Very few people have logged the flight time he has, in fact, only about a dozen people have logged the same amount of cumulative flight time as would be required for a Mars mission, let alone continuous flight time!
We are talking about pushing the limits of human endurance, and requiring at least six people to be able to achieve that, more would need to be sent as backup.
Again, someone has already done it, and was fine. You keep harping on this issue, but there is no reason to suspect that it will be a problem. You talk about "breaking endurance records" as if previous long-duration stays in space were just barely possible, and staying any longer would have been some sort of challenge. In fact, that wasn't the case - there weren't any unmanageable problems, and if anyone wanted to stay in space longer than the current record of
15 months there is no reason to suspect that they couldn't.
We haven't even got plans to deploy that in Earth Orbit within the next ten years afaik.
"No plans to do it" is not at all the same as "we couldn't do it," nor is it even close to "we couldn't do it in 20 years if we started working on it now."
Hmm, no it doesn't. We can recycle water and air fairly well, but Mir and the ISS were still resupplied with both. There is a very limited resupply option on a Mars trip, so basic life support systems need to be improved vastly or;
A vast rocket would be needed to take a crew of six, and everything they need to survive. How much water does a person need for a year in space? I have various hobbies which require me to carry everything I need for a period of time. Once you start monitoring your consumption of basics like water, or notice the degradation of lifestyle once you can't just turn on a tap and take a shower you understand the enormous difficulties of surviving in inhospitable terrain.
Resupply, is limited, because we just don't have a good record of landing robotic missions on Mars, just check out the failure rate. Not good if you are relying on those packages for basic survival.
The ISS only receives about 2.5 tons of supplies for its crew of 3 every 5 months. Even if we assume that a Mars mission is no better at recycling etc. than the ISS, you are still only talking about something like 20 tons of supplies for a crew of 4 for 30 months (which is the mission profile that NASA has in mind). In other words, less than a single space shuttle load's worth of supplies. And like I said, that’s assuming that a Mars mission wouldn’t be any more efficient than the ISS. It seems absurd to suggest that we couldn’t make any improvemnets in resource recycling in the next 20 years.
And at present a replacement for the Shuttle, Orion, is scheduled to send humans back to the Moon, by 2020. You really think firstly that we are going to hit that deadline, and then achieve Mars just a decade later? Even with International co-operation that sounds doubtful to me.
I said that we could do it if we wanted to, and if we were willing to pay - I never said that our current plan/budget would do it. If we wanted to, we could
definitely build a rocket with the capacity to launch 120 tons into low earth orbit or 50 tons into mars transfer orbit in just five years. Heck, we could probably build one substantially larger than that if we wanted.
Nuclear engines? That have not been built, tested for such payloads, or type approved for manned flight, ... hmmm, keep chuffing on that pipe.
Nuclear engines that ran successfully with specific impulses of over 800 seconds were built and tested (on the ground) by NASA in the late 1960s/early 1970s. NASA assumed that they would be using Saturn Vs with nuclear engines in the upper stages by the late 1970s. So, yeah, if NASA thought they were a few years away in 1970, I
suspect that we could have them ready within 20 years, especially since a lot of additional design work has gone into them over the last few decades.
Like I said earlier, we don't have a good record of landing robotic missions on Mars, so resupply missions would have to have that factored in.
Most plans for Mars missions don't involve any resupply of the crew - they are expected to take everything with them. But if we really want to, you can just launch shipments of extra supplies that land automatically before the crew ever departs, so that the extra supplies are waiting for the crew when they arrive. If the supply shipment fails, try again and wait a little longer to launch your crew.
Hand waving over the detail doesn't take it away. Take something we know about, and extrapolate, .. say, a Nuclear Submarine. It takes up about half the volume of a submarine, requires a fairly substantial crew, and can use sea water as a coolant. Now, take that to Mars, it has to be far more compact, self contained, use minimal coolant, and be able to be staffed by just six people. That rather limits the size, and utility.
And yet nuclear reactors have already been used in space for years at a time back in the 1980s. It is pointless to try to argue that a nuclear reactor can't be used in space, because they already have been.
Rather simple nuclear thermocouples, with very limited output. IIRC of the order of tens to a few hundred watts in general, with the odd large version having limited lifespan. There are limits as to how much fissionable material you are allowed to launch on manned missions, btw, and limits on how much toxic metal, I recall having to dispose of a cryostat once because it used beryllium and was no longer flight worthy.
I'm not talking about simply radioisotope thermoelectric generators. The Russians launched a series of radar satellites that were used to track ocean-going ships from low earth orbit. They featrued actual uranium dioxide fission reactors with movable moderators and reflectors. I recall that they produced many kw of power and ran for years with no service. I can't remember the exact numbers, but I might be able to dig them up if you really want them.
There are also serious designs for small multi-megawatt reactors such as the SAFE-400 design that only mass a few tons and can run for years with no service. So far as I know, these have not actually been built. But do you really think it would take over 20 years to get them working? I doubt that very much.
