WASHINGTON — Rocket Lab, the U.S.-New Zealand company developing the Electron small launch vehicle, now plans to begin launches in the middle of this year after completing qualification tests of the vehicle’s main engine.

The company announced March 22 that it has completed qualification tests of the Rutherford engine, allowing it to be used in flights of the Electron vehicle. A video released by the company showed the engine firing on a test stand for more than two and a half minutes.

The first launch is planned for the middle of this year, company spokeswoman Catherine Moreau-Hammond said March 23, with the overall flight test program running through the second half of the year. Those launches are planned from a site the company is developing on New Zealand’s North Island.

The Rutherford engine uses liquid oxygen and kerosene propellants and can generate up to 5,000 pounds-force of thrust. The Electron uses nine Rutherford engines in its first stage and a single engine, fitted with an extended nozzle, in its second stage.

Rocket Lab has emphasized the advanced technology used in the development of the engine. Elements of the engine are 3-D printed, and the engine uses electric motors to power its turbopumps.

Electron is designed to place up to 150 kilograms into a 500-kilometers sun-synchronous orbit, which Rocket Lab argues makes it ideal for a number of the constellations of small satellites under development for remote sensing and communications. Rocket Lab announced a contract with Spire in February to launch some Spire satellites on up to 12 Electron missions from late 2016 through 2017.

“We are seeing the vehicle come together, and are looking to move to manufacturing at quantity for both our test and commercial flights,” Rocket Lab Chief Executive Peter Beck said in a statement.

Rocket Lab’s Rutherford Engine Qualified for Flight from Rocket Lab on Vimeo.