They came, they launched and now they are off home.

Now that their stadium-sized super pressure balloon is floating off the East Coast of the North Island, the Nasa balloon team based at Wanaka Airport are packing up their computer, scientific and engineering equipment and heading back to the United States.

By next week all that will be left from the mission will be locked inside shipping containers.

Campaign manager Justin Marsh said the balloon was operating as expected and was being monitored from Nasa's base in Palestine, Texas.

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A University of Chicago's Extreme Universe Space Observatory (Euso) telescope is attached to the balloon. It is designed to detect high-energy cosmic rays that come from outside our galaxy and penetrate Earth's atmosphere.

About 8pm yesterday, the balloon was about 300km east of Wellington and travelling northeast on a planned 100-day journey around the Southern Hemisphere.

Most of the Wanaka crew will have left by Sunday and the rest will follow shortly after.

There would not be much down time however, as they would start working almost immediately on at least five balloon launches in the United States.

''It's going to be nice to get home but it's pretty much straight into work,'' Marsh said.

Nasa meteorologist Chris Scwhantes said he was pleased he did not have to worry about the weather above New Zealand for a while.

It was the first time Scwhantes had been to Wanaka and said he would leave the town with some very happy memories.

''We get more support here in Wanaka from the public than we do back in the States. You can be walking down town and if you have any Nasa gear people will stop and talk; it's great.

Nasa balloon programme office chief Debbie Fairbrother said a decision on when Nasa would return to Wanaka would probably be made in the next month or two.

''We'll be back. We've got our launch pad out there now and we love coming back to Wanaka so it might not be next year, but we will be here again.''