1.SpaDeX Mission

The Indian Space Research Organisation (ISRO) successfully executed a satellite docking experiment in the early hours of Thursday, “making India the fourth country” after the U.S., Russia and China to achieve this historic feat.

SpaDeX: Space Docking Experiment

Introduction

• SpaDeX (Space Docking Experiment) is an ISRO Technology Demonstrator Mission to showcase in-orbital docking capabilities.
• Significance
  • A giant leap for Indian space capabilities where two small-sized spacecraft perform autonomous rendezvous, docking, and undocking missions in low Earth orbit.
• Low Earth Orbit (LEO)
  • Low Earth Orbit (LEO) is the area around Earth where satellites orbit at an altitude of 2,000 kilometers (1,200 miles) or less. LEO is close enough to Earth for satellites to be used for communication, transportation, observation, and resupply. 

Mission Objective

• Major Objective
  • Design and demonstrate autonomous docking capability between two satellites:
    • SDX01 (Chaser): Actively seeks out the target to dock.
    • SDX02 (Target): Passively waits to be docked.
  • Advanced sensors and propulsion systems are used with Bharatiya Docking System (BDS) to achieve docking.
• Auxiliary Objectives
  • Test direct electric power transfer between spacecraft.
  • Demonstrate improved spacecraft control.

Mission Design

• Launch
  • Two satellites, SDX01 and SDX02, are launched to a 470 km orbit with the Polar Satellite Launch Vehicle (PSLV).
  • Satellites drift apart and then approach and dock at distances of 20 km to 3 meters.
• Bharatiya Docking System (BDS)
  • Identical and androgynous design (same mechanism for both satellites).
  • Low-impact approach with velocities around 10 mm per second, ensuring precision and flexibility for future missions.
• Duration
  • Two years.
• POEM-4
  • PSLV’s fourth stage carries 24 microgravity experiments from academic institutions and startups along with SpaDeX.

Challenges in Space Docking

• The spacecraft orbit Earth at 28,800 km per hour.
• Relative velocity has to be decreased to 0.036 km per hour prior to docking, requiring precise control and synchronization.

Definition and Applications of Space Docking

• A process where two orbiting spacecraft align, approach, and join to form a single unit.
• Applications
  • Assembly of large structures, such as the International Space Station.
  • Crew and supply transfers.
  • Maintenance of orbiting systems.

In-Space Docking

Docking in space is the process of two spacecraft physically joining together. It’s an important operation for maintaining a continuous human presence on the International Space Station (ISS).

How it Will Work?

• The docking mechanism works by “hugging” action, where the chaser satellite enters the target satellite and pulls the target towards the chaser.
• The satellites will also indicate successful connection with the ability to transfer power.

Why Space Docking Technology Is Important for India

• Modular Space Infrastructure
  • Enables the building of large multi-modular structures, which is a critical need for the proposed Bharatiya Antariksh Station.
• Interplanetary and Lunar Missions
  • Supports orbital refueling and payload exchange for missions such as Chandrayaan-4 and further enables lunar bases and Mars missions.
• Human Spaceflight Program
  • Critical for crew transfer and emergency evacuation in long-duration missions, such as Gaganyaan.

• Global Partnership and Market Exploration
  • India becomes the fourth country to master docking after Russia, the US, and China.
  • Unlocks opportunities for satellite servicing, international cooperation, and next-generation space collaboration.
• Satellite Servicing
  • Enables in-orbit repairs, refueling, and upgrades to extend the life of satellites and their capabilities.