Looking at the Mars Colony's development, based on Space X & BFR

SpaceNut · 2018-10-05 18:49:58

Here is what Belter described with bigelow lunar lander.

It was a prototype for Nasa but its not bigelow but is from the original maker of the materials.

cIclops wrote:

ILC Dover inflatable planetary surface habitat and airlock unit
Camping on the Moon Will Be One Far Out Experience - 23 Feb 2007
The first steps in making a lunar outpost a reality are being taken now, as planners intensify their efforts to determine what it will take for humans to safely live and work on the lunar surface.
One team of experts from NASA's Langley Research Center, NASA's Johnson Space Center and NASA contractor ILC Dover LP is looking at inflation-deployed expandable structures as one possible building block for a lunar base.
"Inflatables can be used as connectors or tunnels between crew quarters and can provide radiation shelter if covered with lunar regolith (soil)," said Chris Moore, Exploration Technology Development Program program executive at NASA Headquarters.
As a starting point, ILC Dover has delivered a 12-foot (3.65 meter) diameter inflatable structure made of multilayer fabric to Langley for ground-based evaluation of emerging technologies such as flexible structural health monitoring systems, self-healing materials and radiation protective materials. Attached to the structure is a smaller inflatable structure that serves as a demonstration airlock. Both are essentially pressurized cylinders, connected by an airtight door.
The "planetary surface habitat and airlock unit" can also be used to evaluate materials, lightweight structure technologies, astronaut interfaces, dust mitigation techniques, and function with robotics and other lunar surface equipment.

Update of mass:

The 2,426-pound module was built by engineer and manufacturing company, ILC Dover,

SpaceNut · 2018-10-05 19:26:25

Other interest stuff as well
https://www.ilcdover.com/catalog/space-habitats/

https://www.nasa.gov/exploration/home/i … r-hab.html

This page is more like what Nasa is looking at for mars:
https://www.nasa.gov/exploration/analog … _blog.html

Belter · 2018-10-06 07:46:01

I think that Bigelow released an updated version, but it rides on a solid platform and then inflates after landing. I can't seem to find it though. Like the LEM, but with a blow up habitat instead of ascent module.

My thinking it that any sensible 'drop in' habitat needs to be resting on the ground with the ability connect expandable tunnels between modules. And the ability to land these in *very* tight groupings. Possibly using the Opportunity technique. Or having them somewhat mobile that the can drive themselves into place before inflating or connecting to each other. No one is going to want to be outside that much on Mars. At least, not just to go between modules.

Last edited by Belter (2018-10-06 07:51:52)

SpaceNut · 2018-10-06 08:15:00

I can not say that I have ever seen the Bigelow lander but all the units that they are designing have only 1 or 2 airlock points which sort of limit it as a building block as we need more interconnecting points.

This is the closest that I can find: Bigelow: Moon Property rights would help create a lunar industry

These look like the 1999 moon landers with the inflatable in between them...

louis · 2018-10-06 08:37:37

I can't see this sort of inflatable Bigelow module being part of the Space X project. For one thing that module is pretty small. So you would need something much large for a population of anywhere between perhaps 6 and 10. They will be living on the surface for a couple of years. You can't have them cramped in an Apollo style lander. Fitting a much large deflated hab into the cargo hold of a BFS would be much more problematic as would winching it down after landing. Yes, you can land it independently but one thing we can be clear on is that is simply not part of the Space X design.

I think the logic of the Space X mission architecture points to them assembling a hab on the surface using a semi automated system. If I was approaching the problem of designing a hab for 6 people I think I would opt for:

1. A flat platform on adjustable stands (to ensure the platform is completely flat relative to the surface). Maybe composed of 4 5x5 metre platforms which would be bolted together and also have magnets for close alignment.

2. The main hab would be assembled on top of the platform over an area of perhaps 8x8 metres. This could be compose of two sections which would mostly self-assemble when being held in position by rovers.

3. All the walls, floors and roofs/ceilings would come with aerogel insulation and some radiation protection.

4. The crew would then (working from two exploration rovers) put in place the retention apparatus around the hab which would house the protective regolith cover on top and at the sides.

