This is among the space agency’s most challenging endeavours towards developing essential technology for a fully Reusable Launch Vehicle (RLV) in the future

Before the end of April, the Indian Space Research Organisation (ISRO) is to bring to a crucial phase its ambitious plan to develop the two-stage-to-orbit reusable launch vehicle. At a DRDO (Defence Research and Development Organisation) airstrip in Karnataka’s Chitradurga, 220 km from Bengaluru, the space agency is to test the landing capabilities—a critical component—of India’s Reusable Launch Vehicle (RLV) technology.

The RLV Landing Experiment, or RLVLEX, involves taking an unmanned, winged prototype to an altitude of 2.3-2.4 km on a helicopter and releasing it to land on the airstrip. “The prototype will be released 3.7 km away from the airstrip and it must travel the distance on its own, gain velocity, maintain control and come in like any typical aircraft, touching down with the rear wheels first. A parachute will then be deployed for braking,” says ISRO chairman S. Somanath about the technology demonstrator.

This is among ISRO’s most challenging endeavours towards developing essential technologies for a fully RLV. A series of experiments are essential to prove the worthiness of the technology. ISRO is determined to establish RLV technology considering the prohibitive cost of launchers in space exploration. Cheaper access to space is what makes the RLV attractive.

The configuration of the RLV is similar to that of an aircraft, combining the complexity of both launch vehicles and aircraft. In future, this vehicle will be scaled up to become the first stage of India’s reusable two-stage orbital launch vehicle. It has been configured to act as a flying test bed to evaluate various technologies, including hypersonic flight, autonomous landing, powered cruise flight and hypersonic flight using air breathing propulsion. However, the testing and development for the first full-scale RLV flight is likely to take a decade.

In the run-up, a series of flights have been planned to demonstrate the different technologies, including the hypersonic flight experiment (HEX), autonomous landing experiment (LEX), return flight experiment (REX), scramjet propulsion (SPEX) for its air breathing engine, and the orbital re-entry experiment (ORE) wherein the launch vehicle will be ferried to orbit on a geostationary satellite launch vehicle (GSLV) or a polar satellite launch vehicle (PSLV), and then perform a winged re-entry into the atmosphere before executing an autonomous landing.

The first of these tests, the RLV-TD HEX-01 mission, took place on May 23, 2016. ISRO successfully tested RLV’s descent from an altitude of 65 km for an atmospheric re-entry at around Mach 5 (five times the speed of sound). The vehicle’s navigation, guidance and control system accurately steered it during this phase for safe descent. After successfully surviving high temperatures during re-entry with the help of its thermal protection system, the vehicle glided down to the defined landing spot over the Bay of Bengal, at a distance of about 450 km from Sriharikota in Andhra Pradesh.

Landing it on soil is crucial for the vehicle to be reusable. The LEX mission to demonstrate the critical technology of autonomous runaway approach and landing, which is happening at Challakere near Chitradurga, is therefore a quantum jump in establishing indigenous capability for the RLV. A scaled down version of the intended launch vehicle, without the payload capacity, is being used to demonstrate the necessary technologies to be used in the final RLV, whose first flight is expected in the 2030s.

The development of RLV, despite being on the ISRO drawing board for years, was put on the back burner following the sharper focus on the GSLV programme. The closure of the space shuttle programme in the United States in 2011, which involves RLV technologies, also contributed to the virtual shelving of ISRO’s RLV plans. Rockets in the future are meant to become reusable. While a small part will be destroyed while burning fuel during propulsion, the bulk will re-enter the atmosphere and land like an airplane for use in future missions. Reusable rockets will reduce cost and energy.

The fresh interest in RLVs worldwide has been triggered by the pioneering efforts of private companies like the Elon Musk-founded SpaceX in creating cost-effective launch vehicles that like aeroplanes can fly hundreds of times into space during their lifespan. SpaceX has since December 2015 demonstrated that not only the orbital second stage of a rocket but even the booster used in the first stage of the launch can be brought back to Earth and reused.

Apart from SpaceX, the European Space Agency, Japan’s JAXA space agency as well as private companies like Blue Origin, founded by Amazon founder Jeff Bezos, and the Orbital Sciences Corporation are in the race to develop a fully reusable space launch vehicle. “RLV is a priority. It will bring down the cost of launches drastically. Similarly, we need launch vehicles that can be used up to 15 times. Any scaling down of costs would reflect on more launches and eventually take its benefits to more people,” says Somanath. The Challakere landing this week re- establishes that India and ISRO are not laggards when it comes to space ventures.