NASA Sources tell NBC News that NASA will provide further support for the development of the Boeing Co.'s CST-100 capsule (left), Sierra Nevada Corp.'s Dream Chaser space plane (middle) and SpaceX's Dragon capsule (right).





Update for 12:55 p.m. ET Aug. 3: Boeing, SpaceX and Sierra Nevada are due to receive up to $1.1 billion to continue work on spaceships that could be carrying astronauts to orbit in the 2015-2017 time frame. Check out today's updated story.

My earlier report from Aug. 2: Teams headed by the Boeing Co., SpaceX and Sierra Nevada Corp. will be receiving hundreds of millions of dollars from NASA over the next 21 months for further development of spaceships capable of transporting astronauts to and from the International Space Station, knowledgeable sources told NBC News today.

NASA is to make the official announcement of the winning commercial teams on Friday morning — but NBC News' Cape Canaveral correspondent, Jay Barbree, received word from two sources who were informed of the decision in advance, on condition of anonymity. The sources did not discuss how much money any of the companies would be receiving.

The coming phase of the spaceship development effort — known as Commercial Crew Integrated Capability, or CCiCap — is aimed at producing the design for an entire launch system, including the "space taxi" capsule and launch vehicle as well as ground and recovery operations. The three companies tapped for future funding already have received hundreds of millions of dollars from NASA during earlier development phases. Boeing has gotten $131 million for work on its proposed CST-100 capsule, Sierra Nevada has been allotted more than $125 million for its Dream Chaser space plane, and SpaceX has won $75 million to upgrade its Dragon space capsule to carry crew.

SpaceX, known more formally as Space Exploration Technologies, has also received almost $400 million from a separate NASA program to support the development of the Dragon and Falcon 9 rocket for cargo deliveries to the space station. The successful flight of a Dragon to the station and back in May opened up the way for SpaceX to start regular cargo deliveries under a $1.6 billion contract with NASA.

Representatives of SpaceX and Sierra Nevada had no comment on the news. NASA said it would not announce the agreements until Friday morning, as scheduled. Efforts to contact Boeing were unsuccessful so far tonight. The Wall Street Journal, meanwhile, quoted industry sources as saying that Boeing and SpaceX were expected to share the bulk of NASA's CCiCap money, and that Sierra Nevada seemed likely to emerge with a smaller award.

NASA invited companies to submit proposals in the range of $300 million to $500 million for development of their spaceship designs through May 2014, with potential optional milestones as well. Under an agreement with congressional leaders, the space agency will provide the full negotiated amount for two companies, plus half of the requested funds for a third company. It's an arrangement I like to call "Two and a Half Spacemen," playing off the title of the popular CBS sitcom.

What about the also-rans?

Other companies sought unsuccessfully to win CCiCap funding — most prominently, a consortium that included ATK, Lockheed Martin and Astrium. The consortium's Liberty launch system would adapt the ATK-manufactured solid rocket booster that was used for the space shuttle and the now-canceled Ares 1 rocket. The second stage would be based on Astrium's Ariane rocket. The composite capsule would be provided by Lockheed Martin, which is the prime contractor for NASA's more capable Orion deep-space capsule.

Other contenders from previous rounds of development included Blue Origin, which was founded by Amazon.com billionaire Jeff Bezos; and Excalibur Almaz, which is adapting Russian technology for its launch system.

NASA officials have said they'd be willing to continue advising the also-rans on an unfunded basis. On the other side of the table, all of the companies involved in the CCiCap competition have said they intended to continue spaceship development efforts even if they didn't win NASA's financial support, but at a reduced pace.

What lies ahead?

Boeing, SpaceX and Sierra Nevada have said their spaceships could be ready for NASA's use in the 2015-2016 time frame if they received adequate funding from the space agency. Last month, Ed Mango, NASA's manager for the Commercial Crew Program, told me that the middle of the decade seemed doable, but suggested that 2015 might be too soon.

"By the end of the base period, you need to have an integrated design that you have talked with the government about," Mango said. Actually launching a demonstration spaceflight with a crew might serve as an optional milestone, he added.

Boeing and Sierra Nevada are partnering with other companies to develop their launch system — and the most notable partner in both cases is United Launch Alliance, which could launch Boeing's CST-100 as well as Sierra Nevada's Dream Chaser on its Atlas 5 rockets. SpaceX, in contrast, is pursuing its effort on a solo basis.

With last year's retirement of the space shuttle fleet, NASA must depend on the Russians to transport U.S. astronauts to and from the space station, at a cost of around $60 million a seat. All of the companies involved in the Commercial Crew Program say they can do the job for less money than the Russians. In comparison, the cost of flying the space shuttle was estimated at $1 billion or more per mission.

Like the shuttle, the new space taxis are being designed to carry up to seven astronauts.

The commercial space taxis are an essential piece of the strategy worked out by the White House and NASA to free up money for the development of the Orion multipurpose crew vehicle as well as a heavy-lifting Space Launch System. The Orion and SLS would be used for exploration beyond Earth orbit, featuring trips to a near-Earth asteroid by 2025 and journeys to Mars and its moons in the 2030s.

Update for 11:15 p.m. ET: I want to emphasize that Jay's sources did not tell him which companies are getting more or less money than other companies. They only named the three companies. The Wall Street Journal's report suggests that Boeing and SpaceX will be getting more money than Sierra Nevada, but we don't have any information about that angle of the story. NASA promises that all will be revealed in the morning, and of course we'll pass that along.

More about the spaceship competition:

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.