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India became the fourth country in the world to successfully dock two satellites in space and took the first step towards setting up its own space station -- Bharatiya Antriksh Station (BAS-expected to be in 2035), bringing samples from the moon and others, Indian space agency said.
The year 2025 opened well for the Indian Space Research Organisation (ISRO) with the mating of the two satellites launched under the SpaDex mission happening in the early hours of Thursday.
“Manoeuvre from 15m to 3m hold point completed. Docking initiated with precision, leading to successful spacecraft capture. Retraction completed smoothly, followed by rigidisation for stability. Docking successfully completed,” ISRO said.
On December 30, evening ISRO orbited the two satellites with its workhorse rocket Polar Satellite Launch Vehicle (PSLV-C60), Core Alone variant -- without the booster motors hugging the main rocket.
The SpaDeX mission consisted of two small spacecraft (about 220 kg each -- one called Target/SDX01 and the other Chaser/SDX02) and put into orbit independently and simultaneously, into a 470 km circular orbit at 55° inclination, with a local time cycle of about 66 days.
Earlier on January 12, ISRO brought the two spacecraft to three metres and then moved them back to safe distance in its trial attempt to dock the satellites.
The technology of mating satellites and other objects in space is essential when multiple rocket launches are required to achieve common mission objectives and also for sending people and cargo to space stations.
Aerospace and defence player Ananth Technologies Private Ltd had integrated two satellites for ISRO.
The Indian space agency had said post docking and rigidisation, electrical power transfer between the two satellites will be demonstrated.
Transfer of power is essential for applications such as in-space robotics, composite spacecraft control, and payload operations after undocking.
After that the two satellites will be undocked or separated so that their payloads can start operations. The mission life will be up to two years.
A High-Resolution Camera (HRC) with a 4.5 m IGFOV and a swath of 9.2 x 9.2 km (snapshot mode) and 9.2 x 4.6 km (video mode) from a 450 km altitude is mounted in SDX01. This is a miniature version of the surveillance camera developed by Space Applications Centre (SAC), ISRO.
A Miniature Multi-Spectral Payload (MMX) is mounted in SDX02, developed by SAC/ISRO. This has four VNIR bands (B1/B2/B3/B4) at 450 nm to 860 nm and a 25 m IGFOV with a swath of 100 km from a 450 km altitude. The imaging is useful for natural resource monitoring and vegetation studies.
A Radiation Monitor (RadMon) payload is mounted in SDX02, which will measure radiation dose encountered in space. This will help in generation of a radiation database for future Total Ionization Dosimeter (TID) and Single Event Upset (SEU) measurements for space science studies, with applications in human spaceflight.
Venkatachari Jagannathan can be reached at venkatacharijagannathan@gmail.com