Isro launches space docking satellites, India on path to elite club; PSLV last stage has 24 payloads

India on Monday got a step closer to becoming part of an elite group of nations with space-docking technology — ability to mate two spacecraft in space — with Isro’s putting two small satellites weighing 220 kg each, into orbit.
The satellites, part of the Space Docking Experiment (SpaDeX) mission, lifted off around little past 10pm on the PSLV-C60 from the first launchpad at the spaceport in Sriharikota. They were placed in a 475-km circular orbit some 15 minutes later. The first of the two satellites was separated 15.1 minutes after lift off, and the other happened at 15.2 minutes.
As per M Sankaran, director, UR Rao Satellite Centre (URSC), the satellites — ‘chaser’ and ‘target’ spacecraft — launched separately will initially be released with a small relative velocity between them.
As reported by TOI earlier, the satellites, through a series of carefully choreographed manoeuvres, will distance from each other over the next few days before Isro attempts to dock them. If Isro manages this successfully, India would have taken the first serious step towards mastering the technology, something only the US, Russia and China boast of as on date.

“The rocket has placed the satellite in the right orbit. The satellites moved one behind the other. Their distance will increase to about 20km over the next few days before we close the gap and attempt the docking. We’re hoping to complete docking in the coming week. The nominal date for this is Jan 7,” Isro chairman S Somanath said soon after the launch.
The mission is crucial for India’s future space endeavors including

Chandrayaan-4

and the planned Bhartiya Antriksh Station (BAS), as confirmed by Isro chairman S Somanath.

24 POEM Payloads

In addition to the primary docking experiment, the PSLV Orbital Experimental Module (POEM) carried 24 innovative payloads, including several groundbreaking experiments: India’s first astrobiology payloads are among the highlights, featuring RV College of Engineering’s microbiological experiment studying gut bacteria behavior in space, and Amity University’s investigation of spinach growth in microgravity.
Isro is also launching its own CROPS (Compact Research Module for Orbital Plant Studies) payload to demonstrate seed germination in space, a robotic arm designed to capture space debris and a sophisticated inter-satellite communication system. Isro will demonstrate a unique “walking” robotic arm with 7 degrees of freedom, intended for future space station operations.
The private sector has also sent payloads on POEM: PierSight, an Ahmedabad-based startup, launched Varuna, a precursor to what could be India’s first private Synthetic Aperture Radar (SAR) satellite for maritime surveillance. The company aims to establish a 32-satellite constellation by 2028 for comprehensive ocean monitoring.
The other payloads are Mumbai-based Manastu and Bengaluru’s Bellatrix Aerospace, both testing their respective green propulsion technologies, while GalaxEye from Bengaluru is showcasing their SAR signal processing technology and TakeMe2Space from Hyderabad is demonstrating nanosatellite subsystems.
Other educational institutions participating include SJC Institute of Technology and MIT World Peace University. SJC from Karnataka is sending a multimode message transmitter payload that can transmit audio, text, and image messages from a satellite to the ground using FM modulation and the VHF band. It is designed to provide amateur radio satellite services globally. It was designed in collaboration with Isro’s URSC.