WALLOPS ISLAND, Va. — The maiden launch of Orbital Sciences Corp.’s Antares rocket was delayed again, this time due to high winds, spokesman Barron Beneski said here April 20.

The next launch attempt will be April 21 at 5 p.m. EDT, Beneski said.

Orbital is trying to check off the first of two Antares demonstration flights it must complete before it can start collecting on a $1.9 billion contract it got from NASA in 2008 to haul cargo to the international space station. In the first flight, Antares will send to orbit a dummy payload with roughly the same mass as its companion Cygnus cargo spacecraft. For the second flight, tentatively slated for June or July, Antares will launch the real Cygnus to the space station on a demonstration cargo run.

Orbital has been trying to launch Antares since April 17, when the premature disconnection of a data cable from the roc

ket’s second stage prompted the company to abort 10 minutes before liftoff. Orbital added some slack to the cable and prepared to launch April 19, but bad weather forced another scrub.

Antares launches from Pad 0-A at the Mid-Atlantic Regional Spaceport, a part of NASA’s Wallops Island Flight Facility operated by the state of Virginia. The state charges Orbital $1.5 million per launch.

Dan Leone is the NASA reporter for SpaceNews, where he also covers other civilian-run U.S. government space programs and a growing number of entrepreneurial space companies. He joined SpaceNews in 2011.Dan earned a bachelor's degree in public communications...