BENGALURU: India space research organisation (Isro), which looked set to carry out its first

space docking experiment

early Sunday, conducted only a trial and pushed the actual procedure to later once the analysis of the trial data was complete. The space agency did not, however, provide a timeline.
“A trial attempt to reach up to 15 m and further to 3 m is done. Moving back spacecrafts to safe distance. The docking process will be done after analysing data further,’ Isro, which has been conducting various manoeuvres between the two Space Docking Experiment (SpaDeX) satellites since a little past 12am, said at 7.06am.

More than an hour before this announcement, Isro said SpaDeX satellites — chaser and target — were put in “holding position at 15m”, and even released videos and photos of the spacecraft taken by each other.

Around 3.10am, the satellites were brought to a 105 m distance from an overnight distance of 230 m and some two hours later, Isro said they were ready for “a handshake” at a distance of 15m. From here, the next expected move was to take it to a distance of 3m and initiate the final docking command.
However, Isro appears to have taken a more cautious approach of testing and validating alignment and other parametres through a trial before attempting the final docking.
After the launch on December 30, Isro has been preparing for the docking, which requires multiple steps/stages, each of which was monitored from the ground and given a go-ahead before proceeding to the next.
However, it has had to postpone its docking attempt twice, once on January 7 and again on January 9. On January 6, a day before the first docking attempt was scheduled, Isro had found that the docking process required further validation through ground simulations based on an abort scenario it identified on the day. And the docking was rescheduled for January 9.
And, on January 8, Isro said: “While making a maneuver to reach 225m between satellites the drift was found to be more than expected, post non-visibility period. The planned docking for tomorrow (January 9) is postponed. Satellites are safe.” The space agency had initiated the drift on the chaser spacecraft — the two satellites are designated chaser and target — late on January 8.
On January 9, a day after the drift between satellites caused Isro to postpone SpaDeX for the second time, the space agency managed to put the spacecraft in a slow drift course. “…The drift has been arrested and spacecraft put in a slow drift course to move closer to each other. By tomorrow (January 10), it is expected to reach initialisation conditions,” Isro said Thursday.
The two satellites, by Saturday (Jan 11) evening, achieved a distance of 230m. “Arrested at Inter Satellite Distance (ISD) of 230 m, all sensors are being evaluated. Spacecraft’s health is normal,” Isro said.
On Jan 10, Isro had said: “…Spacecraft are at a distance of 1.5 km and on hold mode. Further drift to 500 m is planned to be achieved by tomorrow (January 11) morning.” And, a day before that it had put the satellites on a slow drift course after it was forced to put off the January 9 docking.
Docking in space is a complex process and so far, only three other countries — the US, Russia and China — have mastered it.