10 reasons why ISRO's RLV-TD test flight isn't a big deal, just yet

India's RLV-TD, the Reusable Launch Vehicle is not reusable and is not a launch vehicle.


India woke up to great news today, of the successful test flight of ISRO's RLV-TD test flight. Twitter is exploding with congratulatory tweets aimed at ISRO. While it is exciting that India too has aspirations for a stellar space program, it is more meaningful to celebrate the exact science involved. The confusing language here is the comparison to the US Space Shuttle program, which achieved a lot more, but was still considered a failure in many ways when it came to achieving the goals and targets it aimed for. The launched vehicle is not a space shuttle. It is not yet re-usable, it not a launch vehicle, it cannot take humans to missions in outer space. Here are the facts, the actual science worth celebrating.

10. RLV-TD is a test flight: The trial run is meant as a test bed for the technologies being developed by ISRO. The "TD" stands for "technology demonstration". This means that scientists are checking if what they have made works in real world scenarios. These includes the heat insulation materials, the aerodynamics of the vehicle during hypersonic flight, and flying in cruise mode.

09. RLV-TD is a scaled prototype: The RLV-TD is a scaled down version of the final vehicle. The vehicle is six times smaller than the final planned size. It is a little unfair to compare it to a space shuttle. The RLV-TD is 6.5 meters long and weighs 1.5 tonnes. The Space Shuttles were 56.1 meters long and weighed 2030 tonnes, without a payload. Even the final version of the indigenous space shuttle alternative, is not going to be as big as the US Space Shuttles.

https://twitter.com/NASASpaceflight/status/734577604154523650

08. The RLV-TD is not reusable: This aspect of the launch has conflicting reports. The RLV-TD oriented itself, and landed on a virtual runway in the Bay of Bengal. There are conflicting reports on whether or not the vehicle will be recovered after it lands in the water. In either case, the main technology being demonstrated was the hypersonic flight, so recovery was not a priority in the design of the vehicle itself. The RLV-TD is not meant to be reused.

07. The final test will be in 2030: This is just the first test in a series of tests aimed to demonstrate all the systems to be used in an advanced RLV. The development for this is expected to take another 10-15 years. The advanced RLV is only expected to be tested by 2030. Actual missions that launch satellites or take humans to outer space will only take place after that.

06. It is not currently capable of launches: The small size, and the lack of payload capacities, mean that the RLV-TD in its current state cannot be considered a launch vehicle.

05. It didn't even go to outer space: There is no clear boundry between the atmosphere and outer space, but The Karman Line at 100 kilometers above the surface of the earth is designated as the line that separates aeronautics and astronautics by the  Federation Aeronautique Internationale for maintaining standards, and its record keeping purposes. NASA considers anyone working above 80 kilometers from the surface of the earth as astronauts. The RLV-TD went up to 70 kilometers from the surface of the planet. This test demonstration was not a space flight.

04. It is not yet historic: India does not have its own home made alternative to the Space Shuttle yet. Only after a series of test flights are done, will the full scale RLV even be designed. The terms used for this vehicle now are "Full Scale RLV" and "Advanced RLV". While this may be a memorable event in the space race, the truly historic moments will be when real shuttles launch with actual missions that advance scientific understanding for humans all around the world. These set of launches only increase the understanding scientists require to launch the vehicles that can do the science.

03. It has an uninspiring name: The RLV-TD is just not as cool as "Space Shuttle" and the nomenclature is misleading. It is not reusable, it is not a launch vehicle. It is just a technology demonstration for a reusable launch vehicle. ISRO could have done better by coming up with a catchier name for the program, one that would have worked better in social media, if not one that is just easier to say out aloud.

02. Private companies are developing reusable launch vehicles: NASA has retired its Shuttle program, and the Soviet Buran program had just one flight. Private companies are stepping into the reusable vehicles space. Airbus has Adeline, Reaction Engines of UK have a pilotless reusable vehicle called Skylon, and SpaceX has been testing reusable rockets.

01. The program has been operational for 15 years: The program has only been working with full focus for five years. Several proposed launch dates have passed. 30 years was the entire duration that NASA had deployed its Space Shuttles for Active missions. India will still  be testing an advanced launch vehicle after developing one for thirty years. There might be some kind of Space Race, but ISRO seems to be following Indian Standard Time.

So what did the RLV-TD test flight actually achieve? It achieved hypersonic flight, which means flying faster than the speed of sound. It achieved autonomous landing, which means that it could have landed back on a runway if there actually was one and not a stretch of ocean. It also achieved trajectory correction and orientation during the landing phase, as a demonstration of what could happen to advanced RLVs after re-entry.

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