Yet another Mars architecture

RobertDyck · 2015-09-27 16:06:26

Checked power calculation (with urine processor):
toilet: 375 watt peak, 0.071875 kWh per day
water processor: 915 watt peak, 1.40 kWh per day
urine processor: 424 watt operating, 108 watt standby, 255.2 watt continuous
oxygen generation: 1.73 kW continuous
CO2 removal: 0.259 kW continuous
dehumidifier: 0.6 kW continuous
circulation fan: 0.312 kW continuous
Total: 3.2 kW

With the equivalent of 5 Tesla Powerwalls, that will give the ITV 10.8779 hours, or 10 hours, 52 minutes, 40 seconds. That does not include power for communications, electronics, lighting, or control of manoeuvring systems. Just power down to 100% life support.

I said in another thread that the surface hab will require more, I suggested 2 Mars solar days. That's 49.32 hours. That will require a battery equivalent to 22.7 Tesla Powerwalls. Again that only includes power for life support. The surface hab will require a big battery.

Also note; I believe the Tesla Powerwall uses lithium polymer batteries. It has the same charge to mass ratio as lithium ion, but lithium polymer is substantially less expensive. But lithium polymer can be much more easily damaged, and if an intermal membrane is ruptured it can balloon up with generated gas. A lithium polymer batter has an aluminized outer bag rather than a metal casing; if that is ruptured to allow air in, as soon as oxygen touches the lithium anode it will burn, generating thick black smoke. When I worked at Micropilot, they got some of the first lithium polymer batteries for the drones they were testing. To test software for the autopilot they manufactured, they used a model airplane kit purchased from a local hobby store. The software didn't always pass the tests. Sometimes they lost control, had to follow the drone until it ran out of fuel and crashed. One crash did damage a battery, it did balloon up. The technician looked up procedure to properly dispose of the battery. Instructions from the manufacturer's website said to cut open the battery outside, in a well ventilated area with a breeze, and stand upwind. He did that, and a few of us watched. It had a red glow as the lithium anode burned, and thick black, stinky smoke. The technician said he'll never do that again. This reminded me of reports that a Boeing 787 Dreamliner filled with thick black smoke while taxiing to the runway. They had to stop and evacuate passengers. To save fuel, that plane does not have generators in its engines. Instead it has a lot of lithium polymer batteries, which have to be charged when the plane is fuelled. Obviously one of the batteries ruptured. The Tesla Powerwall has a hard case to enclose and protect the batteries, they should get damaged. Our Mars lander will have to do the same.

Ps. That black smoke will contain lithium oxide. That's a psycho-active drug. That's what bipolar patients take to even out their mood swings. I suppose being mellow is not all that bad, but you really don't want to breathe that.

louis · 2015-09-27 17:53:26

In other words - a very small and manageable power requirement. I think electric automobiles operate around 5 times that. So we are looking to power 20% of an electric vehicle and we can do that with large solar arrays.

I think you can almost ignore power calculations in terms of getting crews from Earth to Mars, in the sense they are not really critical. The critical issue is cargo and rocket fuel.

But that is why I argue for splitting up a mission so you pre-land lots of equipment and supplies with separate robot missions. This makes it all much more doable with current technology.

Landing then becomes the key issue - how to land those pre-supplies.

RobertDyck wrote:

Checked power calculation (with urine processor):
toilet: 375 watt peak, 0.071875 kWh per day
water processor: 915 watt peak, 1.40 kWh per day
urine processor: 424 watt operating, 108 watt standby, 255.2 watt continuous
oxygen generation: 1.73 kW continuous
CO2 removal: 0.259 kW continuous
dehumidifier: 0.6 kW continuous
circulation fan: 0.312 kW continuous
Total: 3.2 kW
With the equivalent of 5 Tesla Powerwalls, that will give the ITV 10.8779 hours, or 10 hours, 52 minutes, 40 seconds. That does not include power for communications, electronics, lighting, or control of manoeuvring systems. Just power down to 100% life support.
I said in another thread that the surface hab will require more, I suggested 2 Mars solar days. That's 49.32 hours. That will require a battery equivalent to 22.7 Tesla Powerwalls. Again that only includes power for life support. The surface hab will require a big battery.
Also note; I believe the Tesla Powerwall uses lithium polymer batteries. It has the same charge to mass ratio as lithium ion, but lithium polymer is substantially less expensive. But lithium polymer can be much more easily damaged, and if an intermal membrane is ruptured it can balloon up with generated gas. A lithium polymer batter has an aluminized outer bag rather than a metal casing; if that is ruptured to allow air in, as soon as oxygen touches the lithium anode it will burn, generating thick black smoke. When I worked at Micropilot, they got some of the first lithium polymer batteries for the drones they were testing. To test software for the autopilot they manufactured, they used a model airplane kit purchased from a local hobby store. The software didn't always pass the tests. Sometimes they lost control, had to follow the drone until it ran out of fuel and crashed. One crash did damage a battery, it did balloon up. The technician looked up procedure to properly dispose of the battery. Instructions from the manufacturer's website said to cut open the battery outside, in a well ventilated area with a breeze, and stand upwind. He did that, and a few of us watched. It had a red glow as the lithium anode burned, and thick black, stinky smoke. The technician said he'll never do that again. This reminded me of reports that a Boeing 787 Dreamliner filled with thick black smoke while taxiing to the runway. They had to stop and evacuate passengers. To save fuel, that plane does not have generators in its engines. Instead it has a lot of lithium polymer batteries, which have to be charged when the plane is fuelled. Obviously one of the batteries ruptured. The Tesla Powerwall has a hard case to enclose and protect the batteries, they should get damaged. Our Mars lander will have to do the same.
Ps. That black smoke will contain lithium oxide. That's a psycho-active drug. That's what bipolar patients take to even out their mood swings. I suppose being mellow is not all that bad, but you really don't want to breathe that.

