Alternate BFR (Big Falcon Rocket)

SpaceNut · 2018-01-21 17:45:50

The current design of the BFR 2nd stage in any of its uses, as a result of reusability of the first stage forces all fuels to be used in the 2nd stage to achieve orbital status with its max payloads. Which is why its refueled in orbit and at mars surface as it expends all of its fuels.

Now a new 2nd stage that was to be disposable shaped only as a fuel tank with a finishing stage for orbit then you save on mass as its not recycled. The tank stage could be as you put it staged in a serial manner joining the earlier sent up BFR 2nd stage once its refueled.
Or the stage could be pushed ahead via ion drive as it would be the key for mars return of the bfr as it would need less fuels to get back to earth from the mars surface refueling.

Void · 2018-01-21 19:24:57

I like what you have offered Spacenut. Interesting.

What if #4 eventually was composed of a finishing stage, which could land itself, and on occasion land also with it the external tank, or the ion thruster devise for maintenance / upgrade / repairs? Just some wild thinking.

One thing to consider is that the LEM thrust system was a large part of the survival of the Apollo 13 crew, in addition to it's resources. Per a specific mission it might make sense to bring along the finishing stage for that reason.

Maybe however we never land the external tank again, just use a number of times and discard it. That is an option as well. Actually old external tanks might be used for some final purpose, instead of wasting them, if they were still usable.

One thing I previously left out is that I would like to see the BFR upper stages be able to do Aerocapture. In addition to all the other capabilities.

The way I am looking at it now is that BFR's can be connected by the tail, or by the near nose orifice. So, you could daisy chain a Cargo/Passenger/Tanker-Finishing Stage. You would do some failsafe thinking. Perhaps along part of the trip you would use the mass to protect from radiation, and resource dangers. Perhaps along some parts of the trip you would separate the various parts. Some might do various methods of being captured to the Mars or Earth, as might seem the most sensible to achieve the best results.

This is getting to be like lego's per O.F., Modular.

Last edited by Void (2018-01-21 19:30:45)

SpaceNut · 2018-01-22 13:24:18

Posting an image location.... http://www.humanmars.net/2017/10/spacex … ed-to.html
This the BFR second stage docked with the ISS modules to which use a docking node module for the the BFR to join with the second, this will give you the safe haven that you want. That would allow for the transit vehicle to be coupled with the ERV which would be left in mars orbit.

Oldfart1939 · 2018-01-22 14:01:55

I unfortunately am skeptical of the timeline for the BFR--as are most others here on this forum. I'm personally convinced that there needs be an intermediate vehicle/spacecraft architecture that can reasonably demonstrate many of the set of requirements for success. The diameter of the Falcon 9 family is 3.7 meters; Blue Origin New Glenn is 7 meters, and the BFR (last iteration) is 9 meters. I strongly believe a vehicle with a 5 or 6 meter diameter could be mission capable, with something of a shorter development span than BFR. Reference to SpaceNut's linked image showing the BFR docked to the ISS is almost exactly what I had envisioned for the in-orbit assembly of my modular concept vehicle. It would dock the crew module, sent to orbit un-crewed in order to reduce crew weightless time as the thing is assembled. The crew vehicle mass I had envisioned would be 26 Tonnes, including all supplies for journey to Mars and a return. It would be powered from LEO to LMO by a power module sent fully fueled into LEO, then docked with the crewed Earth Departure Stage. A similar fully-fueled Earth return stage would be in LMO prepositioned by using a Electric propulsion interstage. Descent to the Mars surface would be accomplished through a lander/ascent vehicle with a jettisonable descent motor system and landing legs. The MAV to orbit would utilize Hydrazine-type fuel and ISRU prepared LOX. All supplies for a 500 day on Mars surface stay and habitats would be prepositioned robotically. This would undoubtedly require 3 cargo vehicles landed before human presence, due to redundancy of supplies and equipment sent for "insurance" purposes. The size of the crew for such a mission could be as high as 7, but at least 4. A larger crew is better for psychological support than a smaller one. Tis is nowhere a complete architecture proposal, but is a sketchy outline that needs some severe number-crunching.

Added in edit: There would be 2 vehicles sent which would be crew capable; one with crew on board, and the second is the lander/ascent module. The lander/ascent module could also be prepositioned using electric propulsion, however.

Last edited by Oldfart1939 (2018-01-22 14:05:48)

Void · 2018-01-22 15:06:03

O.F. no intention of messing with you desire to project a method.

Guess perhaps we can hop over each other and try not to be rude.

