Landmark Gaganyaan SMPS Hot Tests

On July 3, 2025, ISRO conducted two critical hot-fire tests of the Gaganyaan Service Module Propulsion System (SMPS) at its Mahendragiri Propulsion Complex in Tamil Nadu. The first lasted 30 seconds, followed by a more rigorous 100-second test. Both trials validated the system’s design accuracy against pre-launch predictions 0.

Thrusters & Engines: A Technical Breakdown

The SMPS consists of five Liquid Apogee Motors (LAM) each offering 440 N thrust and 16 Reaction Control System (RCS) thrusters delivering 100 N each. Notably, during the 100-second trial, all LAM engines and RCS thrusters operated simultaneously—demonstrating both steady-state and pulsed mode functionality. This simulation of in-flight and abort conditions is vital for crew safety 1.

Engineering Enhancements & Future Steps

ISRO’s Liquid Propulsion Systems Centre (LPSC) incorporated several design improvements from earlier campaigns to mimic real flight conditions. Following the successful hot-fires, ISRO plans a full-duration test before SMPS integration into the Gaganyaan Orbital Module 2.

Stepping Stones to Crewed Missions

These propulsion tests are integral to upcoming uncrewed missions: Gaganyaan‑1, Gaganyaan‑2, and Gaganyaan‑3, scheduled between late 2025 and 2026. The first crewed flight, Gaganyaan‑4, featuring astronaut-designate Group Captain Shubhanshu Shukla, is now set for Q1 2027 3.

Budget & Expanded Vision

The Gaganyaan programme’s scope and budget—initially around US $1.1 billion—were increased to US $2.32 billion in early 2025. This expansion supports six uncrewed and two crewed missions, development of India’s first space station module (BAS‑1), and lunar mission planning 4.

What Trivia Fans Should Know

• SMPS Engine Count: 5 LAM + 16 RCS thrusters.
• Test Durations: 30 seconds and 100 seconds.
• Tentative Gaganyaan‑1 Launch: Q4 2025.
• Crewed Flight Target: Q1 2027.
• Mission Budget: ₹20,000 crore (approx. US $2.3 billion).
• BAS‑1 Space Station: Cabinet cleared in September 2024.

Looking Ahead: India’s Space Odyssey

With major propulsion tests now cleared, ISRO is closer than ever to launching astronauts from Indian soil—joining the ranks of the US, Russia, and China. The coming years will focus on final uncrewed validations, astronaut training, and mission system integration as India embarks on its historic leap into human spaceflight.

Source: India Today