NASA's 'Artemis II' astronauts are preparing for their splashdown off the coast of San Diego, California, on April 10.
A launch countdown includes “L Minus” to indicate how far away liftoff is in hours and minutes, and “T Minus” to show a sequence of events built into the launch countdown.
NASA officials on Monday started the two-day countdown to the Artemis II mission launch, which will send a crew of four around the moon.
Watch the clock count down to NASA's Artemis II launch ...
NASA started the countdown clock for Artemis II while SpaceX lined up another launch with a record-setting booster.