The necessary gasses are already on Mars in various forms. Identify the path for extracting each (the purpose of this thread), and send the required ISRU equipment instead on early missions.
Quote from: sghill on 02/19/2018 01:49 pmThe necessary gasses are already on Mars in various forms. Identify the path for extracting each (the purpose of this thread), and send the required ISRU equipment instead on early missions.If, and only if, ISRU seems a cheaper, or more reliable way of doing it for a given mission, including development costs. Methane and oxygen also exist in earths atmosphere, nobody ISRUs, because you can get them in better ways. (Buy them) A lot of the posts in this thread are at best theoretical concepts with regrettably few ties to $ and W.
If the choice were between..A a sensible small scale scientific exploratory mission that imports hydrogen in a stable form and in small quantity and uses indirect return.And..B a ramping up of robotic ISRU to a scale necessary to support Musk's architrcture that puts off an actual manned mission another 10-15-20 years.I choose A.
As you mentioned BFR, I chose C. Human operated ISRU.
Quote from: guckyfan on 02/23/2018 05:53 amAs you mentioned BFR, I chose C. Human operated ISRU.To get those humans there to do the ISRU you need to get them there and back and thus you go back to option A first.
Quote from: Russel on 02/23/2018 03:54 amIf the choice were between..A a sensible small scale scientific exploratory mission that imports hydrogen in a stable form and in small quantity and uses indirect return.And..B a ramping up of robotic ISRU to a scale necessary to support Musk's architrcture that puts off an actual manned mission another 10-15-20 years.I choose A.We could have done Option A back in the 1990s when it was suggested, but nobody wants to pay for it. Not an option.SpaceX is working on Option B. Probably will be done within 10 years, if it works at all. This is the only option being funded and it's cheaper.There is no "If the choice were between" for Mars exploration. SpaceX may not be able to pull it off, but it's the only game in town.
Quote from: Russel on 04/01/2018 05:22 pmQuote from: guckyfan on 02/23/2018 05:53 amAs you mentioned BFR, I chose C. Human operated ISRU.To get those humans there to do the ISRU you need to get them there and back and thus you go back to option A first.How so? They go there, get ISRU going and fly home. No option A with hydrogen needed.
Are "planetary protection" issues likely to put a spoke in the wheel of any planned extraction of Martian water for ISRU?
Quote from: Slarty1080 on 04/01/2018 05:48 pmAre "planetary protection" issues likely to put a spoke in the wheel of any planned extraction of Martian water for ISRU?They certainly make it a lot harder to just dive in with the sort of mining needed for colonisation scale ISRU.
Quote from: Russel on 04/01/2018 05:52 pmQuote from: Slarty1080 on 04/01/2018 05:48 pmAre "planetary protection" issues likely to put a spoke in the wheel of any planned extraction of Martian water for ISRU?They certainly make it a lot harder to just dive in with the sort of mining needed for colonisation scale ISRU.Perhaps this issue alone would make it "easier" to make use of hydrated minerals as a source of water and steer away from ice (at least initialy)?
Quote from: Slarty1080 on 04/01/2018 05:48 pmAre "planetary protection" issues likely to put a spoke in the wheel of any planned extraction of Martian water for ISRU?No. If planetary protection protocols effectively stop human missions to Mars then the protocols will be changed.
This looks very interesting. One step production of carbon dioxide (CO2) and water (H2O) into ethylene (C2H4) and oxygen (O2).CO2 + H2O → 0.5C2H4 + 1.5O2http://pubs.acs.org/doi/abs/10.1021/acssuschemeng.7b02110Compare this trying to make methane (CH4):CO2 + 4H2 → CH4 + 2H2O (Sabatier)4H2O → 4H2 + 2O2 (electrolysis)Overall reaction isCO2 + 2H2O → CH4 + 2O2That is, making methane requires twice as much water as ethylene as well as having a lower density and Isp compared to ethylene!Propellants MR dp (kg/L) ve (m/s) Id (Ns/L)O2/CH4 3.6 0.8376 3656 3062O2/C2H4 2.7 0.9007 3678 3313