Recently, there have been small private companies aiming to launch space rockets at a very low cost similar to SpaceX. However, instead of large communications satellites and/or crewed spacecraft, the primary payloads are small satellites built by various universities and subsidiaries of the bigger agencies like NASA. Most of them use primary rocketry parts, but only a small handful use what I consider the most convenient component: electric batteries.
Rocket Lab’s Electron rocket, built using carbon-fiber stages and 3D-printed components, utilize Rutherford engines on the first and second stages. Rutherford engines are 3D-printed and electrically pump-fed as opposed to typical fuel turbopumps on most rocket engines. The first and second stages each have an electric motor that drives the kerosene and oxygens pumps needed to create the liftoff thrust. What’s unique about the second stage is that it’s also powered by three batteries; two of them are detached just before reaching orbit so as to not become dead weight and prevent the rocket from crashing back to Earth.
Just a few weeks ago, Astra launched their Rocket 3 rocket, which came within 15 seconds of reaching orbit. The Rocket 3 also uses electric-pump-fed engines called Delphin. Six of them are used; five on the first stage and a vacuum-optimized engine on the second stage (as opposed to nine Rutherford engines on Electron’s first stage). However, in contrast to Rocket Lab, Astra has been very secretive, keeping their behind-the-scenes work off camera. For all I know, I’m not sure if the Rocket 3 also uses detachable batteries on the second stage. But I know it’ll be some time before Astra goes 100% public if they get through enough successful launches.
With 2021 having been kicked off last Friday, we’ve got a lot of rocket launches on the manifest including Electron and Rocket 3. Those two rockets are the only ones that use electricity to power their main engines, a direct contrast from the handy turbopumps used in most nowadays launch vehicles. When in the future will other countries start to follow the energy-efficient rocketry trend?
