CHAN­DRAYAAN 2: THRILL AND TER­ROR

India Today - - INSIDE - BY RAJ CHEN­GAPPA

Even though Dr K. Si­van, chair­man, In­dian Space Re­search Or­gan­i­sa­tion (ISRO), has been in­volved in over 50 launches, he con­fesses he is still tense dur­ing ev­ery new launch. As he puts it, “My stom­ach churns, my heart beats faster and I feel breath­less.” On June 22, as the count­down be­gan for the launch of Chan­drayaan-2, In­dia’s sec­ond moon mis­sion, from the space port in Sri­harikota in Andhra, he was even more so. A week ear­lier, the first at­tempt to launch the space­craft had to be aborted be­cause of a plumb­ing leak in the up­per-stage en­gine of the 15-storey tall, brand new GSLV Mark-III launcher. Though dis­ap­pointed, Si­van de­cided to post­pone the launch as he was acutely aware that there was so much of ISRO and In­dia’s pres­tige rid­ing on it.

The Chan­drayaan-2 mis­sion is a quantum leap over its suc­cess­ful fore­run­ner launched in 2008 and is crammed with new tech­nolo­gies. The fore­most is the launch ve­hi­cle it­self. In a gutsy de­ci­sion, ISRO de­cided to use its heavy-lift­ing GSLV Mark-III, though it had un­der­gone only two devel­op­ment tests—the Chan­drayaan-2 launch would be its first op­er­a­tional flight. Apart from the new launcher and an up­graded or­biter, space sci­en­tists had built for the first time a lu­nar lan­der as­sisted by a rover that could roam the moon sur­face for a ra­dius of half a kilo­me­tre and per­form crit­i­cal ex­per­i­ments. These were cut­ting edge tech­nolo­gies and, if In­dia suc­ceeded, it would be only the fourth na­tion af­ter the US, Rus­sia and China to have op­er­ated a ro­botic lan­der on the moon. An­other worry for Si­van was that if the glitch was se­ri­ous and they were un­able to at­tempt an­other launch by endJuly they would have to wait till next year to get the per­fect earth-moon align­ment re­quired for the Chan­drayaan-2 mis­sion.

Af­ter it was an­nounced that the first launch was on hold, Si­van rapidly re­assessed the sit­u­a­tion. He told his team mem­bers, “ISRO sci­en­tists have al­ways been ready for chal­lenges, they have al­ways risen to the oc­ca­sion. Why not now?” Spurred on by the ap­peal, the team of sci­en­tists from the Vikram Sarab­hai Space Cen­tre (VSSC) who had built the rocket, headed by direc­tor S. So­manath, worked non-stop for over 36 hours to iden­tify and fix the prob­lem. The snag had oc­curred in the crit­i­cal cryo­genic stage that uses su­per-cooled hy­dro­gen and oxy­gen as fuel. The mal­func­tion­ing joint had caused a no­tice­able pres­sure drop in the he­lium bot­tles that con­trol the open­ing and clos­ing of fuel valves in the en­gine. As Si­van told in­dia today, “The prob­lem was sim­ple, but if we had de­cided to go ahead with the launch with­out cor­rect­ing it, the im­pact would have been cat­a­strophic.”

Af­ter fix­ing the leak­ing joint, sci­en­tists then con­ducted a se­ries of tests at the launch pad it­self to en­sure the prob­lem

wouldn’t re­cur. The sci­en­tists from VSSC—where ISRO’s rock­etry is de­vel­oped—had in the past year made ma­jor mod­i­fi­ca­tions to GSLV Mark-III to meet the in­creased pay­load weight of 4 tonnes that Chan­drayaan-2 re­quired. It was the first time the en­hanced launcher was be­ing put to test, but the VSSC team as­sured Si­van they were con­fi­dent that there would be no fur­ther glitches. The ISRO chair­man was con­scious that space is an un­for­giv­ing zone and even a small mal­func­tion could re­sult in the Rs 1,000 crore Chan­drayaan-2 mis­sion end­ing up in the bot­tom of the Bay of Ben­gal. But he took the brave de­ci­sion to go ahead with the launch be­fore the July win­dow closed.

On launch day, Si­van says he felt the fa­mil­iar ten­sion build­ing up in his gut as the count­down neared zero. It didn’t di­min­ish even af­ter the first stage con­sist­ing of two gi­ant booster rock­ets ig­nited and hurled the ve­hi­cle to­wards its pre­de­ter­mined flight path. It was only 16 min­utes later, af­ter the up­per stage cryo­genic en­gine com­pleted its fir­ing and in­jected the Chan­drayaan-2 into a trans-lu­nar or­bit that his anx­i­ety gave way to “ex­hil­a­ra­tion”. He shook hands with the top sci­en­tists seated near him and hugged some of them. The mon­i­tor had shown that the cryo­genic en­gine had “over-per­formed”, putting Chan­drayaan-2 at an or­bit of 45,000 km at its apogee in­stead of the planned 39,000 km. The gain of 6,000 km, which the lu­nar mod­ule would have oth­er­wise had to achieve by fir­ing its on­board en­gines, would save it con­sid­er­able amount of fuel. Si­van termed it a “bonus” and a jubilant So­manath said, “The GSLV Mark-III has de­clared its op­er­a­tional ca­pa­bil­ity with an even bigger bang.”

While laud­ing the rocket sci­en­tists for their work, Si­van knew there were many more chal­lenges ahead. As he told them, “This is just the be­gin­ning of a his­toric jour­ney.” Chan­drayaan-2 was on track in its 400,000-kilo­me­tre trip. It would ren­dezvous with the moon’s or­bit only by mid-Au­gust. Days af­ter the launch, af­ter the first fir­ing of the mod­ule’s on­board en­gines to push it into a higher or­bit per­formed “beau­ti­fully”, Si­van said he was con­fi­dent that the mod­ule would reach the moon on sched­ule. Only af­ter it sta­bilised its or­bit around the moon would the lan­der car­ry­ing the rover sep­a­rate it­self from the or­biter and per­form an in­tri­cate ma­noeu­vre to land on the sur­face on Septem­ber 7. Si­van de­scribes the en­tire op­er­a­tion “as 15 min­utes of sheer ter­ror for us” till the lan­der touches down. There would be more con­cern as the rover rolls out and, along with the lan­der, be­gins the dozen-odd ex­per­i­ments in­clud­ing search­ing for wa­ter mol­e­cules on the moon. Only af­ter they do so will ISRO de­clare the mis­sion suc­cess­ful. Si­van has a long time to go be­fore he can re­lax. ■

“The lu­nar land­ing will be 15 min­utes of sheer ter­ror for us”

—K. SI­VAN, Chair­man, ISRO

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