ISRO's SpaDeX mission postponed for the third time: Here's why

Today marked the third attempt for the docking process, which had already been postponed twice prior. The complex procedure of bringing two satellites together in space is known as space docking.

This latest attempt kicked off just after midnight, and using the slow drift technique, ISRO managed to narrow the gap between the two satellites down to 15 meters. At that moment, the organization indicated that the satellites were primed to meet. 

During a previous attempt on January 9, the satellites were initially 230 meters apart when the drift exceeded expectations, forcing another postponement. 

Today, as the distance shrank to 15 meters early in the morning, hopes soared across the country for a successful docking. The satellites remained in that position for a while, capturing images and videos of each other. However, when the attempt was made to reduce the distance further from 15 to 3 meters, things took a turn for the worse, leading to both satellites being moved to a safe distance from one another. In the prior attempt, excessive drift had proven problematic. To successfully dock, the satellites must align perfectly; even the slightest directional deviation can jeopardize the process.

ISRO scientists managed to stabilize the drift at zero degrees, but there was a delay in receiving signals from a crucial sensor. Sources at ISRO indicated that an issue was detected with the proximity and docking sensor, which is essential for a successful docking. For safety reasons, the onboard systems are designed to automatically shift the satellites to a safe distance if any disturbances occur. That exact scenario unfolded today. 

Currently, a detailed assessment is underway to troubleshoot the problem with the proximity and docking sensor, and the next docking attempt will only take place once the issue is resolved. 

According to ISRO officials, both satellites are expected to pass over the ISRO ground station later this evening, providing a potential opportunity for another docking attempt. However, if the problem persists, they may have to wait for the next chance. In fact, sources revealed that after two days, visibility of the two satellites from India’s ground station will be lost, pushing the next docking opportunity possibly until March.