The development of the Moon can indeed begin very quickly. I've sat through some excellent presentations on Lunar COTS proposals. These offer near term development at much lower cost than traditional government-led programs.

As I mentioned above, the main anti-Mars argument is that Mars missions require a multi-decade program at enormous cost. Such missions would supposedly require construction of gigantic interplanetary spaceships; requiring advanced propulsion, advanced radiation shields, advanced life support systems and so-on. This is then used to justify spending on various technology development and research programs on the basis that they will be needed for Mars missions at some time in the future.

Mars Direct doesn't require any of these advanced sci-fi technologies or the expensive programs needed to develop them. It uses relatively small spacecraft that can be launched directly from Earth by Saturn V equivalent modern launch vehicles. The plan explains how the various engineering challenges are solved and how the risks to the mission and crew are mitigated. It also makes extensive use of in-situ resources to keep the logistics and therefore the cost of the mission under control.

The main anti-Mars argument is one of affordability. It is generally assumed that crewed Mars missions will require massive increases in space program budgets over many decades, requiring governments to divert funds from other (far more pressing) needs on Earth. It also doesn't help that crewed Mars missions are usually depicted as short stay "flags and footprints" exercises that allow very little actual exploration to occur.

Robert Zubrin's Mars Direct plan allows affordable near-term missions that put human crews on Mars within a decade of program inception. It allows long stay missions that provide astronauts with the mobility needed to explore large areas of the Martian surface. The plan leads to the establishment of a permanent base that supports exploration on a global scale. Through hardware commonality, the plan also allows concurrent establishment and operation of a Lunar base.

Since Zubrin's plan was first published, companies such as SpaceX have arrived on the scene. These have the potential to greatly reduce the cost of spaceflight.

Andy Weir spoke to the recent Mars Society annual convention in Washington DC via Skype (he doesn't like to fly). He explained the great lengths he went to in order to make his novel as scientifically accurate as possible.

The Mars missions depicted in his novel are based on Robert Zubrin's Mars Direct plan. Mars Direct is designed to be developed quickly and at low cost. It doesn't require an increase in the space program budget and therefore doesn't require a "Kennedy moment" as such. What it does require is for the next president to set clear and worthwhile goals for NASA.

It isn't in NASA's near-term interest to publish a clearly defined Mars mission plan. If NASA tried to formulate a plan, they would be obligated to build it around their SLS and Orion make-work programs. Even if such a plan did not have an officially published cost estimate, it would still be possible for critics of the plan to derive an unofficial cost estimate from the plan details.

This would open the way for proposals from around the aerospace industry to do the mission cheaper and sooner with alternative launch vehicles and flight hardware. Missions to Mars (or anywhere for that matter) may be too expensive to do with SLS and Orion, but that doesn't mean that SpaceX and their competitors can't do a better job.

It would have been unreasonable to have expected US taxpayers to have accepted continued "crash program" spending levels for NASA after the Moon goal had been won. After all, the rockets, technology and infrastructure had already been developed. National priorities had changed and NASA funding was reduced. However, the US economy was much smaller then. Since that time, NASA funding has gradually crept back up in real terms.

NASA was able to operate the Space Shuttle, which can be considered an equivalent class of launch vehicle to the Saturn V, for thirty years. It seems reasonable to assume that NASA could have operated a Saturn V equivalent launch vehicle at similar cost and flight rate over this time. This would have allowed a steady rate of crew and cargo flights to the Moon, sufficient to maintain a modest scientific base. With basic development and use of in-situ resources, there could easily have been an ISS sized outpost built and maintained on the Moon by now.

A Saturn V equivalent launch vehicle could then have been used to implement Robert Zubrin's Mars Direct plan, or one of the NASA design reference missions that have been derived from it. Once again, use of in-situ resources would allow such missions to be performed within present day budgets.

Other nations would be unwilling to hand over the vast resources of the inner solar system to exclusive US control. They would therefore develop their own programs to participate as friends or rivals. Commercial Space would have got into the game sooner or later, offering crew and cargo transportation to BEO outposts at competitive prices.

The present stagnant status quo is a painful delay, but not a disaster. The inner solar system is still out there, no matter how long we take to seize it's potential. Somebody has to take the initiative to set goals beyond LEO and challenge the international community to open the new frontier. If the US and her allies can prove that humans to Mars is an attainable goal, then the entire developed world will have to rise to the challenge of the new frontier, or be left behind!

