What is SOLVE?
SOLVE, which stands for Sub-Orbital Launch Vehicle for Experiments, is a new test rocket developed by the Indian Space Research Organisation (ISRO). Its primary purpose is to support the Gaganyaan program, India's ambitious mission to send astronauts
into orbit. Unlike the giant rockets that push spacecraft into orbit, SOLVE is a smaller, sub-orbital vehicle designed for a very specific job: testing the parachute system for the Gaganyaan crew module. On July 3, 2026, ISRO successfully conducted the first ground test of the solid motor that will power SOLVE, marking a major milestone. The test, held at the Satish Dhawan Space Centre in Sriharikota, confirmed that the motor's performance met all expectations.
A Clever Adaptation of Proven Technology
The genius of SOLVE lies in its engineering. Instead of designing a completely new vehicle from scratch, ISRO engineers cleverly adapted existing technology. The solid motor for SOLVE is derived from the strap-on boosters used on India’s workhorse rocket, the Polar Satellite Launch Vehicle (PSLV). These strap-on motors are powerful, reliable, and well-understood, having flown on numerous successful PSLV missions. For SOLVE, the motor was modified to meet the unique needs of the Gaganyaan test flights. Key changes include the development of a slower-burning propellant and a new steering system. This approach of repurposing proven hardware is a hallmark of ISRO’s frugal innovation, saving both time and resources while ensuring reliability.
Simulating a Critical Return
The main job of SOLVE will be to carry a dummy Gaganyaan crew module to an altitude between 10 and 17 kilometres. Once it reaches the target height, it will release the module, simulating a crucial phase of its return to Earth. The focus of these tests is the complex parachute system, which involves a sequence of 10 different parachutes deploying to safely slow the module down before it splashes into the sea. Ensuring this system works perfectly every time is non-negotiable for astronaut safety. The SOLVE vehicle gives ISRO a flexible and dedicated platform to conduct these vital integrated parachute tests under various flight conditions, something that is critical before any human flies aboard Gaganyaan.
Building on a Legacy of Innovation
While SOLVE is a new application, the idea of repurposing PSLV components is not entirely new for ISRO. For several years, the agency has been using the spent fourth stage of the PSLV rocket as an in-orbit scientific platform called the PSLV Orbital Experimental Module (POEM). Instead of letting the final rocket stage become space debris after deploying its satellite payload, ISRO gives it a second life. The POEM stage is stabilised and used to host experiments from startups, universities, and other institutions, providing a low-cost way to test new technologies in space. The development of SOLVE builds on this same philosophy of extracting maximum value from every piece of hardware, further cementing ISRO's reputation for world-class innovation and efficiency.
