In-space docking technology is essential when multiple rocket launches are required to achieve common mission objectives. Through this mission, India is marching towards becoming the fourth country in the world to have space docking technology. File
| Photo Credit: PTI

“The two Space Docking Experiment (SpaDeX) satellites that ISRO is hoping to unite are at a distance of 1.5 km and will be brought much closer on January 11,” the space agency said on Friday (January 10, 2025).

The SpaDeX space docking experiment has so far missed two publicly announced schedules, on January 7 and January 9.

“Spacecrafts are at a distance of 1.5 km and on hold mode. Further drift to 500 m is planned to be achieved by tomorrow morning,” ISRO said in a post on ‘X’.

This announcement came a day after the space agency shared that the drift between satellites that had caused the postponement of the docking experiment for the second time had been arrested and they were put in a slow drift course to move closer to each other.

ISRO successfully launched the Space Docking Experiment (SpaDeX) mission on December 30, 2024.

The PSLV C60 rocket carrying two small satellites, SDX01 (Chaser) and SDX02 (Target), along with 24 payloads, had lifted off from the first launchpad of the Satish Dhawan Space Centre in Sriharikota, and about 15 minutes after liftoff, the two small spacecraft weighing about 220 kg each were launched into a 475-km circular orbit as intended.

After the launch, ISRO has been preparing for the docking, which requires multiple steps/stages.

Docking in space is a complex process, which so far has been mastered by only three other countries — the U.S., Russia and China.

On January 6, a day before the first docking attempt was scheduled, ISRO announced its postponement to January 9, stating that the docking process requires further validation through ground simulations based on an abort scenario identified.

A day ahead of the docking planned on January 9, the space agency had initiated the drift on Spacecraft A (chaser) to move closer from 500 m to 225 m. But shortly after that it announced another postponement of docking, saying that — while making a maneuver to reach 225 m between satellites, the drift was found to be more than expected, post non-visibility period.

According to ISRO, SpaDeX mission is a cost-effective technology demonstrator mission for the demonstration of in-space docking using two small spacecraft that were launched by PSLV. This technology is essential for India’s space ambitions such as Indian on Moon, sample return from the Moon, the building and operation of Bharatiya Antariksh Station (BAS), etc.

In-space docking technology is essential when multiple rocket launches are required to achieve common mission objectives. Through this mission, India is marching towards becoming the fourth country in the world to have space docking technology.

ISRO launches Polar Satellite Launch vehicle (PSLV-C60) with two Space Docking Experiment (SpaDex) satellites and 24 other innovative payloads into orbit from the Satish Dhawan Space Centre, in Sriharikota. File
| Photo Credit: ANI

The Indian Space Research Organisation (ISRO), which had postponed the planned docking of the two SpaDeX satellites, has arrested the drift between the spacecraft.

“SpaDeX Docking Update: The drift has been arrested and spacecraft put in a slow drift course to move closer to each other. By tomorrow, it is expected to reach initialisation conditions,” ISRO posted on Thursday (January 9, 2025).

On Wednesday (January 8, 2025) hours before it was scheduled to carry out the SpaDeX docking experiment, ISRO said that the docking experiment which was scheduled to take place on January 9 has been postponed as the drift between the satellites was found more than expected.

“While making a maneuver 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,” ISRO had announced.

A few hours before this it had initiated the drift on the Spacecraft A to move closer from 500m to 225m.

This was the second time ISRO postponed the SpaDex docking experiment.

The docking of the two satellites was initially scheduled for January 7 but was postponed to January 9. Though ISRO said that the drift has been arrested, it has not announced the new date and time for the docking experiment.