India launched the SpaDeX mission on December 30th for the demonstration of in-space docking using two small (480 pound) spacecraft launched by PSLV. This technology is essential for India’s space ambitions such as Indian on Moon, sample return from the Moon, the building and operation of Bharatiya Antariksh Station (BAS). The PSLV-C60 rocket lifted off from the Sriharikota launch site
In-space docking technology is essential when multiple rocket launches are required to achieve common mission objectives. This mission advances India towards becoming the fourth country in the world to have space docking technology.
According to ISRO, the primary objective of the SpaDeX mission is to develop and demonstrate the technology needed for rendezvous, docking, and undocking of two small spacecraft (SDX01, which is the Chaser, and SDX02, the Target, nominally) in a low-Earth circular orbit. Secondary objectives include:
Demonstration of the transfer of electric power between the docked spacecraft, which is essential for future applications such as in-space robotics
Composite spacecraft control
Payload operations after undocking
The docking mechanism is a low-impact docking system (approach velocity is in the order of 10 mm/s), androgynous (docking systems are identical for both spacecraft, Chaser & Target), and is a peripheral docking system (concept similar to the International Docking System Standard used by other agencies for human missions). The mechanism is smaller (450 mm) with one degree of freedom for extension and uses two motors compared to the IDSS (800 mm) on a hexapod with 24 motors. Multiple test beds were established to test the hardware and software simulation of the docking kinematics to verify and finalise the docking approach parameters.
The SpaDeX spacecraft were designed and realized by the UR Rao Satellite Centre (URSC) with the support of other ISRO centers (VSSC, LPSC, SAC, IISU, and LEOS). The spacecraft, in its orbital phase, will be controlled from ISTRAC using ISRO ground stations and other externally hired ground stations. The full integration and testing of the satellite were carried out at M/s Ananth Technologies, Bangalore, under the supervision of URSC. Presently, after completing all tests and clearances, the spacecraft has moved from URSC to SDSC and is undergoing preparations for launch.