Seriously was composing this thing and then you posted. I don't think my post is anymore important that what you are trying to communicate. I have deep respect after all.

But I need to send no-one needs to respond.

Fueling BFR
First of all, at the beginning I fully support the SpaceX plan to fuel BFR with resources on the surface of Mars. I don't want any members to get into Coniption fits over this.
But then as an economy is evolved, I would like to consider furturist options. I will present some materials which are quite similar to others I have presented in the past, but I think can show progress in the value of the notions.
And in case anyone feels I am going off topic, please understand that all the things mentioned although also perhaps filling other needs will be associated with replenishing the fuel and Oxygen for BFR, in what I hope would be an increasingly cost effective way. Perhaps even a way where the "Mars System" might make revenue by exporting fuel and Oxygen to elsewhere.
By "Mars System" I indicate Mars itself, also Phobos, and also Demos.
And to save needless struggles, let me repeat that I am quite contentent to initially see BFR refueled by the methods that SpaceX specifies at this time, but would like to explore future options. That future could be 10 years away from initial landing or 100 years away. I think that is reasonable behavior on my part to speculate in this manner.
Optimally Phobos and Demos will have all the materials for servicing ion drives, and also recoverable Oxygen, Carbon, and Hydrogen. But we don't know that yet.
I am going to guess that some items will be present, and some not so much so.
The means to extract whatever is available on Phobos and/or Demos will be challenging. Therefore perhaps as much as 100 years to get there. But I am talking about a guessed 10-100 year span after the first landing of BFR in the "Mars System".
The upper layers of those moons seem "Reduced" of Oxygen by the space environment. So if the upper layers were mined the most likely product would be metals. Some of those might be useful in an ion propulsion drive. The other things might be use in constructing orbital/Phobos/Demos machines.
I am from that point going to be consirvative. Optimally we would wish for water ice in the interior of these moons, and also usable Carbon, but I am going to go with the notion that these moons are just "Fluffy" due to their low gravitation and the probable disturbances caused by orbiting Mars.
We might get supper lucky and find water ice and Carbon, but for this post I am going to assume that that is answered with "NO". After that I will upgrade the projections to reflect the weak possibilty that indeed usable Carbon can be obtained. After that I will upgrade the projection with the notion that Hydrogen can be obtained from Phobos and/or Demos.
So.....
Refueling Process 1:
-What SpaceX plans, using Ice and CO2.
Refueling Process 2:
-What SpaceX plans, but getting assistance from ion propulsion, if that is available from metal methods specified by the Neumann Electric Drive.
*Note at the beginning these metals do not have to come from Phobos and/or Demos, but of course I am advocating that eventually they will.
Refueling Process 3:
OK, we hope that O2 can be extracted from these moons. So then, if this were true, you would only bring Methane up from the Martian surface, and would collect your needed LOX from Phobos and/or Demos.
*Note, later on since in this case no Oxygen needs to be brought up to orbit, I have another use for that Oxygen and that will go a bit off topic, but so what.
Refueling Process 4:
It seems that Demos is composed of rock rich in "Carbonacious materials". That sounds like Carbon availability to me.
So, if I have interpreted it correctly, then Carbon for Methane is possible.
So now BFR does not have to bring Oxygen or Carbon up to Orbit. Just Hydrogen.
Rather a light lift I would think.
So, you would make your Methane from Carbon from Demos and/or Phobos, and would get your LOX from one of those moons.
Just Hydrogen from the surface of Mars. Rather a whimpy lifting task I might think, although the container size for Hydrogen might be an annoyance.
Refueling Process 5:
OK should you be super lucky, and find that the "VOIDS" of Phobos and/or Demos are ice filled, or that their are Hydrated materials in one or both of these Moons, then actually all BFR needs to do is get itself up to orbit and visit the resource Depot for fuel and Oxygen.
Now, my off topic segway. This is based on the idea that Hydrgen is not obtainable in a economic way from Phobos or Demos.
So then in that Case: (I used to be a quack programmer).
Then since you are not going to lift Oxygen up to Orbit, or maybe either Carbon, what do you do with it?
Here we go, ice covered lakes and aquaculture again. I never stop with that.
And what about that sand dune material that just would rust if you put it in water?
So, then Salt water interacting with Soil may produce H2 and Nitrous Oxide in a cold anoxic environment. As in some hypersaline Antarctic Lakes.
So, then we might hope to generate some microscopic goop crap from such a process, that is micro-organisms that live off of these resources. But what if we sweeten the deal a bit?
We may not be sending O2 into orbit, so lets consider adding O2 to the lakes water, and turning it from annoxic to aerobic. The sub soils will still be annoxic and might generate H2 and Nitrous Oxide (No promises there), but the environment provided might support some type of cold water fish, clam or whatever.
But not just that perhaps, perhaps you do dump dune dust into this lake at a reasonable rate. It rusts, hopefully more with water in the deep soil that with the Oxygen you provided. Now more food for the fish, clams, or whatever.
What about Carbon?
If you can get Carbon from Phobos or especially Demos, then you don't have to lift it to orbit. If you want to get Oxygen for people to breath however, perhaps you might get some of it from CO2 in the Martian atmosphere. What do you do with the CO or the Carbon that this leaves behind? Well, you drop it in a reasonable proportion into your aquaculture lake. So much more to feed the fish, clams, or whatever. Not so much that you poision them to death, but it would be additional fuel to propel the chemosynthetic food web.
And if there is Hydrogen in abundance avalable on Phobos and/or Demos, give youself a kiss you are rich baby.
Do whatever you like as long as is is not self destructive.

