It's not that we can't go to Mars, as nearly exactly like Dr. Robert Zubrin stipulates.
Going to Mars is technically a positive feasible thing to be doing, just a wee bit expensive along with a serious pot load of risk, at quite a mission delay until all of the rather significant bugs are worked out, then years worth of those preliminary mission deliveries of various essentials and of technology which we do not yet have, at least not until we've spent a few more billions. Then onto delivering the actual crew occupied mission (a small click of four he informs us) is most likely comprised of those having some terminal illness condition because, it's not all that likely they're coming back, at least not without being a great deal worse off for ware, like being solar radiated to a great extent as well as seriously pissed off at each other to say the least.
The amount of overall produced CO2 that is to be remaining on Earth will likely become 100 times whatever is eventually launched towards Mars. Where Dr. Robert Zubrin has indicated a need for several of those 40 tonne payloads (even though Russia could accomodate 100+ tonne payloads at perhaps 10% the cost), I believe four or five of these hefty suckers may become involved, that's perhaps 160 to 200 metric tonnes worth, which obviously equates into 20,000 tonnes worth of brand spanking new and very permanent CO2 produced that's artificially trapped right here on Earth (thanks a bunch guys).
Of course, all of this potential accomplishment is based upon zero failures, of no further unexpected technicalities and that of the micro thin and cold Mars atmosphere of 0.006 bar is actually going to be worth all the effort and of all that additional energy delivery as to sufficiently capitalize upon all that nifty CO/O2. Besides delivering that spendy 100 KW or greater nuclear reactor, the fact that the mission might also be needing a spiffy 50,000:1 compressor (that's delivering all of 300 bar) seems a wee bit of a challenge that perhaps only great gobs of money can resolve. All toll we're looking at perhaps 15 years worth of prep, mission and eventual return of something most likely in a body bag (sounds good to me).
Because of what those Mars microbes can potentially do, as ingreat harm onto Earth's inhabitants (being freezer as well as radiation proof), seems those returning from Mars will need a brief "multi-year" (lifetime) stop-over at a safe lunar base camp, you know, situated right next to some of those carfully landed Apollo lander remains, as previously planted on that clumping 10% reflective (asphalt reflective like) lunar surface, where that lunar destination becomes sort of their microbe "safe house", as to possibly having to live out their lives in a module that's just sort of sitting on that vacuum dry yet clumping (one of a kind) soil/sand of Tranquility Base (so far so good).
Of course, at least as of so far, there's been absolutely no sign of anything that's the least bit artificial, as in active or alive, on Mars, let alone of even a microbe worthy of existing on Mars, so even if we should discover said microbes after melting away at several tonnes of that thick Mars ice (some of that obviously being dry-ice) and, somehow further determine it's sufficiently safe as to be bringing such home, so now that we've spent a couple or more so hundreds of billions and, all that taking perhaps 15 years worth of focused efforts, so what exactly do we have for Earth's humanity, besides all the initial CO2 and then of the entire decade worth of subsequent mission CO2 that's generated for the benefit of increasing Earths' greenhouse, along with the chance we'll all otherwise soon die from something Mars?
The fact alone that the first Mars crew is either nearly dead or subsequently dying from a likely combination of Mars microbes and/or radiation seems a bit morbid, especially after all that time and after such great gobs of bucks.
I'm not going to ever stipulate that we can't accomplish something because, I would be wrong. However, in many countries, the added difference of earning another dollar a day keeps an entire family alive and healthy. So, as for every buck badly invested in Mars is another family that didn't eat or receive basic medication for the day. I'm not certain about how long even healthy humans can hold off eating but, it seems poor folks don't have all that much reserve and, if we're talking about 15 years worth of missions and as such excessively spending until those Apollo cows come home. I may be somewhat exaggerating but, that's something like 17 billion bucks per year or at least 46.5 million souls that will literally have to starve and/or squirm through sickness if not to their death each and every day of each and every year of supporting that Mars program (I thinking that the Pope as well as Hitler would have been damn proud).
OK, lets say that we somehow feed and cared for everybody here on Earth first, even though we've never managed to accomplish such but, then again anything is possible, like for Iraq to donate all of their oil to America at absolutely no cost whatsoever (that's possible). Then because we have such a surplus of revenue as a result of all that free oil and subsequently being capable of further domineering global markets, plus finding all the expertise necessary as to overcoming space travel radiation as well as for getting to/from places at ten times the present speed of delivery. Obviously, now we're cooking with gas and, I'll be all for those willing to risk everyone other's life on the odd chance that those Mars microbes will hold the cure for the common cold, as that achievement alone may be worth the 250 billion dollar investment and of total body irradiation exposing all those astronauts into an early grave.
Mars is obtainable, at least it's within reasonable communications range and our probes have been able to acquire sufficient topography data. However, there seems to be another faction of the "Mars or bust" group that's been looking at those Jupiter moons and, that's certainly pushing things. At a cost of perhaps trillions and yet another decade of just to/from travel, what exactly do we have? Once again Hitler would have been proud as punch of such accomplishments at the demise of perhaps billions of souls back here on Earth, all of this while we still don't seem to know what nor how to deal with another Earth killer space rock (of which there are a good dozen or so worth considering each year). Some of those recorded Earth killer rocks are big enough and going fast enough to essentially terminate and/or exterminate all life as we know it and/or make the remaining situation a true hell on Earth for perhaps a century.