5. Next the crew would "bolt" on the two airlock chambers which would attach to the main hab. The outer one would be big enough to house one of the two main human passenger rovers (whiich might be about 2.5 metres tall, 3.5 metres wide and 4 metres long). The airlock chambers arrangement would allow Mars crew to exit the rover directly into the second chamber without encountering any dust. The inner chamber would be smaller.

The hab would need a failsafe coms system (so more than one method with communicating outside). Aerials and wifi could be integrated into the hab structure. Around the hab you would have a number of cameras set up so that people can "see" what is occurring outside. People in the hab would be able to communicate with the main Rovers, robot rovers, and BFS and, through a ground station, Earth as well. Likewise power cable connections would be integrated into the hab. Once the hab structure was up, the dedicated units such as life support unit, kitchen facilites, other utilities, hygiene (toilet and shower etc) plus furniture (beds, table, chairs) would be introduced. A couple of dedicated crew in EVA suits would then test the air locks, conduct a complete dust clean and removal of the interior, unpack the life support and then conduct a thorough range of tests on the life support. Having done so they would then remove their EVA suits and begin installing the other units.

Once all units were up and running and had been checked, the rest of the crew would enter the hab (though as a matter of routine, it might be the case that there was always someone on duty in one of the two main rovers and the BFS), bringing with them food, hygiene and water supplies, utensils and scientific equipment etc. Screens on the walls of the hab would project camera views from outside, so giving the effect of windows.

The habs would need a vent system for venting gases. Waste material, including faeces,urine and waste water could be removed via the Rovers (on the outside of the Rovers) and deposited externally.

tahanson43206 · 2018-10-06 09:46:00

Regarding capture of fairings ...
For SpaceNut #49 ... The helicopter capture method could certainly work if this were a government operation, with helicopters based on carriers. The fairings appear to be slowed down for re-entry by airfoils, so the helicopters could snag the airfoils. However, there is a new technology that might be worth considering. Drones are now being constructed large enough to transport people, so if Elon were so inclined, he could deploy a couple drones to guide the shrouds to Mr. Steven. It is even possible the SpaceX team is working on guidance for the airfoils, which can be controlled by judicious tugs on the lines.

Well! It turns out SpaceX is considering using speedboats to pull the fairings over to Mr. Steven's net:
https://www.youtube.com/watch?v=mUWmSpTwdes

For Void in #50: The YouTube above seems to match up with some aspects of your idea.

(th)

Belter · 2018-10-06 11:55:15

The Aries 1B makes a lot of sense from a design perspective. Even better if it were designed to lower itself to the ground for easy egress and the ability to drop a ramp for vehicles. To me, the BFR lacks what all 1950s space ships had - an elevator - which is a giant waste of space. Better to keep the ship as wide and low as possible. Likewise, using BFRs are pure cargo craft don't make a lot of sense unless they're planning to return them to Earth for more stuff. If it's a one way journey, make them more practical. Unless the goal here is to make 50 of them in succession to save on construction costs and send them everywhere.

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Last edited by Belter (2018-10-06 14:51:58)

louis · 2018-10-06 14:01:37

The billions of dollars of development costs (I'd estimate probably something like $4 billion over ten years - between 2011 and 2021) will be spread over several applications - that in itself represents one of the reasons why the BFR is so good for Mars.

Not trying to close down your comments, but maybe they would be better placed on other threads as here I was trying to look at how a successful Space X Mars Mission will affect the colony's development rather than examine alternatives to Space X.

Belter wrote:

The Ares 1B makes a lot of sense from a design perspective. Even better if it were designed to lower itself to the ground for easy egress and the ability to drop a ramp for vehicles. To me, the BFR lacks what all 1950s space ships had - an elevator - which is a giant waste of space. Better to keep the ship as wide and low as possible. Likewise, using BFRs are pure cargo craft don't make a lot of sense unless they're planning to return them to Earth for more stuff. If it's a one way journey, make them more practical. Unless the goal here is to make 50 of them in succession to save on construction costs and send them everywhere.

Belter · 2018-10-06 14:17:06

Well, we just have to keep going back to how Space X has no actual plan for any of this, at least, not that they're sharing.

