BENGALURU: Technical issues have erupted on ISRO’s first Space Docking Experiment (SpaDeX) mission, with the two spacecraft, SDX-01 and SDX-02, unable to undock.
The two had autonomously docked (get attached to each other) on January 16 — nine days after the initial plan of docking on January 7. Now, the undocking of these satellites, planned to be done by January-end or February first week, is also facing delays due to technical issues. A senior ISRO scientist involved in the SpaDeX mission informed TNIE that it is “likely to happen only in March-April”.
Undocking is the separation of two spacecraft, and although SpaDeX is a trial docking/undocking mission, separating the two is extremely crucial in a live mission for successfully meeting its objectives. “Power generation in the two spacecraft is not matching the requirements, and the composite control of both is also taking time due to which the undocking cannot be done,” he said.
SDX-01 and SDX-02, which have remained docked since January 16, carry some new technologies for docking/undocking mechanisms. These include a suite of four rendezvous and docking sensors; power transfer technology; an inter-satellite communication link (ISL) for autonomous communication between SDX-01 and SDX-02, incorporated with inbuilt intelligence to know the states of the other spacecraft; and Global Navigation Satellite System-based novel Relative Orbit Determination and Propagation processor to determine the relative position and velocity of the other spacecraft.
‘No fixed timeline...’
Anomalies in one or more of these systems could be posing technical issues preventing the two spacecraft from undocking smoothly.
The senior scientist said although there is no fixed timeline of when the docking and undocking were to be done, the technical issues now encountered could affect payload experiments on the two spacecraft.
As per the mission plan, after successful docking, electrical power transfer between the two spacecraft was to be demonstrated before separating the two. After separation, SDX-01 and SDX-02 were to begin operating their respective payloads for an expected mission life of up to two years.
SDX-01 carries a High-Resolution Camera (HRC) with a 4.5 m instantaneous geometric field of view (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.
SDX-02 is carrying two payloads — a Miniature Multi-Spectral Payload (MMX), the imaging of which is useful for natural resource monitoring and vegetation studies; and a Radiation Monitor payload to measure and generate database on radiation dose encountered in space, relevant to India’s first manned space mission Gaganyaan. ISRO launched the SpaDeX mission on December 30, 2024, with PSLV-C60 from Sriharikotta.