there was a need to run more ground simulations to “improve the accuracy”.
ISRO had launched the two satellites — SDX01 (Chaser) and SDX02 (Target) — as part of the mission on December 30 with the help of PSLV C60 rocket from Satish Dhawan Space Centre in Sriharikota.
A successful docking experiment will make India the fourth country in the world — after the US, Russia, and China — to have the capability.
The docking-undocking capability is essential for future missions that require heavy payloads which cannot be carried in a single launch. For example, the Bharatiya Antariksha Station that will be built by bringing together five modules, the first of which is planned to be launched in 2028.
The planned Chandrayaan-4 mission will require docking capability because the re-entry module, which will be designed to withstand the heat of re-entry into the Earth’s atmosphere, will be launched separately. The transfer module, carrying samples from the Moon, will come and dock with the re-entry module in the Earth atmosphere.