I mean, the major flaws I see is the shape of the ship, how it lands, it's probable inability to offload very heavy cargo without simply falling over, lack of elevators, essentially useless storage tanks in the way of offloading anything, the lack of a robotic system of construction, the lack of a habitat design, the likely inability to land habitats and place them close to each other. There's just a ton of things that they either haven't resolved or aren't telling anyone about how they've done so.

Now, if they can show how they can convert the BFR-C storage tanks into habitats, that would be interesting. Offload the fuel to landers that are going to return. Another way to handle this might be to use an exterior fuel tanks, or put the tanks higher, in the nose cone, and the cargo down below. A little more unstable going up, but more stable going down. Or convert the BFR into a 3-stage affair. One to get above the atmosphere, one to accelerate to escape velocity and then the top half would separate and either crash into Mars or could land near the North pole, close enough to eventually be refilled and put back into orbit.

I just don't see the viability of the BFR as anything more than a good shuttle, but terrible for delivering materials and habitats.

Last edited by Belter (2018-10-06 14:46:40)

SpaceNut · 2018-10-06 14:45:58

Hi Belter the topic for

The Ares 1B makes a lot of sense from a design perspective

Ares I (CLV) - status
Liberty Launch Vehicle aka Ares I

Belter · 2018-10-06 14:48:20

Sorry, I'm a noob. I'm here because I want to start a space engineering academy at my girls' school.

Also, different Aries. 2001 lunar transit ship.

Last edited by Belter (2018-10-06 14:51:05)

louis · 2018-10-06 17:08:59

[Oops - Already posted]

Last edited by louis (2018-10-06 17:10:46)

louis · 2018-10-06 17:21:14

I think that Space X have been clear they are using the BFS to land all cargo and humans on Mars. They have no plans for any other landings apart from BFS craft. Couldn't be clearer really.

You may be new to many of these discussions which have definitely been had here about the issues you raise.

Re stability after landing I think the people here with engineering experience are much happier with the latest design, being a 3 way fin point landing. People who can do the calculations appear to think it is a reasonable design.

You don't need a habitat apart from the BFS immediately on arrival. But within a day or two you could unload a pressurised rover which would become your temporary home. For a six person mission, I see no reason why there couldn't be two 3 person rovers. These could take on supplies from the BFS at intervals, so they could operate for a long time without surface replenishment of energy, water, air, food etc. The point is, that there is no desperate rush to set up the habitat. I would think that could be scheduled for perhaps 5-10 days after landing.

There is no need to re-design the BFR/BFS or try and get people living in propellant tanks! That's absurd.

The BFR-BFS system as proposed by Space X is fit for purpose and will enable us to rapidly put in place an energy, industrial and agricultural infrastructure on Mars.

Belter wrote:

Well, we just have to keep going back to how Space X has no actual plan for any of this, at least, not that they're sharing.
I mean, the major flaws I see is the shape of the ship, how it lands, it's probable inability to offload very heavy cargo without simply falling over, lack of elevators, essentially useless storage tanks in the way of offloading anything, the lack of a robotic system of construction, the lack of a habitat design, the likely inability to land habitats and place them close to each other. There's just a ton of things that they either haven't resolved or aren't telling anyone about how they've done so.
Now, if they can show how they can convert the BFR-C storage tanks into habitats, that would be interesting. Offload the fuel to landers that are going to return. Another way to handle this might be to use an exterior fuel tanks, or put the tanks higher, in the nose cone, and the cargo down below. A little more unstable going up, but more stable going down. Or convert the BFR into a 3-stage affair. One to get above the atmosphere, one to accelerate to escape velocity and then the top half would separate and either crash into Mars or could land near the North pole, close enough to eventually be refilled and put back into orbit.
I just don't see the viability of the BFR as anything more than a good shuttle, but terrible for delivering materials and habitats.

SpaceNut · 2018-10-06 17:40:00

One thing that BFR incantations mean is the ability to loft anything wanted even all the way to mars after refueling in LEO.

That said we could bring water, fuels that are storables or just about anything we would want by just sending more of them to the surface before man even gets to go.

louis · 2018-10-06 18:01:50

Indeed. If Space X can get 500 tonnes to the surface for six people that's 83 tonnes per person. That's a lot of "stuff".

