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"Electron made it through wall! Solid telemetry all the way to sea level with a healthy stage. A massive step for recovery!!"
@peter_j_beck:
Electron made it through wall! Solid telemetry all the way to sea level with a healthy stage. A massive step for recovery!!
This is a big step for Rocket Lab. Getting the booster through reentry without a reentry burn was the big hurdle to Electron reuse. Now they can work on catching them.
Congratulations Rocket Lab!
It sounds like someone is excited, but I have no idea what "made it through wall" means. Better link?
Essentially, they're talking about the first stage surviving reentry through the denser parts of the atmosphere, the "wall".
The first stage of most launch vehicles is separated while the vehicle is still well below orbital velocity; however, this can still be quite fast, and is somewhere between Mach 5 to Mach 12+. Stage separation occurs in the upper atmosphere, where there's very little drag; however, the first stage is on a suborbital trajectory, and begins to descend rather quickly. Soon, it's hitting the denser parts of the atmosphere, still traveling at hypersonic speeds.
Expendable launch vehicles, like ULA's Atlas V or Delta IV, don't need to worry about keeping the first stage intact, so they instead break up before hitting the ocean. For recoverable first stages like the Falcon 9 (and hopefully Electron in the near future,) they need to be slowed down and oriented appropriately to avoid tumbling on the way down. SpaceX uses a reentry burn to slow down (essentially, they point the engines forward and fire three of them for a few seconds); I don't think any information about Electron's method of deceleration has been released (except that it's not propulsive.)
Electron is a very small launch vehicle, and using a propulsive entry burn like SpaceX's Falcon 9 would probably cost a prohibitively large amount of fuel. So they're testing out how to keep the first stage intact until it's through the "wall" of the dense lower atmosphere, so they can add parachutes and catch them mid-air with helicopters. (Yes, seriously.)