...problem[s] can be avoided by keeping mission duration below about 18 months.Ok, but one way eliminates many more problems and costs, but this isn't my issue with the article.
In the section that starts, "Chemical propulsion is really amazingly cheap..." the claim that propellants make excellent radiation shields seems to ignore that fact that most of the fuel is used up in the first few minutes of the voyage. Also, even free fuel should cost about 80% or more of the mission to get it to LEO. If not, that's a really expensive ship they intend to fly. But I do agree that "exotic propulsion technologies" are not required. Hall thrusters to return an empty crew vehicle to earth are not exotic for example.
By not landing on Mars, one avoids the need for high-thrust rockets.This is very misleading. You need high thrust to deal with gravity, earth or mars. You don't need anything more than medium thrust in space regardless of landing on mars. It's the lander that requires the high thrust.
If launched ... at just the right time...Is also misleading. You can launch at any time you have sufficient delta V. The timing is a matter of cost. So now we get into his proposed three steps...
- An unmanned slingshot
- The Inspiration Mars mission.
- A Phobos-Deimos mission.
The unmanned slingshot is proposed because the author doesn't believe the Inspiration Mars mission can make its 2018 launch date, but what's the point of this first mission? None. Then he wants to delay and defocus the Inspiration Mars mission making it less likely to happen at all.
Really, mission 3 is the whole point of his propaganda. This is really the whole objective of the article. Three easy steps is just a smoke screen. The proposed crew demonstrates why this mission would be a bust...
...one medical person, one computer specialist, and two geologists with experience in mineralogy and chemistry to operate the laboratory.
He describes that as five people. Let's assume chemist is the fifth. You don't need a dedicated medical person. All members should have the required first aid training. If they need anything more serious than that they would need more than just a doctor. If they need a computer specialist they are in real trouble. The software they are going to use should be completely tested long before they go on a mission. You don't need one programmer. You are likely to need dozens if not hundreds. They all stay on earth where they belong. Geologists makes sense. On site they can find the best samples. Chemist, not quite so much. That can be done when you get your samples back to earth.
So we save tons of cash by reducing the five to two. This then becomes the asteroid sample mission that Obama has directed be done. Now the final prejudice...
humans operating on the planet's surface are extremely limited in what they can do
In a pig's eye. They can build a permanent presence allowing precisely the opposite of limited. The real limit is the duration of a mars moons mission.