Quote from: R7 on 04/13/2016 04:55 pmQuote from: savuporo on 04/13/2016 03:55 pmMy point is, that propellant isn't a propellant without a functioning propulsion subsystem.It is pointless to argue against lunar methalox ISRU with "current catalogs lack methalox engine therefore no" argument. The methalox ISRU concept happens in the future (if it happens) and obviously assumes that catalogs then do have methalox engines and actual customers using them.At least two companies are working on methalox engines, and the other plans to use them to get to Mars.Besides Blue Origin and SpaceX, you also have Masten Space Systems working on a 60klbf methane engine, which they've already test-fired a 45klbf variant. ...Pretty absurd to consider methane some exotic propellant.
Quote from: savuporo on 04/13/2016 03:55 pmMy point is, that propellant isn't a propellant without a functioning propulsion subsystem.It is pointless to argue against lunar methalox ISRU with "current catalogs lack methalox engine therefore no" argument. The methalox ISRU concept happens in the future (if it happens) and obviously assumes that catalogs then do have methalox engines and actual customers using them.At least two companies are working on methalox engines, and the other plans to use them to get to Mars.
My point is, that propellant isn't a propellant without a functioning propulsion subsystem.
It is time to devise and test tanks that can store methane and LOX for up to 4 years.
For a fun excercise, go try and quote a LOX compatible pyro valve from one of these, for lead time and tested batch price.
Because you have to use those suppliers and could never bring this technology in house... Whatever SpaceX is doing?
Sorry, that was sarcasm and that's not appropriate.
But I think maybe I'm a bit frustrated at the naysaying...
but I think that to suggest everything is TRL1 is also wrong.
Quote from: A_M_Swallow on 04/14/2016 01:38 amIt is time to devise and test tanks that can store methane and LOX for up to 4 years.For a fun excercise, go try and quote a LOX compatible pyro valve from one of these, for lead time and tested batch price.
Quote from: Lar on 04/14/2016 02:19 amBecause you have to use those suppliers and could never bring this technology in house... Whatever SpaceX is doing?And commercial spacecraft industry has existed for much longer than SpaceX. I fail to understand how SpaceX is relevant to everything that happens in space.
There are thousands of very talented individuals in space industry across the world. There are also textbooks and engineering courses. Mere existence of SpaceX has not rewritten any textbooks or invalidated decades of cumulative experience, especially in parts that they haven't even touched yet.It's also generally respectful to not assume that thsee people that have built myriad of complicated spacecraft don't really have a clue
And to the point of "building everything in house" - nobody does that for many good reasons that would be even more off topic here, not SpaceX nor anyone else QuoteSorry, that was sarcasm and that's not appropriate. Unnecessary and tiresome
Quote from: savuporo on 04/14/2016 02:01 amQuote from: A_M_Swallow on 04/14/2016 01:38 amIt is time to devise and test tanks that can store methane and LOX for up to 4 years.For a fun excercise, go try and quote a LOX compatible pyro valve from one of these, for lead time and tested batch price.About $1-2 million for the qual, and 52 weeks on the first lot. Not sure the point you're trying to make. Plenty of catalog components that are useable with methane.
Making a distinction between engineering state of art, and future ideas that might happen or might get superseded by something completely different isn't naysaying in my book.
Because currently it is not, and as far as i know, not in the foreseeable future.
Those people who built many other spacecraft never claimed methane isn't a space-storable propellant.
..., and get back to whether methalox ISRU is viable on Luna? Assume it would need active storage. (and don't mention it again, we all agree...)
Analysis of these data sets suggests the presence of volatiles, including water, hydrogen, carbon monoxide, methane, and others, though their concentration and distribution, both laterally and vertically, seem to be quite variable, and their physical form is not clear.
Perhaps you'd like to elaborate how far is foreseeable future and what reasons prevent space storable methalox propulsion systems from happening during that time.
Suppose we say that yes, under the definition of "doesn't need active heating or cooling, can be stored passively, maybe with some shading but nothing else...." Methalox isn't "storable".. Now what? To me it means that if we want long duration missions that use methalox, or that we want propellant depots, they are going to have to do some systems development... some active (powered) heating and cooling systems have to be developed and brought to sufficient TRL to be worth demonstrating in space as the success chances are high enough.Can we say "yep, thats all true"... agree with each other, hold hands, sing kumbaya, whatever......, and get back to whether methalox ISRU is viable on Luna? Assume it would need active storage. (and don't mention it again, we all agree...)
Well obviously you'll need active storage on the Moon since you'll have to be liquifying it after producing the gas.
Quote from: Robotbeat on 04/15/2016 03:39 pmWell obviously you'll need active storage on the Moon since you'll have to be liquifying it after producing the gas.Active storage? There are even natural PSRs where temps down to 26K. Elsewhere construct an artificial one. Tent poles and reflective foil
There are no spacecraft currently being designed with integrated LOX/CH4 main propulsion or RCS.
Quote from: KelvinZero on 11/09/2015 07:33 amQuote from: sdsds on 11/09/2015 06:22 amYes. The buzz-phrase for this is to say there is a "Strategic Knowledge Gap" regarding (in particular for this thread) lunar ice.Also there is meant to be more CO than H2O in the LCROSS results so lunar methane ISRU sounds plausible and arguably less wasteful of all those volatiles.I know this piece of common knowledge (that LCROSS found more CO than H2O) has been repeated a lot on NSF, but it may not be accurate, based on a conversation I had with Paul Spudis:http://forum.nasaspaceflight.com/index.php?topic=39559.msg1612453#msg1612453tl;dr is that only one of the two sensors showed less H2O, and it's the one they trust a lot less. The IR mass spectrometer data on the LCROSS shepherding craft showed 90-95% of the volatiles were water, and its results have never been revised downward. The LAMP data from LRO (which was within line-of-site for the impact) was revised downward, but we have a lot less experience with interpreting UV spectrometry than we do IR spectrometry.~Jon
Quote from: sdsds on 11/09/2015 06:22 amYes. The buzz-phrase for this is to say there is a "Strategic Knowledge Gap" regarding (in particular for this thread) lunar ice.Also there is meant to be more CO than H2O in the LCROSS results so lunar methane ISRU sounds plausible and arguably less wasteful of all those volatiles.
Yes. The buzz-phrase for this is to say there is a "Strategic Knowledge Gap" regarding (in particular for this thread) lunar ice.