ISRO’s SpaDeX Mission

• Context (IE): ISRO successfully completed the docking of two satellites as part of the SpaDeX Mission, thus making India the fourth country to dock satellites, after the USA, Russia & China.

About Space Docking Experiment (SpaDeX) Mission

• SpaDeX Mission is a cost-effective technology demonstrator mission that will demonstrate in-space docking using two small spacecraft (‘Chaser’ and ‘Target’) designed to be launched from a single PSLV class vehicle and to dock at an altitude of about 700 kilometres.
• Objective: SpaDeX mission aims to demonstrate rendezvous, docking, and undocking technologies, focusing on key technologies like electrical power transfer between the docked spacecraft, in-space robotics, and conducting payload operations after undocking.
• First Experiment: SpaDeX is ISRO’s first satellite docking experiment.
• Launch Details: Launched on December 30, 2024, from Sriharikota by ISRO’s PSLV-C60, placing two 220-kg satellites in a 475-km circular orbit.
• Duration: The mission will run for 2 years.
• Docking Process: The spacecraft will reduce the distance from 20 km to 3 m.
• Biological Research: SPADEx will support biological studies on plant growth and bacteria, green propulsion systems and artificial intelligence labs in microgravity.

What is Orbital/Space Docking?

• Orbital docking is joining two space vehicles together in space. The docking process can be temporary or semi-permanent. For e.g., space station modules can dock with International Space Station (ISS).
• This process, whether manned or unmanned, allows those to operate as a single unit for critical tasks such as refuelling, repair, and crew exchange.

Technologies Involved

• Sensor Suite: Laser Range Finder, Rendezvous Sensor, and Proximity & Docking Sensors were used for precise measurements during the docking process.
• SpaDeX A (Chaser) is equipped with a high-resolution camera for monitoring & imaging, SpaDeX B (Target) carries a multispectral payload, radiation monitor & other scientific tools.
• Robotic Experimentation: Robotic arms will be validated for satellite servicing.
• Docking Mechanism: Androgynous, using identical systems on both satellites.
• POEM (PS4 Orbital Experiment Module): The fourth stage of PSLV will be repurposed to test critical in-orbit technologies, including docking and power transfer.
  • CROPS mission utilised the PSLV Orbital Experiment Module (POEM)-4 platform to cultivate cowpea seeds in a controlled environment with active thermal management.

Indigenous Technologies Involved

• Inter-Satellite Communication Link (ISL) for autonomous communication.
• GNSS-based Relative Orbit Determination Processor for determining spacecraft positions & velocities.
• Autonomous Rendezvous and Docking Strategy developed for precise operations.

Significance of the Mission

• Space Docking is crucial for future space missions such as:
  • Chandrayaan-4 for Moon sample return.
  • Bharatiya Antariksh Station  planned for 2028.
  • Satellite Servicing and Maintenance to extend operational lifespans of satellites.
  • In-space Robotics and future satellite missions for resource monitoring.
• Paves Way for the Third Launch Pad at Sriharikota: Approved for the Next Generation Launch Vehicle (NGLV), supporting future space missions and enabling heavier satellite launches.
• Enhanced Indian Position: Only the US, Russia & China have successfully demonstrated space docking.
• Precision and Coordination: The SpaDeX mission demonstrates India’s ability to control spacecraft at high velocities, which is essential for future deep space missions.
• Self-Reliance: The mission showcases India’s growing space capabilities, moving closer to autonomous space operations.
• Need for Space Weather Monitoring: The mission underscores the importance of real-time space weather forecasts to ensure safe space operations, especially during solar maximum phases.

Impact of Solar Activity on SpaDeX

• Favorable Solar Conditions: The mission occurred during solar cycle 25 with reduced solar disturbances, avoiding interference from solar flares and coronal mass ejections (CMEs), and fewer sunspots, ensuring smooth docking operations.
• Space Weather Risks: Solar flares and CMEs can disrupt spacecraft operations, blinding sensors and causing communication breakdowns.
• Magnetic Storms: High-speed solar winds can lead to positional errors, complicating docking.