A rocket ferrying an Earth-observing satellite is set to launch on a mission to measure the saltiness of the ocean from space.

The Delta 2 rocket is scheduled to blast off at 7-20 a.m. (10-20 a.m. EDT) Friday from Vandenberg Air Force Base after a 24-hour delay so crews could review an issue with the rocket’s flight plan.

Weather looks good for lift-off.

The Argentine-built satellite carries a NASA instrument that will chart changes in ocean salt levels over three years. Other instruments from Canada, France and Italy will collect environmental data.

Scientists hope the $400 million mission will help better predict future climate change and short-term climate phenomena such as El Nino and La Nina.