Photos: Atlas 5 on the pad at sunset

NASA managers Thursday cleared the $1.5 billion Parker Solar Probe for launch early Saturday on a daring mission to “touch the sun,” repeatedly flying through its outer atmosphere to find out why the blazing corona is millions of degrees hotter than our star’s visible surface.

Successfully put through its countdown paces in a critical pre-flight test Thursday, America’s largest rocket currently in service moved closer to a June launch for the U.S. intelligence community.

An Atlas 5 rocket and a Starliner crew capsule stand at pad 41 in these images taken at sunset Dec. 18.