A NASA spacecraft is preparing to head for Jupiter and one of its 95 moons Europa, which is considered to be one of the most promising places for finding life beyond Earth.
Europa Clipper is scheduled to take flight from NASA's Kennedy Space Center in Cape Canaveral, Florida, at 5.06pm UK time while sitting atop a SpaceX Falcon Heavy rocket.
It won't search for life itself but rather peer beneath the moon's icy crust and determine whether conditions there could support it.
Another mission would be needed to find any microorganisms lurking there.
Its massive solar panels make Clipper the biggest craft built by NASA to investigate another planet.
It will take five-and-a-half years to reach Jupiter and the roundabout trip will span 1.8 billion miles.
The spacecraft will have to pass through Jupiter's bands of radiation as it orbits the gas giant and will get within 16 miles of Europa's surface, considerably closer than any other spacecraft.
NASA was set to launch Clipper last Thursday but it had to be postponed because of Hurricane Milton.