Difference between revisions of "Life Support Systems"
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Latest revision as of 04:02, 21 January 2009
cnavarc Life Support Systems
Contents
Intro
Throught history people have adapted to environments that were initially too harsh to live in. They have also made the environments they historically lived in more comfortable. Such methods of adapting to the environment include methods of heating and insulating shelters, warmer clothes and air conditioning. Everything from the pressurized compartments in a plane, the life support systems in a submarine or space station and scuba diving gear are all methods of adapting to the environment.
The Options
Living on Mars presents unique but not insurmountable challenges. While Mars is further away from Earth, it contains all the necessary elements in order to survive. Therefore on Mars there are in principle several methods to sustaining a crew. They are: living off the land (ISRU), recycling the available resources (Closed Loop Life Support System) or simply supplying the needed goods from Earth.
It is possible to support a Mars crew with any of these three methods alone yet some would take one of these options and argue that it is necessary to achieve a certain level of proficiency in this option before one way Mars missions are politically possible. For instance one may argue the necessity of a 100% closed Loop life support system, while others maybe ague for an ISRU proficiency to such a degree that everything that crews need can be produced on Mars without the need of shipping goods from Earth.
Relying Less on ISRU and Closed Loop Life Support
The simplest solution is to require neither a closed Loop Life support system or completely independent ISRU and make up for any deficiencies in these systems simply by shipping goods from Earth. For atwo way Mars mission most would think that shipping goods from Earth is a successful way of dealing with the limitations in ISRU and closed loop life support systems. Currently life support systems are about 90% efficient at recycling resources. Current mission plans use ISRU mostly for the production of the fuel for Mars ascent and to supplement the oxygen supply in the living area.
One Way Life Support
Some would argue that if we can support a two way Mars mission this way, we can support a one way Mars mission this way. They would further argue that the one way mission is just as easy or more easy than a two way mission. While this concept may sound outlandish to some, the extra expense of shipping a space ship to Mars for the return flight home should be carefully considered. For a two way Mars mission all the needed supplies to sustain the crew for two years must be shipped from Earth anyway. One can reasonably ask the question, why not simply send the supplies to keep the crew there instead of shipping them there and back every two years? How much mass and hence cost would this one way mission save? Would the savings be used to sustain a larger crew or something else? How will the permanent Mars crew leverage the resources on Mars so that: in future the cost of supplying the crew is less or equivalently the cost of supporting a larger crew can be done for the price of what it use to cost to support a smaller crew.
The one way concept, although a bit cold, holds tremendous benefits. Any two way mission, pilots and engineers are of primary importance. Any one way mission, scientists and / or builders become the primary need. The difference in expense is HUGE. As economical as Mars Direct is, still 4/5ths of the total budget is for the return. The Mars Direct proposal of consecutive landing sites DOES lend itself well to the possibility of a return at a future time, providing each site is within range of its rovers.
Reliability, risk assessment, I've done the figures, you can certainly as well. The likelihood of a failure resulting in fatalities to get there, in even the best guess scenario, is 1 to strictly single digits. 1 total failure in 3 missions, 2 missions, 10 missions. BUT the likelihood of fatalities on the unsupported return is an order of magnitude worse. IT is a bridge too far. Much of that risk will be reduced once there is a colony on the planet. So the first explorers maybe can return after the third or fourth mission. Years to the first mission launch can be effectively zero. We have all or nearly all required technology today. It is the return 'need' that is the biggest stumbling block.
All of these considerations are cold, but the logic is inescapable. Why would we spend 4/5ths of our science budget to A. produce less data and science, and B.return the used computer to Earth after it has completed its work. I said it is a cold calculation. So don't send young men or women. Send older explorers, not younger. Send scientists and stone masons not pilots. Dean Unick
