How India is Entering the Reusable Launch Vehicle Race to Make its Mark in the Global Space Launch Market

What has the Indian Space Research Organisation (ISRO) got in common with legendary aerospace designer Burt Rutan, Microsoft co-founder Paul Allen, and billionaire entrepreneurs Jeff Bezos and Elon Musk? They are all in the hunt for the Holy Grail of rocketry: a space launch system that can loft satellites into low earth orbit (LEO), re-enter Earth’s atmosphere and glide back like an aircraft to either land on a runway or splash down in the sea to be retrieved. Its short turnaround ensures that after refuelling, it can be used quickly for another launch. These reusable launch vehicles (RLVs) could be used many times, cutting mission costs dramatically and making access to space much more affordable. Advanced RLVs that ride straight into orbit (single-stage-to-orbit, or SSTOs) could carry their own fuel, unlike conventional launchers that typically piggyback on expendable rockets.

More than 50 years after the first space shots of the 1960s, reaching LEO remains a costly affair, with launch prices topping the $12,000 per kilogram mark. Although agencies like ISRO take pride in being able to offer low-cost satellite launches, the fact remains that even the most advanced rockets of today can hardly lift two percent of their launch weight into orbit. This ratio hasn’t really changed in more than half a century of spaceflight! Even if cheaper air-breathing engines were used to penetrate Earth’s atmosphere, it’d still cost a lot of money to loft a kilo into orbit. The chief reason for this has a lot to do with contemporary launch systems, which are all of the ‘use-and-throw’ kind. Once launched, a booster rocket cannot be re-used for another launch. NASA’s iconic Space Shuttles (the erstwhile Soviet Union’s winged spaceplane, Buran, made just one experimental flight before being mothballed) are the only RLVs to have flown successfully. In fact, the Shuttle represented a semi-reusable launch system where the orbiter could re-enter and land and only its solid rocket boosters were recovered using parachutes. The Shuttle fleet, however, was grounded after flying 30-odd years of ferrying crews and supplies to and from the International Space Station and undertaking repair missions to the Hubble Space Telescope

With advanced avatars of crewed spacecraft like the Orion on the horizon, space agencies have turned to private enterprise for help in developing reliable RLV systems that could achieve economies of scale. Which is easier said, considering no space agency would dare to economise by using less expensive launchers with their attendant risks. In rocketry, after all, one just cannot be too careful—a nut tightened carelessly here, or a rubber bush sitting loosely there is enough to send hundreds of tons of metal and fuel up in a terrible fireball. NASA, whose Shuttles are lodestones for developing RLVs, learned this the hard way in January 1986 when the Challenger blew up two minutes into its launch. The shuttle designers of the time had in mind an RLV system that would form—along with an orbiting space station and a moon base—a staging post for astronauts bound for Mars and elsewhere. But in their eagerness to show that space flight could be as routine as air travel, NASA managers cut corners by forcing engineers to stick to tight launch schedules. And on that grey January morning in 1986, the Challenger exploded, killing the seven astronauts on board. Investigators later found that private contractors had supplied an erosion-prone, if less expensive, ‘O’ ring (a rubber seal used in fuel tanks of the shuttles’ booster rockets). NASA managers made it a double jeopardy by failing to install a metal latch on the booster rocket to lock the leaky ‘O’ ring seal tightly.

In 2004, to encourage private entrepreneurship in the space launch business, the X Prize Foundation (whose board of trustees includes prominent names like Ratan Tata, James Cameron, Arianna Huffington and Larry Page) instituted the $10 million Ansari X Prize along the lines of the air races of the early 20th Century. The winner should reach an altitude of 100 km twice in the span of a fortnight with a payload equivalent to a three-man crew, and with less than ten percent of the non-fuel weight replaced between two flights. More than two dozen teams around the world vied for the trophy and Burt Rutan’s Scaled Composites emerged winner with its reusable SpaceShipOne (financed by Microsoft’s Paul Allen). “Manned spaceflight is not just for governments to do,” says Rutan. “We proved it can be done by a small company operating with limited resources.”

Amongst those who competed was Jeff Bezos, whose credentials as the founder of Amazon.com overshadow another significant achievement: locating and retrieving the mighty Saturn V rocket engines from the Atlantic Ocean depths where they sank after powering Apollo 11 on its historic moon voyage in July 1969. The feat has spurred the efforts of space engineers in realising newer and better RLV technologies. Indeed, Bezos’s own company Blue Rider looks set to come up with an ideal RLV if its New Shepard launch system is successfully flight-tested this summer. The message on the company's website which went through an overhaul in November 2011, displayed optimism, “We’re working to lower the cost of spaceflight so that many people can afford to go to space." Elon Musk appeared to just as confident about the RLV developed by his company, Space Exploration Technologies Corporation (SpaceX)—an American aerospace manufacturer and space transport services company based in California —which makes no bones about its intention to grab a considerable chunk of the global space launch business. “We’re at the dawn of a new era in space exploration,” he said in May 2012, when Falcon Rocket, the launch system for which had been developed by SpaceX took off.  SpaceX has already conducted a series of successful space launches and claims it is ready to offer space launch services “at a quarter the cost of what entrenched companies like Ariane charge.” The US aerospace company XCOR’s Xerus, Boeing’s Alpha Space Reusable Vehicle, Starchaser Industries’ reusable Thunderbird rocket and Japan’s Kankoh-Maru—a reusable passenger-carrying SSTO rocket—are some of the major players who are developing their own RLVs.

