Alternate BFR (Big Falcon Rocket)

Void · 2020-04-04 15:50:06

I suppose I was being a bit of a baby when I left here. So, I will try to do better.

Yes an Earthquake fluidizes the ground. Fluidizing a sand dune might be even better, but a lot is required in a hope of master that process.

This thread, is sort of a mish-mash, so I will play here for a while if allowed.

Good chances that what I produce will be correctly disqualified as a way to go, but there is a certain responsibility to be willing to get beat up, if you think you have a chance of producing something of use to the cause(s).

First of all I have attempted to move beyond the "Bell Ships". I hope to get something better.

Philosophy is key to this desire. Zubrin, Musk, Bezos. All with good ideas and accomplishments. So, I have studied what I can about their works, tried to learn something useful. They all have good things to offer.

But I could wear everyone out with excess verbiage about that.

So, I will offer something in my next post here, that could be a bit different and could relate to the thinking of 1, 2, or 3 of them eventually.

Last edited by Void (2020-04-04 16:00:39)

Void · 2020-04-04 16:01:34

I lied. I am going to go wordy on you.

They say that an asteroid struck the Earth ~65??? million years ago. Among the survivors, birds, and mammals. I think most likely the survivors of such an evet would be from the Alpine areas where cold tolerance was a requirement for life. Other protective methods such as burrows, and cliff dwelling might also have helped. Just a speculation.

Where I am going with this is "Methods of procreation". (Not an X rated event). Procreation indicates that your offspring survive into the future. Birds and Mammals present various examples which seem to have success for those not yet extinct.

I think that if Mammals were not so able to kill the offspring of nested birds, and if birds therefore were not required to fly and nest in protected locations, then birds could have had big brains, and perhaps been very advanced in mind power. Many birds have mutual participation in child rearing. Many mammals do not. Some humans are like binary bird pairs in making a family for protection of the offspring. Some are less so.

The differences are something like say a bear. In general the male bears responsibility in life is to be a big bad bear. Then momma bear might be more likely to accept him, because her offspring many also be big bad bears. If he has anything to do with cub bears, it is likely to be him killing them. They failed the test for big bad bearhood.

But nesting creatures such as many birds and humans , are not as much like that. But there is a tension between nesting participation from males of humans, and being big and bad. I feel that many females do quite well with nesting instinct but not all of them. Human males in my opinion are some of each. Nesters, and to not be profane (Big Bad). And I don't use the word for rectum that is profane, quite.

Going to Mars to set up a descendent or an inheritor culture, is a form of procreation. And as for the predicament of birds, weight matters if you are going to fly there. Good binary bird methods, not big bad bears.

So, unless you are in bird school and will be punished for cheating, all the cheat methods against the malice of the universe are quite welcome for me and those like me.

I will return, I hope with Mule Method(s). Need a break.

Last edited by Void (2020-04-04 16:28:17)

SpaceNut · 2020-04-04 16:21:53

I think we have a few topics in the life folder that could be a better fit for the post.
See if this one works Convergent evolution? How much convergence?

Void · 2020-04-04 16:29:57

Actually next I will get technical, or try to. I was just setting the background for why I think we might consider the technical directions I will suggest. But I need a break. But do as you wish. I am going to be very tolerant.

Void · 2020-04-04 16:56:45

There has been a dialog between Zubrin and Musk. I cannot find either wrong. And who cares what I think anyway? Why should you?

But I am bored. Being in lock down, sort of, being a good old boy about it but I will spew my mind at you if allowed under such a situation.

Zubrin suggests smaller ships to move articles useful for nesting a descendent. Musk hopes to achieve a somewhat more generic machine that can do all. I do not think to find fault with either.

But as this is "Alternate BFR", of course I want to provide for nesting materials for what we put on Mars (I hope).

This sort of attempt cannot be without the prospect of failure of what I hope for. But it is still my responsibility to give it a try when I can. My training mandates that I must try even if I don't want to.

