SpaceX Falcon 9 vs ISRO’s Reusable Launch Vehicle
Disclaimer: The views expressed on this page are mine alone and not those of my employer. As these views are based on non-authoritative information, I cannot vouch for the accuracy, nor validity of this post. Feel free to challenge me or disagree with me in the comments section below or at @rsn. This post may be updated as more information becomes available.
ISRO launched a Space Shuttle, claimed many a news outlet. OK, so the headlines were incredibly misleading. Yes, it looked like a shuttle, just that it was a technology demonstrator and experimental in nature. Going by ISRO’s claims, the launch of the Reusable Launch Vehicle- Technology Demonstrator ( RLV-TD) was a success and they have captured enough data from the flight to develop the next stages of their mission. The vehicle, once ready, will be used to launch satellites and possibly humans as well, into space. Naturally, there was also talk about how this was a challenge to SpaceX’s innovative reusable launch vehicle, the Falcon 9 rocket.
The RLV programme, unlike ISRO’s scientific Expeditions like Chandrayaan or Mars Orbiter Missions, has a distinct commercial angle to it: bringing down the cost of satellite launches, increasing launch profitability and making India the preferred destination for low cost launches. The satellite launch market is an incredibly competitive market and a crowded one at that and anything a satellite carrier can do to bring down costs, is always good for business. Right now, SpaceX is eating everyone else’s lunch( and soon dinner and breakfast as well) when it comes to the cost/kg for launches and going by estimates, these costs will only continue to drop.
One thing that has has not been very clear from all the news reports is how will the ISRO RLV, once fully developed, be any different from SpaceX’s reusable vehicle and how will they compare on costs, so here’s my 2 cents.
So to be clear on SpaceX and their reusable rocket technology: their Falcon 9 is a Two Stage to Orbit system (TSTO). The rocket uses a conventional engine, where oxygen carried on-board is mixed with the fuel within a combustion chamber and burned to generate a high pressure gas, that is exhausted through the nozzle to generate the thrust. The 2nd stage, separates at about 80 km from launch and proceeds towards deployment of its payload. The first stage returns back and makes the vertical landing and will eventually be re-used. Elon Musk has already said that he does not plan to recover the 2nd stage, as most of their missions are in the Geo-Stationary Transfer Orbit, 35,000 km, and ends up being too difficult to balance fuel, and build quality to support a recovery.
Read this excellent blog on the future of reusable vehicles. : http://www.justatinker.com/Future/
The RLV from ISRO’s own admissions is going to be a Two Stage To Orbit system, like the Falcon 9. What we saw launched the other day, ‘The Space Shuttle’ is supposed to be the first stage; only that it does not really go into what is is defined as space. It takes off vertically using conventional rocket technology and once it reaches Mach 4, the Scramjet engines kick in to accelerate the vehicle to Mach 8–10.
As opposed to a conventional rocket engine, a Scramjet (supersonic combusting ramjet) engine will collect air from the atmosphere at supersonic speeds, which then passes through the combustion chamber, where it will combust, expand and then be exhausted at supersonic speeds all in less than a millisecond.
The final RLV, once ready, will have the 2nd stage mounted above the nose of the 1st stage.
The 2nd stage, separates around 80–100 km and proceeds towards deploying its payload and eventually re-entering, slowing down using parachutes and finally making a vertical landing.At this stage, apart from this slide that was presented by ISRO, we dont know if it will make a vertical landing. It does not need to. Even if it were to make a parachuted landing, the 2nd stage should still be reusable.
The First Stage “shuttle” will descend back to a specially constructed landing strip, using a number of maneuvers and finally making a horizontal landing, similar to that of a shuttle or aircraft. So, once refuelled and safety checks completed, ISRO should be able to turn this vehicle around and have it prepped up for its next mission within a few days.
Future developments of the RLV, will build on the results of the RLV-TD flight to include tests of its Scramjet propulsion engine, return flight and landing. The timeline provided by ISRO for a launch ready vehicle is around 2030.
Now lets come down to the economics of both:
1. As The RLV will use an Air-Breathing/Scramjet engine, it does not need to carry heavy oxidizers, so will be 80% lighter than a conventional rocket and should be able to carry heavier payload more economically than what could be possible using SpaceX’s conventional engine. Besides, as both first stage and 2nd stages are re-usable, it scores above SpaceX, which reuses only its first stage. From what I have been able to glean off ISRO presentations, the payload size of RLV for both Low Earth Orbit (LEO) and Geostationary Transfer Orbit( GTO) deployment is around 10,000 kg. In many cases, RLV may end up becoming the more cost effective launch vehicle for 10,000 kg payloads and aligning very well with ISRO’s stated ambition of bringing the cost/kg down to $500.
2. SpaceX should still be the undisputed leader, when it comes to “Heavy” launches. The payload sizes of Falcon 9 and the Falcon Heavy is well beyond ISRO’s current capabilities. Based on the version, the Falcon 9 can carry anywhere from 22,000 kg to LEO and 9000 kg to GTO. Falcon Heavy, which is still under development, can carry 54,000kg to LEO and 22,000 kg to GTO.
Finally, a commercially viable RLV is at least 15 years away, with a launch planned for 2030. To put that into perspective, SpaceX is just 14 years old. Whats to say that SpaceX wont develop a commercially viable Reusable Single Stage To Orbit ( SSTO) rocket system before 2030. Throw enough money and engineers behind anything and it ceases to be an insurmountable challenge. Besides, SpaceX’s continued success will only allow it to grow even further and re-invest more into continued development. ( IPO anyone ?)
The Indian space agency has a budget of around $1.2B per year for all its activities, both commercial and scientific. I personally dont believe that $20M here and $15M there is going to allow ISRO to capitalize its current success and accelerate the development of the RLV programme. Its about time the Govt gave a hike to ISRO’s budget gave some boost to the RLV programme when it has a distinct lead in development.
On a final note, remember that the Americans sent men to the moon in 10 years, at a huge cost to feed their collective ego. Most of that cost paid off over the next 30 years or so, which I believe, was the golden age for NASA. If successful, the RLV should pay for itself in a couple of years, by completely disrupting the launch market. But who’s listening in the Indian Govt?
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