The most important point to note is that missions to both the Moon and Mars can be done with the same launch vehicles. Sensibly designed Mars missions, such as Mars Direct, can be flown without the need to build giant interplanetary spaceships. Any Saturn 5 equivalent heavy lift rocket will suffice, whether it be the SLS, or an equivalent built by Commercial Space, or by other national space agencies.

This means that rather than being forced to choose between the Moon or Mars, bases can be established and operated at both destinations at the same time. These would make logical successors to the ISS.

Solar flares would deliver infrequent, but prompt radiation doses, that could lead to radiation sickness. Fortunately, radiation from solar flares can be shielded against. Robert Zubrin's Mars Direct mission plan provides the crew with a solar flare storm shelter for this purpose.

Cosmic radiation, on the other hand, cannot be shielded against. Fortunately, the dose is delivered slowly over time, allowing the body to cope with any damage it causes. Ionisation from radiation can cause chemical reactions in cells, which can create toxins and carcinogens. This is why Robert Zubrin refers to toxins in his article. Provided that the dose rate is kept low, the toxins can be removed from the cell before they can kill it. At higher dose rates, some of the cells will be overwhelmed by the toxins and will die, resulting in radiation sickness as the body struggles to replace them (or not in the case of brain cells). This is why the prompt dose administered to the mice was so harmful to them.

The plan allows for a mission that doesn't land on Mars in 2033, followed by a "short stay" (flags and footprints) landing in 2039. In other words, the astronauts get very little actual exploration done.

Doing crewed missions to Mars, or to anywhere else in space for that matter, requires sending astronauts into harm's way. If the only way NASA can do Mars missions offers effectively zero capability and therefore zero value, then it can't be justified.

The aim of the workshop seems to be to depict crewed missions to Mars as something that could be done...but isn't worth the cost or risk.

This all fits in with the idea that the proper goal should be to go to the Moon first. This of course, sits very well with Orion, which isn't really designed to go anywhere other than the Moon, and needs to be given something to do.

The workshop talks about what NASA is "allowed to say" about future plans. It would seem that NASA want the idea of Mars missions to quietly die after Obama leaves office. Then, they hope, NASA will be allowed to fly Orion to the Moon after they're done with the ISS in 2028.

Whoever replaces Obama will have to decide whether the current status quo is acceptable. SLS and Orion are being depicted as the vehicles that can't go to Mars. They could be vulnerable if NewSpace can offer cheaper and more capable alternatives. Challenging the various commercial space companies to a "NewSpace Race" to the Moon and beyond could prove to be a game changer.

The common arguments made against Mars missions are discussed in Robert Zubrin's book the Case For Mars, which explains his Mars Direct mission plan. His plan was used as the basis for NASA's Mars Design Reference Mission.

It's important to understand the politics of Mars mission design. Mars is well known to be a long term goal for NASA and other space agencies. Many factions within these agencies are forced to compete with each other for funding. They have strong incentives to ensure that their program or project is deemed mission critical to a Mars mission.

As the end of the ISS looms on the horizon, there is increasing discussion of what should happen next. Various factions are declaring, and will continue to loudly declare: "You cant go to Mars unless you give us funding!"

The most commonly declared obstacles are radiation, zero gravity, and human factors. These are usually paired with arguments in favour of various predicable remedies:-

The most common is that a Moon base has to be built first. This is a shame, because the Mars Direct mission architecture allows for eighty percent hardware commonality with Moon missions. An important point to understand is that the launch window to Mars only opens every two years. The personnel who build, prepare, and launch the heavy lift rockets needed to go to Mars need to be given something to do when they aren't sending payloads to Mars. After all, they still have to get paid! Why not put them to work sending payloads to the Moon and NEOs? The Moon isn't required as a stepping stone to get to Mars, but there are other reasons to go to the Moon. Missions to the Moon don't have to happen at the expense of Mars missions.

The various other arguments against Mars missions are essentially all of the same type: "Mars is too hard! Therefore we need to spend vast amounts on certain research programs, space infrastructure, and advanced propulsion technologies!" The unfortunate irony is that an active humans to Mars program would provide a far greater incentive to spend money on making flights to Mars cheaper and safer.

Declaring legions of show-stoppers stops the show. Everyone looses.

SpaceX have offered to develop a heavy lift rocket. Many of their competitors have similar designs on the drawing board. All are estimated to cost far less than SLS.

If Commercial Resupply and Commercial Crew to the ISS are successful; it makes logical sense that the next step should be commercial cargo and crewed payloads to destinations beyond LEO.