One of the engineers NASA depends on to assess the landing systems of the next generation of human-rated spacecraft brings 14 years of experience working with parachutes on launch systems. Plus, as a skydiver, he knows what it's like to have his life depend on a parachute.

"I used to jump out of airplanes," said Jeff Thon, who is a subsystem manager for landing and recovery systems for NASA's Commercial Crew Program. "I started skydiving in 1998 and jumped actively until 2008 and recently picked it back up a couple of years ago when my kids all left the house."

Thon worked with the solid rocket boosters during the space shuttle era. The boosters carried parachutes in their noses so they would float down to the ocean and be recovered for another launch.

Thon started supporting the development of commercial crew systems in 2010. His shuttle experience was invaluable for NASA's Commercial Crew Program because some of the early designs for privately built spacecraft relied on parachutes for the safe return of the crew aboard. All the spacecraft designs, including those with wings, had to be evaluated closely as each phase of development progressed.

"It was early enough in the development program that I could come in green and start to get a grip on what the system looked like and how it should perform," Thon said, "so it was, go learn capsule parachutes."

When NASA awarded the final development and certification contracts to Boeing and SpaceX in 2014, the CST-100 Starliner and Crew Dragon, respectively, featured capsule designs returning under parachutes to land on either land or water.

Almost six years after starting work with Commercial Crew, Thon and the landing systems teams are starting the certification and qualification phase of testing and evaluation for the Boeing and SpaceX spacecraft. That means Boeing and SpaceX are evaluating the systems each plans to use for their respective spacecraft. NASA's role is to ensure the systems are safe to take astronauts to and from the International Space Station.

The mechanisms on both the Starliner and Crew Dragon have seen tests already to show their designs were progressing and were safe. As testing progresses, spacecraft mockups and boilerplate models that are nearly identical to an operational craft will be used to test the performance of the systems. Engineers also are seeing how the parachutes behave in the turbulence and rapid changes that take place in the few seconds after the parachutes are released from their compartments.

"Parachutes don't lend themselves well to computer modeling," Thon said. "Having a bag of 'chutes come out at 300 mph is darn near impossible to model with any kind of computer we have today, so we have to test."

Testing and real-world results have to be performed to adequately show how a landing system will behave, Thon said.

"The team is reviewing the rigorous testing campaign for both Boeing and SpaceX against the standards expected for human spaceflight," Thon said. A system's heritage and history plus how its similarity to other successful parachute systems such as Orion are considered during the evaluation.

The testing isn't just to see how the parachutes will work, it also helps engineers lay out steps for the spacecraft and its crew to take in a number of emergency scenarios.

There have been a couple of parachute-related failures in spaceflight history, including the Soviet-era Soyuz-1 accident in which cosmonaut Vladimir Komarov perished when his Soyuz parachute system malfunctioned during the return to Earth in 1967. NASA's Genesis sample return probe, which carried no crew, crashed into the Utah desert after its parachutes failed to deploy in 2004.

However, NASA has a long history of success with parachute landing systems. Mercury, Gemini and Apollo spacecraft all used parachutes to slow down after re-entry and touch down in the water safely. The space shuttle boosters were recovered intact thanks to parachutes, and the shuttle used a drag chute at landing. That expertise is being leveraged to ensure these systems are safe.

Both Boeing and SpaceX have already conducted demonstration drop tests during earlier phases of development. Now at the certification and qualification phase, when engineers declare the designs safe for use, the testing is more detailed. The test articles carry many more sensors to gather higher fidelity data. All of that data is fed into computers for exacting analysis, especially of those first few seconds of deployment.

"We are aiming to put a check in the box for flight tests and then crewed orbital flight tests," Thon said.

Although the parachutes are an important aspect to a safe landing, Thon also is evaluating the air bags Boeing plans to soften the stop of its Starliner when it touches down.

As with the parachutes, the air bags have to be tested to make sure they will inflate like they need to and that they don't unexpectedly cause damage to the spacecraft.

Thon said the development process is quite a bit different from any other spacecraft the agency has worked on for its astronauts.

"What I love about Commercial Crew is that it's a dedicated group of engineers both on the NASA and on the partners' side," Thon said. "We both work together and use innovative methods to return astronauts to the International Space Station using American spacecraft."