Whether humans should first return to the Moon or go directly to Mars -- or do both -- was the subject of often spirited debate in Washington October 29 as the National Space Society hosted the Space Summit to discuss the future of exploration of the Moon and Mars.
     "Building the Bridge to the 21st Century" was the theme of the day-long conference held at the offices of the American Geophysical Union in Washington. About 100 people, from leading scientists and engineers to grassroots space activists, attended the event.
     The summit featured a full day of talks about the robotic and human exploration of the Moon and Mars, including an update on evidence that life once existed on the Red Planet. A separate event the following day featured visits to Congressional offices by space activists to impress upon them the importance of continued funding for space exploration.

Moon vs. Mars: The Great Debate
The centerpiece of the Space Summit was an extended discussion on the merits of human exploration and settlement of the Moon versus Mars. The discussion was anchored by a debate between two strong pro-Moon advocates and two equally strong pro-Mars advocates.
     Arguing for first returning to the Moon were Dr. Wendell Mendell, a planetary scientist at the Johnson Space Center and leading lunar exploration advocate; and Gordon Woodcock, a former Boeing engineer who worked on the Apollo program and who is now chairman of the NSS's policy committee. Arguing to go directly to Mars were Dr. Louis Friedman, executive director of the Planetary Society; and Dr. Robert Zubrin, chairman of the NSS's executive committee and author of "The Case for Mars". Dr. John Logsdon of George Washington University moderated the debate.
     The debate showed that there are a continuum of positions regarding the roles of the Moon and Mars in the future of human exploration, and not a pair of diametrically opposed stands. Three of the four debaters believed there were roles both the Moon and Mars could play, although they debated their significance.
     Mendell, who said he was "distressed" that such a debate was even taking place between the Moon and Mars, saw the Moon as a testing ground for the technologies needed for a Mars expedition, which would last much longer and be much farther from any help. Quoting from an essay he wrote, published in the current issue of Final Frontier magazine, Mendell said that while auto makers, like aerospace engineers, would "test and test and test" new products for all anticipated failures, he "still would not select the first model of a new design for my trip from Fairbanks to Buenos Aires."
     Mendell's statements were echoed by Woodcock, who saw a Moon base as a "good practice mission" for a mission to Mars. He said such a Moon mission must be integrated into a greater program for Mars so the right technologies are appropriately tested, just as the series of Gemini flights in the 1960s tested equipment and techniques for the Apollo lunar missions. He also saw commercial development on the Moon as a strong possibility.
     Friedman agreed that we should first go to the Moon and then Mars, then noted that we have already gone to the Moon with Apollo and thus should go on to Mars. Claiming that the Apollo lunar landings ended because we "completed the human role of the exploration of the Moon," he saw Mars as the goal of future efforts, largely because it is the only planet outside Earth which could have harbored life in the past and could support human life in the future. Friedman also took a dim view towards claims than lunar ice existed on the Moon's south pole, and claimed that "lunar commercialization is more fictional than lunar ice."
     Zubrin took the most extreme position of the debaters, arguing that any human missions to the Moon would be a "fatal detour" for efforts to explore Mars, given limited political resources. He drew an analogy with the European exploration of Greenland and North America, comparing the Moon with Greenland: both much closer to home, but very resource poor, while greater success was with the more distant North America and would be with Mars.
     "Bob's on a different wavelength," quipped Mendell.
     Other speakers earlier in the day questioned the basis for the "Moon vs. Mars" debate itself. Dr. Michael Griffin, executive vice president and chief technical officer at Orbital Sciences Corporation and former head of NASA's Exploration Office, called the debate a "very small-minded question," as if "we might not be able to do both."
     Griffin noted that a proposed 1999 NASA budget of $12.5 billion worked out to about $0.14 per American per day, an amount too small for most to notice. "I'm sure I waste more money than that," he said. He argued that "who could miss" even $0.25 per person per day, an amount that would work out to an extra $10 billion a year for NASA, "more than enough" for a human Mars mission.
     "Going to the Moon and going to Mars are intrinsically the same, technologically," he said.
     In any event, NASA and space activists will have to work hard to sell their plans for human exploration to the American people, Senator Conrad Burns (R-MT), said in the morning keynote. He said it was "vitally important" to articulate a vision for the next 20 years, and then sell that vision to people on Capitol Hill.
     He also said the most important people to convince are not Congressmen but "that guy sitting in a John Deere tractor" or otherwise working but in any case does not think about space. They need to know why we are doing this, whether we can afford it, and where it will lead us.
     "We have to become salesmen," he said.

