Rockets or catapults, the future of rockets to Low Earth Orbit

The launch suppliers for satellites is growing rapidly with many companies now offering services to get cubesats and other payloads in orbit. There are many more also in development that will be operational in the next couple of years. Technological advances in materials, 3D printing and recovery of rocket parts is making launches generally cheaper and more accessible. The price per kilo to launch a satellite from an Electron rocket (from Rocket Lab) might be considerably more expensive than a Falcon9 launch but with the Electron you get to pick the orbit and don’t have to share you tiny cubesat’s requirements with a larger primary payload requirement, plus you get to launch when you want rather than having to wait for the larger provider’s launch book to fill all for the price of around $6 million. The small rocket market is booming with aircraft launched rockets entering the market alongside their ground launched cousins, all offering flexibility in meeting their customers needs.

Rocket Labs uses a small rocket that’s 17m in height, 1.2m in diameter and can carry a maximum payload of 225Kg. They are able to put multiple payloads into different orbits with their kick stage. This small engine is 3D printed as is most of the primary components of the Rutherford engine they use for the first and second stages of the rocket. They use a lot of composite materials like carbon fibre to keep the rocket light but also strong, thus allowing the payload to give the weight rather than having to expend all of the energy just moving the rocket. The first stage of the rocket is powered by 9 Rutherford engines, giving a total thrust of 41,500 pounds. Though Rocket Labs Electron is outstanding and a marvel of technological advancement and innovation, it is still a chemical rocket, it still operates under the basic principles that have been powering rockets for more than half a century. Space is still expensive and difficult unless there is a game changer.

Without using some other kind of physics then the only advancement will be in price reductions through continued innovation in manufacturing processes and reusability. There’s still the huge amount of propellant used and the inherent dangers that entails. Even for reusability there’s a lot of refurbishment and recertification of components due to the large forces that rockets are subjected to on their way to orbit. For large payloads we seem to be destined, for a while anyway, to look to the likes of NASA’s Space Launch System (SLS) and possibly SpaceX’s Big Falcon Rocket (BFR). For small payloads, though, the options might be more variable.

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The air launched Pegasus rocket has launched satellites into orbit.  (Credit: NASA)

A US Silicon Valley based company called SpinLaunch might be the game changer that has the potential to revolutionise space access. They are becoming a serious contender with their concept of an electrically powered launch system that basically fires a vehicle into space after catapulting it at hypersonic speeds. They have so far managed to attract nearly $40 million in funding to upscale their concept and get a working model going, which they hope to do by 2022. The task to pull this off is huge. The vehicle has to accelerate to huge speeds and then face tremendous drag and deceleration as it is released from the launch system. Additionally the forces to accelerate and the centrifugal forces will be huge, so probably not the most comfortable option for humans just yet, but for robust commercial payloads this might be the way to get things into orbit quickly, cleanly, and cheaply.

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Display of a SpinLaunch vehicle (Credit: https://www.nextbigfuture.com/)

The concept basically uses a large centrifuge to store up energy that is then rapidly transferred to a launch vehicle, presumable by spinning it around as well. This will then catapult the vehicle at nearly 5000km/h into space. I can’t help but think there must be more to this though as that’s nowhere near fast enough to get something in orbit, it needs to be going at least twice that speed. So maybe there’s a plan to have a second stage type of rocket to boost the vehicle in the final phases, regardless of this, having a 5000km/h boost on launch will put them well ahead of the competitors and at there $500,000 per launch cost about /10th the price of other launches. It remains to be seen what the payload will be and the other details, but I think this is a very interesting space to watch and, if it works, could be revolutionary for space access.