RobS · 2015-09-27 18:08:36

By the way, NASA engineers are now designing two plans to get people to Mars in the 2033-43 time frame. You may want to take a look:

http://www.nasaspaceflight.com/2015/09/ … ons-2030s/

It relies of the largest SLS design AND solar electric propulsion, which is used to get all hardware and payload to cislunar space where it is parked until the crew arrives. They are looking at 600+ tonnes in cislunar space for the first manned landing on Mars and about the same for the earlier mission to Phobos. They are figuring 10-14 SLS launches for each flight, spread out over 4 years (they can't get them all launched in time to go every 2 years). How much will an SLS launch cost, though? I doubt we have a real number, but I gather they are so expensive we can't do more than a few every year. that's the big problem with the use of SLS. The link also has lots of really interesting graphics and information about the Mars landers (they are considering 3 different sizes).

SpaceNut · 2015-09-27 18:47:39

Usually with power the source or output desired is at 70% for continous useage for the 100% desired point in other word prorated and with a much higher peak that is rated for a time duration....

Here are the values for keeping a craft running with no humans onboard....
Dragon Family of capsules

The SpaceX Dragon CRS cargo variant solar arrays produce 1,500 W average, 4,000 W peak, at 28 and 120 VDC used for communication and command systems.

Now the battery while it needs ampere hours to deliver the power there is a problem in that as the voltage drops the power needed to be created goes up as a rising current draw depleting the cells even quicker in order to produce the needed power for the devices that it supplies.

SpaceNut · 2015-09-29 21:01:37

I have been poking around in the old lunar topics and here is a quote from one of the links.

"To land one pound of supplies on the lunar surface, it'll require us to launch 125 pounds of hardware and fuel to get it there." So whats the values for Mars?

While this was in the lunar outpost topic this is very much a piece that we will alter to make Mars possible... NASA In-Situ Resource Utilization (ISRU) Development & Incorporation Plans there are a couple of slides that will support the life support numbers that RobertDyck is working on....

I am also looking at the surface habitat and mobility that could be leveraged from the Next generation of Space exploration http://www.nasa.gov/exploration/technol … index.html of which in the phobo mars mission pages there are some simularity....

Two person basic hab module of 28m³ packaged so that it can expand to 56m³ with water stored overhead for radiation protection and thermal control made from a composite structure.

Tom Kalbfus · 2015-09-30 15:39:45

http://www.wsj.com/video/an-ice-house-o … FDD6C.html
An Ice House on Mars: Would You Live There?
9/30/2015 7:18AM

With NASA's findings showing evidence of liquid water on Mars, is the next step building homes on the red planet? See which concepts won NASA's 3-D Printed Habitat Challenge for Mars. Photo: MarsIceHouse.com

Last edited by Tom Kalbfus (2015-09-30 15:42:49)

kbd512 · 2015-10-02 10:36:39

RobertDyck wrote:

You want to revive Saturn V? First remember the first stage was built at the Michoud Assembly Facility, later convert to make Shuttle ET, and now manufacturing core stages for SLS. So that doesn't change the building or which contactor runs it. And tooling has been changed several times, you would have to re-tool to go back to Saturn V stages.
Second and third stages of Saturn V used the J-2 engine. The latest updated version is the J-2X engine. That's been indefinitely mothballed. The reason was salesmen for the RL-10 engine convinced the powers that be to buy their engine. Actually, numbers show an upper stage for SLS would have similar performance for the Moon or Mars, although dramatically reduced payload mass for LEO. And the stage based on RL-10 has significantly less propellant. That means lower cost for stage tanks and propellant to fill them. And the launch pad gantry doesn't have to be as high. That means SLS block 2B would incur less cost to modify the gantry from SLS block 1.
And engines for Saturn V first stage were F-1. The current updated version is F-1B. That engine is proposed for liquid boosters for SLS block 2B. That would be great! However, the powers that be have still not decided. Salesmen from ATK are still trying to push their advanced SRB that adds high explosive to the propellant for increase performance. Ok, yea, at the dilution ratio proposed RDX or HMX will burn as a rich oxidizer. But the advanced SRB would still have segments, ATK proposed going back to 4 like Shuttle. So again nothing but an O-ring separating even hotter solid rocket exhaust from the liquid hydrogen tank of the SLS core stage. And the advanced SRB casing will be composite instead of steel, to reduce weight. That containing even hotter solid rocket fuel combustion. I'm worried about burn-through. Does my bias for liquid rockets show? Tiny solids for medium variants of Atlas V or Delta IV are Ok because they're small and because the casing is one piece; no O-ring. I would like development of LRB using F-1B engines to start now. But reviving Saturn V would also require approving F-1B engines.
And the instrument unit for Saturn V used 1960s electronics. That would have to be completely redesigned with modern electronics. So it's far too late to revive Saturn V.

