NASA says the parachute system for its Orion crew capsule intended to carry astronauts deep into space has successfully completed a "most complex" test to date.

The system, intended to slow Orion's descent as it re-enters the Earth's atmosphere from space, passed its latest test, the 14th in a series carried out in the Arizona desert, the space agency announced.

On Wednesday, the Orion capsule was dropped from an aircraft from an altitude of 35,000 feet, and they also allowed it to gather speed in a free fall of around 10 seconds to fully test the parachutes under the stress of opening, NASA officials said.

"We've put the parachutes through their paces in ground and airdrop testing in just about every conceivable way before we begin sending them into space on Exploration Flight Test (EFT)-1 before the year's done," Orion program manager Mark Geyer said in a NASA statement. "The series of tests has proven the system and will help ensure crew and mission safety for our astronauts in the future."

Two sets of parachutes on the capsule performed perfectly, officials said. An initial set of small chutes was deployed which pulled away Orion's forward bay cover, uncovering and deploying the main set of three parachutes that slowed Orion down to a safe landing speed.

The bay cover is a protective portion that must remain on the capsule until it has begun to re-enter Earth's atmosphere and then must be successfully pulled away for the large main parachutes stored underneath to be released.

The three main parachutes have an area equivalent to an entire football field and can slow the capsule down to a speed of just 20 miles per hour for a safe landing.

In Orion's first launch, expected in December, a Delta 4 rocket will lift an uncrewed Orion capsule to 3,600 miles away from the Earth. That's farther than a spacecraft designed to carry a human crew has traveled in 40 years, NASA pointed out.

In its return from that altitude, the capsule will experience temperatures of almost 4,000 degrees Fahrenheit as it nears speeds of around 20,000 miles per hour.

From that speed its parachute system will have to slow it down for a successful safe splashdown somewhere in the Pacific.

In another parachute system test set for August, NASA engineers will see Orion dropped with one main chute and one stabilizing drogue chute purposely failed, to test if the system can still land the capsule safely.

That test will also allow the engineers to test some new parachute design qualities, NASA said.