Plans for Mars Exploration
While some debated the relative political merits of human exploration of the Moon and Mars, other discussed the technical details of such missions. Doug Cooke, manager of the exploration office at the Johnson Space Center, presented a "reference mission" for a human Mars mission at the conference, illustrating the proposal with a new computer-generated animation of the mission.
     In the proposal, four launches of a heavy-lift launcher, perhaps derived from the shuttle, would send two unmanned spacecraft to Mars in the first launch window. One would go into orbit around Mars and serve as a return spacecraft to Earth, and the other would land on the planet to serve as an ascent vehicle.
     In the next launch window, two heavy-lift launches would send a six-person crew to the planet, where they would land near the ascent vehicle. They would spend 500 days on the planet before using the ascent vehicle to leave the planet and rendezvous with the return vehicle for the trip back to Earth.
     Some of the major engineering details, such as the propulsion system for the Earth-to-Mars and return spacecraft, are still being investigated, with solar and nuclear electric propulsion being strongly considered. In situ creation of propellant for the ascent vehicle would also be a likely technology for use.
     Cooke said the reference mission is being developed with an eye towards use in the 2010-2014 time frame. He said his office is already working with planetary unmanned missions, such as the 2001 Mars landers and orbiters, to include equipment and experiments to test the radiation environment, aerobraking, and the in situ creation of propellant.
     The proposed reference mission appears as a direct descendant of Zubrin's original Mars Direct proposal, which Zubrin presented at the conference as well. The reference mission as presented appeared as a one-time mission to Mars, but Cooke later told SpaceViews that it would be possible to support future missions by launching new ascent and return spacecraft at the same time the first crew was launched.
     Regardless of mission architecture, any human crew that travels to Mars will need a wide variety of skills, astronaut Scott Horowitz noted in a talk. Any long-duration mission needs people to fill the roles of cook, maid, mechanic, medic, and leader, he said, but a Mars mission would impose an additional set of required skills. Mars crews would need the skills of a geologist to study the terrain, computer wizards and electronic technicians to keep vital computers and electronic equipment running, machinists to make and repair equipment, and reporters to effectively communicate their mission to people back on Earth. Horowitz noted that crews would also need the "patience of a saint" to handle the long journey, especially the trip home at the end of the mission.
     Dr. Larry Young, a professor of astronautics at MIT and director of the new National Space Biomedical Research Institute, discussed our current understanding of the detrimental effects of weightlessness on the human body and ways to counteract them. He noted that most countermeasures currently tried have been either ineffective or, in the case of exercise, very tedious. Other countermeasures need to be tried if we are to send people on long-duration missions to Mars. "It's no credit for those of use pushing Mars," he said, if the astronauts are too weak to function once they get there.
     He made a strong case for artificial gravity through centrifugal force, by rotating the spacecraft. He presented research that showed that relatively fast rotation, of 6 to 10 RPM, would be tolerable by astronauts, which would make rotating spacecraft smaller and perhaps more feasible. He argued for further research in the area, including the addition of a human-sized centrifuge on the space station and tethered spacecraft in Earth-orbit, to better understand the effects of variable, artificial gravity.