Alternatively, instead of merely re-creating Saturn V, we could create Nova. 8 F-1B's in the first stage, 3 RS-25's in the second stage, and 1 J-2X in the third stage. That way, we'd actually get a 200t rocket in return for all the billions spent on F-1, RS-25, and J-2 development and testing. By foregoing the insistence on launching from KSC, NASA could have a mobile launch barge that's not limited by the facilities there. The stages could be assembled on the barge and launched from the Atlantic. That idea's no more crazy than spending tens of billions on SLS to develop a rocket with half the lift capability of Saturn V at equivalent cost per launch vehicle.

Someone sold NASA or Congress or both on the idea that reusing STS hardware for SLS would be cheaper than development of an entirely new rocket. NASA then proceeded to develop an entirely new rocket. If the people throwing money at SLS are that dumb, it shouldn't be too hard to convince them that development of NOVA is SLS Block II.

RobertDyck · 2015-10-02 13:37:09

SLS block 2 with 5 SSME for the core stage, and 1 to 3 J-2X engines for the upper stage, and liquid boosters each with a pair of F-1B engines; expected to lift 150t to LEO. Again 3 engine for the upper stage for heavy weight to low orbit, 2 engines for medium weight to medium orbit, or one engine for GTO or the Moon or Mars.

Nova was designed to use 8 F-1 engines for the first stage, 8 J-2 engines for the second stage, and a single J-2 engine for the third stage. Michoud would manufacture first stages, the VAB would assemble, and launch from one of the pads at complex 39. Back when they were talking about Nova, complex 39 was supposed to have 4 launch pads. Only pads A & B were built, pads C and D never were. So Nova wouldn't change facilities.

Launch pad 39A has been converted to Falcon Heavy, and SpaceX is building a horizontal assembly building near the pad. SLS will use pad 39B.

Of course SpaceX released proposals for heavy lift: Falcon X 38kt to LEO, Falcon X Heavy 125kt, Falcon XX 140kt. They didn't announce Falcon XX Heavy, but some estimate if they did it would lift greater than 400kt.

kbd512 · 2015-10-07 10:51:33

RobertDyck wrote:

SLS block 2 with 5 SSME for the core stage, and 1 to 3 J-2X engines for the upper stage, and liquid boosters each with a pair of F-1B engines; expected to lift 150t to LEO. Again 3 engine for the upper stage for heavy weight to low orbit, 2 engines for medium weight to medium orbit, or one engine for GTO or the Moon or Mars.

SLS Block II with liquid boosters isn't going to happen. There's no room on the pad for the TSM's. Engineers who work on SLS have already stated that there's barely enough room for the TSM's for the SRB's.

RobertDyck wrote:

Nova was designed to use 8 F-1 engines for the first stage, 8 J-2 engines for the second stage, and a single J-2 engine for the third stage. Michoud would manufacture first stages, the VAB would assemble, and launch from one of the pads at complex 39. Back when they were talking about Nova, complex 39 was supposed to have 4 launch pads. Only pads A & B were built, pads C and D never were. So Nova wouldn't change facilities.

You missed the part where I stated that instead of launching the vehicle from a pad, NASA should build a barge and launch the rockets from the Atlantic. Since Nova does not use SRB's, the weight of the components that would have to be assembled on the barge would be within reason for a crane attached to the barge.

RobertDyck wrote:

Launch pad 39A has been converted to Falcon Heavy, and SpaceX is building a horizontal assembly building near the pad. SLS will use pad 39B.

Ok.

RobertDyck wrote:

Of course SpaceX released proposals for heavy lift: Falcon X 38kt to LEO, Falcon X Heavy 125kt, Falcon XX 140kt. They didn't announce Falcon XX Heavy, but some estimate if they did it would lift greater than 400kt.

The flight hardware to build Nova is in a far more advanced state of development than any of SpaceX's super heavy lift rockets. The J-2X development is complete. The latest RS-25D variant development is nearing completion. NASA also seems intent on completing development of the F-1B engines. Granted, there's a lot more work to be done to integrate them into a launch vehicle, but it's not like they're starting completely from scratch, either, which would be the case if SpaceX decides to complete development of their methane powered rockets.

If NASA wants a super heavy lift rocket that's less complicated than SLS and has the throw weight they were after before Congress and the President pulled the rug out from underneath them several times, then a Nova type rocket is the way to go. If they're intent on development of liquid boosters for SLS, even though they can't actually use them with SLS and their current launch pad infrastructure, I could see development of a Saturn V-23(L) type vehicle using 4 liquid boosters and a standard Saturn V type core stage. We could easily have a 15M payload shroud with this type of vehicle.

