Rocketlab sent this engine to space and then retrieved it: A new test shows it's still working fine

Reusable rocket engines have become all the rage lately, even as NASA's continually delayed Artemis I mission attempts to launch with non-reusable technology. Realistically, the only way to significantly lower launch costs is to reuse the engines rather than build them from scratch every time. Another small start-up company, RocketLab, has successfully retested a rocket that has flown in space.