NASA has cleared the way for Boeing (BA -0.87%) to deliver an astronaut to the International Space Station during what was supposed to be a manned test of its Starliner spacecraft, showing faith in the aerospace giant and its transport vessel to solve the growing problem of how to get American astronauts into orbit.

On April 5, the space agency said it had updated its Commercial Crew Transportation Capability contract with Boeing to allow the test voyage to take up to six months, up from two weeks, and carry a third astronaut instead of just the previously agreed-upon two-person crew. The changes would in effect make the Starliner test flight a normal mission.

Although Boeing bills itself as a jack-of-all-trades with operations spanning commercial aerospace, defense, and space, in recent years the commercial segment has been the growth engine. Space and defense generated just 22% of total revenue in 2017. If Boeing is to counter that trend, it is going to need multiple project wins on the space and defense side. Success by the Starliner alone won't fix the problem, but it would be a solid step in the right direction.

Boeing's Starliner spacecraft

Artist's concept of Boeing's Starliner crew transport vessel. Image source: Boeing.

In 2014, Boeing and privately held SpaceX, which is run by Tesla CEO Elon Musk, each won contracts to build Commercial Crew transports that would be able to ferry U.S. astronauts to the space station. The original contract called for the missions to begin in 2017; however, setbacks have led to delays.

Both Boeing and SpaceX plan to fly test missions without crew to the space station this year prior to test flights with a crew on board. After each test flight, NASA plans to evaluate the in-flight performance in order to certify the systems and begin regular post-certification crew rotation missions.

The clock is ticking on NASA

NASA currently transports American astronauts to the ISS via Russian Soyuz rockets, but it has no seats booked on the Russian rockets after 2019. After that, it is going to be up to Boeing and SpaceX to provide the needed lift.

"This contract modification provides NASA with additional schedule margin if needed," William Gerstenmaier, associate administrator of the Human Exploration and Operations Mission Directorate at NASA, said in a statement. "Modifying the contract now allows NASA and Boeing an opportunity to tailor the duration to balance the mission needs with vehicle and crew capabilities."

With NASA paying about $75 million per seat for lift on Russian rockets, the agency has every reason to want to transition to U.S.-made transports as soon as possible.

This would not be the first time in recent memory that NASA has expanded the scope of test flights. In 2012, the agency had SpaceX carry real cargo to the ISS on its commercial cargo demonstration flight.

Boeing is ahead in this space race

Investors can take this latest move by NASA as further evidence of something my Fool colleague Rich Smith has been saying for a while now: While both Boeing and SpaceX have Commercial Crew contracts, Boeing is staking its claim on being the preferred contractor. While the initial 2010 contracts specified that each contractor perform the same services, Boeing was to be paid $4.2 billion for the services, while SpaceX only received $2.6 billion.

In January, NASA released updates on test date targets, announcing a schedule that has Boeing completing its uncrewed and crewed tests ahead of SpaceX's Dragon vessel. The agency's latest decision seems to reinforce the idea that NASA sees Boeing's Starliner as being ready for service ahead of SpaceX.

NASA, which has lacked a domestic method for getting astronauts into space since it canceled the Space Shuttle program in 2011, is desperate to see the Commercial Crew program a success. If Boeing's Starliner can rise to the challenge, there should be a steady stream of business coming from NASA as a reward.

For investors interested in buying into Boeing for its diversification between commercial and government sales, the Commercial Crew program is a small, but important, step in making sure that balance remains intact.