RobertDyck · 2015-10-07 11:57:37

kbd512 wrote:

SLS Block II with liquid boosters isn't going to happen. There's no room on the pad for the TSM's. Engineers who work on SLS have already stated that there's barely enough room for the TSM's for the SRB's.

NASA is determined that a booster for Block II is not yet selected. ATK is trying to sell their advanced booster, Dynetics is trying to sell liquid boosters using the F-1B engine, and there are other companies trying to sell their engines. NASA has an open competition for these boosters.

NASA announced they will build Block II when they first announced SLS, but media announcements reveal current concerns indicate it won't be built. They don't want to develop a core stage with 5 engines, and they'll build an upper stage using 4 RL-10 engines instead of one J-2X. Block 1B will use that new upper stage with 5-segment SRBs, block 2B will replace SRBs with advanced boosters. The only question is which advanced booster will win the competition. Are you trying to bias the competition toward ATK and their advanced solid?

kbd512 wrote:

RobertDyck wrote:
Nova was designed to use 8 F-1 engines for the first stage, 8 J-2 engines for the second stage, and a single J-2 engine for the third stage. Michoud would manufacture first stages, the VAB would assemble, and launch from one of the pads at complex 39. Back when they were talking about Nova, complex 39 was supposed to have 4 launch pads. Only pads A & B were built, pads C and D never were. So Nova wouldn't change facilities.
You missed the part where I stated that instead of launching the vehicle from a pad, NASA should build a barge and launch the rockets from the Atlantic. Since Nova does not use SRB's, the weight of the components that would have to be assembled on the barge would be within reason for a crane attached to the barge.

I didn't miss it. I explained that it'll never happen. Nova is an old design that is dead. It was never designed to be launched that way. If NASA were to revive Nova, it would be simpler and less expensive to launch the way they had originally intended: from a launch pad at complex 39. The only one still available is 39B. KSC has said one reason for removing the static service structure is to accommodate different launch vehicles, each with it's own mobile launcher. So launching Nova from that pad does fit KSC's intent.

kbd512 wrote:

RobertDyck wrote:
Of course SpaceX released proposals for heavy lift: Falcon X 38kt to LEO, Falcon X Heavy 125kt, Falcon XX 140kt. They didn't announce Falcon XX Heavy, but some estimate if they did it would lift greater than 400kt.
The flight hardware to build Nova is in a far more advanced state of development than any of SpaceX's super heavy lift rockets. The J-2X development is complete. The latest RS-25D variant development is nearing completion. NASA also seems intent on completing development of the F-1B engines. Granted, there's a lot more work to be done to integrate them into a launch vehicle, but it's not like they're starting completely from scratch, either, which would be the case if SpaceX decides to complete development of their methane powered rockets.
If NASA wants a super heavy lift rocket that's less complicated than SLS and has the throw weight they were after before Congress and the President pulled the rug out from underneath them several times, then a Nova type rocket is the way to go. If they're intent on development of liquid boosters for SLS, even though they can't actually use them with SLS and their current launch pad infrastructure, I could see development of a Saturn V-23(L) type vehicle using 4 liquid boosters and a standard Saturn V type core stage. We could easily have a 15M payload shroud with this type of vehicle.

These are the same arguments for SLS. It was supposed to be built upon Shuttle and Saturn V technology and infrastructure, so less expensive than building a new launch vehicle. But it's taking more time than developing Saturn V, and the cost is as if they're developing a new launch vehicle. Nova would be built by the same "Old Space" contractors, so have all the same problems as SLS.

By the way, engineers who worked on Nova are all either retired or died from old age. Young engineers have never seen Nova, so to them it's new. Old Space corporate executives want to maximize profits, so they'll find any excuse to charge as if it's a new launch vehicle. The fact it's new to the engineers they currently have just gives them more of an excuse. Again, Nova would have the same development time and cost as SLS.

GW Johnson · 2015-10-07 12:55:26

I don't remember a 15-16,000,000 lbth NOVA, based on 8 F-1's uprated some. What I remember are a multitude of configuration proposals ranging from 25 Mlb to 45 Mlb in the first stage. The large end of this spectrum was projected to be about 600 feet tall.

Besides the enormous cost, there were two other compelling reasons we never built rockets that large: (1) a pad explosion was too energetic an event to tolerate, and (2) the noise of a successful launch was itself lethal out to a range of a few miles from the pad, also not tolerable.

As for launching from barges, the sea is quite often not very still. Tall things tip over quite easily. Ask the late crew of the Faro about that, if you are clairvoyant enough to reach them.

GW

RobertDyck · 2015-10-07 14:14:51

GW Johnson wrote:

I don't remember a 15-16,000,000 lbth NOVA, based on 8 F-1's uprated some. What I remember are a multitude of configuration proposals ranging from 25 Mlb to 45 Mlb in the first stage. The large end of this spectrum was projected to be about 600 feet tall.

