Rocket Lab fires up its first recovered engine, on track to full booster reusability

Four months after the spectacular feat that was catching a descending rocket stage in mid-air, Rocket Lab has re-ignited one of the engines from that booster — an important step on their roadmap to fielding a fully reusable rocket.

The Rutherford engine, one of nine that power the Electron launch vehicles, went up on the mission "There and Back Again" in May, culminating in the livestreamed capture of the booster as it descended under a parachute. They ended up having to drop it in the ocean anyway because it was affecting the helicopter's maneuvering, but aside from that it worked like a charm.

Of course any engine that has been through so much will need to be inspected, cleaned and, if necessary, repaired, especially if they spent a little time in the drink.

The lucky engine in this case went through the full battery of tests new engines must pass, ultimately blasting for 200 seconds straight. According to Rocket Lab, the used engine performed to the same standard required of a new one. You can watch the test from start to finish here:

Don't worry, those aren't parts of the engine flying around. These things are cryogenically cooled so that's mostly just water and ice.

"Being able to refly Electron with minimal refurbishment is the ultimate goal, and so the fact that the recovered components on this engine performed on the test stand with minimal rework is further validation that we’re on the right path," said CEO and founder of Rocket Lab Peter Beck in a press release. "If we can achieve this high level of performance from engine components recovered from the ocean, then I’m optimistic and incredibly excited about what we can do when we bring back dry engines under a helicopter next time."

Reusable boosters are increasingly seen as the best way to achieve both a high cadence and relatively low-cost launch operation. Building new engines and rockets is hard work — why throw them away when you're done? But a rocket designed to be used once may be very different from one designed for reuse, and Rocket Lab has been adjusting its approach to embrace the latter.

The next mission where they will attempt to capture a falling first stage booster will take place before the end of the year, the company said, but there's no set date yet.

I've asked Rocket Lab for a few extra details and will update this post if I hear back.