LAUREL, Md. — While a dozen space agencies, including NASA, have agreed upon a Global Exploration Roadmap that lays out general plans for human missions leading up to Mars, an April 10 workshop revealed continued disagreement on the best way to get there, particularly regarding the role of human missions to the surface of the Moon.

The NASA Community Workshop on the Global Exploration Roadmap, held at the Applied Physics Laboratory here, brought together representatives from NASA, industry and other space agencies to discuss the updated version of the roadmap. That report, released last year by the International Space Exploration Coordination Group (ISECG), a group of 12 space agencies, outlined pathways for human exploration leading to humans on the surface of Mars.

“We all agree that, as a common, long-term goal, humans on the surface of Mars is something we all strive for,” NASA’s Roland Martinez, one of the meeting organizers, said in an opening presentation at the workshop. He added there was also strong support for using the international space station as a starting point in those exploration plans.

In between the ISS and Mars, the report identifies three “mission themes” for missions that eventually lead to Mars: missions to near-Earth asteroids, the vicinity of the Moon and the surface of the Moon. However, the sequence and schedule of missions in those three areas remains unclear. “What we do in the middle is really gray right now,” Martinez said.

Martinez said that one of those three mission areas, humans to the surface of the Moon, was something NASA was not interested in pursuing. “It’s not part of NASA’s critical path to Mars,” he said. Instead, NASA plans to move on from the ISS with its Asteroid Redirect Mission and, later, as-yet-undefined deep-space missions before going to Mars.

Others at the workshop, though, argued that human missions to the lunar surface are essential to eventually sending humans to Mars. “The Moon is in the critical path for getting back to Mars,” argued Mark Robinson, a professor in the School of Earth and Space Exploration at Arizona State University and principal investigator of the main camera on NASA’s Lunar Reconnaissance Orbiter. “If you want to get to Mars with human beings, you’ve got to go to the Moon first so you can learn how to live and work on another planet.”

Bernhard Hufenbach of the European Space Agency’s European Space Research and Technology Centre, also argued for human missions to the lunar surface for reasons beyond technical preparations for Mars. “You will not be able to build an international partnership if you don’t include the Moon in your roadmap,” he said, citing interest by various space agencies, including ESA, in missions to the Moon.

He also argued that missions to asteroids and other locations in deep space may not be interesting enough to maintain public interest. “I don’t think you can do missions to deep space, the lunar vicinity, or asteroids for a period of 20 years without sending humans to a planetary body like the lunar surface,” he said. “It will not be inspiring enough. You will not keep the public engaged.”

While NASA representatives at the workshop did not appear to be swayed by those arguments, they acknowledged the overall plan of missions leading to humans on Mars is still in its early phases of development. “I don’t think anybody thinks it makes sense today to define a detailed architecture for how we get to Mars,” said Kathy Laurini, who leads NASA’s participation in the ISECG, citing evolving technologies and partnerships.

NASA, though, may soon be tasked to develop a more detailed plan. A NASA authorization bill approved April 9 by the House Science Committee’s space subcommittee would require NASA to develop an “Exploration Roadmap” that includes “the specific capabilities and technologies necessary to extend human presence to the surface of Mars and the sets and sequences of missions required to demonstrate such capabilities and technologies.” That roadmap would be due to Congress 180 days after the bill’s enactment.

Jeff Foust has more than a decade of experience writing about space policy, entrepreneurial ventures and regulatory affairs. In 2001, he established to aggregate and summarize the day's space-related news stories. In 2003, he started The...