When NASA was working on Apollo in the 1960s, they had a problem. They originally intended to land the CSM on the Moon, and lift off again. Calculations showed a Saturn V was not large enough to launch it. They changed the service module from one stage to two: descent stage and ascent stage. At one point they came up with a design on paper that split the ascent stage into two, so a total of 3 stages. Even that was not good enough; even a Saturn V couldn't launch it. They were concerned that a larger launch vehicle would be necessary. NASA had originally designed on paper several launch vehicles: Saturn A-1, A-2, A-3, A-4, A-5, B-1, C-1, C-2, C-3, C-4, C-5. They selected the Saturn C-1 and C-5. Saturn C-1 became Saturn 1B, and Saturn C-5 became Saturn V. There was another design: Saturn C-8. It used the same engines as Saturn V, but 8 engines for each of the first and second stages, and correspondingly larger propellant tanks. As concerns grew that Apollo engineers would require a launch vehicle larger than Saturn V, serious consideration grew that NASA may need Saturn C-8. They even gave it a name: Nova. But NASA really did not want to build it, for the reasons GW Johnson just gave. Then one engineer came up with the idea to split Apollo into a Lunar Excursion Module (LEM) and mothership. The name "LEM" was later shorted to Lunar Module or LM, but astronauts continued to pronounce it "LEM". The "mothership" was the command module NASA had already developed, plus a service module based on the one they were working on, but substantially smaller. It used the same engine that was developed as the ascent stage from the Moon, which is why that engine was so big. The service module could have used a smaller engine, but it was too late to start over.

After Apollo 11, when the Soviet Union learned they lost the race to the Moon, they hoped to trump NASA's achievement by sending men directly to Mars. When American spy agencies told NASA of this, NASA started designs to send men to Mars. There was discussion of brushing off designs for Nova, using that to send a modified Apollo to Mars. Again, the same concerns GW Johnson raised were repeated. NASA did develop a new heat shield, an upgrade to the Apollo Command Module to permit it to enter Earth's atmosphere from a trajectory returning from Mars. Apollo used AVCOAT to return from the Moon, but it wasn't good enough to return from Mars. They developed PICA to return from Mars. They developed NERVA as a replacement for the third stage of Saturn V, with the hope a Saturn V could launch Apollo to Mars. They actually completed all ground tests of the NERVA engine, all that was left to do was test it in Earth orbit.

The Soviet Union launched Mars 2M No.521 to Mars on 27 March 1969, known to NASA as Mars 1969A: launch failure. They launched an identical probe on an identical launch vehicle, Mars 2M No.522 on 2 April 1969, known to NASA as Mars 1969B: launch failure. I know, this is actually months before Apollo 11 landed. They launched 3MS No.170, aka Kosmos 419, on 10 May 1971: launch failure. They launched 4M No.171, aka Mars 2, on 19 May 1971: success but global dust storms completely obscured the surface. The orbiter operated for 362 orbits, but storms lasted longer so it never saw anything. They launched 4M No.172, aka Mars 3, on 28 May 1971: operated for 20 orbits, but storms obscured the surface again. They launched SA 4M No.172, aka Mars 3 lander, 28 May 1971: it did land successfully but contact lost 14.5 seconds later.

I could go on, but after all this NASA realized a Soviet manned mission to Mars is really not a threat. The Soviets eventually decided to focus on space stations instead. And for years the guys at JPL joked that the Mars planetary defence system is fully operational. The local planetarium had a show that listed all Mars missions with a scoreboard: Mars vs Earth, with Mars going up one for each mission that failed. It was quite humorous.

My point is Nova was Saturn C-8. Yes, there were other designs. No, it was never built. Yes, there were concerns that launching it wasn't safe.

Last edited by RobertDyck (2015-10-07 14:54:56)

SpaceNut · 2015-10-12 21:57:34

food for thought
"Radiation Studies for a Long Duration Deep Space Transit Habitat"
http://spirit.as.utexas.edu/~fiso/telec … -31-12.pdf

Future In-Space Operations (FISO) Working Group Presentations Archive 2007-2009
http://spirit.as.utexas.edu/~fiso/archivelist07-09.htm

Future In-Space Operations (FISO) Working Group Presentations Archive 2010-2012
http://spirit.as.utexas.edu/~fiso/archivelist10-12.htm

SpaceNut · 2015-11-03 22:29:19

Most of the module pieces could be manufactured by this company...

https://en.wikipedia.org/wiki/Thales_Alenia_Space

The company built the Multi-Purpose Logistics Modules, which was used to transport cargo inside the Space Shuttle orbiters. They also built several modules for the International Space Station, those modules are Cupola, Columbus, Harmony, Tranquility and Leonardo. They currently build the pressurized vessels for the Automated Transfer Vehicle and Cygnus spacecraft.

I was impressed that they could change the Cygnus unit so quickly in time to place it onto the Atlas V in slightly over a years time.

tahanson43206 · 2020-01-01 09:34:43

The forum archive is rich with discussion of the Sabatier process, and what would be required for it to succeed on Mars.

In several posts, GW Johnson called for testing equipment intended for Mars on a location such as the Queen Elizabeth islands in Northern Canada.