I realize that Venus is so bla, as it's been reported as so damn hot and nasty and that it's only a few light minutes away seems rather insignificant of the aspirations of those looking at Mars and beyond. But folks and fellow village idiots; guess what? Wherever there's heat, at least there's lots of free energy and even more so if that planet should have sufficient CO2 and, with said energy one can certainly deal with a little heat. Actually it's not all that hot if one spent the majority of their time aboard one of those nifty (air conditioned) rigid airships, say cruising just below those clouds and within the nighttime season of Venus (that's floating in an ocean of crystal clear and stable CO2 and as even having some added gradient percentage benefit of O2). With the outside temperature becoming perhaps 325 K (a bit higher altitude and you're below 300 K) and, all the O2 you could possibly choke down, as that being derived by the airship's onboard CO2-->CO/O2 conversion and, of all the pure H2O you could ever want being easily gathered and subsequently extracted via efficient vacuum distillation from the contents of those clouds residing another 5 km to 10 km above you, what more could you possibly want. That airship is certainly not small, it's at least 180 X 1200 meters and much larger is perhaps within the realm of what's already situated on Venus. Via S band microwave, nearly continuous two way communications with Earth is another done deal and, along with that VL2 platform would enable all that much more communications relay, including foreign exchange via laser beam as well as microwave to/from Earth.
First of all, our existing technology can efficiently deliver a sufficient VL2 platform (TRACE-II), as well as another Magellan-II capable offering 1 meter resolution at 16 bit depth, then of what we again have in our inventory (referring to those old shuttle craft), we have the capability of obtaining our goal, where as, by the time we place that mission underway we'll either have established contact and made the necessary reservations for our stay onboard one of their airships and, if they should refuse or object as to accommodating us, then we can first nuke them and then go about building our own rigid airship that can be delivered and dropped or flown through those nighttime clouds, along with the rather substantial crew of this "mission to hell". In case you're wondering, I've already resolved my concerns of space travel radiation, as for utilizing any one of those Earth killer rocks as our solar shield (offering an effective and obviously cheap 10+ tonnes/m3 shield), whereas any one of those 100+ meter rocks should due quite nicely, at least until we obtain our VL2 station keeping where the planet itself will likely provide most of what's needed from that point on, as effectively shielding VL2 at up to 95% of whatever is solar generated (obviously one can navigate off VL2 sufficiently to further improve one's chances when there's a known solar event worth avoiding altogether).
Every 18 months we'll have the best opportunity of our jumping ship (at least leaving VL2 behind) and returning home or, that of receiving more supplies (beer, vodka, pizza, new sex partners and such) and of whatever new technology that can be sent from Earth, as to be added to our occupation of Venus air space. I'm certain that our lizard host will not realize what's happening until they see all of our barbecues loaded with something reptilian and, obviously by then it'll be too late.
Now, I do realize all of this Venus stuff is terribly cheap, as well as so freaking obtainable, as being really not all that much of a challenge for our cloak and dagger NASA wizards to have to deal with, but, there certainly are a number of other nations capable and perhaps willing to exceed where Lord NASA has met their match. At least this Venus mission offers trillions worth of viable commercial enterprise venture potential as well as for all of that lizard meat just sitting there. So, as long as they (Venus Islamic or perhaps Cathar lizard folk) don't get the jump on us, we could become the proud owners of the hotest real estate on Venus, or at least via our superior (laser cannon armed) rigid airships could soon dominate and subsequently rule their ocean of CO2, as well as capitalizing upon whatever to/from planetary trade. If it should turn out that we're technically smarter then those Islamic lizard folks, then here again, we'll have the upper hand and most likely profits to boot (sort of like our first pummelling and then offering mere peanuts to those Mexican's, in exchange for essentially obtaining billions worth of Texas and California).
If you have some better ideas (better syntax to boot), as in more efficient and safer plans for those of Venus and/or of goals worth promoting, that's exactly what I'm looking for and, perhaps exactly what NASA has not been looking for. Even though I use a good deal of satire in order to get my point across, I obviously mean no harm onto those folks of Venus and, I'll be the first to see that others perpetrating anything against those Venus souls are eliminated, terminated if need be, as in thoroughly made dead, as we have absolutely no right in altering anything that's been established and has obviously been working sufficiently fine and dandy (in spite of our ongoing arrogance and utter stupidity).
Of course, I have no objections to all those desiring as to doing that Mars thing, just as long as they're utilizing fully taxable privet funds for such a high risk luxury sport (I might even offer as much as 10% tax support, just in order to get those fools off Earth), that which is more then obviously become tailored for benefiting and/or entertaining the wealthiest of individuals or as for satisfying NSA/DoD agendas of devising upon their next generation of highly visible WMDs, as otherwise not one cent of public funding (same goes for SETI) need be invested. Whereas the planet Venus seems to hold all sorts of public/enterprise potential (that's including all of that icky humanitarian stuff getting in the way again) and, it's certainly a highly obtainable goal at a mere fraction of one percent of accomplishing nearly anything Mars, let alone Jupiter.