New Mars Forums

Official discussion forum of The Mars Society and MarsNews.com

You are not logged in.

Announcement

Announcement: As a reader of NewMars forum, we have opportunities for you to assist with technical discussions in several initiatives underway. NewMars needs volunteers with appropriate education, skills, talent, motivation and generosity of spirit as a highly valued member. Write to newmarsmember * gmail.com to tell us about your ability's to help contribute to NewMars and become a registered member.

#1 2014-01-10 03:49:20

Quaoar
Member
Registered: 2013-12-13
Posts: 600

Zero boil-off active cooling for LH2

I have read this work on a battlestar galactica 360 ton NASA NTR spaceship. To keep cool the huge amount of LH2 for almost 2 year, it proposes a Bryton cycle zero boil-off active cooling unit: it weight only 920 kg and needs almost 9 KW.

http://ntrs.nasa.gov/archive/nasa/casi. … 004085.pdf

If it's really possible to build such device, that can be easly feeded by solar panel on a chemical rocket propelled spaceship, LOX-LH2 may become the best propellant choiche for a manned Mars mission.

Last edited by Quaoar (2014-01-10 03:50:12)

Offline

#2 2014-01-10 12:41:37

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,617
Website

Re: Zero boil-off active cooling for LH2

I think LOX-LH2 is the best solution,  yes.  There are "cryocoolers" available already,  and I think they're lighter and lower power requirement than the Brayton thing in the old NASA study.  So,  yes,  we can prevent significant hydrogen boiloff over long times.  If you add foil-and-foam layered meteor armor,  it doubles as a very effective insulation and sunshade.  That reduces boiloff further,  and lets you use smaller cryocooler equipment. 

I don't really think a 300-600 ton ship is an unaffordable "battlestar galactica",  unless you choose to launch it in chunks that are too big,  which forces you to develop a gigantic one-use rocket.  That's really expensive.  If you build it in many smaller chunks,  you can use commercial rockets to launch these chunks far less expensively,  and then just dock it all together in orbit.  There is no reason at all that all the propellant for any one burn need be in one single tank.  Just use a bunch of one single tank module design. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

Offline

#3 2014-01-10 13:58:34

Terraformer
Member
From: Logres
Registered: 2007-08-27
Posts: 3,363
Website

Re: Zero boil-off active cooling for LH2

Are we talking about a 500+ tonne drymass ship? Because if so, good. We can fuel up at L1 from Lunar fuel (after fueling up in LEO to get it there...), and go do a proper exploratory mission.

500+ tonnes, though, would be 10 Falcon Heavy launches. Perhaps we could combine the upper stage with it, and get engines and tankage included in the deal? Maybe even launch a small (well, huge, relative to most designs...) ship in one piece as an upper stage...


"I guarantee you that at some point, everything's going to go south on you, and you're going to say, 'This is it, this is how I end.' Now you can either accept that, or you can get to work." - Mark Watney

Offline

#4 2014-01-10 15:28:26

Quaoar
Member
Registered: 2013-12-13
Posts: 600

Re: Zero boil-off active cooling for LH2

GW Johnson wrote:

I think LOX-LH2 is the best solution,  yes.  There are "cryocoolers" available already,  and I think they're lighter and lower power requirement than the Brayton thing in the old NASA study.  So,  yes,  we can prevent significant hydrogen boiloff over long times.  If you add foil-and-foam layered meteor armor,  it doubles as a very effective insulation and sunshade.  That reduces boiloff further,  and lets you use smaller cryocooler equipment. 

I don't really think a 300-600 ton ship is an unaffordable "battlestar galactica",  unless you choose to launch it in chunks that are too big,  which forces you to develop a gigantic one-use rocket.  That's really expensive.  If you build it in many smaller chunks,  you can use commercial rockets to launch these chunks far less expensively,  and then just dock it all together in orbit.  There is no reason at all that all the propellant for any one burn need be in one single tank.  Just use a bunch of one single tank module design. 

GW

Thanks for the lesson!

I've seen your very interesting docked module rigid baton: you used LOX-LH2 with active cryocooling system, even for your landers. For safety, in the first mission you choosed to bring all the ascent propellant and utilize ISPP only for optional extended explorations, hopping in other sites. It makes sense.
If I have correctly understood, your ISPP devicie will melt water ice and produce propellant via electrolysis: will it produce both LOX and LH2 or only LOX, bringing the LH2 from Earth?

Last edited by Quaoar (2014-01-10 15:44:16)

Offline

#5 2014-01-10 22:45:56

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,316

Re: Zero boil-off active cooling for LH2

One thing that we forget is that we should do what we can with the least amount of energy as we do have it as a limiting facture for the initial flights regardless of if its just one before moving into a full out assault on mars colonization or way more flights and decades which I do not hope for to actually trying to be a colony.

Offline

Board footer

Powered by FluxBB