WASHINGTON — U.S. President Barack Obama views China as a potential partner for an eventual human mission to Mars that would be difficult for any single nation to undertake, a senior White House official told lawmakers.

Testifying May 4 before the House Appropriations commerce, justice, science subcommittee, White House science adviser John Holdren said near-term engagement with China in civil space will help lay the groundwork for any such future endeavor. He prefaced his remarks with the assertion that human exploration of Mars is a long-term proposition and that any discussion of cooperating with Beijing on such an effort is speculative. [Photos: China's First Space Station]

"[What] the president has deemed worth discussing with the Chinese and others is that when the time comes for humans to visit Mars, it's going to be an extremely expensive proposition and the question is whether it will really make sense — at the time that we're ready to do that — to do it as one nation rather than to do it in concert," Holdren said in response to a question from Rep. Frank Wolf (R-Va.), a staunch China critic who chairs the powerful subcommittee that oversees NASA spending.

Holdren, who said NASA could also benefit from cooperating with China on detection and tracking of orbital debris, stressed that any U.S. collaboration with Beijing in manned spaceflight would depend on future Sino-U.S. relations. [Gallery: Future Visions of Human Spaceflight]

"But many of us, including the president, including myself, including [NASA Administrator Charles] Bolden believe that it's not too soon to have preliminary conversations about what involving China in that sort of cooperation might entail," Holdren said. "If China is going to be, by 2030, the biggest economy in the world … it could certainly be to our benefit to share the costs of such an expensive venture with them and with others."

Wolf, who characterizes China's government as "fundamentally evil," said it is outrageous that the Obama administration would have close ties with Beijing's space program, which is believed to be run primarily by the People's Liberation Army, or PLA.

"When you say you want to work in concert, it's almost like you're talking about Norway or England or something like that," an irate Wolf told Holdren, repeatedly pounding a hand against the table top in front of him. "As long as I have breath in me, we will talk about this, we will deal with this issue, whether it be a Republican administration or a Democrat administration, it is fundamentally immoral."

Holdren said he admired Wolf's leadership in calling attention to China's human-rights record, but noted that even when then-U.S. President Ronald Reagan referred to the former Soviet Union as "the evil empire" in the late 1980s, he continued to cooperate with the communist bloc in science and technology if doing so was deemed in the U.S. national interest.

"The efforts we are undertaking to do things together with China in science and technology are very carefully crafted to be efforts that are in our own national interest," Holdren said. "That does not mean that we admire the Chinese government; that does not mean we are blind to the human rights abuses."

Holdren said that as White House science adviser, his capacity to influence the president's diplomatic approach to Beijing is limited.

"I am not the person who's going to be whispering in the president's ear on what our stance toward China should be, government to government, except in the domain where I have the responsibility for helping the president judge whether particular activities in science and technology are in our national interest or not," Holdren said.

Recently enacted legislation prohibits U.S. government collaboration with the Chinese in areas funded by Wolf's subcommittee, whose jurisdiction also includes the U.S. Commerce and Justice departments, the National Science Foundation and the National Institute of Standards and Technology.

When asked how he interpreted the new law, part of a continuing resolution approved in April that funds federal agencies through Sept. 30, Holdren said the administration will live within the terms of the prohibition.

"I am instructed, after consultation with counsel, who in turn consulted with appropriate people in the Department of Justice, that that language should not be read as prohibiting actions that are part of the president's constitutional authority to conduct negotiations," Holdren said. "At the same time there are obviously a variety of aspects of that prohibition that very much apply and we'll be looking at that on a case by case basis in [the White House Office of Science and Technology Policy] to be sure we are compliant."

Rep. John Culberson (R-Texas), who joined Wolf last fall in opposing an official visit to Beijing by Bolden, accused Holdren and the White House of plotting to circumvent the law.

"It's not ambiguous, it's not confusing, but you just stated to the chairman of this committee that you and the administration have already embarked on a policy to evade and avoid this very specific and unambiguous requirement of law if in your opinion it is in furtherance of negotiation of a treaty," Culberson said. "That's exactly what you just said. I don't want to hear about you not being a lawyer."

Holdren said a variety of opinions and legal documents indicate the president has exclusive constitutional authority to determine the time, scope and objectives of international negotiations and discussions, as well as the authority to determine the preferred agents who will represent the United States in those exchanges. [The Best (and Worst) Mars Landings]

Culberson reminded Holdren that the administration's civil research and development funding flows through Wolf's subcommittee, and that funding could be choked off if the White House fails to comply with the law.

"Your office cannot participate, nor can NASA, in any way, in any type of policy, program, order or contract of any kind with China or any Chinese-owned company," Culberson said. "If you or anyone in your office, or anyone at NASA participates, collaborates or coordinates in any way with China or a Chinese-owned company … you're in violation of this statute, and frankly you're endangering your funding. You've got a huge problem on your hands. Huge."

This article was reprinted with permission from SPACE.com.