Out of 500 tonnes, you might have 100 tonnes for your complete energy system, 50 tonnes for your propellant plant facility, 10 tonnes for habs, 50 tonnes for human and robot rovers,... where are we at? 210 tonnes...leaves 290 tonnes over...

SpaceNut wrote:

One thing that BFR incantations mean is the ability to loft anything wanted even all the way to mars after refueling in LEO.
That said we could bring water, fuels that are storables or just about anything we would want by just sending more of them to the surface before man even gets to go.

Belter · 2018-10-06 20:12:42

There is something of an issue though that needs to be addressed, which is long distance planetary travel. The place to setup up a base is going to be closer to the equator, but the accessible water is at the poles. So fuel is almost certainly going to have to be transported around. Perhaps even flown. Or maybe the base could be 100km or so from the poles or right at the edge at maximum size. Then vehicles will have to go back and forth with ice water. This is why I like the idea of an automated refueling facility that can refuel reusable booster engines similar to the Falcons.

Like I said, my issue isn't that Space X is committed to the BFR (and SFR), but how they are going to do the other things *with these particular machines*. I don't think any moon rover they launch could possibly be air tight and it would be somewhat foolish to make them that way. The air loss, size and shipping weight is impractical. More likely a few exposed vehicles that are very light weight and operate like pick up trucks, but with some mechanical work attachments. Something that can be craned out of a BFR easily. I haven't seen a BFR design that really gets into the logistics issues of moving things in and out, but maybe I've just missed it. They can't just slide out a 10m wide habitat from the units.

One thing Musk needs to do is start doing landing tests in a rocky desert and see if he can keep a Falcon from tipping over.

I also don't see what is nuts about recycling a large fuel tank into living quarters. Most of these early ships are going to be 1-way trips, so being able to turn the fuel tanks into habitats seems pretty logical. Unless they can figure out how to build the fuel manufacturing right into the ships themselves, and the only thing that needs to be supplied directly is water.

I also think the Cargo ships need to be pretty robotic. In theory, you should be able to send an unmanned rover from one ship to another and have it lower the supplies right on to the cargo bed of the rover. Especially if the distances are long.

Another issue is that they're not going to want to have a single Mars base. There's too much varied topography and formations to keep it in a single place, another reason why planetary transport is going to come up. An SFR could be used to shuttle around the planet to different areas, once the refueling stations are created.

The lack of specific though are going to raise a lot of questions until he mans up and answers them. By this time, he should have narrowed down the landing spots. And if they're not at the north pole, he needs to detail where he thinks he's going to get the water and how. They can't be digging up the whole planet for drops of water, they need a substantial source with minimum effort.

I think one thing that will work in the favor of making things workable is that there will probably only be 8-10 member crews at most, maybe as low as 6. Fewer people to lose, but also, a lot less oxygen, water and food to send. More ability to send raw materials and machinery. I mean, 3 years worth of supplies for a human crew of any size is a boatload of storage and mass.

Last edited by Belter (2018-10-06 20:31:31)

SpaceNut · 2018-10-06 21:39:53

There is water near the equator but the amount at the surface is less than at the poles but what about subsurface as thats the unknown? Then again we do have the burried glaciers to determine if we can get to them as well.

Falcon fuel is changing to methane for the insitu manufacturing and the engines will be Raptors rather than merlins for the BFR.

The oxygen tank would work out fine to be reclaimed for the purpose of creating habitat expansion space to live in for sure.

The rocky test flight of a falcon 9 would be a good test to see it would be probable to make a safe landing but the bfr is way larger and will not be of the same landing structure as its got wings versus folding legs.

I find that utubing videos while they convey information they are not a plan....

spacetechsforum · 2018-10-07 01:41:03

I think, given proper machines are available, the 1-way BFRs can be adapted to serve colony. I did not do any analysis on this, so I do not know if it is possible and feasible, but doing it i would start with this option:

Place BFR horizontally (remember - we are working in lower gravity and with empty tanks).
Remove engines - I do not see any use for this part.
Remove tanks from shell - use them as storage for water (fuel tank) and oxygen (LOX tank). They do not need to stand vertically.
Adapt the empty shell as habitat.

