Currently, the Russian Federal Space Agency, or Roscosmos, charges NASA about $70 million a seat to send astronauts to the space station. With Boeing and/or SpaceX, the cost will be reduced to around $58 million a seat.
"I don't ever, ever want to write another check to Roscosmos, " said NASA Administrator Charles Bolden.
Boeing is about to celebrate its first 100 years in business, and its commercial airplane segment brings in nearly $70 billion.
Read MoreCheaper fuel offsets airlines' storm losses
"I believe firmly that when the company celebrates its second hundred years, there will be a division of Boeing that's building commercial space vehicles, that will be of that magnitude, of that size, " said John Elbon, who heads up Boeing's space exploration division. Manufacture of his company's proposed space taxi, called the CST-100, will begin later this year. Boeing plans to have the first uncrewed test flight in April 2017, and the first crewed flight in July 2017.
"Never before in the history of human space flight has there been so much going on all at once, " Elbon said.
SpaceX President Gwynne Shotwell estimated the first crewed flight of her company's capsule—called the Dragon 2—could be sooner, by early 2017. SpaceX is working on a number of upgrades to ensure the Dragon "is as reliable as it could possibly be, and ultimately we plan for it to be the most reliable spaceship flying crew ever."
NASA's Bolden justified funding two separate development programs by pointing to what's happened on the cargo mission side. The agency offered contracts to both SpaceX and Orbital Sciences to shuttle supplies to the space station, a decision which now looks wise after Orbital Sciences' rocket blew up on launch last fall.
"You've heard both of them say they think they'll be flying by 2017, " Bolden said of SpaceX and Boeing's taxi efforts. "If we can make that date, I'm a happy camper."
Monday marked the first time NASA had updated the public on the space taxi competition since a third company, Sierra Nevada, challenged the selection of Boeing and SpaceX. The Government Accountability Office overruled the challenge.
NASA's Kathy Lueders said having an American space taxi will do more than save money, it will also double science and research capabilities aboard the space station. And even as the two companies are "frenemies" competing against each other, they are also collaborating.
You might also like:
Elon Musk: 10 Lessons In Business, Innovation And Entrepreneurship From The Self-Made Billionaire And Visionary (Tesla, SpaceX, And The Quest For A Fantastic Future)