/sci/ - Science & Math

>>16243268
>>16243278
Solar propulsion is pretty close to the age of sail in mechanics and ship layout, and it turns out almost all the solid land in the solar system is contained on Mercury, Venus, Earth, the Moon, and Mars. The only scifi tech needed for an age of space-sail is paraterraforming, and maybe an FTL or fusion-laser highway to get to the outer system or other stars.

An LH2 based Solar Moth gets an Isp of about 900s. This means a water prop Solar Moth should get an Isp of at least 300s based on ratios from NTP studies, probably more since the "fuel element" is sunlight concentrated into a zirconium oxide or diamond focus that doesn't mind exposure to steam plasma.

Consulting basic delta V maps, a rocket with an Isp of 300s and no boiloff risk could do a fully propulsive transfer LEO to LVO with a mass ratio of about 5.5, super doable with water tankage, and less with aerocapture/braking like Magellan did.

This means if we can shrink the solar moth system down far enough to be 4 tons launch mass including payload, a whole Venus mission could be launched on a Transporter mission. At Starship prices ~$100/kg that's crowdfundable.

https://www.projectrho.com/public_html/rocket/mining.php#id--Asteroid_Mining--Mining_Ships--Robot_Asteroid_Prospector

>>15652600
Yes they are.

t. motorcycle rider and solar moth fan

>>15617552
Moon Moth is a reserved name for Solar Moth spacecraft making the LEO-LLO shuttle run.

Continuing from the last thread, I did a bit of math on the electric solar moth. The classic 1979 thermal solar moth design (picrel) uses mirrors with 175m diameter, so 87.5m radius, which works out to about 32MW of solar energy at 1AU. Even with a relatively conservative 20% efficient concentrated-photovoltaic array at the focus point, that's about 6.57MW of delivered electricity, or 2.89MW of delivered electricity at Mars orbit, or 177.4kW at Jupiter orbit. That sort of energy budget wipes out the need for nuclear power in space for anything but landers operating out of line of sight of the sun closer than, say, Uranus. The only challenge would be finding an appropriate cooling system for the CPV cells.

Unless of course I'm reading this wrong and that's 175m diameter PER mirror, in which case you can double all of those power values.

Given all the high profile failures of solar panel origami, I think we should take another look at something like the Solar Moth architecture, albeit with inflatable mirrors focusing sunlight on to a smaller set of higher quality, less mass-sensitive PV panels instead of directly heating LH2. We've already seen with ROSAs that gas-pressurized unfolding works fine in space.

>>14506113
A lot of it got derailed by the solar vs. nuclear shitposting war, or by SpaceX and NASA publicly embracing proonting. Also there was a paper on how to get GCNTR performance out of beamed laser thermal with LH2 propellant so now between that and Starship the transportation problem is political more than anything else. (Zubrin has also written a three part blogpost on why the problem with nuclear is political.) At this point the best thing for space colonization is pro nuclear politics or laser killsats.