After capturing the rocket stage, the helicopter crew was forced to let it go for safety reasons.
It was later collected by a waiting boat.
The California-based aerospace company launched the Electron rocket in the late morning from New Zealand's Mahia Peninsula, sending 34 satellites into orbit before the main booster section began falling back to Earth.
Its descent was slowed to about 10 meters per second by a parachute.
The helicopter then used a long line and a hook to grab the booster's parachute lines at around 6,500 feet.
However, the load on the helicopter was greater than in tests and simulations.
The event – named "There And Back Again," a reference to J.R.R. Tolkien's classic fantasy novel "The Hobbit" – was streamed live.
Peter Beck, Rocket Lab's founder, heralded the mission as a success.
|RKLB||ROCKET LAB USA||4.58||+0.21||+4.81%|
"Incredible catch by the recovery team, can’t begin to explain how hard that catch was and that the pilots got it," he tweeted. "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 noted that almost everything went according to plan and that the unexpected load issue was a "nothing in the scheme of things."
"They got a great catch. They just didn't like the way the load was feeling," he said in a conference call after the launch.
Beck added that further analysis should reveal the reasons for the discrepancy in the load characteristics.
The chief executive is pushing to make its Electron rockets reusable, in order to reduce costs and increase the number of launches Rocket Lab makes.
Beck said he still hoped the company could salvage some or all of the spent rocket booster.
The Associated Press contributed to this report.