Kick­start­ing space shut­tle – A ma­jor mile­stone

SP's MAI - - AEROSPACE VIEWPOINT - LT GEN­ERAL P.C. KA­TOCH (RETD)

Even as the In­dian Space Re­search Or­gan­i­sa­tion (ISRO) has launched 20 satel­lites from a sin­gle mis­sion in June 2016, on May 23, 2016, ISRO suc­cess­fully launched its pro­to­type space shut­tle that splashed down as planned in the Bay of Ben­gal, some 450 km from Sri­harikota. The launch was of the winged re­us­able launch ve­hi­cle (RLV), over­all cost be­ing ` 95 crore. Af­ter a suc­cess­ful lift on board a HS9 rocket booster that lasted 91.1 sec­onds to a height of about 56 km, the RLV-TD sep­a­rated from the HS9 booster and fur­ther as­cended to a height of about 65 km, then de­scended at about five times the speed of sound till splash­down to the de­fined land­ing spot. The ve­hi­cle was tracked dur­ing its flight from ground sta­tions at Sri­harikota and a ship-borne ter­mi­nal; val­i­dat­ing crit­i­cal tech­nolo­gies like au­ton­o­mous nav­i­ga­tion, guid­ance and con­trol, and re­us­able ther­mal pro­tec­tion sys­tem. The flight du­ra­tion from launch to splash­down was some 770 sec­onds.

While ISRO has un­der­taken tests of RLV tech­nol­ogy twice in the past, sev­eral na­tions and pri­vate space en­ti­ties have ex­per­i­mented with this tech­nol­ogy. NASA had closed its 1981 ini­ti­ated space shut­tle pro­gramme in 2011 af­ter us­ing its re­us­able ve­hi­cles Dis­cov­ery, En­deav­our, Columbia and Chal­lenger, to launch the In­ter­na­tional Space Sta­tion and the Hub­ble Tele­scope. In­ter­est­ingly, the DRDO had con­ducted a con­cept study in 2001 termed ‘Avatar’, acro­nym for Aer­o­bic Ve­hi­cle for Transat­mo­spheric Hyper­sonic Aero­space Trans­portaion; con­cept be­ing un­manned sin­gle-stage re­us­able space-plane ca­pa­ble of hor­i­zon­tal take-off and land­ing. But this re­mained a study only and is not linked to ISRO’s RLV-TD launch on May 23 this year.

ISRO’s ob­jec­tive of de­vel­op­ing the re­us­able sys­tem is to bring down the costs of satel­lite launch, and to in­crease the fre­quency of launches as satel­lites and sci­en­tific in­stru­ments need to ride on rock­ets to go into space. Re­us­able rock­ets would save costs of build­ing a new ve­hi­cle for ev­ery launch be­sides sav­ing on man­u­fac­tur­ing time and en­able more fre­quent launches. With­out RLV tech­nol­ogy, ve­hi­cles launched into space ei­ther fall into the sea or add to the fly­ing de­bris in space.

Cur­rently, it costs ` 6,00,000 to ` 8,00,000 to send a one kg pay­load into a low earth or­bit. The PSLV and GSLV carry pay­loads of 1,000-2,500 kg per flight. It is es­ti­mated that once the RLV is fully de­vel­oped it could bring down launch costs 8 to 10 times.

It may be re­called that in Jan­uary 2007, ISRO launched a 555-kg space cap­sule aboard PSLV-C7 that re­mained in or­bit for 12 days be­fore re-en­ter­ing the at­mos­phere and crash­ing into the Bay of Ben­gal. Again in De­cem­ber 2014, ISRO car­ried out the Crew Mod­ule At­mo­spheric Re-en­try Experiment, send­ing a heavy pay­load to a height of 126 km on the in­au­gu­ral ex­per­i­men­tal flight of GSLV-Mk III, an ad­vanced launch ve­hi­cle still un­der de­vel­op­ment. The pay­load sep­a­rated and re-en­tered the at­mos­phere, and fell into the Bay of Ben­gal af­ter a nearly 21-minute flight. How­ever, both these reen­tries were meant to re­sult in crash land­ings. The ve­hi­cle could be re­cov­ered but not reused.

The cost ad­van­tage of a re­us­able ve­hi­cle can be­come ev­i­dent only over sev­eral launches be­cause de­vel­op­ment cost of a RLV far ex­ceeds the man­u­fac­tur­ing cost of an ex­ist­ing launch ve­hi­cle of one-time use. While ISRO spent some ` 95 crore to de­velop the pro­to­type RLV, this would ob­vi­ously go up over the next decade when the fi­nal ver­sion is de­vel­oped. It may be more than the av­er­age cost of a PSLV and GSLV at ` 120 crore and ` 170 crore re­spec­tively. But then what is ex­pected is over­all sav­ings de­pend­ing upon how many times the RLV is reused.

The winged RLV pro­to­type was struc­tured dif­fer­ently to en­able it mak­ing a soft land­ing like an air­plane, and thus much more chal­leng­ing. The ac­tual RLV, when it is de­vel­oped, would have to land on a run­way. ISRO plans a five-km run­way at Sri­harikota for the In­dian space shut­tle. The 6.5me­tre RLV weighed some 1.7 tonnes was worked upon by some 600 sci­en­tists for five years.

The May 23 test was his­toric in ISRO un­der­tak­ing the maiden flight of a fully in­dige­nous pro­to­type space shut­tle with delta wings that glided onto the Bay of Ben­gal. Though much hard work lies ahead for de­vel­op­ing the fi­nal space shut­tle, what ISRO has demon­strated over the years is a re­mark­able sense of ded­i­ca­tion and progress in the space arena at min­i­mal costs. In fact, had sci­en­tist in DRDO worked with the same zeal, In­dia would have been self-suf­fi­cient in meet­ing de­fence re­quire­ments in­dige­nously to a very large ex­tent, like China. With ISRO, In­dia is con­fi­dent in achiev­ing ev­ery pos­si­ble suc­cess in space.

Though much hard work lies ahead for de­vel­op­ing the fi­nal space shut­tle, what ISRO has demon­strated over the years is a re­mark­able sense of ded­i­ca­tion and progress in the space arena at min­i­mal costs

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