Millionaire Dennis Tito has revised his plan to send a husband and wife around Mars in 2018 — and is calling on NASA to take the lead role in the mission.

"This partnership is a new model for a space mission," Tito told lawmakers on Wednesday during a Capitol Hill hearing organized by the House Science, Space and Technology Subcommittee on Space. "It is not the model of traditional contracts or subsidies for vehicle developments, although those models are embedded in the NASA programs to be leveraged for this unique mission. It is a philanthropic partnership with government to augment resources and achieve even greater goals than is possible otherwise."

Inspiration Mars, the nonprofit venture that was founded by Tito earlier this year to spearhead the space effort, released a 26-page mission architecture study that supplemented his testimony. The concept was hashed out over the course of 90 days in cooperation with NASA experts, and draws heavily on technologies being developed for the space agency.

Tito initially envisioned the flyby as an effort primarily backed by private contributions, but the 90-day study determined that the mission had to be done with NASA hardware. "This is really a NASA mission," Taber MacCallum, Inspiration Mars' chief technology officer, told NBC News. "This is a mission we believe NASA should do."

In an emailed statement, NASA said it's willing to share expertise with Inspiration Mars "but is unable to commit to sharing expenses with them."

"However, we remain open to further collaboration as their proposal and plans for a later mission develop," David Weaver, the agency's associate administrator for communications, said in the email.

How to fly past Mars

Inspiration Mars' concept calls for using NASA's big but yet-to-be-built rocket, known as the Space Launch System or SLS, to put the Mars transit vehicle into Earth orbit. Then the two-person crew would be sent into orbit atop a commercial rocket — for example, a Falcon 9 or an Atlas 5 — to rendezvous with the transit vehicle. That vehicle would consist of a service module to handle avionics, control and communications; an Orbital Sciences Cygnus cargo capsule, modified to serve as a deep-space habitat module; and a re-entry pod based on the Orion capsule currently being developed for NASA's use.



A beefed-up SLS upper stage would blast the transit vehicle out of Earth orbit for its long, looping ride around the Red Planet. The flight profile would follow the scenario Tito outlined when he announced the Inspiration Mars effort: Because of a favorable planetary alignment, the spacecraft could go around Mars and make a "free return" to Earth with virtually no expenditure of fuel — as long as it left Earth by January 2018.

The 314 million-mile (505 million-kilometer) trip would take 501 days, culminating in a high-speed re-entry through Earth's atmosphere and splashdown on May 21, 2019. Tito favors sending a husband and wife — not only because that would presumably make for compatible crewmates, but also because the history-making trip would thus include both genders of the human species. But NASA would play the key role in astronaut selection.

Tito said the timetable could jump-start NASA's plans to send humans around Mars — a feat that's currently scheduled for the 2030s. "Why not move this mission to the here and now, and not wait until the '30s?" he asked.

Follow the money

Tito estimated that the mission would cost less than $1 billion, and that about $300 million could be raised from private contributions. However, he said those contributions would probably come in only after the flyby launches were firmly scheduled on a manifest.



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By Tito's tally, that would leave roughly $700 million in incremental costs to be covered by NASA. He noted that the space agency was already working on some of the components for the mission, including an SLS rocket that's due to be built for an unmanned, around-the-moon flight test in 2017. He said that rocket could instead be used to launch the hardware for the Inspiration Mars mission. However, in order to meet the mission requirements, work on an advanced version of the SLS' upper stage would have to be accelerated.

Tito framed the 2018 Mars mission as a challenge to American know-how and national will. "If we need a Plan B, there is a mission 88 days longer that flies by Venus before going by Mars, a unique trajectory that could be flown in 2021. However by then, another country — almost surely China — will have seen our missed opportunity, and taken the lead for themselves," he said.

He offered the subcommittee what he called "a frank word of caution."

"The United States will carry out a Mars flyby mission, or we will watch as others do it — leaving us to applaud their skill and their daring. If America is ever going to do a flyby of Mars — a manned mission to another world — then 2018 is our last chance to be first," he said.

Reality check

Before Tito's testimony, the lawmakers were generally supportive of the Inspiration Mars concept. Rep. Lamar Smith, R-Texas, chairman of the House Science, Space and Technology Committee, said it was "the type of space endeavor we should encourage." But after Tito's statement, some questioned whether NASA could afford to spend several hundred million dollars on the flyby, particularly in an era of tighter federal budgets.