I also do not see any need to build the whole colony at once. For the first crews not connected habitats may suffice (as those will be mostly science missions), and as the time goes on and the needs grow a better shelters may be delivered.

Last edited by spacetechsforum (2018-10-07 01:52:57)

louis · 2018-10-07 06:52:17

Belter wrote:

There is something of an issue though that needs to be addressed, which is long distance planetary travel. The place to setup up a base is going to be closer to the equator, but the accessible water is at the poles. So fuel is almost certainly going to have to be transported around. Perhaps even flown. Or maybe the base could be 100km or so from the poles or right at the edge at maximum size. Then vehicles will have to go back and forth with ice water. This is why I like the idea of an automated refueling facility that can refuel reusable booster engines similar to the Falcons.

There are glaciers in mid latitudes, there is water pretty much every in the northern hemisphere, just not necessarily at high concentrations. I favour the north East edge of Chryse Planitia. Also don't forget, throughout the summer months there is water than can be extracted from the atmosphere. That could yield tonnes of water per sol if you had sufficiently powerful dehumidifiers on board.

One thing to remember is the seasonal changes are not quite as rigidly fixed to latitude as on Earth because (IIRC) Mars wobbles more. In fact I think the highest solar radiation is around the 25-29 degree mark north of the equator (or south presumably). So your base can be set up at quite a distance from the equator.

The problem really is meeting all the requirments - safe landing area, water resources, solar radiation (for a PV system).

Like I said, my issue isn't that Space X is committed to the BFR (and SFR), but how they are going to do the other things *with these particular machines*. I don't think any moon rover they launch could possibly be air tight and it would be somewhat foolish to make them that way. The air loss, size and shipping weight is impractical. More likely a few exposed vehicles that are very light weight and operate like pick up trucks, but with some mechanical work attachments. Something that can be craned out of a BFR easily. I haven't seen a BFR design that really gets into the logistics issues of moving things in and out, but maybe I've just missed it. They can't just slide out a 10m wide habitat from the units.

As for unloading the BFS we've seen artist's illustrations of cranes, that's about it. It now seems there will be a cargo hold at the base as well - that could be very useful. A crane winch might work well...or it might need to be balanced (so have a weighted section stick out on the other side of the BFS).

There are obviously cranes that can lift objects like cars. The Davit crane seems the nearest in conception to Space X images:

http://www.pacificmarine.net/constructi … -truck.htm

Another alternative would be a kind of rail track - not unlike a dolly track...

https://www.123rf.com/photo_97806044_be … e-sho.html

I would estimate the rail track would need to be about 30 metres long (could it be made strong enough to function without support other than the ground?). I am sure engineers and money could solve the problem of automated assembly - I am envisioning it being in say 6 sections (possibly connected to facilitate the automated assembly) of 5 metres. Cargo is loaded on to and secured to the rail track platform inside the BFR and then tips on to the rail track - the platform is then winched down the track. I would estimate it would be at about 30-45 degree angle to the BFS.

Why on Earth couldn't you make a Moon Rover air tight?

One thing Musk needs to do is start doing landing tests in a rocky desert and see if he can keep a Falcon from tipping over.

I would agree that will be an imperative. First hop tests to on a conventional landing platform, then hop tests on rocky ground or slab rock.

I also don't see what is nuts about recycling a large fuel tank into living quarters. Most of these early ships are going to be 1-way trips, so being able to turn the fuel tanks into habitats seems pretty logical. Unless they can figure out how to build the fuel manufacturing right into the ships themselves, and the only thing that needs to be supplied directly is water.

I'd say it's absurd because it would involved so much labour, time and planning effort which could be better expended elsewhere. The tanks would have to be cleaned and you would have to design all the fittings around the structure of the tanks. Why bother, whether you can simply take habs which you. Once the base is established it will be a lot easier to build habs through cut and cover methods.

I also think the Cargo ships need to be pretty robotic. In theory, you should be able to send an unmanned rover from one ship to another and have it lower the supplies right on to the cargo bed of the rover. Especially if the distances are long.

I agree this should be a very robotic mission. We have cars that can park and drive themselves, so it's all quite feasible. The difficulty will be that the first cargo unloading will likely involve humans doing EVAs - a complicated procedure best avoided.

