I'm not alone in my concerns for the Mars One plan. I don't think they will raise more than a third of their funding from a reality show and I think dependence on life support equipment from earth makes it a suicide mission. But these are objections that can be addressed and overcome. I would like to respond to those and others.
1) Does not have existing flight ready hardware.
Correct, but so what? It's not like we haven't anything at all and we already have a good idea of the cost: 3 landers, 2 transit ships, 1 F9/Dragon to orbit. One billion for vehicles and one billion for fuel putting the first dozen on mars. We should add landers for precursor missions to preposition supplies to improve chance of survival.
2) Four colonists will not have the specialized skills to survive.
In principal correct, but not entirely. A single person could have all the skills but more is definitely better. I suggest a dozen for the first landing and another 3 dozen two years later. Four dozen allows for a complete industrial ecology (meaning the foundation exists for everything else) with plenty of overlap in skills.
3) Funding: not enough and not in time.
They do not need all the funding up front. If they did happen to get a lump sum of $6b at any time, that would be enough to pay for everything using just the interest, the $6b would exist forever to provide indefinite funding. $300 million per year is more than enough. That would provide four resupply mission each launch window for instance. The transit vehicles are reusable so only have a one time cost other than consumables. Launch to orbit may be $20m per person today but simply increasing the number put in orbit on a single vehicle (using Falcon Heavy instead of F9 for example) could reduce that cost to 20% or 10%.
4) Can't land in the martian atmosphere.
We've already landed in that atmosphere. This is an engineering challenge. Nothing more.
5) They can't handle the isolation.
Give me a break. So don't isolate them. Four dozen in two years with plenty of work to do takes care of most of this concern. Send more and often.
6) Environment will kill them.
Some of them? Probably. All of them? Not likely. We've already overcome harsher environments. With proper preparation, old age will be the most common killer.
7) Landing too far from supplies (or vice-versa.)
This is why human landers should include a small electric vehicle with a battery range of about 50km. This is not nearly as complicated as the lunar buggy. It's just a small tractor most of which is the batteries pulling a very strong but low mass unfolded trailer for the astronauts. They land with two weeks of supplies but will likely not be more than a few hours from their destination. They will have solar panels to recharge the batteries to extend their range. They could even drag the solar panels behind the trailer (mitigating for dust) for continuous daylight range.
Another possible mitigation: We keep supplies in orbit for after humans land. If they happen to land too far from ground supplies we send in more supplies closer to where they did land. In any case, there is no reason we can't demonstrate the required precision.
8) Not a big enough gene pool.
Semen will be relatively easy to send.
Not deadly. Chlorine and oxygen can both kill you but we do find them useful as well. Take along a biochemist to explain it to you.
10) If we don't think of everything they will die before being resupplied.
Wrong on multiple levels. We only need to think of enough things, not every thing. For everything we do think of we should have multiple solutions and always a solution that can be provided for using ISRU. This is one of the obvious flaws in the Mars One plan that is easily solved and will likely be given the time they will have before sending anyone.
11) Funding may be cut off after the first colonists land.
Absolutely. So getting them to independence ASAP is vital, but does not require as many colonists as some naysayers would demand. Also, they will never be fully cut off. Communication with earth will allow them the depth of knowledge to help overcome any challenges they may face. Plus they will have all the resources they need withing walking distance (but they'll use trucks) to grow their society after being given a proper start. Even limited funding would be enough to send other seeds and such for diversity they may need.
12) Isolation will kill them.
Yes, I'm repeating item 5 because it's being hyped by the naysayers and I have more to say. If they have work to keep them busy, work they give themselves to improve their lives because they have ownership, they will not feel isolated. It's an old story... "Martha, too many people are coming to our valley. I think we should head west for some more elbow room. There must be at least a dozen families in this valley." Most people today aren't used to this level of isolation but even today hundreds of thousands live in communities of less than 100 individuals. The solution to isolation is we send more people and stop wringing our hands about it.
13) It's just nonsense!
Such a strong negative assertion. Doing it is the best way to answer such smugness.
14) Dust! Toxic abrasive dust.
You're giving me shivers. How could we ever deal with dust? First realize that everything is both toxic and abrasive. "The only thing we have to fear, is fear itself." Not sure if that's right, but the fact is we deal with toxic and abrasive on earth all the time. We can do it on mars. This is why I propose the 50m Zubrin Hobby farm be directly accessible from the habitat and would seal out any dust (other than human skin which can be filtered out if desired.) The airlock that does go directly to the martian surface will let in dust. A combination of positive pressure and a water bath/wash for the environment suit (which you leave in the airlock, it's not required in the habitat of course) keeps the dust from being any sort of problem. This is not high tech. and is easily fixed if it does somehow break down (fans do break occasionally.)
15) Radiation. Gravity.
Already answered numerous times. Read my blog. Not the big deal some make it out to be. Even the naysayers have to acknowledge that it takes years to kill even without mitigation. Sudden high doses of radiation are not what we're talking about. The levels that are known to exist are easily dealt with.
More... I see we already have a structure as a foundation for real estate development.