OK and yes, can you get N2 and O2 and Co from the Martian atmosphere, and reject CO2 to another purpose? I think yes. Use reverse osmosis methods. Inject the CO, O2, N2 into the lake. You want farming soil? Well, I am guessing that you can get lots of it from the rusting of dune materials, in the presence of fish poop and microbial action from the rusting of that dune material.

Last edited by Void (2018-01-22 15:28:50)

Oldfart1939 · 2018-01-22 17:07:28

Void-
Nope. We don't step on one another on this forum, unlike several others of which I've been a contributor. Polite here is nice.

My alternative architecture was never meant to REPLACE Musk's BFR, but strictly for the pioneer missions for proof of concept and establishment of some kind of foothold on the Red Planet. I'm actually a HUGE supporter of the ISRU, but the scale on which he is thinking boggles my scientific imagination w/r scale of propellant production. There is no doubt in my mind that he can pull it off, but NOT in the time frame he's stated. One other consideration is individual life span and individual interest. As I interpret things, BFR is Elon's personal wet dream, so anything that materially affects his finances could conceivably impact the project--as could his "having a big one."

So...take what I've written with my grain of salt, so to speak, and consider that I'm suggesting a mechanism by which we can get to Mars before 2030, and subsequently still beat NASA to the destination. Some of my featured payloads could conceivably be sent by a "souped up" Falcon Heavy, and the second stage could conceivably be boosted out of LEO with a set of strap-on Solid Propellant boosters, reserving the liquid fuels for inflight course corrections and adjustments to the deltaV.

Last edited by Oldfart1939 (2018-01-22 17:07:48)

Void · 2018-01-22 19:49:37

O.F. very good! I think I understand. Do what can be done within the constraints of what might actually happen. We will not of course know what actually happens until it does. having chances to build more upon what actually happens. How could we be wrong? It has to be the good cause.

Last edited by Void (2018-01-22 19:50:24)

SpaceNut · 2018-01-23 22:45:43

The current nasa plan is to use the moon as a sort of proving ground with the deep space gateway..

Oldfart1939 · 2018-01-24 00:29:39

SpaceNut-
That may be the plan, but so far there has been no congressional authorization, nor any approval by a new NASA administrator for the DSG! So far, that's all eyewash and some PR. Howcum we didn't need a DSG the first time we went to the moon? NASA has a bad case of saying we're going to X, and then coming up with a "oh, but first we need to do Y." I've been highly opposed to the entire DSG proposal and it's potential involvement in any possible Mars activity. My estimate for DSG (including the fabled SLS, which has yet to fly) comes to $30 to $40 Billion and taking 10 years to accomplish, and is subject to the vagaries of congressional funding. Just another everyday "workfare project," of which NASA already has many. The SLS in particular.

Last edited by Oldfart1939 (2018-01-24 09:12:26)

elderflower · 2018-01-24 03:38:13

Trouble with using the moon as a stage on the way to Mars is the need to brake against its gravity, using propellant, and then to get back off it's surface using propellant. Plus associated risks. We might as well go directly to Mars.
The moon may be useful as a proving ground, but it isn't that similar so you still face a new environment on arrival at Mars. For instance there is no wind to blow the dust around, no atmosphere providing some protection against micrometeoroids and radiation, there are no known salt deposits, pemafrost or ice is a rarity and vulcanism stopped billions of years ago.
The moon may be a good target itself, but it's a diversion for a Mars directed enterprise.

