Some random resources and excerpts for a debate on whether NASA should send humans to Mars.

Reaction to Bush's directive to NASA to explore manned exploration of Mars: NASA's Moon-Mars Initiative Harms Science: American Physical Society Report .

"Returning Americans to the Moon and landing on Mars would have a powerful symbolic significance," the APS report observes, "but it would constitute only a small step in the advancement of knowledge, since much will already be known from exploration with the robotic precursor probes that are necessary to guarantee the safety of any human mission."

[...] "The APS report is false on its face," Zubrin told SPACE.com. "In fact, NASA's most cost-effective science program to date has been the Hubble Space Telescope, a human spaceflight activity. Hubble may have cost twice the Galileo mission to Jupiter, but it has returned more than 100 times the science. This is proof that when human spaceflight activities are properly targeted, they can achieve far more science return than is possible with robotic means."

NASA's current plan for Mars exploration is focused on robotic missions: NASA Explores the Red Planet: Beyond 2009 .

In the second decade of the 21st century, NASA plans additional science orbiters, rovers, and landers. One proposal is for a Mars Sample Return mission that would use robotic systems and a Mars ascent rocket to collect and send samples of martian rocks, soils, and atmosphere to Earth for detailed chemical and physical analysis.

[...] Another proposal is for an Astrobiology Field Lab that would conduct a robotic search for life. It would be the first mission since Viking in the 1970s to look specifically for evidence of past or present life. The robotic lab would carry instruments for identifying and measuring the chemical building blocks for life.

Mars society page of FAQs, including details on the Mars Direct plan: The Mars Society Frequently Asked Questions .

Mars Direct is a sustained humans-to-Mars plan developed by Dr. Robert Zubrin that advocates a minimalist, live-off-the-land approach to space exploration, allowing for maximum results with minimum investment. Using existing launch technology and making use of the Martian atmosphere to generate rocket fuel, extracting water from the Martian soil, and eventually using the abundant mineral supplies of Mars for construction purposes, the plan drastically lowers the amount of material which must be launched from Earth to Mars, thus sidestepping the primary stumbling block to space exploration and rapidly accelerating the timetable for human exploration of the solar system.

[...] If done in a cost-effective manner such as Mars Direct, human exploration of Mars can be accomplished easily under the existing NASA budget -- which currently accounts for less than 1% of federal discretionary spending. A total mission cost of $30 billion, when spread out over the 20 years envisioned by Mars Direct (10 years to first flight, 10 years afterwards during which fivce missions are flown), represents approximately 10% of the $300 billion NASA budget for that time frame (based upon current annual funding levels of $15 billion).

Slashdot post on the House stripping funding for manned exploration of Mars from NASA's budget: Subcommittee Stops Human Mars Mission Spending .

Last week's House Appropriations Subcommittee for Commerce, Justice, and Science FY08 budget markup would prevent work on programs devoted to human missions to Mars. According to a House Appropriations Committee press release, the markup language states that NASA cannot pursue "development or demonstration activity related exclusively to Human Exploration of Mars. NASA has too much on its plate already, and the President is welcome to include adequate funding for the Human Mars Initiative in a budget amendment or subsequent year funding requests." The Mars Society is already leading an effort to get the language removed.

Recent article about timeline for returning to moon and then Mars: NASA on target for return to the moon by 2020--officials .

Despite funding uncertainty, NASA is on track to return humans to the moon by 2020 and set up a lunar outpost to serve as a springboard to explore Mars, officials said Monday. "Our job is to build towns on the moon and eventually put tire prints on Mars," NASA's Rick Gilbrech told reporters here.

[...] "We're hoping we get a budget passed by Congress," he said, pointing out that only six-tenths of a penny of every tax dollar went to funding NASA's space programs. "We're making plans to be ready for any and all scenarios. The (budget proposal) we put in keeps our program on track for the March 2015 initial operating capability... and full operating capability a year later."

More links:
Physiological challenges
Space weather
Ion engine
Colonization of Mars