The first reason Mars is cheaper is because it has an atmosphere. Thin thought it is, it is enough to require less fuel than Luna. The trick is you can use aerobraking to reduce your speed at Mars but for Lina you have to take fuel for reverse thrust.

Second, getting to orbit is pretty much 90-95% of the fuel to get anywhere in the solar system. Climbing out of the gravity well is the main hurdle.

Third, Mars' atmosphere again helps once there. With hydrogen feedstock we can make all the air and water we want, and do it before we even arrive. Also, the difference between a near-absolute vacuum on the moon and op the thin one on Mars means less read shielding required adpnd your suits are much, much thinner, lighter and more maneuverable.
Fourth, look at the moon footage. That hop they do isn't just for show. It happens to be the way to move around in the very small amount of gravity on the moon. On Mars your gait would be much easier and less ungainly - virtually normal compared to Luna. As CircuitGuy and DriveTrain refeenced, Zubrin's book goes into great detail on the specifics. It even includes a deeper explanation with tables on the delta-v for cruising various points in our solar system. Mars is the gateway to the stars for mankind barring some miracle breakthrough that cuts through known laws of physics or technology.

Exactly. Zubrin hashed out a viable plan not only for going to Mars but for establishing a continuous, permanent and failsafe presence there, in his book "The Case for Mars." His price tag for it was orders of magnitude less than the government's cost projection at the time, and Zubrin showed how it could be done almost entirely with COTS hardware (a big part of why it could be so cheap.)

Getting sidetracked on building a Moon base as an intermediary step (instead of a completely separate endeavor,) would be a waste for several reasons, not the least of which is the fact that it's a more harsh place even than Mars. The Moon's only advantage is proximity - but the inexpensive craft Zubrin details for his Mars transit would render radiation shielding over long time periods the single biggest obstacle. Everything else would be more difficult to do on the Moon than on Mars.

Not that it wouldn't be cool to have a Moon base - and we almost certainly will at some point - just that it's unnecessary for going to Mars. And as in every case of new exploration in human history, the drive to space exploration will not truly take off (pun if you want one,) until private enterprises a.) see a ton of money to be made in space and b.) governments have sufficiently unshackled private enterprises to allow them to go after it.

"Some of us do indeed want to set Mars up as a new frontier for freedom. "
I love the notion, but I think it's more practical to find an inhospitable out-of-the-way place on Earth. The colonists will thrive if they can find the sweet spot of trade with the rest of the world without interference from the rest of the world.

Or as counter-mass in a tethered rotation system to provide in-transit gravitational acceleration. ;)

The little green men may still have a religious crisis unless their elite betters can convince them that the rocketship is just a weather balloon..
Let us pray for a happy outcome.

Incidentally, nothing in Shadows Live Under Seashells isn't based on actual science.Every aspect of Mars, like every other projection made throughout the book, is entirely grounded in fact. :)

Moot point. Chickenshit wouldn't consider going unless there was a golf course.

Pure (or very high concentrations of) Oxygen is quite dangerous. However, that is an issue if the system in place to regulate the partial pressure of Oxygen breaks down.

It is not just a matter of O2/N2 mix. A person can survive quite well in an O2 rich environment with a lower pressure, or an O2 reduced environment with higher pressure, until Nitrogen Narcosis becomes a problem.

Divers, particularly those that are nitrox or rebreather certified, are pretty familiar with these issues, although they generally think about higher pressures, not lower ones. Climbers think about the O2 pp.

OK, now you have just added more equipment and $$! :)
I know nothing about how much space, power, fuel,
chemicals, etc. CO2 scrubbers use.
But I can see that technically the Oxygen problem could be solved - every pound of mass from Earth used to solve it though gets more and more pricey.
Hopefully you do not need an Ocean for low cost/use of materials operation.

Part of what I got from the brief article is that these guys were not bringing enough stuff to survive - like perhaps a CO2 scrubber in addition to a lighter
(to be used before Oxygen levels would ignite the entire place!).

This. This right here is what precious few understand. If I could vote you up yet, I would.

And there you go, my first vote goes to you. ;)

Frontiers are what happen when occupied areas reach saturation. And on the way to that point, organization gets more complex and tightened, as well, with rules and regulations introduced to the totalitarian choking point. Then those with guts look for ways to break through the frontiers, which the overcrowded culture needs for survival. Either spread to virgin territories, or clean up the mess at home.

Our planet has few areas left to spread to: polar regions, deserts, ocean bottoms, mountaintops. Not the most hospitable places, though still easier to get to than Mars. Terra-forming Earth to be fit for human life will, of course, find objection from climate crazies and gaia gurus.

Governments tend to be lenient with pioneers into new frontiers at first, until enough work and progress has been done for looters to be attracted. Even building the internet followed that formula. Just watch the current attempts to milk it.

"First steps down new roads"...and the herd soon follows. In today's world, the frontiers are internal, intellectual, psycho-epistemological. Winning individual liberty in action, not just lip service, is that frontier. Let's hope to achieve it by persuasion, not violence.

We've been mocking this up for quite a long time now.