Space Shuttle Aftermath: Does China Threaten U.S. in Space?

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But U.S.-Chinese relations run hot and cold, and China's intentions in space, like America's, are military as well as scientific. In 2007, the Chinese used an old weather satellite for target practice for an anti-satellite missile. The result: Thousands of pieces of debris were left in the Earth's orbit, a potential risk to the space station and other vehicles. The United States protested, but the damage was already done.

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Marcia Smith, a longtime space policy analyst at the Congressional Research Service who now consults and runs her own website, SpacePolicyOnline.com, said the Chinese may be talking bigger than they're actually doing.

"There are space enthusiasts who have been hoping for years that the Chinese would launch America into a new space race," she said, "but it's just not happening."

Astronaut Ferguson said in a preflight interview with ABC News, "It is going to take an Apollo-like commitment to really bring Mars into focus. Do I think it is going to be a unilateral commitment by the USA? No. I think it is going to be a global commitment by space-faring nations to pool their resources, realizing this is something beyond the capability of any one country."

ABC News' Gina Sunseri contributed to this report. Additional reporting by the Associated Press.