"SpaceX is the new kid on the block, but it's proven its capabilities very quickly," said Marco Caceres, director of space studies with Teal Group, a Fairfax, Virginia-based consultant. "SpaceX would love to be the first commercial company to land its own private astronauts on the moon and eventually go on to Mars."

"It's entirely possible that we wake up one day and the Russians say, 'We're not taking your astronauts up anymore,'" said Marco Caceres, director of space studies at Fairfax, Virginia-based consultant Teal Group. "NASA's anticipating this possibility. That's why they want to move as quickly as possible with this program."

"They're being borderline delusional if they think they're going to meet the 2015 target," Richard Aboulafia, an aerospace consultant with Fairfax, Virginia-based Teal Group, said in a telephone interview. "That's not going to happen. If it's the first half of 2016, I will call that a strategic victory." Aboulafia has more than 20 years of experience in the aerospace industry and writes reports providing forecasts of aircraft markets.

Funding two ventures may raise development costs while also fostering competition and giving NASA an alternative if one vehicle encounters technical difficulties, said Marco Caceres, director of space studies with Teal Group, a Fairfax, Virginia-based consultant.

Congressional opposition to a similar arrangement for the crew contract has waned as the fraying U.S.-Russia relationship focuses attention on NASA's dependence on Soyuz rockets to put astronauts into orbit, Caceres said in a telephone interview.

"The Russians have done NASA a favor in terms of funding," Caceres said.

"As the prospects for growth have decreased in the defense industry, the way that defense companies can attract investors is by showing that they can increase profit margins," Philip Finnegan, director of corporate analysis at the Teal Group, an aerospace and defense market research firm, told Politico. "There's been a drive in the defense industry to increase profit margins and return more to shareholders."