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#76 2018-10-07 19:05:49

louis
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From: UK
Registered: 2008-03-24
Posts: 4,634

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

When you look at the Space Shuttle against all those rockets, I can't help wondering "What the hell were they thinking of?"  Looks like one of those ideas that just ran off with itself and people followed.

Last edited by louis (2018-10-08 11:16:44)


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#77 2018-10-07 19:16:25

louis
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From: UK
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Re: Looking at the Mars Colony's development, based on Space X & BFR

In a desperate attempt to get this thread back on point...

1. Don't believe the artist's illustrations that Space X put out. Think about the mission architecture and the mission goals, and then work forward from those.

2.  The Base is definitely not going to be as compact as in the illustrations.

3. The buildings are not going to be so exposed to cosmic radiation.  There will be regolith cover. It will look more like a pueblo village than a shiny new outpost of humanity...

http://www.megalithic.co.uk/a558/a312/g … 595_sm.jpg

4. The BFSs are not going to be that close to each other.

5. The PV arrays will not be the tiny things depicted in the Space X illustrations - they will be huge covering a much more extensive area than the habitat. They will probably be the thing that first catches the eye - as the panels glint in the sunlight.


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#78 2018-10-07 19:40:53

SpaceNut
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From: New Hampshire
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Re: Looking at the Mars Colony's development, based on Space X & BFR

The image of BFR are the 2 earlier version to which the latest is quite a bit different than the one on page 3 that I posted.
The city images are on page 2 with distance on a verticle drawing is somewhat decieving as the hiegth of the bfr is easily 3 to 4 times from unit to unit landing targets.
The structures of the building I would agree seem odd for surface dwellings if made from insitu regolith.

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#79 2018-10-07 20:14:33

louis
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From: UK
Registered: 2008-03-24
Posts: 4,634

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

The quickest most efficient type of protection from cosmic radiation is regolith...I suppose Space X might ignore that and decide they want to have a shiny city from the get-go...as I understand it various plastics, water and ice could serve the same protective purpose. But even those are going to get a pretty good dust covering within a few weeks...So unless Space X are planning on having an army of people or robots cleaning all surfaces, it ain't gonna look like the pics!


SpaceNut wrote:

The image of BFR are the 2 earlier version to which the latest is quite a bit different than the one on page 3 that I posted.
The city images are on page 2 with distance on a verticle drawing is somewhat decieving as the hiegth of the bfr is easily 3 to 4 times from unit to unit landing targets.
The structures of the building I would agree seem odd for surface dwellings if made from insitu regolith.

Last edited by louis (2018-10-08 03:44:44)


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#80 2018-10-07 20:34:02

Belter
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Registered: 2018-09-13
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Re: Looking at the Mars Colony's development, based on Space X & BFR

The problem with water extraction from the air is that the air is intensely thin and simply can't hold that much.  And the planet is literally a desert.   And trying to chill air that is -100 to -200 degrees to squeeze some water from it is pretty tough.  What you *could* do is set up passive condensers that collected moisture when the sun goes down.  But there just isn't much to collect.  If there were, there would likely be life living on the surface.   It might be doable near the poles.   If you look at a moisture map of mars, the water is clearly above/below 60 degrees latitude.

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#81 2018-10-07 20:37:20

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

The problem with not having a docking station for a sealed rover is just the lost of air every time, plus you'd still try to pump a lot of it out, so you'd have to sit in an airlock for awhile while as much air as possible is pumped out.   I think most of the surface exploration and work is going to be done with wheeled robots in real time, unlike the automated systems required of current rovers.   Telepresence is far safer and far faster. 

The Space Shuttle was the equivalent of the Honda CBX, that let everyone thinking "WHY?"   Admittedly, it was cool and sleek, but it didn't solve any problems or save any money.

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#82 2018-10-08 04:37:08

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

Well the air isn't always at -100.  It's often above 60. And one part of the puzzle that is not so problematic is energy generation.

