Heavy Lift Launch Vehicle

Is ISRO Working on Three Reusable Rocket Designs at Once?

ISRO’s recent announcements suggest it wants to secure a competitive advantage as quickly as possible in all segments of the launch services market: light, medium and heavy.

The Indian Space Research Organisation (ISRO) is working on at least three different designs of reusable launch vehicles at the same time.

Together with its endeavours to increase the number of objectives per mission and deploy purpose-built rockets, it seems like ISRO wants to secure a competitive advantage as quickly as possible in all segments of the launch services market: light, medium and heavy.

Last week, ISRO chairman K. Sivan told Times of India that they will be soon testing a prototype two-stage rocket in which both stages will be recoverable after launch. Sivan’s specifications suggest that this project is in addition to, and not in relation to, two others aimed at building rockets with reusable parts.

The first project that ISRO began testing is simply called the Reusable Launch Vehicle (RLV). It is modelled along NASA’s Space Shuttle. However, differences include the fact that it will be powered by five semi-cryogenic engines during ascent and a scramjet engine during descent. When completed by around 2030, it will be able to lift over 10,000 kg to the low-Earth orbit.

Also read: After Successful Test of Reusable Vehicle, ISRO Has Further Plans for Slashing Launch Costs

ISRO doesn’t yet have a testable prototype in the second project yet. In fact, its details emerged only a month or so ago. Called ADMIRE, it envisions a small two-stage rocket the size of an L40 booster used on the GSLV Mk II. Its payload capability is not known.

But it is known that ADMIRE’s first stage will be recoverable after launch in similar fashion to the first stage of SpaceX’s Falcon 9 rocket. The second stage will be lost after delivering the payload, just like with the Polar (PSLV) and Geosynchronous Satellite Launch Vehicles (GSLV).

The third project, according to Sivan, involves a two-stage rocket. The first stage will be like ADMIRE’s first-stage. The second will resemble a smaller version of the RLV shuttle.

Reusable launch vehicles reduce cost by allowing space agencies to shave off the expense of the recovered stage for every subsequent launch. The only other expenses are capital costs for the infrastructure and a recurring refurbishment cost (which hasn’t been finalised yet).

Though the NASA Space Shuttle typified this paradigm for many decades, it was the Falcon 9 rocket that really popularised it. To SpaceX’s credit, it showed that reusable rockets didn’t have to be as large as the Space Shuttle and didn’t require infrastructure at that scale either. Since then, many space agencies – public and private – have been pursuing their own reusable launcher programmes.

However, why ISRO is pursuing three of them, if not more, at once is not clear. The payload capacities of the ADMIRE and the third project could help understand the organisation’s eventual plans better.

The RLV will be a heavy-lift vehicle, capable of lifting 10,000-20,000 kg to the low-Earth orbit. The second and third projects could be aimed at lower payload capabilities. This would explain their smaller sizes and they would also fit within ISRO’s broader programme of cashing in on the growing small satellites launch market.

Also read: Why ISRO Rockets Aren’t Comparable to Falcons or Arianes

The shuttle-like upper-stage of the third project has technically been tested. In May 2016, ISRO flew a scaled-down prototype of the RLV shuttle in a technology demonstration mission. The eventual upper stage is expected to have similar dimensions as the prototype.

However, there are some potential differences between the RLV shuttle and the third project shuttle. For example, the RLV shuttle is larger and will be powered by a scramjet engine during its descent. On the other hand, the third-project shuttle will – to use Sivan’s words – “glide back to Earth and land on an airstrip”.

Since such gliding will require a source of power, it is plausible that ISRO will tack on a scramjet engine to the shuttle stage as well. However, the vehicle’s potential use in lighter missions also suggests ISRO will want to keep the vehicle as light as possible.

ISRO successfully tested its scramjet engine in August 2016, atop an Advanced Technology Vehicle (ATV), essentially a modified version of the RH560 Rohini sounding rocket. An official press release had said that the time that the ATV and scramjet engine together weighed 3,277 kg. Since the RH560 weighs 1,300 kg, the scramjet weighs around 1,900 kg.

In sum, if the third project uses the ADMIRE vehicle’s first stage, then it would work the following way.