GW Johnson wrote:

Update:
I looked at Zubrin's Sabatier paper. Very intriguing process. I did notice that the pressures in the system used gas feeds at 50 to 75 psi (3+ to 5+ bars), and the reactor was at 0.8 bar (Denver ambient). How to compress on Mars was unaddressed, something very worrisome considering that compressor weight is proportional to inlet density and something like 10 stages will be needed at minimum.
And, I rather suspect the conversion in the Sabatier reactor works better and better as reactor pressure increases. Chemistry is usually density dependent (another word for mass/volume concentrations in your Arrhenius-type overall reaction rate equations or empirical models). This atmospheric gas compression issue is a critical design issue for using technologies like this on Mars. That near-vacuum of an atmosphere is a real impediment, for a lot of things.
GW

I am hoping that bringing this topic back into view will allow members to provide updates on the status of development of the process.

(th)

SpaceNut · 2020-01-01 09:49:32

Like GW noted for the output its gaseous and it needs to be put into any rockets leaving mars as a liquid which means removal of heat from compressing. Using the natural cold of mars goes along ways for doing this with heat exchanging tubing running in the tank or on the outside of a tank with a circulating pump. I gave links elsewhere for the compression ratio to high pressure for tank comstruction and volume of space that it reduces to.

As for location why not do it on Devon Island where we are training personnel to behave as if its mars. The risk of the equipments safety is there for testing and monitored for what we might see for failure modes and we can get it fixed unlike with mars. This is a needed skill for those that are going to go.

Another thing to remember is mars atmosphere is compressed from the 0.006 bar to the levels which we need for the reactor inlet pressure as GW meantioned. Next is the electrolysis of water followed by compression of the hydrogen for its inlet pressure to allow for the mix ration to work in the chamber as well.

So you can see that we are doing lots of compressing and cooling in order to make it work all from an energy stand point making the reason for solar go out the window as it requires more mass for the panels and batteries to achieve the energy level required.

Edit
I am reminded by reading a few pages that mars we need to be able to go with not using energy to do everything in order to be able to land the mass we need.

tahanson43206 · 2020-01-01 10:40:51

For SpaceNut re possible Best Practices topic ...

Please add to your "think about it" list the possibility of creating a topic for "best we can do to date" "Best Practices" for various technologies for Mars.

The forum has demonstrated the capability of updating anchor posts with new edits as new information comes in. We have been doing that in the My Hacienda topic, and the practice can be extended.

In past years, before this idea was introduced, almost all posts were newly created. That is why the forum archive is filled with so much material that is repeated over and over again, albeit getting better with each iteration.

A "Best Practices" topic would feature anchor posts on particular subjects, such as the Sabatier Reaction. From scanning posts that included "Sabatier" I can see that there is already a body of knowledge assembled here, but it is scattered over multiple years, and it is often repeated because new members show up who ask about the topic all over again.

In an ideal world, NewMars forum would contain a post which would contain all the links that an investor would need to follow to understand requirements for a successful mission to make fuel for one of Elon's rockets.

The implication that Mr. Musk is planning to lead a team to do this is beside the point. I have no doubt that Mr. Musk would gladly buy fuel from an entrepreneur who offered it on Mars. The NewMars forum is as good a place as any currently existing on Earth to encourage young people with talent, and older folks with resources, to combine to build a service station on Mars.

And! The initiative elsewhere in this forum, to design a system to make methane (or other useful energy carrier substances) by harnessing wind that blows steadily and strongly all year around Antarctica could certainly feed into the process.

(th)

tahanson43206 · 2020-01-01 10:50:37

This is for Calliban re GW Johnson's post, as reproduced in #715 above ...

Updated 2020/01/02

GW Johnson mentioned 10 stages of compression of Martian atmosphere to arrive at the pressures needed for the Sabatier reaction.

My impression is that the system with 10 stages would consist either of 10 small pumps, each designed for a given input pressure to deliver an output pressure, or a smaller set of pumps which pass the compressed gas back and forth between each other.

Can ** you ** design a single long pump capable of performing the entire job in a single stroke?

Is there some physical limit that dictates what can be done with matter to compress gas?

I can easily imagine that steel would melt if gas temperature exceeds the heat removal capability of a given system.

Perhaps the tensile strength of pump walls is the limit?

But you gave us a possible clue, when you showed us the hundred(s) year old Trompe process.

Gravity is lower on Mars, so a Trompe system would have to be longer, but Mount Olympus has plenty of elevation. Would a system need all that distance?

Edit: Inspired by GW Johnson's post reproduced above, I am back for Calliban with this question:

Is there any reason why the Trompe system has to be one continuous pipe? Just because it was done that way in the past does NOT mean we have to keep doing it that way forever.

GW Johnson gave a figure (possibly an estimate?) of 10 stages needed to compress Martian atmosphere to the point it can profitably be fed into the Sabatier reactor.

So! Can a Trompe pipe be broken up into 10 stages (or more, for that matter)?

The compressed output of one stage would then be fed up the compression pipe by a transfer pipe designed to stand the pressure of the gas at that stage.

A distinct advantage of that design is that the components could be sized to fit inside one of Elon's landers, and then assembled on the ground by clever robots programmed and tested repeatedly on Earth to perform that function efficiently and effectively.

Another distinct advantage is that gravity would be harnessed to perform the actual compression and cooling. The only mechanical components imported from Earth would be fluid movers at the bottom of each stage of downpipe.

