Rocket Lab caught a falling rocket off Mahia on Tuesday morning as a global audience watched via its livestream, and the New York Times followed events on its home page.
The mission was only a qualified success, however, with founder Peter Beck posting shortly after the capture:
"Incredible catch by the recovery team, can't begin to explain how hard that catch was and that the pilots got it. They did release it after hook up as they were not happy with the way it was flying, but no big deal, the rocket splashed down safely and the ship is loading it now."
Beck later told the Herald that the pilots released the booster "at their discretion" because the load was outside parameters encountered during simulations. "But it was trivia ... it was one per cent," he said.
Nevertheless, Rocket Lab will now do more operational testing before it attempts another mid-air capture, Beck said.
Following a 10.49am Electron launch, a customised twin-engined Sikorsky S-92 helicopter captured the rocket's booster at 11.06am by hooking its parachute line as it fell at a speed of 10 metres a second, or 36km/h.
The mid-air capture was designed to maximise the odds that the booster would be un-damaged, so potentially reusable.
Live footage from the helicopter captured the tense minutes before the dramatic mid-air snatch, which was followed by cheers from the black T-shirted technicians at Rocket Lab's Auckland Mission Control Centre as the booster stage first drifted into view then was successfully snagged. (Start watching the clip below at the 52-minute mark for the immediate build-up to the grab. The launch is at around the 37-minute mark.)
The first and second stages separated two minutes and 30 seconds after launch (see timeline below).
The mid-air snatch took place around 150 nautical miles off the east coast.
The giant S-92 is a seven-tonne helicopter capable of carrying a payload of up to 12.8 tonnes. Its top speed is 306km/h. The US-made model is billed as the largest helicopter in New Zealand. It's owned by Advanced Flight. The pilot requested anonymity.
The Rocket Lab first stage or booster it captured is 12.1m tall with a diameter of 1.2m. It weighs some 22 tonnes at lift-off. With its fuel expended, it's a much lighter piece of metal but still weighs just over 1 tonne.
Beck said earlier that while difficult, the mid-air capture will mean less wear-and-tear on the Electron than the previously used retrieval-by-ship after an ocean splashdown.
While the helicopter snatch has grabbed headlines, the launch is also notable for carrying a satellite made by Astrix Aeronautics, the startup founded by Auckland wunderkind Fia Jones. Beck has part-funded Jones' startup, which is developing cheaper, more efficient solar panels for satellites.
Rocket Lab's next rocket - the much larger Neutron, due to launch in 2024 - will be designed to be reusable from the get-go. It will be designed to land back on the launch pad after a mission and from there it would be returned to a production complex for refurbishment and relaunch.
Beck says that's a step up on Space X's Falcon, whose three boosters self-land but on a pad at sea.
The helicopter retrieval attempt begins an intense period for Rocket Lab, which next month is due to stage New Zealand's first lunar launch from Mahia.
An Electron rocket will blast a Nasa microsat into orbit, then one of Rocket Lab's Photon spacecraft will ferry it into orbit around the moon.
The Kiwi-American firm has also recently announced its first US launch. An Electron mission scheduled for "no earlier than December 2022" will launch satellites for geoanalytics company Hawkeye 360.
And earlier this month, Rocket Lab broke ground on its new Neutron production and mission control complex in Virginia. The effort is being subsidised to the tune of close to $70m by the US state.
Recovery mission profile
• About an hour before lift-off, Rocket Lab's Sikorsky S-92 will move into position in the capture zone, approximately 150 nautical miles off New Zealand's coast, to await launch.
• At T+2.30 minutes after lift-off, Electron's first and second stages will separate per a standard mission profile. Electron's second stage will continue on to orbit for payload deployment and its first stage will begin its descent back to Earth reaching speeds of almost 8300km/h. The stage will reach temperatures of around 2400C during its descent.
• After deploying a drogue parachute at 13km altitude, the main parachute will be extracted at around 6km altitude to dramatically slow the stage to 36km/h.
• As the stage enters the capture zone, Rocket Lab's helicopter will attempt to rendezvous with the returning stage and capture the parachute line via a hook.
• Once the stage is captured and secured, the helicopter will transport it back to land where Rocket Lab will thoroughly analyse it and assess its suitability for reflight.