WASHINGTON — Citing a lack of confidence in its contractor’s ability to deliver, NASA has abandoned plans to fly a solar-sail mission in 2015 after investing four years and more than $21 million on the project.

The Sunjammer mission, including the spacecraft and a deployable 1,200-square-meter solar sail, was being developed by L’Garde Inc. of Tustin, California, under a contract awarded in September 2011. The contract is slated to expire this coming December, and NASA has no plans to continue the work, according to an internal memo circulated at NASA headquarters here the week of Oct. 7.

“NASA is working with L’Garde to de-scope the existing contract to close out the documentation and deliver completed work to the Agency by the end of 2014,” the memo reads.

NASA spokesman David Steitz said problems with the program surfaced a year ago. “During the annual review last October NASA identified key integration issues that increased the schedule risk,” he said via email Oct. 7.

Nathan Barnes, president of L’Garde, said in an Oct. 17 phone interview that the company’s final delivery to NASA will be a design for a spacecraft module and solar sail that in theory could propel a small spacecraft by harnessing the energy of photon strikes. L’Garde will turn over its design in a Critical Design Audit scheduled for Nov. 7, he said.

After that, L’Garde will lay off about 16 employees, all of them in Tustin, cutting the company’s head count roughly in half. L’Garde employed some 35 people when the Sunjammer project was in full swing.

The mission had been manifested as a secondary payload aboard a Space Exploration Technologies Corp. Falcon 9 rocket scheduled to launch the National Oceanic Atmospheric Administration’s Deep Space Climate Observatory in 2015.

As designed, Sunjammer’s solar sail — measuring only about 0.005 millimeters thick — would generate about 0.002 pounds of thrust, or roughly equivalent to the amount of energy a packet of artificial sweetener exerts on an upturned palm. But even that would have been enough for Sunjammer to perform station-keeping maneuvers in near-perpetuity at its intended solar orbit roughly 3 million kilometers away from Earth.

The craft was being designed to serve as an experimental space weather buoy and would have used a pair of U.K.-funded instruments to detect so-called coronal mass ejections from the sun that upon reaching Earth can disrupt sensitive electronic systems, including spacecraft.

NASA’s current early warning system for these events is the 16-year-old Advanced Composition Explorer.

Barnes admitted L’Garde underperformed relative to the work it promised in the 2011 proposal, “Beyond the Plum Brook Chamber; An In-Space Demonstration of a Mission-Capable Solar Sail,” that won it the Sunjammer contract.

L’Garde proposed to develop and build both the experimental solar sail — which would have been the largest ever built — and the spacecraft that would carry it to its operating orbit. The company has built novel space structures before, such as the Inflatable Antenna Experiment that flew aboard the Space Shuttle Endeavour’s STS-77 mission in 1996, but has no experience whatsoever with procuring and integrating spacecraft.

Barnes said that in 2011 he reached out to several NASA centers and companies that he believed could build the spacecraft and leave L’Garde free to focus on the solar sail. None of those he approached — he only identified NASA’s Jet Propulsion Laboratory in Pasadena, California — took him up on the offer.

Rather than give up on the opportunity to land a NASA contract, L’Garde decided to bring the spacecraft development in house. It did not work out, and as of Oct. 17, the company had taken delivery of about $2 million worth of spacecraft hardware including a hydrazine tank from ATK Space Systems of Commerce, California, and four mono-propellant thrusters from Aerojet Rocketdyne of Sacramento, California.

Sunjammer would have used its propellant-free solar sail to maintain its intended orbit, but it still would have needed a chemical propulsion system to reach that orbit, Barnes said.

NASA is “not ruling out possible opportunities for flight of the sail in the coming years,” Steitz said.

Steitz would not speculate on the timing of a future mission, but Barnes said it would have to be a launch profile similar to the one Falcon 9 will provide to get NOAA’s Deep Space Climate Observatory on its way to the gravitationally stable Earth-sun Lagrange Point 1.

“The closest date we were hearing bantered about was 2018,” Barnes said.

Sunjammer enjoyed a run of good publicity during its development, including on Capitol Hill, and one Republican on the House Science Committee said he was disappointed to learn NASA had put the brakes on the project.

“Obviously, I’m very disappointed that we won’t complete this,” Rep. Dana Rohrabacher (R-Calif.) wrote in an Oct. 17 email. “We never seem to be able to afford these small technology development projects that can have potentially huge impacts … but we can find billions and billions of dollars to build a massive launch vehicle with no payloads, and no missions,” he said, referring to NASA’s Space Launch System heavy-lift rocket.

“It looks like it just wasn’t big enough for us to afford it,” Rohrabacher added.