WASHINGTON — Space Exploration Technologies Corp. (SpaceX) now says it will attempt to launch its cargo-carrying Dragon spacecraft on a rendezvous and berthing demonstration mission to the international space station (ISS) on May 19.

SpaceX announced the new launch date in a May 4 statement. This mission was originally scheduled to launch in late February but the date has slipped repeatedly — most recently from May 7 — as SpaceX continues to test the software that will guide its automated Dragon cargo vehicle toward ISS. When Dragon gets close enough, station astronauts will use a robotically controlled arm to capture the craft and berth it with the orbital outpost.

“SpaceX and NASA are nearing completion of the software assurance process, and SpaceX is submitting a request to the Cape Canaveral Air Force Station for a May 19 launch target with a backup on May 22,” Kirstin Grantham, a SpaceX spokeswoman, wrote in the statement.

NASA issued a separate statement May 4 affirming the new launch target.

“There are a few remaining open items but we are ready to support SpaceX for its new launch date of May 19,” William Gerstenmaier, NASA’s associate administrator for human exploration and operations, said in the statement.

Dragon will ride to space on SpaceX’s Falcon 9 rocket. If NASA deems the mission a success, SpaceX will be free to begin regular deliveries under the $1.6 billion Cargo Resupply Services contract it signed with the agency in 2008.

SpaceX agreed in 2006 to fly three demonstration missions before beginning regular space station resupply runs, but NASA agreed last year to allow SpaceX to combine the second and third demonstration into a single mission.

Following liftoff, Dragon is expected to spend several days catching up with the space station and demonstrating various maneuvers, including a series of confidence-building approaches and retreats. If Dragon does not pass these initial on-orbit tests, NASA could deny the craft permission to approach ISS for berthing and require SpaceX to conduct a third demo mission.

“In theory, SpaceX can launch whenever they want to,” said Josh Byerly, a NASA spokesman at the Johnson Space Center in Houston. “But NASA still holds authority over vehicles approaching and berthing with the space station.”

Meanwhile, SpaceX continues to work on a crewed variant of Dragon under a $75 million Space Act Agreement that NASA awarded the company last August. In a May 8 press release, NASA said SpaceX recently passed an evaluation showing that the layout of a crew-carrying Dragon will allow astronauts to maneuver effectively in the vehicle. During a pair of two-day-long reviews at SpaceX headquarters, several space shuttle astronauts and NASA engineers put a Dragon prototype through a series of so-called human factor assessments that included entering and exiting the vehicle under normal and emergency scenarios.

The astronauts also performed reach and visibility evaluations.

“This milestone demonstrated the layout of the crew cabin to support critical tasks,” SpaceX Commercial Crew Development Manager Garrett Reisman said in a statement. “It also demonstrated the Dragon interior has been designed to maximize the ability of the seven-member crew to do their job as effectively as possible.”

Ed Mango, manager of NASA’s Commercial Crew Program, said the crew cabin evaluation — the seventh of 10 milestones SpaceX must meet under a Commercial Crew Development Program agreement that runs through July 31, gave NASA the opportunity “to provide feedback on these critical interior systems while the company maintains its flexibility to appeal to other customers.”

Dan Leone is a SpaceNews staff writer, covering NASA, NOAA and a growing number of entrepreneurial space companies. He earned a bachelor’s degree in public communications from the American University in Washington.