A fisherman yesterday found the first stage booster from Atea-1, the first rocket from New Zealand aerospace company Rocket Lab, which was launched from Great Mercury Island on Monday.
But the 2kg payload and the flight computer, both of which could have valuable data about the flight, has yet to be recovered.
"There's over 100sq km to look for it unfortunately, so it could take a little bit of time," company director Mark Rocket said.
Finding the payload would be especially useful as some of the communications system with the rocket failed during the flight, Mr Rocket said.
But he said the flight had been a success, whether the payload was recovered or not.
"We had a good 22-second burn and the recovery of the booster showed we had a good stage separation," Mr Rocket said.
"From what we can see it made it to an altitude of 100km, which is where space begins." Any marine traffic in the area off Great Mercury Island is asked to keep a lookout for the payload and take note of GPS co-ordinates.
Mr Rocket said the 6m-long, 60kg rocket reached its target speed of 5000kmh before splashing down.
He said once found, the payload should not be handled as it was "potentially hazardous" and contained delicate instruments.
