No American launch system has sent humans into space since the space shuttle Atlantis’s final flight in 2011, but that’s about to change. And when it does, it will herald a new era of human space flight: Two private companies will be competing for mission contracts to send people and supplies to the International Space Station and, maybe one day, Mars. Both Boeing and SpaceX have contracts with NASA to provide this service, and both plan to run their first crewed test flight in 2017.

Congress recently announced it would fund this program fully in 2016. Boeing and SpaceX will earn about $51 million per astronaut on each mission for their services. Currently, NASA pays the Russian space agency about $83 million per astronaut that hitches a ride to the ISS on board its Soyuz spacecraft. The idea behind the commercial crew program is to save taxpayer money on space transport and keep it in the American economy. It’s also about fostering competition between companies so that spaceflight continues to innovate and push forward.

“I think that both companies along with NASA recognize that having two healthy and robust systems for American transport of crews is vitally important,” says NASA’s Rebecca Regan.

But having the money and the will isn’t enough. A lot has to go right for the commercial space race to kick off in earnest.

“In the last year, Boeing and SpaceX have made tremendous progress,” says Stephanie Martin with NASA. “Our program and the people here at NASA are working side by side with Boeing and SpaceX, so we really are going through this process in a partnered manner…. It’s not like they send us a vehicle and the end, and tell us they’re ready to launch.”

One major milestone was the selection of four veteran NASA astronauts that will work with both companies through the testing, including the first crewed test flights.

Commercial Crew astronauts, left to right, Bob Behnken, Suni Williams, Eric Boe, and Doug Hurley stand on the Crew Access Arm leading to the White Room at a construction yard near NASA's Kennedy Space Center in Florida.

The astronauts have been spending time getting to know both companies’ systems and the people building them, says Martin. “They’ve had an opportunity to get to know the people behind the hardware, and those people really know more about our astronauts. It helps to remind everyone that we have astronauts’ lives in their hands.”

SpaceX successfully completed a pad abort test earlier this year, which proved the system for the crew to escape to safety if something goes wrong during the launch. Boeing has yet to complete that step, and plans to do so in early 2017.

Both companies need to prove their systems on an unmanned test flight. That will involve sending the shuttle to the International Space Station, docking there for some time and then returning safely home. SpaceX plans that test in late 2016, while Boeing plans to complete that step in 2017.

Both companies are aiming to complete a crewed mission, which will be similar to the uncrewed test, in 2017.

They are working towards the same goal, but taking different paths to get there.

NASA’s approach has been to work closely with the companies to ensure astronaut safety and system reliability, but has left room for innovation, explains Kelly Kaplan with Boeing.

“NASA has to check the box on each of these milestones, to say that yes, we in fact completed them. But they also give us leniency in the way they write the guidelines, so that we can bring our ideas to the table as well.”

As a result, the systems that Boeing and SpaceX have built are very different.

For example, Boeing’s CST-100 Starliner Capsule will be designed to land on hard ground. “Obviously saltwater is very corrosive, so when you land on land, that makes the capsule reusable up to 10 times, and it gives you very quick access to science that’s coming down as well as the crew,” says Kaplan. (SpaceX plans to land its Crew Dragon in the ocean with parachutes, at least in early flights.)

The company is working on engineering the high powered SuperDraco engines that are already part of the spacecraft’s launch escape system so that eventually the Dragon will be able to land on hard ground, too, a SpaceX spokesperson confirmed.

SpaceX is also planning an optional in-flight abort test, which would prove the systems for allowing crew to escape if the mission runs into trouble further into the journey. Boeing opted against completing this step.

When each company successfully completes a crewed test flight, it will enter the final stages of becoming certified by NASA for human spaceflight. After certification, NASA has committed at least two missions to each company to bring four crew members plus cargo to the ISS.

Photos via NASA/Kim Shiflett, NASA