Elon Musk says SpaceX will again attempt to launch its Starhopper prototype rocket around 5 p.m. ET today, 24 hours after engineers were forced to scrub the launch with one second remaining on the countdown clock.

Musk tweeted that the launch had to be aborted over a wiring problem with Starhopper's igniters on its Raptor engine. In response to a question from a journalist, he called the issue "embarrassing."

Starhopper is SpaceX's precursor to its Starship rocket, which Musk has said will one day carry humans to Mars. The squat, metallic prototype rocket completed its first "untethered" flight earlier this summer when it successfully lifted off and hovered about 65 feet off the ground. This next test, if and when it is successful, will launch Starhopper 500 feet into the air, at which point it will attempt to make a three-point landing on the launchpad at the SpaceX facility in South Texas.