ISRO Completes Its Reusable Launch Vehicle Technology Demonstrations Through LEX Trio

Space agency ISRO said on Sunday it has achieved a third consecutive success in the Reusable Launch Vehicle Landing Experiment by demonstrating the autonomous landing capability of the launch vehicle under more challenging conditions.

This mission simulated the approach and landing interface and high-speed landing conditions for a vehicle returning from space, reaffirming the Indian Space Research Organisation's expertise in acquiring the most critical technologies required for the development of a Reusable Launch Vehicle, or RLV, the space agency said.

The third and final test in the series of Landing Experiment, or LEX-03, was conducted at 7:10 1ST at the Aeronautical Test Range in Chitradurga, Karnataka.

Following the success of the RLV LEX-01 and LEX-02 missions, ISRO in a release said, RLV LEX-03 re-demonstrated the autonomous landing capability of the RLV under more challenging release conditions (cross range of 500 miles against 150 miles for LEX-02) and more severe wind conditions.

The winged vehicle, named 'Pushpak', was released from an Indian Air Force Chinook Helicopter at an altitude of 4.5 km from a release point 4.5 km away from the runway. "Pushpak autonomously executed cross-range correction manoeuvres, approached the runway, and performed a precise horizontal landing at the runway centerline," it said.

Due to this vehicle's low lift-to-drag ratio aerodynamic configuration, the landing velocity exceeded 320 km per hour, compared to 260 km per hour for a commercial aircraft and 280 kmph for a typical fighter aircraft, it said.

ISRO said that after touchdown, the vehicle's velocity was reduced to nearly 100 km per hour using its brake parachute, after which the landing gear brakes were employed for deceleration and stopping on the runway.

During this ground roll phase, Pushpak utilises its rudder and nose wheel steering system to autonomously maintain a stable and precise ground roll along the runway, it said.

According to the space agency, 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.

The space agency noted that this mission validated the advanced guidance algorithm that caters to longitudinal and lateral plane error corrections, which is essential for the future Orbital Re-entry Mission.

The RLV-LEX uses multi-sensor fusion, including sensors like an inertial sensor, radar altimeter, flush air data system, pseudolite system, and navIC, it said, adding, "Notably, the RLV-LEX-03 mission reused the winged body and flight systems as such without any modification from the LEX-02 mission, demonstrating the robustness of ISRO's capability of design to reuse flight systems for multiple missions."

The mission, led by Vikram Sarabhai Space Centre, was a collaborative effort involving multiple ISRO centres—Space Applications Centre, ISRO Telemetry, Tracking and Command Network, and Satish Dhawan Space Centre SHAR, Sriharikota.

The mission received significant support from the Indian Air Force, Aeronautical Development Establishment, Aerial Delivery Research and Development Establishment, Regional Centre for Military Airworthiness under the Centre for Military Airworthiness and Certification, National Aerospace Laboratories, Indian Institute of Technology, Kanpur, Indian aerospace industrial partners, the Indian Oil Corporation of India, and the Airport Authority of India.

S Somanath, Chairman, ISRO/Secretary, Department of Space, congratulated the team for their efforts in maintaining the success streak on such complex missions.

S Unnikrishnan Nair, Director of VSSC, emphasised that this consistent success boosts ISRO's confidence in the critical technologies essential for future orbital re-entry missions.

J Muthupandian is the mission director, and B Karthik is the vehicle director for this successful mission.