First, the two-stage rocket will take off. Once the first stage is exhausted, it will separate from the second stage, glide through the air until it is suitably over the spot it has to land on (in the Bay of Bengal), and descend using retrograde thrusters.

By this time, the second, shuttle-like stage will have reached a suitable altitude at which to deploy the payload. Once that is done, the shuttle will glide back down, similar to the first stage, and descend on an airstrip.

Apart from these tests, ISRO has also been working on accomplishing more per mission itself. During the PSLV C34 and C35 missions, the organisation showed off the rocket’s ability to launch satellites into multiple orbits at different altitudes.

Also read: As ISRO Works on Human Spaceflight, a Glimpse of Its Challenges From 45 Years Ago

The PSLV C44 mission will do something similar. On January 24, it will lift off with two satellites: the Microsat-R, an imaging satellite built by the Defence Research and Development Organisation, and a student-built satellite called Kalamsat.

After launching Microsat-R, the rocket’s fourth and uppermost stage will climb into a higher, more circular orbit. There, Kalamsat will switch on and use the orbiting stage as a platform to perform some experiments in space.

Finally, later this year, ISRO will conduct the first test flight of its planned Small Satellite Launch Vehicle. It will be a three-stage rocket partly derived from the PSLV, and capable of carrying 300 kg to a Sun-synchronous orbit and 500 kg to the low-Earth orbit.

Its USP is that it can prepared for launch within 72 hours, rendering it highly available – in much the same way ISRO itself wants to be.

SpaceX Didn’t Lose Just a Falcon 9 Rocket in Cape Canaveral Explosion

The Falcon 9 has seven other missions this year, excluding the ones for AMOS 6 and NASA, and at least three of which have time-bound expectations riding on them.

A Falcon 9 rocket goes up in flames at Launch Complex 40, Cape Canaveral, on September 1, 2016. Source: YouTube

A SpaceX rocket blew up on its pad at Cape Canaveral, Florida, a day before it was set to launch. It was carrying a $200-million Israeli satellite and supplies to the International Space Station. SpaceX CEO Elon Musk had tweeted that the explosion was triggered by an issue with the rocket’s upper stage, although final details will take at least six months to emerge. The mishap has many implications for the private space-launch company, most notably for the Israeli satellite-maker Spacecom, SpaceX’s relationship with NASA, its competition with Boeing and its assurances to the wider business community.

There’s also been an implication for Facebook. The social networking company was going to lease some of the bandwidth from the Israeli satellite, AMOS 6, to improve internet connectivity around Africa. However, this loss is relatively minor in comparison to what else SpaceX stands to lose: its reputation of being reliable and state-of-the-art at the same time. In fact, speculations were rife that a new rocket refuelling technique, concerning the upper stage Musk tweeted about, it has been testing since 2015 may come to be implicated in the accident.

The rocket, a Falcon 9, is at the heart of SpaceX’s plans to expand its offerings – up to building a super-heavy launch vehicle and taking humans to Mars within the decade. However, achieving these objectives behooves the company, led by Musk, to constantly innovate and bring launch costs down. Most recently, the company’s engineers have been able to demonstrate that the first stage of the Falcon 9 could return to land on the surface in an upright position after launching the second stage into orbit. The reusability saves SpaceX millions of dollars as well as eliminates the need to build it again for a subsequent mission.

Last year, the innovation also took the form of changing the nature of the propellants carried by the rocket. SpaceX is currently developing its Raptor cryogenic engine. However, unlike other cryogenic engines (including ISRO’s), where oxygen is cooled to really low temperatures at really low pressure, the Raptor will be fed really cold oxygen at really high pressure. The difference is that the oxygen contents in the tank become more dense, allowing the tank to hold more oxygen in a given volume. This in turn frees up space for the fuel (liquid methane), and increases the distance the rocket can travel as well as the amount of payload it can carry. According to SpaceX, the increase in density is of the order of 8%.

However, loading such a mass of oxygen into the tank before each mission has been a recurring problem for SpaceX. In 2014, a Falcon 9 rocket carrying an SES-9 satellite took off only after four failed attempts one week, three of which involved issues with the propellants. Unless SpaceX perfects the attendant techniques, it is going to be neither reliable nor state-of-the-art, at least as far as heavy lift missions are concerned.