Oldfart1939 · 2018-01-24 09:17:38

Elderflower-
Your arguments are spot-on, and pretty much reiterate what Dr. Zubrin has been saying for 30 years. If we want to go to Mars, then plan a mission which takes us there directly.
My issue w/r the moon is the 14 days of total darkness which really restricts activity for surface exploration/development. The DSG provides even less advantages than the planetary surface, and adds in higher exposure to GCR to the already wonderful zero g effects on crews.

Void · 2018-01-24 12:43:09

Quote:

Elderflower-
Your arguments are spot-on, and pretty much reiterate what Dr. Zubrin has been saying for 30 years. If we want to go to Mars, then plan a mission which takes us there directly.
My issue w/r the moon is the 14 days of total darkness which really restricts activity for surface exploration/development. The DSG provides even less advantages than the planetary surface, and adds in higher exposure to GCR to the already wonderful zero g effects on crews.

Then again it is important to follow the money. There are large sums of money that want to work with the Moon. Jeff Bezos & Branson I believe, and quite a few international outfits that also have plans for the Moon. Nobody here really has a say as to what they will do.
What we could get as a freeby, however from this is biological testing in the Moons gravity field. No charge to us.
As for NASA, the Gateway will also likely be an international program. That is not to say that a Mars mission could not be, but for the example of Japan for instance, I think it likely that they would be more interested in spending their money on the possibility that they could get minerals and energy from the Moon. So it's not entirely wrong for NASA to give consideration to the ambitions of other international players.
SpaceX may do the Hail Mary, and get away with it. I cannot stop them or that much help them do it. If they do then we may get biological data from the gravity field of Mars.
......
Back to the Gateway then since for now it is the plan. It is intended to be first directed at the Moon and then Mars. I can live with that. However, I want it to be the "Hub" for instance of a future synthetic gravity machine.
We don't know which precisely comes first.
-Data on biology for organisms on the Moon.
-Data on biology for organisms on Mars (SpaceX does it)
-The Gateway hub.
But at some point we should have three data points for biology in gravity fields other than Earth's. (We have zero gee data, but want Moon and Mars, if we can get it).
Then I feel an educated guess could be made on what level of synthetic gravity would be sufficient for a base on Phobos and/or Demos.
If we know what resources are available from Phobos and/or Demos, perhaps economic entities could become interested in helping to obtain them.
That is why I would want something like a BFR mission to each of those moons.
It would speed up the process of setting up a "Civilization" on Mars quite a bit I feel, to have a connected interplanetary business system.
End.

Void · 2018-01-24 13:06:11

Mars Space Station:

I would like to modify my thinking on a synthetic gravity machine from the Gateway.
If it were done, instead of landing it on Phobos or Demos, I think it could be teathered to each of them in turn. Starting with the one of best value.
The rotor which would produce synthetic gravity should be inside of an envelope of processed materials.
A relatively safer place for it to be located would be above the side of Phobos locked to Mars.
Then from one direction Mars would block radiation, and from another Phobos would block radiation.
Materials from Phobos or Demos could then be put in place on the non-rotating shell, to improve radiation protection.
At some point a synthetic gravity machine would be consructed within Phobos, and then the teathered machine could be moved to Demos, for the same to be done. Or vice versa.
As has been discussed, it seems likely that Phobos or Demos could provide some kinds of propulsion mass for a space economy.

Oldfart1939 · 2018-01-25 11:06:56

Oldfart1939 wrote:

Void-
Maybe--just maybe--we should consider building a von Braun "bicycle wheel" space station in Mars orbit so there would be a chance of getting some gravitational reconditioning prior to a Mars landing? And before a return Hohmann transfer ballistic trajectory back to Earth?

In response to your suggestion of artificial gravity in Mars orbit....

Last edited by Oldfart1939 (2018-01-25 11:08:26)

SpaceNut · 2018-01-25 18:19:35

I do believe that the commercial launch systems will follow the money and will develope where they thing the quick turn on the dollar (moon) will be as they are not large enough for long term investment with slow gains (mars).

Void · 2018-01-25 20:08:48

Agreed Spacenut. O.F. I agree that in fact you did recommend the Mars station. Our views are convergent I think. Lets agree to be open about the possibilities.

I suggest that the station could be used to start a shell world on Phobos, the Demos, and then if possible to the Asteroid belt, to start other such worlds. Maybe from there even the the Trojan Asteroids.

