New Delhi: After multiple delays, the Indian Space Research Organisation (ISRO) Thursday successfully completed the Space Docking Experiment (SpaDeX). With this, India has consolidated its position in the small list of countries that have displayed such capabilities in space.
India is now the fourth country, after the US, Russia and China, to have developed and tested space docking technology.
“SpaDeX Docking Update: Post docking, control of two satellites as a single object is successful. Undocking and power transfer checks to follow in coming days,” ISRO said in a statement after the successful completion of the experiment.
SpaDeX marks a key milestone as the lessons are expected to help India achieve its future space missions. These include Chandrayaan-4, as part of which samples will be brought back to the Earth from the Moon; the Bharatiya Antariksha Station (BAS), a planned modular space station to be constructed by India and operated by ISRO; and landing the first Indian on the Moon by 2040.
ThePrint explains how SpaDeX was conducted and why it will be significant for India’s future space achievements.
Docking in space
A manoeuvre was conducted Thursday to reduce the distance between Target (spacecraft A) and Chaser (spacecraft B) from 15 to three metres.
In simpler terms, Target and Chaser were brought close to each other, after which they grabbed onto each other and acted as a single unit.
Once docking was completed, the craft displayed power transfer capabilities, with a stream of electricity transfer between the two satellites turning on a power heater. This confirmed a connection with Target and Chaser.
“Manoeuvre from 15m to 3m hold point completed. Docking was initiated with precision, leading to successful spacecraft capture. Retraction was completed smoothly, followed by rigidisation for stability. Docking successfully completed,” ISRO said in a statement.
A trial attempt, as part of which the two craft were brought close to each other (three metres), was conducted on 12 January.
Once stabilisation tests were completed, Target and Chaser were moved away again.
This was done primarily to test whether the two craft could hold their positions at such close distance. The craft have also captured pictures and recorded videos of each other to confirm their position.
The last progress in the docking process before the final attempt was made Tuesday.
Timeline of delays
On 30 December, ISRO launched SpaDeX onboard the Polar Satellite Launch Vehicle (PSLV-C60). In-space manoeuvring was originally scheduled for 7 January, as part of which the two craft were set to display rendezvous, docking, and undocking.
A day before the manoeuvre, however, the space agency announced the postponement of the experiment to 9 January.
“The SpaDeX Docking scheduled on the 7th is now postponed to the 9th. The docking process requires further validation through ground simulations based on an abort scenario identified today,” ISRO said in a statement on 6 January.
While the space agency made multiple attempts to move the craft toward and away from each other, the final docking attempt could not be conducted on 9 January either.
This was because the craft could not stay put at the required position, and were drifting away from each other.
“While making a manoeuvre to reach 225 m between satellites, the drift was found to be more than expected, post non-visibility period. The planned docking for tomorrow is postponed. Satellites are safe,” the agency said.
Senior ISRO officials told ThePrint that while the hiccups were not ideal, the agency was sure of the experiment’s success because the two craft were in good health and had enough fuel to conduct multiple attempts.
“The idea was to get the experiment right and not hurry unnecessarily,” a senior ISRO official involved with SpaDeX, who wished not to be named, told ThePrint.
Crucial for future missions
By mastering rendezvous, docking, and undocking technologies, ISRO aims to enhance its operational flexibility and expand its mission horizons.
SpaDeX is a milestone in advancing India’s capabilities in space docking. The mission findings will be critical for future space missions, satellite servicing, space station operations, and interplanetary missions.
In its mission document, the space agency said the primary objectives of SpaDeX were to develop and demonstrate the technology for rendezvous and docking using two small spacecraft, and to demonstrate controllability in the docked condition, exhibiting the potential for extending the life of the target spacecraft.
“Additionally, the mission aims to test power transfer between the docked spacecraft. The secondary objectives include post-docking activities where the spacecraft will perform independent payload operations,” it read.
(Edited by Radifah Kabir)