> There is no gravity: whereas on earth the propellant separates relatively cleanly into liquid and gas this isn't the case in space
can you use a plunger, instead of a pump? more like a syringe?
can you use a plunger, instead of a pump? more like a syringe?
Instead what they do is use thrust to accelerate the whole vehicle a little, which presses all the liquid into one end of its tank where it can be pumped out. Instead of carrying special settling thrusters, they originally planned to use ullage gas for this but it's not clear that can work.
deeper discussion with math: https://forum.nasaspaceflight.com/index.php?topic=60124.60
If you go for a narrower range of temperatures (ie. not structurally stable above 0C), it would need to be manufactured, transported, stored, tested and installed at seriously low temps which probably negates the possible advantage with the added technical complexity.