The amount of water in the atmosphere on Mars is 10,000 times that on Mars, I read. The question really is how much energy and mass of machinery would be required to concentrate the required volumes of atmospheric gas at the required concentrations. Of course, we (or rather Space X) need to capture CO2 gas in any case, in order to obtain the carbon for methane, so concentration of the atmosphere is "killing two birds with one stone" if it also delivers significant quantities of water. Presumably intake fans would be one method. You'd no doubt need some automated dust filter system on them as well.

In terms of gas pressure, you'd have to intake 158 as much volume of Mars air to equal the pressure of Earth air. On Earth water vapour accounts for between 0 and 4% of atmosphere...let's average that at 3%. If water vapour percentage on Mars is 0.03, that means you need 100 times the amount of Earth air at the same pressure to get the same amount of water vapour.

I think the air heating is probably a relatively trivial energy cost. Maybe at most in the tens of Kws constant over a sol. I seem to recall  pressurising will also generate heat in any case.

The heating and the water extraction seems doable.

The feasibility of atmospheric extraction rests on how much energy is required to concentrate the gas in the requirement amounts.

I guess you might need to process 83,000 cubic metres of Earth air  to obtain 3 tonnes of water in a day or 1,311,000,000 cubic metres of Mars atmosphere. If operating throughout the sol, that would mean 53,527,000 cubic metres would have to be processed every hour.

Sounds a lot but a big jet engine processes about 500 kgs per second or 1.8 million cubic metres per hour.

So on even this basic analysis, water extraction from Mars air is not impossible. It probably comes down to whether there are more efficient ways of extracting water than this brute "pressurisation plus dehumidification" approach ie can you efficiently extract the water at much lower gas pressures than one bar.

The "moisture maps" you refer to relate to ground water. Water vapour is much more evenly spread although it is seasonal.


Belter wrote:

The problem with water extraction from the air is that the air is intensely thin and simply can't hold that much.  And the planet is literally a desert.   And trying to chill air that is -100 to -200 degrees to squeeze some water from it is pretty tough.  What you *could* do is set up passive condensers that collected moisture when the sun goes down.  But there just isn't much to collect.  If there were, there would likely be life living on the surface.   It might be doable near the poles.   If you look at a moisture map of mars, the water is clearly above/below 60 degrees latitude.


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#83 2018-10-08 06:34:56

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

If the figures I read are correct, water vapor is less than 1/10th of Earth's water vapor by percentage, which means about 1/2000th the amount available.  Getting enough water from the air to produce several tons of fuel per day is going to be almost impossible.  CO2, sure, but the water is going to have to come from the ground.   The problem is around the equator, there land is so dry, there's little to pick up, making a passive condenser pretty useless.   I'm thinking that the North Pole in summer is going to be the best time and place to refuel, but there are two large areas at 30 and 180 degrees right near the equator that could have some ground water in the permafrost. If those don't pan out, not sure how they can avoid going up to 60 degrees or higher.

You're talking burning more energy than you can extract.     Remember that not only do you have to collect water with the least amount of energy possible, but you have to break it and CO2 down to their component parts, which uses more energy than is created.  We need to collect enough energy with solar power to blast at least one ship every two years out of orbit.   A compact nuclear reactor may be necessary.

Last edited by Belter (2018-10-08 06:39:11)

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#84 2018-10-08 07:05:54

louis
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From: UK
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Posts: 4,634

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

I think you're overerestimating the amount of Mars vapour - it's more like 1/100 th of Earth's, roughly, by percentage.  But on the other hand intake fans can draw in huge amounts of atmospheric gas at a fast rate. There may also be engineering solutions that might allow for faster intake, since this is really about surface area and rate of intake.

I don't know what you mean by "burning more energy than you can extract".  PV energy can generate large amounts of energy. Also, as I stated, pressurisation creates heat, so that must aid the process.

If your compact nuclear reactor fails, then you are stuck on Mars. So first off, you need at least two! This has been the subject of lengthy discussion. I think both PV energy and nuclear would be feasible. But both would need to be supplemented.