SpaceNut · 2018-01-25 20:20:53

ION propulsion has already been proven well with the visits via the Dawn probe to many of the asteriods as it would be great for the mars ISS to go and do more than just circle mars forever doing soem first hand looking at them for the science and then for the ability to get man even further from earth to places we could only dream of.

Void · 2018-01-25 20:50:23

I want to do a new twist on this "Alternate BFR" thing.
And yes I will borrow materials from others, such as G.W.
I want to introduce a "Re-Cycling Spaceship". Probably not an original idea.
But it would not be a "Cycling Spaceship". Cycling spaceships have been conisdered, and most on this board do not care for them. I can understand some of the reasons. The transfers with subships would be very dangerious. If you mess it up you probabbly die.
Recycling spaceship:
-I don't see why after geting a Martian civilization started, you would want to keep moving BFR ships in an interplanetary fashion. It seems to me that later on if you want to move your 1,000,000 people, a better way could be found.
I recommend larger mass ships that do not land. I reccommend that BFR be changed so that they just had seats, and not cabins. I don't see why you would care to continue to move the cabin mass up and down from the surface of the Earth or Mars up to LEO.
So, the Recycling ship would perhaps use the Neumann drive. And it would travel back and foruth from LEO of Earth to LEO of Mars and vice versa.
I consider that it should be massive. Maybe 1000 passengers, maybe 10,000 passengers.
As I see it the more massive a ship, the better the radiation protection. Just the passenger bodies, protect each other. However I anticipate using a more sensible method than human bodies as radiation protection. Simply a large size an mass of a ship. Elon Mush has said that staceships of the future will be truely massive. But if you tried to land or launch such a ship from the Earth or Mars, and something went wrong with your gazillion number of raptor engines, you could expect a massive unacceptable level of explosion.
But if it is a planet to planet craft using Neumann drive the dangers are not that much.
If I imagine traveling in BFR, I wonder about Vomit, Diareaha, boogers, pee, and wipe cloths in zero gee with 100 or so passengers. If one person vomits, and sees and smells the vomit of another, don't the others tend to get bucky, and start puking as well?
Not sure I want to be on that voyage.
I want to solve that problem using a minimum synthetic gravity and vomit/poop/pee freezers as simple as an outhouse.
I don't know if 1/20th Gee would be enough. I am just grasping.
But doing this you get rid of coplex zero gravity toilets, and do not impdiately recycle the waste products. In fact you likely do not do a recycle until the ship is back to the Earth/Moon system.
This would get rid of a lot of complex technological devices that can break, and as a member G.W. has said waste water can be used for radiation shielding. In this case, it will be vomit cycles, poop-cycles, and pee-cycles.

I am under siege from munchkins and mad people, and they are not all on this web site. I can elaborate later. Now is no longer OK. Dropping communications.

elderflower · 2018-01-26 05:26:46

Due to an unfortunate lack of research, nobody knows how much gravity, whether artificial or not, is required to moderate low g effects to an acceptable level over a long term. There hasn't even been work on rats or mice to my knowledge.
Sorry to hear you are leaving us, Void. Come back soon!

Oldfart1939 · 2018-01-26 09:06:22

Void-
Your contributions have been valuable to this group--don't leave us permanently! We may frequently disagree, but this is a very civil group--for the most part.

Void · 2018-01-26 09:51:27

Oh! You misunderstand. I was visiting relatives. The Munchkins were little children and a Cousin within 3 feet or so of me. Just to disruptive too continue the post further.

But I will now try a little bit more.

While the use of synthetic gravity could involve solving other medical problems that we are becoming aware of in zero gee. Just now I am addressing Hygiene.

My conclusion is that for Mars, a water dominant Hygiene should be preferred, here I am trying to get the best solution for interplanetary transit Hygiene.

So the minimum necessary synthetic gravity to make human fluid and semi-fluid emissions to drop into a toilet freezer is the suggested objective.

Since the vehicle would be visiting Earth LEO, then I suggest a paper dominant Hygiene.

Not unlike a rugged camping trip, it might not be best to bring flush toilets, but to use more rustic methods. I would prefer that peoples bodily emissions would not be capable of floating up towards me

So, I did a trial balloon 1/20th Gee. No idea if that it optimal or sufficient. Just a starting point.

For the ship, the minimum gravitation necessary would be preferred, to minimize the investment in structural strength requirements.

