Featured Image (Credits ISRO)

Thursday, January 3, 2013

ISRO Reusable Launch Vehicle Program: AVATAR & TSTO

One of the Space Visions of ISRO is to enable low cost access to space, which is not possible with the present expendable launch systems. The present launch cost of expendable systems, is roughly 10,000 US $/ kg for LEO orbit and around 20,000 US $/ kg for GSO orbit.  ISRO is aiming to bring down this cost by half in the short term by the use of its new LVM3 (GSLV Mk3) and ULV expendable systems. But to make the harnessing of space resources more affordable, it is imperative that the cost of access to space must be substantially brought down by an order of magnitude. 

Demand and Costs of Launch systems (credit: BN Suresh ISRO)
Future needs demand reusability of launch systems (credit: BN Suresh ISRO)
To achieve low cost access to space, ISRO has chalked down a plan to develop a new breed of reusable launch system called AVATAR to substantially cut down the launch costs (vehicle hardware contributes 70% of the total cost of the launch vehicle that is presently expended after one launch).  AVATAR will be a Single Stage To Orbit (SSTO) launch system that will attempt to reuse maximum sub-systems and will use turbojet and dual mode ramjet-scramjet propulsion. The use of air-breathing ramjet-scramjet engines will preclude need for carrying all the propellants , particularly oxidizer, that will enable cutting the system cost. 

Reusable Launch Vehicles (credit: BN Suresh ISRO)
AVATAR SSTO launch system (credit ISRO)
Avatar is an ambitious program and with the kind of engine and material technologies required, such SSTO launch system will take a long time to develope. Accordingly, ISRO has decided to first develop a Two Stage to Orbit (TSTO) reusable launch system for the immediate future by utilizing its current capabilities and target development of AVATAR in the long term.  
TSTO for the immediate future  (credit: ISRO)
Targeted TSTO Features:

  • 10 Ton to LEO and GTO payload capability.
  • Vertical take off.
  • Semi-cryogenic booster stage with avg. Isp of 330 seconds and cryogenic orbiter stage with avg. Isp of 400 seconds. 
  • Total lift off weight < 700 tons. 
  • Winged body booster that will boost the orbiter to Mach 10 at an altitude of 80-100 km then separate and return to launch site and land conventionally on an air-strip.
  • Orbiter will deploy the payloads in the intended orbits and then deboost, re-enter  and land on airbags or vertically on legs. 
  • Vehicle structure designed for 100 flights and engines for 50 flights.
  • Turn around time should be 30 days. 
  • Payload fraction = 2%.
  • Cost effectiveness < 1000 US $/ kg for LEO payload.
Possible TSTO mission profiles:

To realize the TSTO and associated new technologies, ISRO has been working on the development of a RLV technology demonstrator (RLV-TD) and is setting up necessary technology development infrastructure.