ISRO postpones SpaDeX docking for second time as satellites drift apart
By Girish Linganna | First Published Jan 8, 2025, 11:50 PM ISTISRO postponed the Spadex mission's docking operation due to unexpected drift detected after a non-visibility period. The delay ensures optimal conditions for a safe docking attempt, with the satellites remaining secure. A new schedule will be announced soon.
In a recent update, ISRO announced the postponement of a critical docking operation as part of its Spadex mission.
The docking, originally scheduled for January 9th at 8:11 AM, was delayed due to an unexpected drift detected after a scheduled period of non-visibility, during which communication with the satellites is temporarily lost as they pass out of range of ground stations. While the satellites remain safe, the team has decided to delay the docking operation to ensure optimal conditions for a successful attempt.
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Confirming the development, ISRO’s official X (formerly Twitter) handle posted at 9:00 PM on January 8th, stating:
"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 (9th Jan) is postponed. Satellites are safe."
What Is docking ?
Docking in space refers to the process of two spacecraft or satellites joining together while in orbit.
This process is highly complex and requires precise alignment, positioning, and movement to ensure the two objects connect smoothly without any damage.
In this case, as part of the Spadex mission, ISRO was attempting to dock two satellites in orbit, bringing them together for further interaction or testing.
The maneuver involved reducing the distance between the satellites to 225 meters before the final docking.
However, during the approach, an unexpected drift in their positions was observed, which led to the postponement.
Why was the docking postponed?
Space docking requires extreme precision. The satellites must approach each other at a controlled speed and align perfectly to avoid collisions or mechanical failure.
The unexpected drift—likely caused by external forces like microgravity, slight inaccuracies in thruster firings, or other orbital dynamics—meant that the satellites were no longer on the exact trajectory required for docking.
Attempting the docking under such conditions could risk damage to both satellites. By postponing, ISRO ensures the mission’s safety and success.
An everyday example to understand docking
To put this into perspective, imagine two cars trying to park side by side in a narrow space. If one car drifts slightly out of its position, even by a few centimeters, it could make parking impossible or result in a collision. In space, the stakes are much higher, as the satellites are moving at thousands of kilometers per hour while trying to join together gently.
The docking process involves multiple steps: approaching the target, slowing down, aligning, and finally making physical contact. In the Spadex mission, the satellites were in the approach phase, and the unexpected drift disrupted this critical step.
What happens next ?
ISRO will now analyze the cause of the drift, recalibrate the satellites, and plan a new docking schedule. This delay ensures that when docking is attempted again, all parameters are within safe limits. ISRO has reassured the public that the satellites remain safe and that a new docking date will be announced soon.
The Spadex mission is an important milestone for ISRO, as it demonstrates the ability to perform complex docking operations in space—a capability essential for various future missions, including on-orbit servicing, debris removal, and assembling modular spacecraft.
Delays like this are common in space missions, as ensuring safety and mission success always takes precedence. The postponement highlights the complexities of orbital mechanics and the meticulous planning required for a successful docking operation.
(The author of this article is an award-winning Science Writer and a Defence, Aerospace & Political Analyst based in Bengaluru. He is also Director of ADD Engineering Components, India, Pvt. Ltd, a subsidiary of ADD Engineering GmbH, Germany. You can reach him at: girishlinganna@gmail.com)
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