Strengthening the Case for Life on Mars
Dr. Everett Gibson of the Johnson Space Center, one of the members of the team which found evidence of past, primitive life in Martian meteorite ALH 84001 last year, presented an update on his team's research in this field at the meeting.
     Gibson spent much of his talk presenting objections other researchers had raised to his team's work, and his rebuttals to those objections. A key point of contention has been claims that the carbonate globules seen in the meteorite formed at high temperatures, which would rule out a biological origin for them. Gibson referred to research on the isotope ratios in the globules as well as the magnetism of the globules, each of which point to origin temperatures no higher than 100 degrees Celsius. Gibson said work by a UCLA group which estimated a temperature of origin as high as 250 C, too high for life, was in fact subjected to a calibration error which has since brought their temperature estimates to 100-150 C.
     Gibson also rebutted criticism that the microfossil-like structures seen in the meteorite were too small to truly be fossils. While much smaller than typical microfossils on Earth, they are comparable in size to microfossils seen in sections of Columbia River basalt that were not discovered until recent years.
     Gibson also addressed claims that the polyaromatic hydrocarbons (PAHs) seen in the Martian meteorite were actually contamination from Antarctic ice and not indigenous to Mars. Gibson pointed out that PAHs were not seen in other, younger Martian meteorites also recovered from Antarctica, thus, the PAHs came from Mars, and were created by biological processes.
     Gibson also pointed out some intriguing new features seen in the meteorites in recent months. In addition to the segmented microfossils first shown last year, they have seen evidence of microscopic appendages and also unusually nesting microfossils, both of which have yet to be explained. They've also seen evidence of fossilized "biofilm", a layer of organic material secreted by bacteria on Earth.
     While Gibson said they have not found the "smoking gun" for life on Mars, they have evidence that they feel is "60 to 70 percent in our favor," he said. He pointed out eight criteria for proving life existed on Mars: geologic context, age, microfossils, colonies and communities, chemical disequilibrium, biological isotope patterns, organic "biomarkers", and indigenous features. Gibson said they have evidence in all eight areas to prove life once existed on Mars.
     "We feel stronger today than when we wrote that [first] paper," Gibson said. Additional papers are due out in coming months in research journals like Science as well as an article for laypersons in Scientific American.

Robotic Exploration: Present and Future
While the focus of the meeting was on the human exploration of the Moon and Mars, robotic exploration of the two worlds was also discussed. Dr. Jeffrey Plescia, a planetary scientist at JPL, provided an overview of the scientific results returned to date by the Mars Pathfinder and Mars Global Surveyor missions.
     Plescia focused on the geological and atmospheric results from Mars Pathfinder. The instruments on the lander showed that wide variations in atmospheric pressure at the surface were quite common, and the formation of dust devils, like those in terrestrial deserts, were quite common. The frequency of dust devils may provide a mechanism for getting dust into the atmosphere and trigger larger dust storms.
     The dust itself showed a tendency to collect on solar panels, cutting their effectiveness by about a third of a percent a day. It's not known if the deposition of dust is temporary or permanent, since the Viking missions seemed to show that dust eventually was removed by winds.
     Plescia addressed the current problems with communications with the lander. He said that although there have been no transmissions in a month, they have received what they think are carrier signals on a couple occasions, but each time they were unable to establish anything more. He said if efforts don't work in the next few weeks to establish a link to the lander, they may wait until next Martian summer, when temperatures warm enough for the lander's electronics to function normally again.
     Plescia also talked briefly about the early science data returned by Mars Global Surveyor, which has returned images, altimetry, and spectral data from its current elliptical orbit. He said a crack in a solar panel may not make it possible to place MGS in its final circular orbit, but that the spacecraft could still do a lot from an elliptical orbit. [Ed. Note: the day after the Space Summit, NASA issued a press release stating that aerobraking would begin again, at a slower rate, in November.]
     Alan Binder, director of the Lunar Research Institute, discussed the Lunar Prospector mission, which is scheduled for launch January 5. The Discovery-class mission is designed to return data on the composition of the lunar surface and the magnetic and gravity fields of the Moon.
     The cost of the mission -- $63 million, of which just $20 million was spent on the spacecraft itself -- was kept low by adopting a philosophy of keeping the spacecraft and mission as simple as possible. For example, the spacecraft lacks an on-board computer, instead relying on a set of 60 commands relayed to the spacecraft from Earth. The spacecraft's low data rate, just 3600 bits per second, several times slower than a typical low-speed modem, keeps the power and mass requirements of the spacecraft to a minimum.
     Of particular interest to the mission is the search for lunar ice deposits. The spacecraft's neutron spectrometer will look for ice by searching for excess deposits of hydrogen, which Binder said would be linked to ice. An extended mission in which the spacecraft is put into a lower elliptical orbit will allow scientists to get higher-resolution data on the lunar poles to aid in their search for ice.

The Space Summit likely changed few minds about the relative priorities of the exploration of the Moon and Mars, but did an excellent job is discussing the issues that will need to be resolved before humans voyage back to the Moon and/or on to Mars. The current situation was summed by Apollo 11 astronaut Buzz Aldrin in a brief speech at the end of the conference. "We don't know all the answers," he said. "We have an awful lot of work to do."