ISRO Completes Key CM-SM Separation Tests for Gaganyaan Mission

ISRO has finished an important series of Crew Module and Service Module separation tests for the Gaganyaan programme. The tests were held at the Vikram Sarabhai Space Centre (VSSC) in Thiruvananthapuram on 16th October, 2026, and mark a major step before the first uncrewed flight.

What Is the Gaganyaan Mission?

Gaganyaan is India’s human spaceflight programme run by ISRO. Its aim is to send astronauts into low Earth orbit and bring them back safely. Before any crew flies, ISRO is testing each system through uncrewed missions. The first of these, called G1, is targeted for launch in 2026.

The spacecraft, called the Orbital Module, has two parts:

• Crew Module (CM): The part where astronauts stay and which returns to Earth.
• Service Module (SM): The part that supports the mission in orbit.

What Are Crew Module and Service Module Separation Tests?

The two modules are joined together before launch and work as one unit until the orbital phase ends. They are connected by a separation system and by umbilical lines that carry electricity and fluids between them.

Before re-entry into Earth’s atmosphere, the Crew Module must detach from the Service Module. This involves several precisely timed events using pyrotechnic devices and jettisoning systems. The CM-SM separation tests check whether this process works correctly.

ISRO CM-SM Test Overview & Objectives

ISRO built a full-scale test setup at VSSC with detailed instrumentation to copy the CM-SM assembly. The tests recreated the separation, including the cutting of several umbilical connections.

The main objectives were:

• Confirm that the separation system design is adequate.
• Ensure safe, clean separation just before re-entry.
• Show that important Crew Module systems can survive the shocks of separation.

What Type of Tests Were Conducted?

These were ground-based simulation tests of the separation system. They covered three areas:

• Mechanical separation test: Checked the pyrotechnic devices and jettisoning systems that detach the two modules.
• Umbilical disconnection test: Verified the smooth cutting of the electrical and fluid lines between the modules.
• Shock and vibration survivability test: Checked whether equipment inside the Crew Module can withstand the strong mechanical shocks created during separation.

Subsystems Tested for Shock Survivability

• Avionics systems
• Inertial Navigation Systems
• Thermal Protection System in the Aft and Conical Heat Shield
• Crew Module Deployable Umbilical Shield
• Pyrotechnic devices of the Crew Module Uprighting System
• Pyrotechnic devices of the Thermal and Humidity Control System