ISRO's Spadex Mission to Demonstrate Satellite Docking on December 30

The Indian Space Research Organisation (ISRO) is set to close the year with the Spadex mission, scheduled for launch at 9:58 pm on December 30 from the Sriharikota spaceport. This mission involves two satellites, SDX01 (Chaser) and SDX02 (Target), aimed at demonstrating docking capabilities in orbit. By showcasing the alignment, connection, and power transfer between these satellites, the mission is expected to pave the way for future endeavours, including the Chandrayaan-4 and the proposed Bharatiya Antariksh Station.

Mission Details and Objectives

According to reports, the Polar Satellite Launch Vehicle (PSLV-C60) will place the 220-kg satellites into a 470-km circular orbit. The satellites will begin by separating to a distance of 10–20 km using relative velocity adjustments provided by the rocket. The Target satellite's propulsion system will then maintain this distance to prevent further drift, marking the start of what is referred to as the "far rendezvous." Gradual approaches by the Chaser satellite will follow, reducing the gap in calculated stages until docking is achieved.

Once docked, the satellites will demonstrate electrical power transfer and joint spacecraft control. Following separation, both satellites will operate their respective payloads, which are designed to function for two years.

Technological Highlights and Payloads

The Spadex mission is reported to employ innovative technologies, including docking mechanisms and advanced sensors, ensuring precision during the docking process. A relative orbit determination and propagation system, based on navigation constellations, is also part of this mission. The Chaser satellite features a high-resolution miniature surveillance camera, while the Target satellite carries a multispectral payload for monitoring vegetation and natural resources. A radiation monitor onboard the Target will collect space radiation data for analysis.

Additional Experiments

As per several reports, the rocket's final stage will host experiments involving 24 payloads, including a robotic arm for debris capture and a study on seed germination and plant growth. The mission marks a significant leap in demonstrating small satellite docking, a challenging feat requiring precise control and coordination.