Another suspect is the launchpad itself, the one called Launch Complex 40 at Cape Canaveral. A video made available by USLaunchReport.com (below) shows extensive damage caused to it by the explosion, including to the strongback, the steel tower supporting the rocket. Such damages typically take many months to fix, and until then that’s one less launchpad for SpaceX. However, if the launchpad had been poorly maintained and if it turns out to be that the explosion was triggered by something on the ground, then SpaceX can deflect criticism away from the Falcon 9. It could also use the nearby Launch Complex 39A, but which will only be ready for use in December 2016.

Had the September 1 explosion not occurred and the Falcon 9 taken off today, the AMOS 6 civilian communications satellite would’ve been placed into a geosynchronous orbit around Earth and taken over duties from its predecessor, the AMOS 2 that ends operations this year. However, AMOS 6’s loss means that Facebook will terminate its contract with Spacecom, the company that built the satellite in a deal with the Israeli Aerospace Industries, by January 1, 2017. More significantly, Spacecom’s being acquired by the Beijing Xinwei Technology Group for $285 million has also been called into question after the explosion sent shares of the former down by more than 9%.

SpaceX has contracts worth $10 billion for commercial satellite launches as well as NASA missions, at least $7 billion of which involve the Falcon 9. Apart from this, the company also has two deals with NASA: one worth $1.6 billion to fly resupply missions to the International Space Station and another worth $440 million to build and modify the Dragon, a capsule that NASA hopes to use in the future to send American astronauts onboard American rockets to space (between two and six missions). The agency currently leases slots on Russian rockets.

The resupply mission had been slated for November, at least as of June 2016. NASA has had to grapple with three delayed resupplies in the recent past. On October 28, 2014, an Antares rocket operated by the private company Orbital ATK crashed seconds after liftoff on October 28, 2014. In April 2015, a cargo module launched by a Russian Soyuz 2-1A rocket tumbled out of orbit and burnt up in the atmosphere before it could reach the ISS. In June 2015, a Falcon 9 rocket blew up a few minutes after takeoff. Musk later blamed a steel strut that collapsed under 2,000 pounds of pressure against the 10,000 pounds a supplier had claimed it’d be able to withstand.

The uncrewed and crewed test flights of the Dragon capsule had been slated for May and August 2017, respectively. However, the September 1 explosion will have thrown the schedule off whack. And the blowback won’t be from NASA alone.

NASA also has a contract with Boeing to fly two to six crewed missions for the agency, and with a maximum potential value $1.6 billion greater than its contract with SpaceX ($2.6 billion). The terms of the contract allow Boeing and SpaceX to “own and operate the crew transportation systems and be able to sell human space transportation services to other customers in addition to NASA, thereby reducing the costs for all customers”. At the same time, these services are required to be ready in 2017, when the US plans to eliminate its reliance on Russian launchers. A failure on SpaceX’s part to keep up with this schedule, and ensure the reliability of its Falcon 9 rocket by then, could increase NASA’s reliance on Boeing.

It can seem good for SpaceX that its failures are happening now, not when the bigger crewed missions come along. However, its road to reliability is not its road alone but a journey it undertakes along with all of its clients. SpaceNews reported that the Falcon 9 has seven other missions this year, excluding the ones for AMOS 6 and NASA, and at least three of which have time-bound expectations riding on them. What we can be thankful for are the repeated tests and countdowns every operator performs before launches, how much these tests drive up launch costs, and how these are the costs that aren’t being cut. After all, #SpaceIsHard.

After Successful Test of Reusable Vehicle, ISRO Has Further Plans for Slashing Launch Costs

ISRO’s immediate priorities are to make its own launch vehicles more reliable, increase the payload they are able to carry and reduce the cost of their manufacturing.

ANI images showing the solid-fuel booster lofting the RLV technology demonstrator before the descent begins. Source: ANI_news/Twitter

ANI images showing the solid-fuel booster lofting the RLV technology demonstrator before the descent phase begins. Source: ANI_news/Twitter

On Monday morning, the Indian Space Research Organisation successfully flight tested its ‘Reusable Launch Vehicle – Technology Demonstrator’ (RLV-TD) from the Satish Dhawan Space Centre (SDSC) in Sriharikota, Andhra Pradesh. This winged craft, with its distinctive twin tail-fins, is intended as a key step toward the space agency’s goal of creating a reusable launch vehicle that could cut launch costs by as much as nine-tenths.

