Elder scientists work to send humans to MarsGerald Voecks (left), Michael Hecht (second from left), and Jeff Hoffman (right) are working on technology to turn carbon dioxide into oxygen on Mars“Look, I’m 80 years old — I might be dead before this project is over. Who knows!” said Donald Rapp, an energetic member of the team who has been retired from NASA’s Jet Propulsion Laboratory for more than a decade.
The Mars Oxygen ISRU Experiment (MOXIE) Michael H. Hecht, Donald R. Rapp, and Jeffrey A. Hoffmanhttp://ssed.gsfc.nasa.gov/IPM/PDF/1134.pdf
In a human scale Marsmission, the ISRU system would be operated continuouslyin a steady state without interruption for manymonths, adapting autonomously to atmospheric variability(temperature, pressure, dust). Such a full-scalesystem would produce roughly 25-30 metric tons of O2during the ~17-month period between arrival of theISRU system and ascent vehicle on Mars, and the decisionto launch the human crew at the next launch opportunity.This requires a production rate of approximately2.2 kg/hr.The SOXE architecture is a stack of cells, arrangedvertically like a multi-story building. The two MOXIEstacks each utilize 11 cells. An assembly of 100 stacks,each containing 20 MOXIE-sized cells, would produce>2 kg/hr of O2 with an energy investment of ~12 kW.A full-size CO2 acquisition system requires 8 kg/hrof martian atmosphere, ~0.14 m3/s at 7 mbar.
Because everyone likes ISRUQuoteElder scientists work to send humans to MarsGerald Voecks (left), Michael Hecht (second from left), and Jeff Hoffman (right) are working on technology to turn carbon dioxide into oxygen on Mars“Look, I’m 80 years old — I might be dead before this project is over. Who knows!” said Donald Rapp, an energetic member of the team who has been retired from NASA’s Jet Propulsion Laboratory for more than a decade.https://www.bostonglobe.com/metro/2015/02/08/elder-statesmen-science-unite-for-mars-mission/N5sZQqOEuhKC56rdtE4uPN/story.htmlThe Mars Oxygen ISRU Experiment (MOXIE) Michael H. Hecht, Donald R. Rapp, and Jeffrey A. Hoffmanhttp://ssed.gsfc.nasa.gov/IPM/PDF/1134.pdfMars ISRU for Production of Mission Critical Consumables – Options, Recent Studies, and Current State of the Art - Jerry Sandershttp://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150016009.pdfhttp://planetaryprotection.nasa.gov/file_download/90/29-Sanders.Mars.ISRU.PP_Sanders.V2.pdfTo add, Rapp has written two books heavily focused on Mars and ISRU technologies.http://www.amazon.com/Extraterrestrial-Resources-Missions-Astronautical-Engineering/dp/3642327613http://www.amazon.com/Human-Missions-Mars-Technologies-Exploring/dp/3540729380
With water ISRU, you have fuel, oxidizer, oxygen for the crew, lots of water for the crew and for maintenance (now you can wash off the dusty spacesuits, wash clothes, clean filters, etc...), and feedstocks for simple plastic production (can make polyethylene and polypropylene from methane and some oxygen, given the right catalysts and reaction chambers).
Quote from: Robotbeat on 10/17/2016 02:21 amWith water ISRU, you have fuel, oxidizer, oxygen for the crew, lots of water for the crew and for maintenance (now you can wash off the dusty spacesuits, wash clothes, clean filters, etc...), and feedstocks for simple plastic production (can make polyethylene and polypropylene from methane and some oxygen, given the right catalysts and reaction chambers).Can i refer you to a very recent dissertation called Risk-value optimization of performance and cost for propellant production on Mars that factors in all the previous work, including NASA DRM 3 and DRA 5 studies, everything that Dr. Rapp has written and then some, and does actual modelling and design trades ? The conclusions are well worth a read.And then, lets keep this thread on MOXIE or at least on CO2 solid oxide electrolysis ?
I've seen little analysis about actually using that carbon monoxide as fuel. It seems people either are unaware it's possible, or they're aware but only remember "it has low Isp," dismiss it out of hand as such, and aren't actually aware of a serious trade that incorporates carbon dioxide as a fuel
If solid oxide and MOXIE tech has a real future in the long-term beyond a niche use maybe for ECLSS, then it requires building a capability to use carbon monoxide as a fuel.
Quote from: Robotbeat on 10/17/2016 03:41 amI've seen little analysis about actually using that carbon monoxide as fuel. It seems people either are unaware it's possible, or they're aware but only remember "it has low Isp," dismiss it out of hand as such, and aren't actually aware of a serious trade that incorporates carbon dioxide as a fuelThen i can only conclude you are not actually interested in the subject. Like i mentioned, CO based rockets have been discarded like 10-15 years ago.
Easily the most referenced comprehensive study:http://www.niac.usra.edu/files/studies/final_report/340Rice.pdf
Quote from: savuporo on 10/17/2016 03:59 amQuote from: Robotbeat on 10/17/2016 03:41 amI've seen little analysis about actually using that carbon monoxide as fuel. It seems people either are unaware it's possible, or they're aware but only remember "it has low Isp," dismiss it out of hand as such, and aren't actually aware of a serious trade that incorporates carbon dioxide as a fuelThen i can only conclude you are not actually interested in the subject. Like i mentioned, CO based rockets have been discarded like 10-15 years ago.Without good reason.
I recently saw correspondence with the lead of that effort at Glenn Research Center (as it's now called), and she certainly thought it was still very promising. And the fact that a non-optimized low pressure version has difficulty igniting in one iteration doesn't mean it's inherently a bad propellant to use, I've had problems getting perfectly good propellant combinations to reliably ignite in some combinations. You're grasping at straws trying to find an authoritative rationale for CO's rejection.It wasn't "abandoned" for any good reason. The same excuse pops up almost every time it's rejected: "low Isp."
Quote from: Robotbeat on 10/17/2016 05:20 amI recently saw correspondence with the lead of that effort at Glenn Research Center (as it's now called), and she certainly thought it was still very promising. And the fact that a non-optimized low pressure version has difficulty igniting in one iteration doesn't mean it's inherently a bad propellant to use, I've had problems getting perfectly good propellant combinations to reliably ignite in some combinations. You're grasping at straws trying to find an authoritative rationale for CO's rejection.It wasn't "abandoned" for any good reason. The same excuse pops up almost every time it's rejected: "low Isp."It has been evaluated plenty of times, and every time the answer is : engineering complexity of building an actual working rocket engine that would reliably work in any conditions, is very high. That's just in lab on Earth, nevermind Mars. High combustion temperature combined with materials compatibility issues of high temperature CO make it simply unattractive option. Similar reasons why nobody is flying around LF2/LH2 SSTOs.Handwaving.