Astra is finally making themselves known publicly by way of an Ashlee Vance feature for Bloomberg. Some really cool details of their setup:
At the former Alameda Naval Air Station, Astra took over a decrepit building used decades ago to test jet engines indoors, which has helped keep its secrecy intact. The facility has two long tunnels that send fire and scorching hot air up through exhaust towers and thick concrete walls capable of absorbing the explosive impacts of tests gone wrong.
This setup has allowed Astra to conduct thousands of runs on its rocket engines without its neighbors noticing much of anything. It’s also meant Astra can put the engines through their paces on-site and make adjustments to the hardware quickly, instead of going to the Mojave Desert or an open field in Texas where other rocket makers typically run engine trials.
In addition to tidbits like that, the feature has a few nice photos and videos of their factory, so be sure to check those out.