Belter wrote:

If the figures I read are correct, water vapor is less than 1/10th of Earth's water vapor by percentage, which means about 1/2000th the amount available.  Getting enough water from the air to produce several tons of fuel per day is going to be almost impossible.  CO2, sure, but the water is going to have to come from the ground.   The problem is around the equator, there land is so dry, there's little to pick up, making a passive condenser pretty useless.   I'm thinking that the North Pole in summer is going to be the best time and place to refuel, but there are two large areas at 30 and 180 degrees right near the equator that could have some ground water in the permafrost. If those don't pan out, not sure how they can avoid going up to 60 degrees or higher.

You're talking burning more energy than you can extract.     Remember that not only do you have to collect water with the least amount of energy possible, but you have to break it and CO2 down to their component parts, which uses more energy than is created.  We need to collect enough energy with solar power to blast at least one ship every two years out of orbit.   A compact nuclear reactor may be necessary.


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#85 2018-10-08 08:42:15

Belter
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Posts: 184

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

I probably *am* exaggerating the amount of water, though keep in mind, I'm talking about "per cubic meter", not total.   In any case, a dust storm like Mars had could cause astronauts to be stranded for an additional 2 years.    That might make a good sequel called "The Martians".    If you put something under pressure, yes, you'll generate heat, but you still burn a ton of energy pressurizing it.   The methane combustion is *enormously* powerful, so it will take multiples of that energy to produce it.  I'm sure someone has run the calculations but it's going to take a pretty large solar field to do it and machines working every day, if not 25/7.      If I did't screw up my calculations, it would take about 5000 solar panels working for 2 years straight just to fill one rocket.

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#86 2018-10-08 08:52:21

SpaceNut
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Posts: 15,594

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

The nuclear vs solar debate we done before to which its does take backups for both and standy units for them as well.

Atmospher numbers for moisture is a volume or cubic feet per minute flow rate to which it takes 158 volumes to be comparable to earths.

https://www.engineeringtoolbox.com/maxi … _1403.html
https://www.engineeringtoolbox.com/mois … d_281.html
https://en.wikipedia.org/wiki/Humidity

As temperature drops the ability to hold moisture also drops and mars will not have much due to that. You will need lots more heat from other sources to get the moisture from the soils into the air. So digging and warming the soil is the better option for more water.

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#87 2018-10-08 09:12:48

tahanson43206
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Registered: 2018-04-27
Posts: 787

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

For SpaceNut ... Using #86 as an anchor ... Can you suggest a search term for any projects which members of the forum may have undertaken to achieve an I objective in support of going to Mars?  I tried the word "project" and the system came back with 56 pages of citations.  That's too many (for me at least). Thanks !
I am aware of Mars Society initiatives, but (I suspect) those are independent of the forum.
(th)

For Josh ... It seems to me your idea of using ions stripped of electrons as an energy storage method for space propulsion is worth pursuing.  Could you possibly work that up as a proposal for directed research?  Your opening message contained arguments in support of the idea which might be expanded.
(th)

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#88 2018-10-08 10:15:15

SpaceNut
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From: New Hampshire
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Re: Looking at the Mars Colony's development, based on Space X & BFR

The search function

To search by keyword, enter a term or terms to search for.
Separate terms with spaces. Use AND, OR and NOT to refine your search.

The topics are meant to be focused discusion within the first post as moderated by the topic poster but it sometimes wanders quite a bit.
As for project "projects" we really are not structured to do these as an open forum. Thou if the topics stay true to the opening its as close as we can come.

Is there something you are looking for?

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#89 2018-10-08 10:31:16

tahanson43206
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Registered: 2018-04-27
Posts: 787

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

For SpaceNut ...
Thanks for endorsement of the proposal suggestion to Josh in the ion topic.  This would mean extra work for Josh of course, but I am gambling that there is a reservoir of talent with visibility into this forum, beyond the high level I have already seen.  Non-posters with visibility into the forum are likely to know of individuals whose studies or interests lead in the direction Josh is pointing.

