Following the triumph of Chandrayaan-3, the Indian Space Research Organisation (ISRO) is in full swing, focusing on the advancement of technologies pivotal for the Chandrayaan-4 mission, set to return lunar rock samples to Earth. Scheduled for launch in the latter part of this decade, Chandrayaan-4 will entail intricate in-orbit spacecraft docking, a critical step in securely retrieving lunar samples.

SPADEX, or Space Docking Experiment, is a mission developed by the Indian Space Research Organisation (ISRO) to test technologies for orbital rendezvous, docking, and formation flying. The mission involves two satellites, the Chaser and the Target, which will attempt to dock and separate as a mock drill for the Moon mission. 

SPADEX is a twin spacecraft mission aimed at testing technologies for orbital rendezvous, docking, and formation flying. The mission, costing ₹124.47 crore, involves two satellites, a Chaser and a Target, which will attempt docking and advance human spaceflight capabilities.

Two IMS Satellites with docking locks

SPADEX or Space Docking Experiment is a twin spacecraft mission being developed by the Indian Space Research Organisation (ISRO) to mature technologies related to orbital rendezvous, docking, formation flying, with scope of applications in human spaceflight, in-space satellite servicing and other proximity operations.

The SPADEX mission involves a spacecraft with two components - Chaser and Target - that will dock and separate as a mock drill for the Moon mission. While in the low-Earth orbit (LEO), the Chaser and Target will separate only to rendezvous autonomously later on.

The SPADEX mission involves launching two spacecraft, the Chaser and the Target, which will engage in a complex and autonomous docking procedure in orbit. The successful execution of this manoeuvre will exemplify ISRO's advanced capabilities in space navigation and robotics.

The mission will help advance human spaceflight capabilities and has applications in in-space satellite servicing and other proximity operations. The successful execution of the docking procedure will demonstrate ISRO's advanced capabilities in space navigation and robotics.

The ground breaking technology pivotal for this mission is poised for testing during the ongoing development of the SPADEX (Space Docking Experiment) mission. The launch date for the mission is yet to be finalised. The mission, conceptualised to refine capabilities in orbital rendezvous, docking, and formation flying, is making substantial progress.

Comprising two IMS class satellites, weighing 200 kg each, the SPADEX initiative features a twin spacecraft system: a Chaser and a Target. These spacecraft are designed to execute precise orbital manoeuvres, marking significant advancements in human spaceflight, in-space satellite servicing, and other proximity operations.

Scheduled for launch aboard the Polar Satellite Launch Vehicle from the Satish Dhawan Space Centre, the SPADEX campaign will witness both spacecraft being injected into marginally distinct orbits, a critical aspect of the experimental mission.

The primary objectives of the SPADEX mission encompass autonomous rendezvous and docking capabilities, including the unique task of controlling one spacecraft using the Attitude Control System of the other while in a docked configuration.

Furthermore, the mission aims to demonstrate formation flying techniques and conduct remote robotic arm operations, signalling a leap forward in space technology.

The journey towards the realisation of SPADEX began with preliminary studies in 2016, culminating in the project's approval by the Government of India in 2017, initially backed by a ₹10 crore funding allocation. ISRO subsequently sought proposals in June 2019 to explore remote robotic arm operations and related technologies on the PSLV fourth stage (PS4) orbital platform, further solidifying the mission's development.

Currently, the SPADEX mission has received a substantial funding injection, amounting to around ₹125 crore.