An unmanned SpaceX rocket was supposed to blast off before sunrise Tuesday but the countdown was halted with just one minute remaining.
Officials said the problem was with motors needed for second-stage rocket thrust steering. If controllers had not aborted the launch, computers would have done so closer to flight time, NASA launch commentator George Diller said.
The soonest SpaceX can try again to send the rocket to the International Space Station is Friday.
Four boys from McGowan Park Elementary School in Kamloops, B.C., had won a contest to have their experiment join 17 other student projects from across North American on a trip to the orbiting station.
But the amateur experiments — along with a payload of supplies destined for the space station — were destroyed on Oct. 28 when a NASA-contracted rocket exploded in a spectacular fireball in eastern Virginia.
If and when the Kamloops students' experiment gets to the station, it will examine how the zero-gravity environment of space affects the growth of crystals.
The students prepared silicon tubes containing solutions that, when mixed, cause crystals to form. On the space station, astronauts would remove small clips keeping the solutions apart. When the tubes returned, the students would analyze the crystals and compare them to crystals grown on Earth.
The projects are part of the Student Spaceflight Experiments Program, which is run by the Arthur C. Clarke Institute for Space Education.