ISRO to test Reusable Launch Vehicle in March

In a major leap towards affordable launching of payloads into space ISRO is all set for a test demonstration of reusable space vehicle in March. A reusable vehicle system (RLV) is designed to carry a launch vehicle into space more than once. In contrast to 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 is 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 $5000. India currently spends Rs 300 Crores annually on satellite launches. Scientists has hit upon the promising idea of using Reusable Launch Vehicle- Technology Demonstration Program (RLV-TD) to cut down the expenses by 10 times. Also, a manned reusable space vehicle if developed can boost the lucrative business of space tourism as well. Along these lines, AVATAR (Aerobic Vehicle for Trans Atmospheric hypersonic Aerospace Transportation) was aimed at developing a single- stage reusable space vehicle capable of horizontal takeoff and landing by DRDO, ISRO and other institutions way back in May 1998 at the Aero 98 exhibition at Bangalore. Accordingly, it was approved in January 2012 to build and test a prototype RLV-TD by 2015 and the first manned AVATAR flight is proposed for 2025.

A winged RLV-TD 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 will be developed in phases through a series of experimental flights. The first in the series is the hypersonic flight experiment (HEX) followed by the landing experiment (LEX), return flight experiment (REX) and scram jet propulsion experiment (SPEX). The aerodynamics characterisation of RLV-TD was carried out by the National Aerospace Laboratories. The unmanned-prototype will weigh 12 tonnes at take-off and has a diameter of 0.56mt and length of 10 mts. RLV-TD will be mounted on the top of the rocket and would be launched beyond the atmosphere. After separation from the rocket, it will re-enter following the hypersonic regime.

The initial ground tests on the vehicle were completed by ISRO. It is now getting ready for the hypersonic flight and landing on water. It is actually a winged vehicle which will take off vertically and land horizontally like an aircraft. It is fitted with solid strap on thrusters similar to those used in PSLV’s. It will reach a speed of five times the sound (mach 5) to reach an altitude of 100 mts in five minutes. After ascent the vehicle will take a 180 degree turn and activates its control system for eventual re-entry and splashing into Bay of Bengal 20 minutes after takeoff. Water landing has been planned as India doesn’t have a run way of 5 km. In the 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. The third attempt would be to take it to a higher altitude and prepare for ground landing. The concept of reusable space vehicle is much popular among the private companies in the US and currently Space X a private company is developing reusable vehicles.

Scientists at Vikram Sarabhai Space Centre (VSSC) opined that if rocket structure is made of 98% of propellant and 2% of the structure then reusability is possible. But rocket structure doesn’t give such a lee way and usually rocket structure accounts for 5-10% and 90% of propellant. Propellant is not costly but the hardware is very sophisticated and expensive. It needs to be reused to make space travel affordable.

Attempts at developing a reusable vehicle haven’t been successful so far. Only two space shuttles have come closer the reusable vehicles. The US Space Shuttle developed by NASA and the Buran launch vehicles developed by Russia were only partially reusable. Some components were expendable.

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, used to service and repair International Space Station and 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 completed one unmanned space flight in 1988 but the programme was cancelled in 1993 following the dissolution of Soviet Union.

 

 

@ Copyrights reserved.