The head of the Mars Society is Robert Zubrin, who is a well qualified and inventive aerospace engineer. I assume the rest of their work at least involves doing the relevant math.

The Mars One project's problem isn't wanting to go to Mars, it's the missing step two in their plan:

(1) Raise around a million dollars from crowdsourcing, tee shirt sales, and application fees
(2) ???
(3) Finish $6 billion worth of space hardware and launch it.

Elon Musk/SpaceX also want to go to Mars, but they have actual rockets and customers, and his other businesses (Tesla and Solar City) both stand to make a lot of money, and are useful to the original goal. You will need electric rovers, batteries for power storage, and solar panels on Mars. It helps if you have companies that already make that stuff. So I rate the SpaceX Mars program way higher on the probability scale.

Hey, uninformed person, these drones have lithium batteries, and sunlight is more powerful at high altitude due to less atmospheric absorption. So it can fly for years or until something breaks.

> Could you not place solar panels underneath the windmills?

In theory yes. In practice the wind resource is highest in the Midwest, and certain mountain passes. Midwest combines wind and field crops, because the wind turbine only needs about 1% of the land area to install the tower and the access road. The turbine as a whole doesn't create too much shade, so crops grow just fine around it. Mountain passes have too much geography in the way, and are not ideal for collecting sunlight.

Solar is getting installed preferentially in dry areas of the Southwest, because you get more sunlight hours per year there, and on industrial/commercial and home rooftops, because it's easier to compete with retail electric rates. The big desert solar farms have to compete with wholesale utility plants. It's popping up in other places too, I saw some panels in a field in NW Georgia, but the ones I mention above account for most of the installations at present.

There is no need to terraform the bulk of Mars until you have enough people there to justify it. Until then it makes much more sense to restrict the terraforming to the space underneath your habitat domes and arches.

Ideas that Mr. Robinson may not have been aware of also make colonizing easier. One is "Seed Factories" - self upgrading automation that grows from a starter kit, the way a tree grows from an acorn. The starter kit includes plans for the sequential addition of new machines, until you have a fully grown industrial capacity. Another is an improved space elevator system. The static ground-to-synchronous orbit elevator is not the lowest mass design by a long shot, and improved designs can be built with today's materials, rather than requiring "unobtainium".

> Of course I could be nitpicking and point out that the sun actually is a huge nuclear reactor.

We live near an unshielded gravitational confinement fusion reactor, that floods the entire Solar System with several kinds of lethal radiation. We only survive here on Earth because we have a strong magnetic field *and* a thick atmosphere to protect us. Even so, the Sun causes over 100,000 cases of malignant skin cancer every year, and lots of other causes of death. It would never have passed safety review if we treated it like we do new power sources.

Parts of the Moon have natural concentrations of Thorium in the 10 ppm range. A little nuclear waste won't make a difference:

https://upload.wikimedia.org/w...

> And lunar He-3 mining is pretty useless.

There's another reason besides the ones you mention. Parts of the Moon have Thorium concentrations of 15 parts/million. That's about 1000 times higher than the He-3 concentration, and the energy output from fission isn't that much lower than fusion. Not to mention we know how to build Thorium reactors. So for a given amount of mining work, you would get more energy mining Thorium on the Moon. Now, considering that Thorium isn't terribly scarce on Earth, you can figure out that Lunar mining for Earth use isn't very sensible. And if you need power on the Moon, solar works much more easily. Nighttime power can be handled with solar-thermal. Vacuum makes a great insulator. Heat up a bunch of rocks with concentrated sunlight, then use that heat to run a generator at night. You will never run out of rocks on the Moon's surface, nor sunlight for that matter.

> There's not much to do in space.

Yeah, that's why space industry is only $300 billion/year and growing.

> Wind turbine speed doesn't change nearly as fast as you think it does.

Agreed. A single wind turbine has flywheel inertia in the blades, so it doesn't instantly stop and start. A whole wind farm changes even more slowly, because the turbines are typically spaced about 400 meters apart, and average wind speed is ~6 m/s, thus about a minute between turbines. Across many turbines in a wind farm, you are talking about ~10 minutes. Across a grid with multiple wind farms, the reaction time is even longer for a change in wind speed to propagate.