As private enterprise closes in on frontier RLV technology, national space agencies, too, are very much in the race. ISRO has scheduled the maiden flight of its 12-tonne RLV-TD (Technology Demonstrator) for the first week of August. Resembling a small airplane, the RLV-TD will be launched from Sriharikota on an expendable single stage solid booster. The RLV will be put through its paces in three stages. The August launch is primarily a Hypersonic Flight Experiment (HEX), where the hypersonic (above Mach 5, or five times the speed of sound) flight characteristics and guidance systems of the vehicle are tested. Next would be the Landing Experiment (LEX) where the turbofan engine performance is monitored as the RLV makes a computer-aided horizontal landing on a runway. In the third Return Flight Experiment (REX), the RLV is launched into orbit and then re-enters the atmosphere for landing on a runway. In the final Scramjet Propulsion Experiment (SPEX), the complete RLV profile along with its scramjet engine would be tested.

There will be quite a few crossed fingers at Mission Control as later versions of the RLV-TD enter the crucial hypersonic phase during the descent stage. Its supersonic combustible ramjet (or ‘scramjet’ in the argot of scientists) engine compresses oxygen in the high atmosphere and mixes it explosively with hydrogen to ignite the fuel. The exhaust, consisting mostly of water vapour, is expelled through a nozzle to create thrust. The efficient functioning of the engine is dependent on the aerodynamics of the airframe. So, the biggest challenge for the designers of the RLV-TD is not the sound barrier, but heat, as friction on re-entry produces temperatures exceeding 1300 degrees Celsius. Imagine creating a super thermos flask that can keep a liquid cold in a furnace, as it flies at several times the speed of a bullet! Only instead of a liquid, the RLV-TD’s hypersonic structure must protect sensitive flight instruments—and later, even humans—and keep the heat from vaporizing the liquid hydrogen.

Re-entry into the atmosphere is a complex manoeuvre. Disasters like the space shuttle Columbia—which disintegrated during re-entry in February 2003—are a grim reminder for  spaceflight researchers to figure out how best to overcome the heat generated by friction as a spacecraft is slowed in the atmosphere. Increasing the drag on a spacecraft reduces the heat it generates, deflecting much of it away from the craft. The RLV-TD therefore faithfully sticks to the time-tested ‘blunt body’ design: unlike needle-noses, the blunt nose forms a thick shockwave ahead of it to deflect the heat and slow the spacecraft more efficiently. Still, even with the current raft of new technologies and techniques, surviving the fiery re-entry remains tricky. Come in too steeply, and you burn up; approach at too shallow an angle, and you skid off the atmosphere, spinning madly into space.

After gliding back to Earth in a controlled descent, the vehicle would splash down in the Bay of Bengal to be retrieved by waiting ships. Why a sea landing? “We don’t have much of a choice,” said M.C. Dathan, Director, Vikram Sarabhai Space Centre, Trivandrum. “There is no runway in the country at present that is long enough for a space plane to land after re-entry.” The longest existing runways in India are hardly two kilometers long and an RLV would need twice that distance to make a horizontal landing. According to S. Somanath, Director, Liquid Propulsion Systems Centre (LPSC) at Trivandrum, “We plan to enlarge the RLV configuration so that it could be powered by an air breathing scramjet which is under development at the Mahendragiri test facility (in Tamilnadu).” ISRO’s effort, he told me, is “to eventually develop a fully functional two-stage-to-orbit (TSTO) vehicle.”

This effort is clearly inspired by an Ansari Prize of a different kind: a slice of the nearly $50 billion space launch market—more specifically, the global satellite-launch market, whose future is all about communication satellites. ISRO wants to capture five to 10 per cent of the mid-range satellite segment (two tonnes and more) of this market before the decade is out. But this will remain a pipedream unless the space agency augments its launch capability to compete with the heavy-lift launchers of the triumvirate that currently dominates commercial space launches: the United Launch Alliance (Lockheed/Boeing), Arianespace (Airbus and French government), and International Launch Services (Lockheed, and the Russian majors Khrunichev and Energia). While ISRO may have other options like the GSLV-Mark III—which could launch three-tonne payloads into higher geo-stationary orbits (and reduce India’s dependence on foreign launchers to launch heavy satellites)—an RLV would still be the best bet for future proofing itself.