WASHINGTON — NASA and Space Exploration Technologies (SpaceX) will invite 50 of their Twitter, Facebook and Google+ followers to a two-day event at Kennedy Space Center, Fla., expected to culminate with the April 30 Falcon 9 launch of SpaceX’s Dragon cargo capsule to the international space station.

“Participants will have unique in-person experiences with SpaceX and NASA, which they are encouraged to share with others through their favorite social network,” NASA and SpaceX said in an April 2 press release. “Guests will view the launch, tour NASA facilities at Kennedy, speak with representatives from both organizations, view the SpaceX launch pad, meet fellow space enthusiasts who are active on social media, and meet members of SpaceX and NASA’s social media teams.”

Participants will be selected from online registrations. Sign up opened April 5 and closed April 6.

The April 30 launch is SpaceX’s second and possibly final Commercial Orbital Transportation Services demonstration flight. If all goes well, the unmanned Dragon capsule will berth with the space station, setting the stage for the spacecraft to start making periodic resupply runs to the orbital outpost under a $1.6 billion Commercial Resupply Services contract NASA awarded SpaceX in 2008.

Before Dragon is cleared to approach the space station, the spacecraft will conduct a series of checkout procedures in orbit, including a fly-under of the station at a distance of 2.5 kilometers to validate the operation of sensors and flight systems necessary for a safe rendezvous. Dragon will be required to demonstrate its ability to abort the rendezvous.

Assuming Dragon passes these tests, the spacecraft will perform its rendezvous while astronauts inside the space station work to grapple the vehicle with the station’s robotic arm. Dragon will then be berthed to the Earth-facing side of the station’s Harmony node. At the end of the mission, the crew will reverse the process, detaching Dragon for its return to Earth.

The flight readiness review for SpaceX’s upcoming mission is scheduled for April 16 at Johnson Space Center in Houston.