> People always say this about "Hollywood accounting" but I seriously doubt that the tax authorities (for instance) just let film companies make up their profit figure.

Hollywood was invaded by organized crime a long time ago through the stagehands labor unions. Read the credits on a film sometime. Do you really need 20 catering staff on call? The method is to pad staffing, with people who aren't really needed, or in some cases don't even exist. The movie production company writes off the expenses, with payrolls and invoices to make the IRS happy. They show a loss on the movie. But the padded expenses come back under the table.

It makes the IRS' job harder that many films are made by production companies organized by the job, hiring staff and laying them all off when the movie is done.

> There is no multi-billion dollar return for putting people on Mars.

Actually, there almost was, in the 1980's. A major TV network came to Boeing, where I worked at the time, and asked us how much for a Mars mission. We worked out a mission concept, and gave them an estimate. The network figured they could sell as much advertising for the mission as an Olympic games, but spread over a couple of years. Unfortunately the mission cost we came up with was twice the ad revenue, so it died at that point.

If you can boost the revenue with things like "Mars, the video game", and "Mars, the branded merchandise", and cut costs with modern technology, you *might* get it within reach of break-even. Throw in some government-funded science payloads, and it might work a profit.

Back then, there were only three TV networks, and they could command a big audience. I'm not sure a network could front that much these days, although they still compete for the Olympics.

With proper tech, the penalty for Mar's gravity well can be made pretty small. For example, one of the giant volcanoes on Mars sits right on the equator. It is so tall that the top is essentially in vacuum. So you can build an accelerator that throws things into Mars orbit. From low Mars orbit to Phobos you can use the Rotovator type space elevator.

Mars has advantages that loose asteroid's don't. Tectonics, internal heating, water, and other geological processes have sorted the planet into differentiated ores. But focusing on the Moon or Mars or Asteroids as if you have to choose one is as silly as focusing on only California, Minnesota, or Texas when expanding the United States. The right answer is to expand outwards in terms of difficulty, and using the fuel and supplies you can produce at one location to leverage getting to the next. The right answer is "everywhere in the Solar System", though some places will need to wait quite a while until our tech and needs demand using them.

The actual energy to reach Earth orbit, at retail electric rates, is about what Walmart sells bags of potatoes for. It costs way more than that because we basically are using weapons of war (rockets descended from ballistic missiles) to do the job. The cost of a ballistic ICBM is limited by the value of the targets it destroys, so cost was not seriously limited.

As soon as billionaires rather than governments got involved, where cost came out of their own pocket, sanity began to reign. Carrier airplanes to raise launch efficiency, using the expensive aerospace hardware more than once, etc. Launch costs have room to drop about 50-fold from today's prices, and still be well above raw energy costs, the way airplane trips are well above fuel cost.

From Earth orbit to Mars we can build a chain of "truck stops" that supply food, fuel, and other necessities, rather than launching it all from here. Physics says it makes much more sense to get your supplies from a nearby asteroid than the bottom of a deep gravity well (Earth). The particular locations would be Earth-Moon L1, Mars Cycling Transfer Orbit, and Phobos. We already know of 12,000 Near-Earth asteroids, and the region between and near Mars should have just as many. They are farther away, so our Earth-based telescopes can't spot them as easily.

Using local materials, we can gain another 50-fold price reduction for the trip. So instead of $1 billion/seat, we are looking at $400K per person, which a corporation may well finance to get people to the work location.

Developers are already building solar farms in the Atacama:

http://www.bloomberg.com/news/...

Not only is it very sunny, it is high altitude and cold. Less air above it means the sunlight is more intense, and solar cells are more efficient when they are cooler. The combination makes it the best place in the world for solar, aside from the fact nobody lives there and you need power lines to the coast, where people actually live.

I guess you don't have any idea how much land is disrupted when you strip mine for coal. It's a lot, and it continues as long as you need to feed the power plant. Solar is a one time installation.