Live coverage: SpaceX grounds launch to wait for better recovery weather

The Earth observing spacecraft will study clouds and aerosols to further our understanding of climate change. Liftoff happened at 3:20 p.m. PDT (6:20 p.m. EDT, 2220 UTC).

A commercial Dragon cargo craft wrapped up a two-day trip to the International Space Station on Monday with a glacial laser-guided final approach before astronauts grasped the supply ship with a robotic arm, completing the refurbished capsule’s second journey to the orbiting research complex.

Within days, NASA is expected to select a winner from a roster of nine eligible companies to try and become the first commercial entity to accomplish a soft landing on the moon with a robotic spacecraft. The privately-developed probe would be the vanguard in a series of unpiloted missions intended to deliver science instruments to the lunar surface and prepare for a human expedition as soon as 2024.