SPADEX A, B

SPADEX [ISRO]

SPADEX (Space Docking Experiment) is an Indian technology mission to demonstrate autonomuos docking.

This project will develop and demonstrate the technologies needed for docking two spacecraft (Chaser and Target) and to control one spacecraft from the Attitude Control System of other spacecraft in the docked condition. Subsequent to docking, the Chaser and Target will be separated so that they would carry-out their designated experiments with payloads. This technology will be a forerunner to future planetary missions including crew transfer, international participation etc.

SPADEX spacecrafts named as Spacecraft A and Spacecraft B are built on an extended Microsat Bus, each with a mass of approximately ~220 kg. These spacecrafts are androgynous in nature i.e. either of the spacecraft can act as chaser (active spacecraft) during docking. They are equipped with solar panels, lithium-ion batteries, and a robust power management system. The Attitude and Orbit Control System (AOCS) includes sensors such as star sensors, sun sensors, magnetometers, and actuators like reaction wheels, magnetic torquers, and thrusters.

The docking mechanism of SPADEX is motor-driven, featuring capture, extension/retraction, and rigidization mechanisms. There is also a power transfer connector mechanism for experimental power transfer post-docking and a video camera tilt mechanism for monitoring the docking process. The docking procedure is meticulously planned with multiple phases: initial separation and controlled drift, sequentially closer approach phases with hold points for safety and control, and the final docking phase with capture, retraction, and rigidization.

For standalone mission phases after docking experiments, the spacecrafts are equipped with payloads. Spacecraft A is containing with High Resolution Camera (HRC) and Spacecraft B is accommodated with two payloads viz. Miniature Multispectral (MMX) payload & Radiation Monitor (RadMon). These payloads will provide high resolution images, natural resource monitoring, vegetation studies and onorbit radiation environment measurements which find numerous applications.