Britten (7), Quinn (5) and Sahara (9) Ferguson made their own rocket-boosters during the school holidays last year and wanted to use them to go to the moon, their mother, Sara, said.
Yesterday, they came within touching distance of it.
That was thanks to a 4m replica moon, printed with high-resolution Nasa imagery, which is hanging from the ceiling of Hanover Hall.
Ms Ferguson said the replica was a "very good" second choice to going to the actual moon for her children.
"We love this stuff ... I could probably lay here all day.
"We appreciate that we can have activities during the school holidays that teach the kids a few things and get a bit of energy out of them," she said.
Festival director Dan Hendra said the hall was at "full capacity" for the first day of the exhibition.
"People are absolutely loving it ... the little kids are looking up in wonder.
"It really makes them think about the moon and the world around them.
"That is the goal of the science festival — making it more accessible."
And the moon could not get much more accessible than hanging a couple of metres from people’s reach, he said.
Along with the moon, the event also includes a photographic exhibition on Nasa’s science experiments in space, Nasa’s past, present, and future space travel, a feature display focusing on traditional Maori practices of star navigation, and hands-on arts and crafts.
It is on each day at Hanover Hall until Sunday.
