Space Teddy has been found safe and well - but he's stuck up a tree and faces a night alone in the bush before he can be rescued.
The fluffy would-be astronaut became lost in dense bush on Waiheke Island this afternoon after plummeting back to Earth when his attempt to set a new world record failed.
The weather conditions were perfect for students at Forrest Hill Primary to launch the stuffed toy, dubbed Space Teddy, into space today.
Last year, students managed to launch it 28km above the earth until the balloon it was attached to burst. This time, a group of eight Year 6 pupils had set the bar even higher.
They had been hoping to launch the bear 40km high - that would be 5km above a current world record.
At 2pm however, NZH Focus learnt the balloon the bear was attached to burst at 21km.
Team leader Marius van Rijnsoever believed the age and size of the balloon were probably to blame and a rescue mission was under way to retrieve it from where it landed on Waiheke Island.
Space Teddy landed in dense bush, 50m off the road on Waiheke Island an hour and a half after the balloon popped.
Police had been unable to find him so van Rijnsoever headed to the island to look for Space Teddy himself tonight.
He was eventually located 10m up a tree in tight, dense bush in a remote part of the island after van Rijnsoever called for backup from an amateur radio enthusiast.
Professional help will be brought in tomorrow to rescue the stuffed bear.
He did not want to disclose the exact location because of Space Teddy's valuable radio transmitting gear, but said it was "on the west coast of Waiheke". He said it was lucky Teddy didn't land in the sea.
"This is much easier than diving," he said.
"Basically, the transmission goes for two or three days but this is really, really dense so we can't get a directional antenna.
"We do have a backup GPS on it but it looks like it's covered under deep scrub so we can't find it."
Earlier today, the students had high hopes to break a second world record of dropping a bunch of paper planes from that height as well.
Despite the 10 am launch not quite going to plan, the final preparations were made around half past.
Once the giant weather balloon - five times bigger than last year's one - was filled with helium and tied up, it was just a matter of minutes to take off.
It all happened very suddenly, taking everyone by surprise.
Van Rijnsoever said it didn't matter that it was "accidentally" let go a bit too quickly, as everything was in order.
In just a few minutes, it quickly became more and more difficult to spot in the sky.
Back in the control room, the students gathered around the screen to watch Space Teddy in action and monitor its whereabouts.
The ascent had been set to take around three hours, and the descent about an hour.