Following GW Johnson's oft repeated recommendation, the ENTIRE system could be tested in a suitable location at great length.

Edit#2: One more addition for you Calliban ... fluid movers do NOT have to be fans, as might be traditional. The human body, and countless other biological systems move plenty of fluids using tube squeezing subsystems. I'm thinking here primarily of the swallowing mechanism, but there may well be others I'm not aware of or have forgotten about.

A swallowing system for moving fluids might reduce (although not eliminate) failure modes of a system deployed to Mars.

Edit#3: Back for Calliban again ... is there any reason why the fluid used for compression cannot be reused? The original Trompe design took advantage of the natural environment, which included ample supplies of freely running water helpfully lifted in elevation through Solar evaporation and distribution via Solar powered wind.

An adaption for Mars need not waste ANY of the liquid, as far as I can see right now, lacking (as of course I do) the special insight your experience brings to bear on the problem.

Edit 2020/01/02 The discussion in a Physics forum at the link below addresses some of the issue raised in this post:
https://www.physicsforums.com/threads/p … pe.732878/

One contributor was actually talking about trying to accumulate pressure serially, while running downpipes in parallel.

Another contributor explained why the design should employ a vertical pipe instead of a slanted one.

The discussion is about driving a small pneumatic motor, although some contributors objected that a direct use of water might be an alternative to consider. That issue does not apply in the case under consideration in this topic, which is strictly performing compression of Mars atmosphere.

From the standpoint of a design for Mars, the question at hand is which system of compression would prove most reliable over a period of time, in addition to which method is most efficient.

The three competing methods I know of at this time are:

1) Traditional piston compression: compression of a gas by a mechanical solid, using a complex mechanical action
2) Scroll pump compression (apparently far more efficient than piston designs) This is mechanical compression with simple rotation.
3) Trompe compression of gas by a fluid. It is not clear to me at this point how much mechanical input is required.

Edit #2: The term I was looking for is peristalsis:

Courtesy of Mr. Google:
per·i·stal·sis
/ˌperəˈstôlsəs,perəˈstalsis/
Learn to pronounce
nounPHYSIOLOGY
the involuntary constriction and relaxation of the muscles of the intestine or another canal, creating wave-like movements that push the contents of the canal forward.

Edit #3: NASA researched a fluid that could be propelled by magnetic fields in the 1960's. While the method was never used for the original purpose, several companies (including Sony) have adapted the method for various non-space applications.

https://spinoff.nasa.gov/Spinoff2015/cg_2.html

I am posting the link to the story here, because the technology could perform in a Trompe system to reduce dependence upon mechanical equipment, such as pumps. At this point, I doubt the technology could entirely REPLACE mechanical pumps, but perhaps it could augment gravity on the compression down stroke, and decrease the influence of gravity when returning fluid to the top of the column.

Note: The Wikpedia article on Trompe includes some illustrations of its use in earlier times.

(th)

Last edited by tahanson43206 (2020-01-02 18:41:45)

SpaceNut · 2020-01-01 14:29:38

A radial torque device like the piston of the engine needs for to move the piston in the chamber such as to over come the compressing back push from the gas not wanting to become smaller. Its the torque that under high pressure that is the issue. The chamber length and diameter is what is the volume to compress that we must push hard enough to force the gas into the smaller space.

Think of a stage of the 10 pumps as a count down system where the weakest pressure is the volume of 10 and count the chambers down in size as each compression happens. Its the force which must exceed the one before it which gets higher for the torque. This is also why you need to cool each compression to remove the heat force of expansion from each effort to make the gas fit in a smaller space than the one before it.

One could look at how atmpospheric pressure builds to the surface as the mass of it starts out small and builds from the compressing which happens over distance of the mass piling up until it gets to the surface at 14.7 psi for earth.

The moxie experiment is using a scroll chamber rotary device to compress and deliver the co2 of mars to the electrolysis unit to make oxygen for the crew. This is being delivered on the 2020 rover mission. Having more of these is a parallel system and that gets volume of movement of the co2 and not pressure.

Reposts that relate to why we are still talking about:

Russel wrote:

For a 4.5Km/s dV you need in one case 1.2 tonnes of hydrogen and 7.4 tonnes of oxygen. But in the other case you need 2.8 tonnes of methane (0.72 tonnes of seed hydrogen) and 10.1 tonnes of oxygen.
You see, the version that requires you to convert hydrogen to methane might require 60% of the hydrogen, but then you need to create 36% more oxygen. And most importantly you end up with a heavier vehicle overall. And these sorts of trade offs occur all over the place. Again, conversion of hydrogen to methane makes a lot of sense if you've got a local source of hydrogen

.

JoshNH4H wrote:

For getting the oxygen out, you have to repeatedly pressurize and depressurize, as well as cool the ambient atmosphere. To obtain 1 kg of molecular oxygen, you need to process 1060 kg of atmosphere. To obtain 75 tonnes of LOX, you need to process almost 80 million kg of the stuff. At ambient density, that's 5.7 billion cubic meters. 5.7 cubic kilometers. A cube of atmosphere 1.8 km (a bit over a mile) to a side. It needs to be compressed from .006 atm to several atmospheres, cooled, the remainder extracted, and then the process has to be repeated.
To go from gaseous to solid CO2 requires the removal of approximately 600 kJ/kg of energy from the CO2. Fortunately, because the Martian ambient temperature is so cold to begin with, this can be done with the input of as little as 100 kJ/kg of mechanical energy.

