ISRO Docking Satellites Trial

Source: This post on ISRO Docking Satellites trial has been created based on article “ISRO to attempt ‘docking’ satellites in space: What it means, why it matters for future missions published in The Indian Express on 13^th January 2025.

UPSC Syllabus topic– GS Paper 3- Technology

Context: The article discusses the Indian Space Research Organisation’s (ISRO) upcoming attempt to demonstrate space docking through its Space Docking Experiment (SpaDeX) mission. This marks a significant milestone in India’s space technology capabilities, making it the fourth country to achieve this feat after the United States, Russia, and China. The experiment involves two small satellites, the Chaser (SDX01) and Target (SDX02), which will be maneuvered into close proximity and then joined together in orbit.

What is the docking experiment ISRO is attempting?

1. ISRO is attempting to dock two satellites, SDX01 (Chaser) and SDX02 (Target), in space for the first time.
2. This involves bringing the satellites closer together in orbit and joining them mechanically and electrically.
3. A successful attempt would make India the fourth country with this capability after the US, Russia, and China.

What is docking, and why is it important?

1. Docking Defined: Docking is the process of maneuvering two spacecraft into the same orbit, bringing them closer, and joining them, either manually or autonomously.
2. Importance:
   • Enables the assembly of heavy spacecraft in space.
   • Essential for building space stations like ISRO’s planned Bharatiya Antariksh Station.
   • Crucial for missions requiring multiple launches, such as crewed lunar missions or sample return missions like Chandrayaan-4.

When and how did the concept of docking originate?

1. First Docking: Achieved by NASA in 1966 during the Gemini VIII mission with the Agena target vehicle. It was crewed by astronauts, including Neil Armstrong.
2. First Automated Docking: Conducted by the Soviet Union in 1967 with Kosmos 186 and 188.
3. China’s Achievement: Demonstrated docking in 2011 with Shenzhou 8 and Tiangong 1, followed by its first crewed docking in 2012.

Why is ISRO conducting this docking mission now?

1. Long-Term Vision:
   • To set up a space station by 2035.
   • To achieve human lunar exploration by 2040.
2. Immediate Needs:
   • Docking technology is required for modular space station assembly.
   • Missions like Chandrayaan-4 will involve docking multiple modules in orbit to return lunar samples.
   • Testing technologies for autonomous and precision docking critical for future missions.

What will happen during the docking experiment?

1. Step-by-Step Maneuvering:
   • The satellites will drift closer, halting at key distances: 5 km, 1.5 km, 500 m, 225 m, 15 m, and 3 m.
   • At 3 meters, the docking rings will engage and lock.
2. Post-Docking Actions:
   • Satellites will share power and operate as a single unit.
   • Commands will be sent to both satellites simultaneously.
   • After undocking, the satellites will remain in orbit to conduct experiments for two years.

What is unique about India’s docking mechanism?

1. Androgynous Design: Both satellites have identical docking systems, similar to the International Docking System Standard (IDSS) but with only two motors compared to 24 in IDSS.
2. Advanced Sensors:
   • Laser Range Finder, Rendezvous Sensor, and others for precision measurements.
   • New processors using satellite navigation for relative positioning and velocity.
   • These advancements pave the way for fully autonomous docking in future missions.

What future missions will benefit from docking capability?

1. Bharatiya Antariksh Station:
   • Will consist of five modules assembled in orbit, starting with a robotic module launch in 2028.
2. Chandrayaan-4 Lunar Sample Return:
   • Requires docking of multiple modules in lunar and Earth orbits.
3. Human Lunar Mission:
   • Likely to follow a similar modular assembly approach.