Another issue is that they're not going to want to have a single Mars base. There's too much varied topography and formations to keep it in a single place, another reason why planetary transport is going to come up. An SFR could be used to shuttle around the planet to different areas, once the refueling stations are created.

I don't think will be any issues with setting up further bases once you are established on Mars. It is getting that first base up that is the difficult part. Mission One will be a single base mission I am sure.

The lack of specific though are going to raise a lot of questions until he mans up and answers them. By this time, he should have narrowed down the landing spots. And if they're not at the north pole, he needs to detail where he thinks he's going to get the water and how. They can't be digging up the whole planet for drops of water, they need a substantial source with minimum effort.
I think one thing that will work in the favor of making things workable is that there will probably only be 8-10 member crews at most, maybe as low as 6. Fewer people to lose, but also, a lot less oxygen, water and food to send. More ability to send raw materials and machinery. I mean, 3 years worth of supplies for a human crew of any size is a boatload of storage and mass.

There was a NASA forum which set out a lot of possible sites (around 40 I think) and there was a vote that determined the best. This thread sets it all out.

http://newmars.com/forums/viewtopic.php?id=8247

Paul Wooster (Space X Chief Engineer) has given a run down of the criteria, so clearly they have their short list already.

I favour 6 people for the crew, as do a lot of people. And maybe even 3 in two BFSs, so the Mission can still survive a catastrophe to one BFS en route. I think there is a consensus as well that 10 would be a maximum for a Mars first mission crew.

Last edited by louis (2018-10-07 06:54:17)

Belter · 2018-10-07 08:55:44

I don't see a particular issue with an air tight rover except it will suck up a boatload of weight and then every time you're in and out you'll have to replace that O2 by making more. And there's no way of docking it to anything. So it becomes almost pointless.

The fueling facility is going to have to be 100% robotic to make it work. It's going to have to find its own H2O with robots and spend its days just churning out methane without human supervision. And from what I saw, which may be incorrect, they have to scale up their output by several orders of magnitude on a foreign body. It would have to find and separate nearly 3 tons of water per day to fuel a single BFR. And there will be two to fuel, which makes me think one will remain. I also think that they're going to have to extract the excess fuel from all of the other units to refuel a single BFR. I would be shocked if this isn't the backup plan already (or the hidden primary plan).

Seems to me that the actual fuel factory (and storage) should be in the ships themselves, actually. That each ship would bring robotic diggers to retrieve slush, and that slush would be heated and processed outside the ship, and then purified water sent into the ship where it would go through hydrolysis which isn't that big of a deal, and then Sabatiering the methane. This would avoid transporting and accidents. It should be able to be done on board, the question is, how much size and weight is required to put out the kind of quantities required. And if it's going to take a large factory, too big to be integrated into the ship, then it's going to be quite the hassle to get setup and running, and then to safely get the fuel pumped on board.

Both crews could live on one ship for safety while the other ship is refueling itself. Then transfer to the other when they're ready to leave.
And having an integrated factory would be the surest way to have something that is proven to work in advance.

Last edited by Belter (2018-10-07 09:02:52)

SpaceNut · 2018-10-07 09:18:33

https://en.wikipedia.org/wiki/BFR_(rocket)

Belter · 2018-10-07 11:51:41

Seems like Gusev Crater is the place to go if they're looking for water near the equator.

louis · 2018-10-07 14:29:48

Belter wrote:

I don't see a particular issue with an air tight rover except it will suck up a boatload of weight and then every time you're in and out you'll have to replace that O2 by making more. And there's no way of docking it to anything. So it becomes almost pointless.

Well you won't be able to do much exploration in an open rover. And do you know how long it takes to get into a conventional EVA space suit - I think it's something like 2-3 hours and then a similar amount of time getting out of it...

As for mass, well that's why the Space X BFR is designed that way, so that the mission has the advantage of the having the right tools for the job. Not sure what you mean by "docking it to anything".

And as regards the oxygen, well wherever the humans are, they will be breathing in oxygen, so not sure what your point is there.

