RLV LEX: The Indian Space Research Organisation's (ISRO's) reusable launch vehicle prototype, called Reusable Launch Vehicle - Technology Demonstrator (RLV TD), successfully performed an autonomous approach and landing test on a runway in the early hours of Sunday, April 2.
The air-drop landing experiment, called RLV LEX, was conducted in collaboration with the Defence Space Research Organisation (DRDO) and the Indian Air Force (IAF) at the Aeronautical Test Range (ATR), Chitradurga, Karnataka.
The air-drop landing experiment marks the first time a winged body has been carried to an altitude of 4.5 kilometres by a helicopter and released for carrying out an autonomous landing on a runway.
Watch RLV TD's autonomous approach and landing here:
ISRO conducted the first experimental mission of RLV-TD on May 23, 2016, from Satish Dhawan Space Centre, Sriharikota. As part of this experimental mission, critical technologies such as autonomous navigation, guidance and control, and the reusable thermal protection system were successfully demonstrated.
All about ISRO’s RLV LEX mission
One of the critical technologies that ISRO had to demonstrate was the approach and autonomous landing of RLV-TD on a runway. The Indian space agency accomplished this milestone as part of the RLV LEX mission. This was the second phase of the technology demonstration missions for the reusable launch vehicle prototype.
For the mission, the RLV-TD was carried at 7:10 am IST by a Chinook Helicopter of the Indian Air Force, as an underslung load. The RLV-TD flew to a height of 4.5 kilometres above mean sea level, ISRO said in a mission update.
Once the predetermined parameters were attained, the RLV-TD was released mid-air. The release conditions included 10 parameters, such as position, velocity, altitude and body rates, among others.
RLV-TD was released autonomously. After being released, it performed approach and landing manoeuvres using its Integrated Navigation, Guidance and Control System.
RLV-TD completed an autonomous landing on the ATR air strip at 7:40 am IST. With this, ISRO has successfully achieved the autonomous landing of a space vehicle.
The autonomous landing of RLV-TD was carried out under the exact conditions required for the landing of a space vehicle that has re-entered the atmosphere.
Conditions were simulated in a way such that the vehicle's speed was the same as what it would have had while arriving from space.
Landing parameters such as ground relative velocity, the sinking rate of landing gears, and precise body rates, which are likely to be experienced by an orbital re-entry space vehicle in its return path, were also taken into consideration.
The vehicle exhibited a high-speed autonomous landing at 350 kilometres per hour.
What's next?
Now that the RLV-LEX mission is complete, ISRO aims to accomplish the RLV Orbital Re-Entry Experiment (RLV ORE) milestone, according to the Vikram Sarabhai Space Centre (VSSC). As part of this mission, an ascent vehicle derived from the existing Geosynchronous Satellite Launch Vehicle (GSLV) and Polar Satellite Launch Vehicle (PSLV) stages will take a winged-body called orbital re-entry vehicle to orbit. The orbital re-entry vehicle will stay in orbit for a fixed time, and then re-enter Earth's atmosphere.
After this, the vehicle will autonomously land on a runway with a landing gear.