India Scales New Heights with ISRO's Reusable Launch Vehicle (RLV)

On May 23^rd ISRO has successfully tested the reusable launch vehicle (RLV), a precursor to the spacecraft. In a major leap towards affordable launching of payloads into space ISRO test demonstrated RLV from the Sriharikota space port. A winged RLV-TD (Reusable Launch Vehicle-Technology Demonstrator) has been configured to test various technologies like the hypersonic flight, autonomous landing, powered cruise flight and hypersonic flight using air-breathing propulsion. RLV-TD is aimed at realising the Two Stage To Orbit (TSTO) fully reusable launch vehicle. These technologies are developed in phases through a series of experimental flights. In the initial hypersonic flight experiment (HEX), RLV-TD will lift off from HS-9 solid rocket booster and will be launched beyond earth’s atmosphere. After separation from the rocket, it will re-enter following the hypersonic regime. This feat was successfully accomplished by ISRO with the recent launch. It will be followed by gruelling landing experiment (LEX) where the performance of the turbofan engine will be monitored as RLV makes a computer aided horizontal landing. In the Return Flight experiment (REX) RLV will be launched into orbit and then enters re-enters. Finally during the Scram Jet Propulsion Experiment (SPEX) entire profile of RLV will be tested with a scramjet engine (Supersonic combustible ramjet). Final stage will be crucial wherein the scram jet compresses atmospheric oxygen and uses it to ignite the liquid hydrogen fuel. The resulting water vapour pushed out through a nozzle generates the needed thrust.  

In the preliminary tests carried out yesterday, a double-delta winged vehicle was launched by the two staged Rohini sounding rocket.  The winged vehicle fitted with solid strap on thrusters similar to those used in PSLV’s will take-off vertically and land horizontally like an aircraft. The prototype, 1.65 mt long, weighing 1.75 tonnes after reaching an altitude of 56 mts separated from the boosters. After reaching an incline of 65 mts, vehicle made re-entry into earth’s atmosphere at five times the speed of sound (Mach 5). Steered by the control systems guiding its navigation, the vehicle made a safe descent into Bay of Bengal at a pre-determined destination of 450km away. The current HEX was aimed at testing hypersonic re-entry into earth’s atmosphere, its survivability, vehicle re-entry capability, characterisation of aerodynamic design, validating avionics, guidance systems, testing thermal protection systems (TPS). Recovery experiments were validated by ISRO previously. Total duration of the flight from launch to landing of the RLV-TD lasted for 770 seconds. These included recovery of the unmanned 555-kilogram Space Capsule Recovery Experiment (SRE-1) launched by PSLV on January 10^th 2007 and recovered on January 22^nd from Bay of Bengal. This was followed by recovery of the Crew Module Atmospheric Re-entry Vehicle (CARE) launched by GSLV Mark-3 on December 18^th 2014. The current experiment is third one in a row. Hence landing and recovery are not prime aspects of current launch. Each phase of testing will focus on the different aspects involved in developing a spacecraft.

Water landing has been planned as India doesn’t have a run way of 5 km. In subsequent steps attempts would be made to land the vehicle on the runway by releasing it from an aircraft from a height of about 5 km.  In subsequent experiments, attempts will be made to take it to a higher altitude and prepare for ground landing. The current project is a concerted of 600 scientists who worked for over 5 years expending 95 crores.

Ever since US retired from the space shuttle program in 2011 private space companies like Space X and Blue Origin have been working towards developing the winged vehicles that can make horizontal landing. Now Europe is developing mini-space shuttles and in February 2015, a prototype Intermediate Experimental Vehicle (IXV) was successfully tested. But European Space Agency is suffering from numerous delays and funding problems. The Hope-X of Japanese Space Agency started in 1980 is now scrapped. The US Space Shuttle first launched in 1981 carried out 135 missions till July 2011 when it was finally decommissioned. It had a fleet of five orbiter space planes: Atlantis, Challenger, Columbia, Discovery and Endeavour. Columbia and Challenger were destroyed following tragic accidents. These were developed to deploy satellites into orbits, carry scientific experiments, to service and repair International Space Station & orbiting satellites and to carry out military operations. These constituted the Space Transportation System (STS) and they had orbiter, propulsion systems-two solid rocket boosters (SRB), three main engines and an external fuel tank. Buran, the space shuttle of Russia started in 1973 in response of US Space Shuttle Program completed one unmanned space flight in 1988 before its cancellation in 1993 following the collapse of Soviet Union. Till now only US, Russia, Europe and Japan successfully launched space shuttles.

Traditionally, a reusable vehicle system (RLV) is designed to carry a launch vehicle into space more than once. In contrast the expendable satellite launch vehicles that are launched once and discarded as different stages burn off and separate from the vehicle. Space exploration and space utilisation are often deterred by huge expenses incurred in building instruments for space access. The cost of delivering 1 kilogram of payloads into designated orbit using conventional rockets is $12000. India currently spends Rs 300 Crores annually on satellite launches. The lofty challenge of sending payloads to even Low Earth Orbits (LEO) even after 55 years of initial space affair remained a formidable task. Even now the advanced rockets could hardly carry 2% of the vehicle launch load. Scientists eventually hit upon the promising idea of using RLV to cut down the expenses by 10 times through recovery of solid rocket boosters using parachutes. RLVs are basically preferred to achieve economies of scale. The recent technology demonstrator is mere initial test success before reaching the milestone of developing a technologically full-fledged Indian Space Shuttle. Lowering cost of space flights can increase affordability boosting the lucrative business of space travel.

Despite being a test demonstration, RLV-TD received international attention since ISRO with its amazing economies of scale has caught the imagination of the west. Notwithstanding the sophistication and excellence attained by NASA, a comparison is drawn between NASA and ISRO with regards to cost benefit ratio. West seriously considers India as a potential competitor and is now keenly following every move of ISRO. But for India the dream of an Indian Space Shuttle is still 10-15 years away. Currently ISRO is keen on capturing the global space market for mid-range satellite segment. The focus on RLV now is to carry payloads and not for carrying astronauts. In the meanwhile developing the RLV technology can be an excellent option as it can potentially enhance the capabilities and competencies of ISRO.

 @ Copyrights reserved.