Does India have vertical takeoff and vertical landing guidance for rockets?

Reusing a rocket stage instead of discarding it lowers launch cost by 5 to 20 times. The software that makes reuse possible — guiding a booster from hypersonic descent to a pinpoint upright touchdown — is held by only three nations: the United States, China and India.

The hard part is not the engine. It is the guidance. A returning stage must predict its own trajectory in real time, correct for wind and cross-range error, and command thrust and steering surfaces down to the last metre — all autonomously, with no human in the loop. Cold gas thrusters trim attitude, grid fins steer through the atmosphere, and a re-ignitable, throttleable engine arrests the fall. The onboard navigation, guidance and control system must fuse all of this fast enough to survive a descent from hypersonic speed.

India has demonstrated the guidance half of this problem on a winged vehicle. ISRO completed three consecutive autonomous landing experiments — RLV LEX-01 through LEX-03 — with the RLV-TD, beginning with the 2 April 2023 release from 4.5 km altitude. The final test, RLV LEX-03 on 23 June 2024 at the Aeronautical Test Range in Chitradurga, re-demonstrated autonomous landing under harder conditions: 500 metres of cross-range against 150 for LEX-02, and more severe winds. The integrated navigation, guidance and control system held.

What India has not yet demonstrated is retro-propulsive booster recovery — the vertical descent under engine thrust that SpaceX first achieved with a Falcon 9 in December 2015, and has since repeated across more than 500 booster recoveries at reuse rates above 90 percent. ISRO is developing this separately through ADMIRE, a test bed for vertical landing technology aimed at retro-propulsion capabilities comparable to the Falcon 9.

The gap persists because winged landing and retro-propulsive landing are different control problems. A gliding vehicle bleeds energy aerodynamically; a booster must balance on its own thrust, a fundamentally harder stabilisation task. The foundational pieces — inertial navigation, throttleable restartable engines, cold gas reaction control, deployable landing legs — are in production or demonstrated. What remains is integrating them into a single autonomous descent.

Closing the gap runs through the Next Generation Launch Vehicle, designed to replace the PSLV with a reusable first stage using vertical landing technology. Vikram Sarabhai Space Centre is developing the steerable grid fins, deployable legs and advanced avionics required. The longer aim is a fully reusable two-stage-to-orbit system — the point at which demonstrated guidance becomes routine, recoverable flight.