7:45pm Wednesday update: Under brilliant, blue skies a used Falcon 9 rocket launched Wednesday, delivered its payload into orbit, and then the first stage returned to make a landing on a droneship in the Atlantic Ocean. About 30 minutes later, the upper stage of the rocket deployed the EchoStar 105/SES-11 satellite into geostationary orbit. The third flight of a used Falcon 9 booster was apparently flawless.

Original post: Fresh off a successful launch on Monday from California's Vandenberg Air Force Base, SpaceX will go for a second mission in three days on Wednesday from Kennedy Space Center in Florida. With a two-hour launch window that opens at 6:53pm ET, SpaceX will attempt to launch the EchoStar 105/SES-11 communications satellite to geostationary transfer orbit. Weather conditions in Florida look fine this evening

The highlight of Wednesday's mission is the company's re-use of a previously flown first stage booster. This rocket first flew in February, when it launched a cargo resupply mission to the International Space Station and subsequently returned to a landing zone along the Florida coast.

This is only the third time SpaceX has launched what it terms a "flight proven" booster. Luxembourg-based satellite operator SES has been one of SpaceX's most faithful customers, having previously employed a used booster. SES has repeatedly demonstrated confidence in the rocket company's ability to make reusable launch technology safe. And with three successful reuse flights, it will probably become easier for SpaceX to find customers for future "flight proven" rockets.

A successful launch Wednesday would also continue what has been a remarkably productive year for SpaceX in terms of overall launches. Wednesday's launch would be the company's 15th flight of the year, and it would keep SpaceX on pace for 20 flights this year, likely allowing the California-based company to fly more orbital rockets this year than any other company or country around the world.

The webcast for Wednesday's launch attempt should begin about 15 minutes before the launch window opens. After the rocket's first stage delivers the payload into orbit, it will attempt to land on a droneship, Of Course I Still Love You, at 8 minutes and 33 seconds after launch. The satellite is scheduled to be deployed into its high transfer orbit about 36 minutes after the launch.