ISRO's Reusable Launch Vehicle passes landing test

 The Indian Space Research Organization(ISRO) on Sunday successfully conducted an experiment that it said would propel the country forward in its goal to send reusable rockets into space. The space agency conducted the "Reusable Launch Vehicle Autonomous Landing Mission(RLV LEX)" at the Aeronautical Test Range of the Defense Research and Development Organization (DRDO) in Karnataka's Chitradurga district.

According to ISRO, the RLV took off as the underslung load of a Chinook Helicopter of the Indian Air Force and , after reaching an altitude of 4.6 km, was released for carrying out an autonomous landing on a runway. This test was the second of five tests that are part of ISRO's effort to develop RLV's or space planes/shuttles, which can travel to low earth orbits to deliver payload and return to earth for use again. The experiment was carried out nearly seven years after the technology demonstration of an RLV and the first experiment was conducted successfully by ISRO in 2016, on the RLV-TD (HEX) mission.

ISRO's RLV-TD project

• According to ISRO, the series of experiments with the winged RLV-TD are part of efforts at developing essential technologies for a fully reusable launch vehicle to enable low-cost access to space.

• The RLV-TD will be used to develop technologies like hypersonic flight(HEX), autonomous landing(REX), powered cruise flight and Scramjet Propulsion Experiment (SPEX).
• In the future, this vehicle will be scaled up to become the first stage of India's reusable two-stage orbital (TSTO) launch vehicle.
• ISRO's RLV-TD looks like a aircraft. It consists of a fuselage, a nose cap, double delta wings, and a twin vertical tails.
• The spacecraft traveled at a speed of Mach 5 which is 5 times the speed of sound, when reentering the earth's orbit and traveled a distance of 450 km before splashdown in the Bay of Bengal.
• When the first experiment was done in 2016, ISRO officials described it as a "baby step " in the development of an RLV.
• A rocket carrying the 1.75 tonnes RLV-TD was launched into space for 91.1 seconds and reached a height of about 56 km, when the RLV-TD separated from the rocket and climbed to a height of about 65 km.
• From this height, the RLV-TD began its return to earth and entered the atmosphere at a speed of around Mach 5 and was navigated by the vehicle's own systems to a predetermined landing spot in the Bay of Bengal, around 450 km from the launch site at Sriharikota.
• The RLV was tracked during the flight from ground stations at Sriharikota and a terminal on a ship. While re-entry into the earth's atmosphere happen at a velocity of 8 km/sec the RLV TD HEX1 was tested at a much lower velocity of 1.7 km/sec to 2 km/sec. 

  
What are the advantages of Reusable rockets?

While the costs acting as a major deterrent to space exploration, a reusable launch vehicle is considered a low-cost, reliable, and on-demand mode of accessing space. By using RLVs the cost of a launch can be reduced by nearly 80% of the present cost. Reusable rockets have been in existence for a long time with NASA space shuttles carrying out dozens of human space flight missions. The use case for

reusable space launch vehicles has revived with the private space launch service provider Space X demonstrated partially reusable launch systems with its Falcon 9 and Falcon Heavy rockets in 2017.