The Indian Space Research Organisation (ISRO) successfully demonstrated the landing of the Pushpak reusable launch vehicle for the third time on Sunday, bringing it one step closer to using the vehicle for an orbital mission. Announcing the success, the space agency wrote on X, ‘Hat-trick for ISRO in RLV LEX! ISRO achieved its third and final consecutive success in the Reusable Launch Vehicle (RLV) Landing EXperiment (LEX) on June 23, 2024. “Pushpak” executed a precise horizontal landing, showcasing advanced autonomous capabilities under challenging conditions. With the objectives of RLV LEX accomplished, ISRO embarks into RLV-ORV, the orbital reusable vehicle.’ Interestingly, the third demonstration of Pushpak reused the winged body and flight systems from the second experiment without any modifications. To bring down launch costs and to remain competitive, the reusable launch vehicle is designed to take satellites up to space and return and land on a runway like an aeroplane. Unlike the SpaceX vehicle that lands back vertically, to achieve the horizontal landing ISRO’s vehicle has wings to help it glide. The third demonstration, undertaken using a helicopter in Chitradurga, Karnataka, was to test the vehicle in more challenging conditions—when there is a higher degree of deviation from the intended orbit while the launch vehicle comes down and when there are more severe wind conditions. The deviation during the third demonstration was 500 m as compared to 150 m during the previous experiment, according to the space agency. The winged vehicle was dropped from an altitude of 4.5 km by an Indian Air Force Chinook helicopter. After release, the vehicle autonomously undertook manoeuvres to correct course and precisely landed on the centreline of the runway. The space agency also said the aerodynamic design of the vehicle, which means a low drag on it when landing, led to the velocity exceeding 320 kmph on Sunday. For comparison, the velocity at landing for commercial planes is 260 kmph and for fighter planes it is 280 kmph. After touchdown, the vehicle’s velocity was reduced to nearly 100 kmph using its brake parachute. Then the landing gear brakes were deployed for further deceleration and stopping on the runway. “This mission simulated the approach and landing interface and high-speed landing conditions for a vehicle returning from space, reaffirming ISRO’s expertise in acquiring the most critical technologies required for the development of a Reusable Launch Vehicle (RLV),” the space agency said. Sunday’s demonstration validated one of the critical technologies needed for the reusable launch vehicle—an advanced algorithm for correcting longitudinal and lateral plane errors. The vehicle uses multiple sensors such as inertial sensor, radar altimeter, pseudolite system (a ground-based positioning system), as well as the country’s own NaVIC satellite-based positioning system.