The fueling facility is going to have to be 100% robotic to make it work. It's going to have to find its own H2O with robots and spend its days just churning out methane without human supervision. And from what I saw, which may be incorrect, they have to scale up their output by several orders of magnitude on a foreign body. It would have to find and separate nearly 3 tons of water per day to fuel a single BFR. And there will be two to fuel, which makes me think one will remain. I also think that they're going to have to extract the excess fuel from all of the other units to refuel a single BFR. I would be shocked if this isn't the backup plan already (or the hidden primary plan).

We are used to automated capture of water from the atmosphere - lots of people have dehumidifiers. Atmospheric extraction should definitely not be ignored because of its simplicity. Looking at this machine,

https://www.condair.co.uk/m/0/condair-d … -en-rt.pdf

it can produce 1.4 kgs of water per hour (34 kgs per sol) and weighs in at 28 kgs. To produce 3 tonnes of water per sol, that would require 88 of the machines at a mass of 2.46 tonnes.

Now, I realise that you might also need a lot of equipment to concentrate the Mars atmosphere and to heat it, to match that performance. But maybe with something like 10 tonnes you could match that performance and produce 3 tonnes of water per sol. But then it would depend how the trip to Mars corresponds to the summer months. The shorter the timespan, the more equipment you will need.

That's a good point about extracting the remaining fuel and propellant from the other BFRs. That's the first time I've seen that suggested. 5 BFRs each with say 50 tonnes of fuel/propellant on board = 250 tonnes would be a useful short cut.

For an area with 5% water in the regolith, to obtain 3 tonnes of water you would have to process 60 tonnes of regolith. It's challenging but not impossible. With regolith, robotic processing should not propose major problems.

Seems to me that the actual fuel factory (and storage) should be in the ships themselves, actually. That each ship would bring robotic diggers to retrieve slush, and that slush would be heated and processed outside the ship, and then purified water sent into the ship where it would go through hydrolysis which isn't that big of a deal, and then Sabatiering the methane. This would avoid transporting and accidents. It should be able to be done on board, the question is, how much size and weight is required to put out the kind of quantities required. And if it's going to take a large factory, too big to be integrated into the ship, then it's going to be quite the hassle to get setup and running, and then to safely get the fuel pumped on board.
Both crews could live on one ship for safety while the other ship is refueling itself. Then transfer to the other when they're ready to leave.
And having an integrated factory would be the surest way to have something that is proven to work in advance.

I guess an onboard propellant facility is not out of the question. It might be an elegant solution.

That said, I don't think the propellant plant is going to be a major problem wherever located. I think the water sourcing is the most difficult issue. One advantage of Space X's two-part Mission is that the cargo BFRs could have onboard robot rovers or other equipment which can test the regolith for water, so that you are guaranteed it's there before humans are sent.

SpaceNut · 2018-10-07 15:26:29

The 250 ton of fuel is only 1/5 the way there for the bfr to come home with.

Using the internal tanks of the bfr reduces mass delivery for refueling insitu operations as all that you would need is the other items.

The humidifier will need a 100 kw power source delivery at 24/7 which will be behind the time required to get all of the moisture from the air as you need time to process it into fuel and way more power to accomplish that task.

Measure is in mm 430 x 402 x 469 so 1,000 mm for a meter for a packed volume of roughly 4 x 5 x 5 meters of the ship that they are on.

louis · 2018-10-07 19:02:14

It would be nice if we could actually bottom out exactly how much fuel/propellant is required for the journey home. I'm guessing it's less than for the journey out to Mars as Earth has a bigger gravitational pull. But happy to be corrected on that. I don't know where I got it but a figure of 750 tonnes is kind of sticking in my mind.

The energy requirement for the humidifier is relatively trivial I would say. Propellant production from the water and compressed CO2 will be much more costly in terms of energy.

SpaceNut wrote:

The 250 ton of fuel is only 1/5 the way there for the bfr to come home with.
Using the internal tanks of the bfr reduces mass delivery for refueling insitu operations as all that you would need is the other items.
The humidifier will need a 100 kw power source delivery at 24/7 which will be behind the time required to get all of the moisture from the air as you need time to process it into fuel and way more power to accomplish that task.
Measure is in mm 430 x 402 x 469 so 1,000 mm for a meter for a packed volume of roughly 4 x 5 x 5 meters of the ship that they are on.

Last edited by louis (2018-10-07 19:03:22)

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