September 27, 2016 Space Show appearance

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For those that want to listen to me discuss Elon Musk’s speech as well as other space matters for two hours, you can download the podcast at The Space Show website. David Livingston also provides at this link a short summary of some of the topics we covered during last night’s show.



  • Calvin Dodge

    For the caller who appeared to be concerned Mars didn’t have enough carbon dioxide, its atmosphere weighs in at 25 trillion tons, and it’s at least 95% carbon dioxide.

  • J Fincannon

    There is plenty of CO2 to make O2, but you still need the other half of the rocket fuel. I suppose you have to either bring it and make it from something else on Mars.

  • Localfluff

    J Fincannon, The H4 in the CH4 has a mass of only 25%. In the reaction O2+CH4, H only makes up 9% of the combined mass (and you obviously need a bit more O2 than CH4 so the real mass share is even lower). Hydrogen will have to be brought from Earth or be extracted from underground H2O on Mars. There’s a shortage of it on Mars, but a small problem to carry it there if needed.

  • Edward

    Localfluff wrote: “Hydrogen will have to be brought from Earth or be extracted from underground H2O on Mars.

    It may not be easy to pump the underground water (which is not guaranteed to be there), as it may not flow as quickly as on Earth and may be slow to replenish the well, leaving the well dry or a low-flow source. However, another source is the ice at the poles, especially the north pole, which has less CO2 ice covering the water ice.

    Musk noted this polar ice during his presentation on Monday, but he did not mention underground water as a source. Most likely he did not want to give anyone the opportunity to criticize the colonization idea due to lack of available hydrogen (since the underground water is not guaranteed).

    Mars will be a difficult place to explore and colonize. Heinlein told us that “The Moon Is a Harsh Mistress,” but Mars will be no picnic, either.

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