But could it be similarly useful for extending astronaut EVAs?
Quote from: sanman on 10/07/2014 03:04 am But could it be similarly useful for extending astronaut EVAs?No.Read the original paper, look at figure 2. Desorption and resorption fluctuates the crystal mass between ~98.7% and ~95.6% of original over longer period of time. This translates to horrible ~3% propellant mass fraction for this kind of "crystal tank".Might enable lighter, more compact portable oxygen concentrators for respiratory challenged earthlings.
It's a reasonable question whether a tank which only needs to contain gas at low pressure might be lighter, not only because of smaller size, but also because of reduced skin thickness. A reduced bulk to the backpack might also be a benefit in and of itself.
BTW, re energy to release the oxygen, the graph attached above shows temps of 110-120C. Is more required to initiate release?
Oxygen is rarely held at pressures higher than 200 bar / 3000 psi due to the risks of fire triggered by high temperatures caused by adiabatic heating when the gas changes pressure when moving from one vessel to another. Average sea-level pressure is 101.325 kPa (1013.25 hPa or mbar) or 29.92 inches (inHg) or 760 millimetres of mercury (mmHg). So it looks as if to me if most pressurized oxygen tanks aren't held at higher that three times the atmospheric pressure ...
Extending EVA O2 supply would just push the limitation elsewhere. Make the suit last forever and you're still going to have around the same EVA time limits due to crew fatigue. That's why O2, CO2, and other EVA consumables all last roughly the same time.