In the flight test, the RLV-TD was carried aloft by a rocket booster and reached an altitude of about 65 km. It then descended, reaching a peak velocity of five times the speed of sound, before landing in the Bay of Bengal about 13 minutes later. “The vehicle’s navigation, guidance and control system accurately steered the vehicle during this phase for safe descent,” an ISRO release said, and the craft successfully survived the “high temperatures of re-entry with the help of its Thermal Protection System.”

ISRO’s current conception for such a reusable launcher is to have a two-stage-to-orbit configuration. A winged first stage would incorporate an advanced air-breathing propulsion system that takes in air as it flies to burn the fuel carried onboard. This stage would take the second stage and payload high up into the atmosphere and, after separating from the latter, return to land on a runway.

The second stage would accelerate the payload the rest of the way using conventional rocket propulsion. Afterward, this second stage too would be brought back to the ground. However, such an advanced launch vehicle may materialise only “some 20 years from now”, according to K. Sivan, director of the Vikram Sarabhai Space Centre in Thiruvananthapuram, ISRO’s lead centre for launch-vehicle development.

But with SpaceX, the American spaceflight company started by entrepreneur Elon Musk, promising to achieve rocket reuse and bring about lower launch costs with existing technology, ISRO has some plans to ensure it remains competitive in the short-term as well.

SpaceX’s Falcon 9 rocket, with just two stages powered by liquid engines, has carried satellites into orbit and sent its Dragon capsule, loaded with cargo, to dock with the International Space Station. On three such flights, the rocket’s first stage, after separating from the second stage, fired its engines again and successfully made a controlled descent back to earth. On one occasion, it returned and made a vertical touchdown a short distance from the launch pad it had left a short time earlier. Then, in two recent flights, it landed on a drone ship stationed out in the ocean.

SpaceX intends to reuse the first stages that return but has yet to demonstrate this capability. The company’s president, Gwynne Shotwell has indicated that such reuse could lead to a 30% saving in costs.

Sivan made it clear that ISRO’s immediate priorities are to make its own launch vehicles more reliable, increase the payload they are able to carry and reduce the cost of their manufacturing. If the Geosynchronous Satellite Launch Vehicle (GSLV), which can launch a 2.2-tonne communications satellite, is able to carry a 3.5-tonne satellite, “the vehicle becomes more efficient,” he remarked. And with vehicle cost remaining unchanged, the cost per kg for the satellite it launches comes down.

In the case of the next generation GSLV Mk-III rocket, its payload capability could be increased from four tonnes to six tonnes. Then, substituting a semi-cryogenic engine, which is currently being developed, for the two Vikas liquid propellant engines in the rocket’s core booster could further raise its payload to 7.5 tonnes.

Vehicle costs could also be reduced. One measure being considered is to shift from maraging steel used for the big solid boosters that form the first stage of the PSLV and the GSLV to a cheaper steel, Sivan said.

In addition, ISRO was “very seriously” thinking of retrieving and reusing the core boosters of the GSLV and GSLV Mk-III in a SpaceX-like manner, according to him. The next generation Heavy Lift Launch Vehicle could also be designed with such reuse in mind.

The GSLV’s first stage, along with the four liquid-propellant strap-on boosters attached to it, account for almost three-fourths of the launch vehicle’s costs. “If we are able to recover and reuse [it], our reduction in cost will be maximum,” he said.

The GSLV’s payload would be halved if the the rocket’s first stage and strap-ons were manoeuvred back to the SDSC. However, the loss in payload would come to only about 80 kg if the stage soft-landed where it would naturally fall after separation. India could take advantage of the Andaman Islands and get the first stage to land there after equatorial launches from Sriharikota, Sivan remarked.

Gopal Raj is a science journalist based in Thiruvananthapuram. He has written extensively about the Indian space programme, including a book, Reach for the Stars: The Evolution of India’s Rocket Programme.