I prefer the "Toilet Freezer" since space is cold. The sun is hot/warm, but if you construct the ship properly, then it may be possible to make a cylinder which is cold enough to freeze the biological emissions and render it relatively inert. Further treatments would be toilet seats which would keep the odors local except when in use, and also air freshener methods if possible.

The sanitation process then would be "Batch" rather than "Continuous".

I would expect professional cleaning services to clean and refurbish the ship when it was in LEO, and to recycle or dispose of the waste as might be the most cost desirable.

While doing this, if somehow 1/20th Gee would help to keep people from vomiting, that would be nice. Don't know. But some of this could be tested on the "Vomit Comet" planes. So, we could find out the tolerable amount of synthetic gravitation to get the turds to drop into the bucket.

So, the idea is to avoid complex continuous recycling, and to instead do batch recycling.

The food, water, and waste are all radiation protection after all. We presume that the Neumann drive will compensate for the heavy weight, as it is supposed to be quite efficient. Effective power supplies required.

https://en.wikipedia.org/wiki/Reduced-gravity_aircraft

Probably the orbital path will be spiral as mentioned by G.W. elsewhere, and perhaps Ballistic-Similar capture could assist.

End.

Last edited by Void (2018-01-26 10:14:33)

Oldfart1939 · 2018-01-26 10:31:56

I 1/20 th gee isn't much, w/r to physiological processes. Lunar gee is probably the minimum that would be physiologically useful and that's about 0.25 Earth gravity.

But--as you stated--gotta' keep the crap in the crappers!

Last edited by Oldfart1939 (2018-01-26 11:25:26)

Void · 2018-01-26 11:31:52

OK, I think we can basically agree. There could be gravity assisted hygiene which will be the lowest gravity that can work, as tested in the Vomit Comet. 10, 9, 8, 7........Drop the turd simulation into the bucket!

And then their is gravitation sufficient to keep people relatively heathy for a period of time in gravitational fields less than 1 gee

Plan A:

I see three phases of BFR.
1) Using External tanks either taken along, or projected to Mars by ion drive. On these missions, no serious attempt would be made to do large scale Insitu processing on the surface of Mars.

2) BFR as is currently advertised by SpaceX/Elon Musk. Hard core stuff. Hohmann transfers, harsh aeroburns, to surface landings. Intense Insitu. If you want to live, you better get it right the first time. Not for average people.

3) A people conveyor. Geared towards a more average population. Synthetic gravity for Hygiene primarily. If necessary when the travelers arrive by gentle process, they are moved to the O.F. Synthetic Gravity Wheel/Baton, and re-acclimated to higher synthetic gravity. Then when they are ready they are brought down to the Martian surface.

*Note: It looks like SpaceX currently wants to try to do #2, and might be contemplating #3 eventually.

Plan B:

*One note: We have no proof on the true health possibilities for people on the surface of Mars. If it turns out that .38 Gee has serious health problems, then you try to go to plan B, where people live in well protected synthetic gravity machines in Orbit, but visit the surface of Mars, and also use telepresence on the surface of Mars.

Last edited by Void (2018-01-26 11:33:21)

Terraformer · 2018-01-26 11:49:23

Do we know how much gravity we need to use regular plumbing? Reduced gravity flights should be able to tell us that much, at least. If 0.1g allows us to cook and shower and do everything else we need, even if it's not enough to keep us healthy, then we can build centrifuges to that specification. Maybe we'll be able to design exercises and equipment that mimic the impact of gravity (repeatedly hitting a wall? Hmmm...).

SpinCalc tells me that 0.1g at 4 RPM requires a radius of 5.5m. Perhaps BFR with a bigger fairing could manage it? If not, maybe we could construct the centrifuge on orbit. If the radius is 10m, we can do it with 3 RPM.

Oldfart1939 · 2018-01-26 12:10:33

Small radius has associated problems of inner ear-related disorientation. Bigger radius require less RPM. We need to SERIOUSLY look at the von Braun "bicycle wheel" space station around Mars as a transition point to the planet surface if to synthetic gravity is provided on the BFR.

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#101 2018-01-21 17:45:50

Re: Alternate BFR (Big Falcon Rocket)

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Re: Alternate BFR (Big Falcon Rocket)

#122 2018-01-26 10:31:56

Re: Alternate BFR (Big Falcon Rocket)

#123 2018-01-26 11:31:52

Re: Alternate BFR (Big Falcon Rocket)

#124 2018-01-26 11:49:23

Re: Alternate BFR (Big Falcon Rocket)

#125 2018-01-26 12:10:33

Re: Alternate BFR (Big Falcon Rocket)

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