"Right now, I don't see evidence that a lot of money would be available," Tito acknowledged.

As it now stands, the plan would require retooling the multibillion-dollar SLS-Orion project, and entrusting mission success to a heavy-lift rocket on its very first launch. The concept also assumes that commercial space taxis will be ready to carry astronauts by 2018. NASA currently projects that the taxis will enter service by 2017 — but there's always a chance that the schedule will slip, particularly if development funding doesn't meet NASA's projections.

The 2021 scenario would be more doable. In 2021, NASA currently plans to send another SLS on a test flight around the moon with an Orion capsule and crew.

Update for 5:30 p.m. ET Nov. 20: Tito and MacCallum shed more light on the shift in the Inspiration Mars mission during a follow-up teleconference with reporters. Tito admitted that when they started looking into the Mars flyby, they had a much simpler mission profile in mind — and assumed that commercial space vehicles could handle the challenge. "We found out that it couldn't be done in the inexpensive fashion that we first thought a year ago," Tito said. "Now the price goes up. Now you're talking about using NASA resources."

MacCallum said the 90-day study was "an independent evaluation that to do these kinds of missions, you really do need SLS."

Tito said NASA would have to take steps sometime in the next few months to keep the mission on track for the crucial 2018 launch, and he hinted that legislation might be introduced in Congress next week to address the issue. However, he declined to say who might introduce the bill.

If 2018 doesn't work, Tito said he would continue to press for the 589-day Mars flyby in 2021, which he said would also bring the transit vehicle within about 500 miles of Venus. "I'm ready to stay involved," the 73-year-old investment adviser told NBC News. "I want to see this get done, [but] if somehow we're four years from now and we're in the same place and nothing is happening, then I'll probably fold, because I'm not going to wait until 2033."

Several other issues surrounding commercial spaceflight came up during the hearing:

House Majority Whip Kevin McCarthy, R-Calif., said "many believe that commercial spaceflight is poised to have its own 'dot-com moment' in the near future," and touted the trend as a creator of high-quality aerospace jobs.



Space Subcommittee Chairman Steven Palazzo, R-Miss., signaled House support for extending the federal provisions on commercial space launch indemnification for another year, and he suggested that the issue should be revisited when Congress considers a comprehensive commercial space bill next year. Space News, meanwhile, reported that Sen. Bill Nelson, D-Fla., would introduce a bill extending the liability limits through 2016.



Stuart Witt, CEO of the Mojave Air and Space Port in California, said the story of his facility's involvement in commercial space development was "100 percent a good-news story." Virgin Galactic and XCOR Aerospace are testing the technologies for their suborbital rocket planes at Mojave, and they're expected to start commercial service as early as next year. Witt said that rocket-powered hypersonic business travel from point to point "is where I see the needle moving."



In his email, NASA's David Weaver discussed commercial spaceflight in general as well as Inspiration Mars in particular. Here's the full text of the statement:

"NASA is facilitating the success of the U.S. commercial space industry, opening up new markets and supporting the creation of good-paying American jobs -- all on a path to send humans to Mars. The agency is developing its most powerful rocket to date, getting ready for a test flight of a crew capsule that will take astronauts farther into space than ever before and planning an ambitious mission to capture, redirect and explore an asteroid. We have a robust Mars exploration program with important science missions, such as Curiosity and MAVEN, to help us better understand the Red Planet. Every one of these activities is laying the groundwork for future human missions."At the same time, the American commercial space industry is on the rise, with multiple firms competing to explore space and create economic growth opportunities here on Earth. Two American companies have started cargo resupply operations to the International Space Station, and NASA has issued a ground-breaking request for proposals to certify private U.S. companies to fly astronauts to the space station."NASA has had conversations with Inspiration Mars to learn about their efforts and will continue discussions with them to see how the agency might collaborate on mutually-beneficial activities that could complement NASA's human spaceflight, space technology and Mars exploration plans. Inspiration Mars' proposed schedule is a significant challenge due to life support systems, space radiation response, habitats, and the human psychology of being in a small spacecraft for over 500 days. The agency is willing to share technical and programmatic expertise with Inspiration Mars, but is unable to commit to sharing expenses with them. However, we remain open to further collaboration as their proposal and plans for a later mission develop."

More about commercial spaceflight:

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.