SpaceX, NASA astronaut launch to International Space Station called off at last minute

A SpaceX Falcon 9 rocket, with the company's Dragon spacecraft on top, is seen at sunrise on the launch pad on February 23 at NASA's Kennedy Space Center in Florida.

(CNN)SpaceX and NASA have called off an astronaut launch to the International Space Station after an issue with the rocket's ground system was detected.

With about two minutes left on the countdown clock, the launch was called off because of a problem related to the TEA-TEB ignition fluid, which is used to ignite the SpaceX Falcon 9's rocket engines at liftoff.
The decision to wave off the launch was made "out of an abundance of caution," said Kate Tice, a SpaceX systems engineer, in commentary on Monday's webcast.
    The four astronauts exited the spacecraft after waiting for it to be drained of its fuel.
    The four astronauts, who were strapped into their Crew Dragon capsule atop the rocket in the hours leading up to launch,