Thanks too, for pointing out the search instructions.  I am embarrassed to admit they were right there on the search page, but I overlooked them.

Thanks (finally) for explaining that this forum is not set up to support projects.  I am not surprised.  I have never encountered a forum that was designed specifically to facilitate co-working.  On the other hand, there certainly are co-working web sites, and I've even used what is now UpWork with good results.

Back on the first hand ... this appears to be a gathering place for people who are interested (broadly) in Mars Society goals, and that would not be the case at a commercial co-working site.

(th)
You said:
The search function

To search by keyword, enter a term or terms to search for.
Separate terms with spaces. Use AND, OR and NOT to refine your search.

The topics are meant to be focused discusion within the first post as moderated by the topic poster but it sometimes wanders quite a bit.
As for project "projects" we really are not structured to do these as an open forum. Thou if the topics stay true to the opening its as close as we can come.

Is there something you are looking for?

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#90 2018-10-08 11:11:36

RobertDyck
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From: Winnipeg, Canada
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Posts: 5,701
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Re: Looking at the Mars Colony's development, based on Space X & BFR

The first forum in 1998/'99 proposed a quite ambitious project, but Robert Zubrin didn't approve it. I described it in another thread. I was involved with the Mars Homestead Project phase 1.
http://www.marshome.org

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#91 2018-10-08 11:28:27

louis
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From: UK
Registered: 2008-03-24
Posts: 4,634

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

Belter wrote:

   In any case, a dust storm like Mars had could cause astronauts to be stranded for an additional 2 years.

Dust storms on Mars are pretty weak, compared with storms on Earth. We've discussed the issue of energy production during dust storms. There's no reason to think that either with PV power or nuclear power a dust storm would prevent energy generation. With PV power you have to build in redundancy - probably take 140% of the amount of generation required in the absence of dust storms (so you can "make hay while the sun shines"). The additional power generated can be stored in chemical batteries, as compressed CO2  or as methane/oxygen.  There is still solar radiation reaching the surface during dust storms.  Probably unlikely to go below 20% of normal for any length of time - ie for more than a few days. For the average sort of dust storm it's more like 40-60%. Also, dust density varies - some places are a lot worse than others.


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#92 2018-10-08 14:27:08

Belter
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Posts: 184

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

The Opportunity Rover disagrees.   I'm just pointing out that, yes, there will have to be backup power or a ton of overbuilding because a large dust storm could kill propellant production for weeks or months.  Just enough to cause a delay if the production couldn't be caught up.  Also, I do believe I forgot to factor in night time, so that would bump us up to something like 10,000 panels, just to get one ship fueled with no room for error.

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#93 2018-10-08 16:23:32

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

The Opportunity Rover is a small rover that was having to generate its own energy. It did survive one dust storm, even so.

10,000 sq. metres of panelling would be not be problematic at all - it's only 100 metres by 100 metres We can probably use ultra light weight panelling (remember the weather is so benign on Mars that there is no need for a lot of structure to support the panels).  The pioneers will be on the surface for something like 18 months to 2 years. Dust storms are seasonal.  The longest one ever recorded was 9 months -but the idea the sun is blocked out for months is plain wrong.

Let's take a scenario of a two year visit  where 100 equals normal insolation in six months of high summer on Mars in the absence of a dust storm and the seasonal variation are calibrated to that figure. This is the minimuim required In order to propellant production

Winter low - 60 x 6 =  360

Winter high - 80 x 3 x 2 = 480

Summer high - 100 x 6 = 600

Summer low =  90 x 3 x 2 = 540

TOTAL - 1980

If we assume a worst case dust storm scenario with 6 months of high summer at average 40% of normal insolation and 1.5 months either side (3 months in total) at 60%, that would produce a deficit of 468 equating to 23.7%.  So if you over design your systems by that amount, you should be able to cover your propellant production.  I would add a further margin of safety and overdesign by 40%.