Its the shear volume and energy needed for large mass back to orbit which is the issue as in the BFR starship and while the mars direct or semi were lower we will need to do better.

RobertDyck · 2020-01-01 16:49:08

Dr Robert Zubrin's system would harvest CO2 from Mars atmosphere with the Mars Atmosphere Carbon Dioxide Freezer (MACDOF). The basis is Mars atmosphere at night is very close to the temperature at which CO2 gas freezes to dry ice, so very little energy is needed to freeze those last few degrees. It freezes dry ice, but other gasses from Mars atmosphere do not freeze at that temperature. Every dawn the canister is closed with the block of dry ice frost inside. Freezer coils are reversed, heating to sublimate the dry ice. Because this is inside a sealed canister, the phase change from solid to gas self-pressurizes.

The gas inside the canister will be almost pure CO2. There will be whatever Mars atmosphere was inside and not displaced by dry ice frost, but will be swamped with all the CO2. A Sabatier Reactor can use CO2 with trace amounts of other Mars atmospheric gasses.

This only works with CO2, no other gasses. But it was only intended to produce propellant, so that's all it needs.

Only sublimating dry ice during the day means warmer ambient temperature can be used to help warm the dry ice to sublimate. More energy optimization.

SpaceNut · 2020-01-01 17:27:42

The freezing of co2 has been meantioned before in
http://newmars.com/forums/viewtopic.php?id=6826&p=12 at post 278
http://newmars.com/forums/viewtopic.php?id=7316&p=2 at post 36

https://isru.nasa.gov/CarbonDioxideOxygen.html

It is part of the MARCO POLO/Mars ISRU Pathfinder Project.

https://sciences.ucf.edu/class/wp-conte … o-JoAE.pdf

This is the webview https://view.officeapps.live.com/op/vie … esting.doc

http://canada.marssociety.org/winnipeg/ … esting.doc

Sabatier test stand
prototype-development-of-an-integrated-mars-atmosphere-and-soil-processing-system-13-638.jpg?cb=1422583549

https://ntrs.nasa.gov/archive/nasa/casi … 001808.pdf
Mars Atmospheric Capture [and Processing]

tahanson43206 · 2020-01-01 20:54:12

For SpaceNut re #721 and references to scroll pump ...

The link you provided to the NASA site came up with a powerpoint dated 2017, with a number of references to work by Dr. Zubrin and associates.

The technology of a "scroll pump" is new to me. Someone might be interested in the page at Wikipedia:

https://en.wikipedia.org/wiki/Scroll_compressor

In the NASA powerpoint, only two stages of compression are shown, moving from Mars atmosphere to input to the Sabatier reaction.

(th)

RobertDyck · 2020-01-01 21:35:36

NASA SBIR - 1998 (abstract only): Mars Atmospheric Carbon Dioxide Freezer

NASA Technical Report Server (NTRS) - 2012: Mars In Situ Resource Utilization Technology Evaluation

We have examined the technologies required to enable Mars In-Situ Resource Utilization
(ISRU) because our understanding of Mars resources has changed significantly in the last
five years as a result of recent robotic missions to the red planet. Two major developments,
(1) confirmation of the presence of near-surface water in the form of ice in very large
amounts at high latitudes by the Phoenix Lander and (2) the likely existence of water at
lower latitudes in the form of hydrates or ice in the top one meter of the regolith, have the
potential to change ISRU technology selection. A brief technology assessment was performed
for the most promising Mars atmospheric gas processing techniques: Reverse Water Gas
Shift (RWGS) and Methanation (aka Sabatier), as well as an overview of soil processing
technology to extract water from Martian soil.

NASA NTRS - 2011: Evaluation of Mars CO2 Capture and Gas Separation Technologies

NASA NTRS - 2017 (slides): The Technology and Future of In-Situ Resource Utilization (ISRU)

RobertDyck · 2020-01-01 22:12:32

I'm flattered SpaceNut included a link to my paper. I presented it at a Mars Society convention. It deals with harvesting other gasses from Mars atmosphere, not CO2. Yes, it requires a compressor pump. Compressing from Mars ambient to 10 bar pressure for the processing chamber with be very energy intensive, requiring a multi-stage pump.

The link that includes "winnipeg".

SpaceNut · 2020-01-02 11:46:05

Here is the topic that gets How Do You Get Nitrogen Buffer Gas On Mars?

New Mars Forums

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Re: Yet another Mars architecture

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Re: Yet another Mars architecture

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Re: Yet another Mars architecture

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Re: Yet another Mars architecture

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Re: Yet another Mars architecture

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Re: Yet another Mars architecture

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Re: Yet another Mars architecture

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Re: Yet another Mars architecture

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Re: Yet another Mars architecture

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Re: Yet another Mars architecture

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Re: Yet another Mars architecture

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