A SpaceX Falcon 9 rocket launched 74 satellites from California early Saturday morning (March 15), then came back to Earth for a landmark touchdown.

The $488 million Spherex mission aims to explain how galaxies formed and evolved over billions of years, and how the universe expanded so fast in its first moments.

The postponement, driven primarily by thick clouds, was the second scrub of the flight since an issue with the rocket on Saturday night.