Belter wrote:

The Opportunity Rover disagrees.   I'm just pointing out that, yes, there will have to be backup power or a ton of overbuilding because a large dust storm could kill propellant production for weeks or months.  Just enough to cause a delay if the production couldn't be caught up.  Also, I do believe I forgot to factor in night time, so that would bump us up to something like 10,000 panels, just to get one ship fueled with no room for error.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#94 2018-10-08 17:06:34

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

Do not be decieved by the number as its a 1 meter panel for all of the collected amounts and they are in watt hrs accumilated during a days collection as indicated for the seasons.

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#95 2018-10-08 20:49:51

Belter
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Registered: 2018-09-13
Posts: 184

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

Before Space X launches its first manned ship to Mars it should be able to:

1.  Land a BFR in a rocky desert
2.  Robotically offload and construct a solar panel field
3.  Offload robotic diggers that can dig down into the desert
4.  Extract via digging about 10 tons of water *per day*
5.  Return it to the ship
6.  Have the ship hydrolize and sabatier the liquid fuel
7.  Store the fuel in liquid form
8.  Launch and return to base and land.

Last edited by Belter (2018-10-09 06:13:16)

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#96 2018-10-08 21:48:51

SpaceNut
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From: New Hampshire
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Re: Looking at the Mars Colony's development, based on Space X & BFR

That would be a hell of a dry run even using a Falcon 9 or heavy to do just that with any design still attached instead of a second stage plus capsule.

Substitute a new shell for what we need if it was a BFR
First stage – Booster
Length    63 m (207 ft)
Second stage – Spaceship (BFS)
Length    55 m (180 ft)

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#97 2018-10-09 04:44:40

louis
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From: UK
Registered: 2008-03-24
Posts: 4,634

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

Well definitely 1, I think.

I don't see particularly why 2-7 can't form part of the Moon Mission itself after thorough testing on Earth, although as far as I know Space X do NOT plan to do any robotic water mining and processing prior to the arrival of the human passenger BFS on Mars (so fully robotic processing is not necessarily required).

Re 8, I am not sure of the relevance of that for Mission One (are you thinking of exploration by rocket? - I doubt that will happen on Mission One).

I have previously argued for a Mars Analog Facility  - a large warehouse like facility with Mars sol/night cycle, Mars analog soil, Mars temperature range and air pressure...so you could test out machinery, robotic rovers and so on. Designated crew could also be located there and and could test out human passenger rovers and a mock up of the habitat. It would cost a few hundred million dollars to put together but I think it would be worth it. Crew could spend several months there.


Belter wrote:

Before Space X launches its first manned ship to the moon it should be able to:

1.  Land a BFR in a rocky desert
2.  Robotically offload and construct a solar panel field
3.  Offload robotic diggers that can dig down into the desert
4.  Extract via digging about 10 tons of water *per day*
5.  Return it to the ship
6.  Have the ship hydrolize and sabatier the liquid fuel
7.  Store the fuel in liquid form
8.  Launch and return to base and land.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#98 2018-10-09 06:13:39

Belter
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Registered: 2018-09-13
Posts: 184

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

Sorry, I meant Mars

They will definitely have to do most of this robotically.   Otherwise, there's no point in sending the ships in advance.

Last edited by Belter (2018-10-09 06:15:09)

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#99 2018-10-09 06:25:53

kbd512
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Registered: 2015-01-02
Posts: 2,834

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

The first time I see a successful outcome associated with the first item from that list, SpaceX can concern themselves with everything else required to actually live on Mars.

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#100 2018-10-09 06:53:08

Belter
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Registered: 2018-09-13
Posts: 184

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

I'm also thinking that there's no reason they shouldn't put a nuclear reactor in the unmanned ships and have them do the fuel processing.    In theory, a ship like that could take off, go to Europa, take off, go to another moon.   Fly around the solar system almost endlessly.

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