Human Rated Atlas V for Bigelow Space Station details emerge

[jongoff]

Meiza,
Having a LOX-only depot is definitely easier than trying to store LH2 as well...but you also lose one of the big benefits in my opinion.  A LOX/LH2 stage in LEO is going to be boiling off a lot of LH2.  If you can't top that off, you always run a risk of losing the mission (and the hardware) due to launch delays or other similar problems.  If you can top off the LH2, it drops the LOM numbers, and gives you more flexibility.

And in reality, storing and handling LH2 on orbit isn't really that much harder than storing and handling LOX on orbit.  It's not trivial, but I'd be surprised if the first cryo propellant depot in orbit didn't offer both LOX and LH2.

~Jon

[Bill White]

I wish to channel Dennis Wingo: "It's all about the ISRU, ISRU,  & ISRU. Did I mention ISRU?"

Lunar LOX extraction can happen anywhere on the Moon, no cold traps needed. No geopolitical fights over whether we or the Chinese get first dibs on the best frozen water deposits, no need to import nuclear reactors for the energy need to crack water into H2 and O2. No need to wonder whether there really is any extractable water, an unproven hypothesis at this point.

We KNOW lunar regolith contains significant amounts of oxygen.

My favorite lunar ISRU method is simple vacuum pyrolysis using Lowe's grade mylar to make parabolic mirrors to heat regolith to ~2000 F and thereby outgas O2.

LOX is over 80% of the mass needed for an H2/LOX engine. Bring the H2 or CH4 or kerosene from Earth and extract the LOX from everywhere and anywhere on the Moon.

= = =

Or we can hang Mike Griffin in effigy and DEMAND dry launch EELV together with Congress purchased LEO fuel depots and postpone lunar return until these fuel depots are built and thereby end up instead with Senator Bill Nelson and Senator Kay Bailey Hutchinson finding a way to keep the orbiters flying until 2020, or beyond.

If NewSpace would focus on lunar LOX extraction, and accomplish it, plenty of other stuff would fall into place very quickly.

[meiza]

jongoff - 8/2/2007  2:17 AM

Meiza,
Having a LOX-only depot is definitely easier than trying to store LH2 as well...but you also lose one of the big benefits in my opinion.  A LOX/LH2 stage in LEO is going to be boiling off a lot of LH2.  If you can't top that off, you always run a risk of losing the mission (and the hardware) due to launch delays or other similar problems.  If you can top off the LH2, it drops the LOM numbers, and gives you more flexibility.

And in reality, storing and handling LH2 on orbit isn't really that much harder than storing and handling LOX on orbit.  It's not trivial, but I'd be surprised if the first cryo propellant depot in orbit didn't offer both LOX and LH2.

~Jon

Yes, it's a trade. Both have their good and bad sides. But the LH2 is so light (one seventh of the total!) that a Delta IV heavy or even an Ares I can very probably carry the EDS or LSAM with all the needed LH2 loaded in. It's just these two launches where LH2 is needed, so it's not _that_ delay sensitive. The launch order of CEV, LSAM and EDS can be optimized regarding the greatest threats. (Ie launch CEV first? Or last? How much do extra supplies weigh? Does EDS have lots of insulation (does it do TLI?)? Is LSAM more margin sensitive?)

[ApolloLee]

Nice new video on Bigelow's site: http://www.bigelowaerospace.com/out_there/Genesis_I_Earth_Rotate.php

[josh_simonson]

Since the Depot doesn't require any Delta-V changes, it can afford the weight of LH2 reliquification hardware.  The main issue with that is the weight of the equipment and power supply for it are prohibitive on a spacecraft, but this is not the case on a relatively immobile platform.  With regular use the weight of this gear would easilly be recouperated in LH2 savings.