Mariners are being urged to keep a lookout for the payload from New Zealand's first home-grown space rocket.
The rocket, dubbed Manu Karere, or Bird Messenger, was launched from Great Mercury Island, off the Coromandel coast yesterday afternoon.
The six-metre long, 60kg, rocket reached its target speed of up to Mach 5, or 5000kmh, and flew to an altitude of at least 100km before splashing down.
Rocket Lab director Mark Rocket said he hoped to find the payload, once the GPS signal was located.
He urged any marine traffic in the area to keep a lookout and take note of GPS co-ordinates.
Mr Rocket said the payload should not be handled as it was "potentially hazardous" and contained delicate instruments.
The rocket was unlikely to have sunk or burnt up on re-entry, he told Radio New Zealand.
"We suspect that it's just bobbing around out there and we're going to be analysing currents to see where might end up."
Yesterday's launch was delayed by seven hours when a fuel line aerocoupler froze, tethering the rocket to its launch pad.
A helicopter was sent to Whitianga to pick up another hydraulic coupling - worth about $6 - from an engineering supplier.
While the Atea-1 is New Zealand's first home-grown and privately-funded space rocket it is not the first to be launched from these shores.
In 1963 an imported rocket was launched to a height of about 75km to conduct upper atmospheric research in a joint venture between Canterbury University's physics department and the Royal New Zealand Air Force.
It was launched from Birdlings Flat, 44km southeast of Christchurch, spent about 2 1/2 minutes airborne and landed in the sea.
NZPA