So, with that excessive buildup... Mule Methods.

More break time I am afraid. I am retired from reality, and like it.

This will be a break of at least one day. It is not that good, really, but I have to consider the current reality.

Last edited by Void (2020-04-04 17:18:25)

Void · 2020-04-05 19:00:57

So, with an utter lack of confidence I reenter.

It looks like Elon and SpaceX are to some extent dealing with bitter moments. They are the best.

You can be prepared to be underwhelmed by what I may present. Perhaps indeed I am beneath your contempt! But I is what I is. Not much hope for more.

OK, a bird would bring to its nested children what they need, if it could. The logic here is that for a time period, they cannot get everything they need on their own. So, there is a time period of necessity. It would be wonderful if at touchdown, the first humans on Mars could get everything they needed insitu. But reality suggests that a infancy time period is required. Or if you like you can choose failure.

I have been quite entertained by the output of Zubrin. Good dude. I am not inclined to easily give my approval, but after all he seems to be something good.

I am interested in the contrast between what he proposes and what Musk intends. As I have said before I do not find fault with either.

As for blue origins, it seems a curiosity. I think it will be joined eventually.

Well, Zubrin has suggested a smaller BFR launched with a falcon 9. That so far has been rejected. I don't stake a judgement on that I understand the logic of SpaceX. I just don't know.

…..

There are many things that have confused me. Why no attention to ballistic capture methods. It seems curious to me that that is not addressed. But I suppose they have their logic. I am rather small, why should I ask these questions?

Anyway, as I understand it Zubrin wants to deliver "Stuff" to Mars, and thinks it is unwise to time bound up a delivery vessel such as the proposed Starship of SpaceX.

So there is a possible set of options between what Zubrin and Musk currently intend. I would like to work on those possible options, even if I only make a fool of myself.

Starship to Mars is proposed and yet not real in our world. SpaceX is our best hope that it will eventually become real. Bitter moments seem to be required to get there.

The starship holds cargo inside it. Not sure that is required in all hopes of method.

Cargo for the fledgling baby are the most important issues after actually establishing a human pattern replication process on Mars.

In my small opinion, we may ask what to the little children require the most? I think it might be aluminum and Fluorine.

You can feel free to offer other notions. I am going to take a break. Not trying to be a nasty joke, just need time to think further.

Last edited by Void (2020-04-05 19:40:34)

Void · 2020-04-08 10:33:28

So just for giggles, I suggest some possible methods to get special materials to Mars in the window of time where it is relatively hard to produce them on Mars. I would really hope that will be a short period of time.

I think I might have a novelty for delivering Aluminum, I do not think I have a great plan for Fluorine. I tried, but I just don't think I have it.
I have silly proposals to give, but little faith in them.

So, I will try Aluminum. I would request tolerance, because I am going to actually propose a broad spectrum of possibilities. And from my point of view, if even 1% stimulates some kind of progress, then I feel very little shame for the 99% that turned out to be useless. Most of us are trapped at home anyway, so, perhaps at the very least you can consider entertaining yourselves, by swatting me down

I will sort of get right to some type of skeleton for the notion now, or you might all fall asleep.

A variant of Starship, actually there are likely many variations. Starship now, carries cargo inside of it. And that is necessary for passage from the surface of the Earth, through the atmosphere, and to LEO. But after that we could consider playing a different kind of game. Inside out sort of. I guess I would call it a Mule ship. Boosting cargo to were you want without having the cargo inside of it, but connected to it's outside portions.

There can be any number of arguments about this. But a Mule Ship would be pretty much all propellent tanks, engines, power systems, and AI navigation. It's purpose would be to escort multiple loads to a destination. In this case I am considering Mars.

The "Loads" must then make a landing on their own. This makes things complex, but it also increases the surface area for aerobraking, which could be an advantage. Mars has such a thin atmosphere, so that more surface area is what we might want. This is the reverse of Earth, where we want less surface area in relation to mass and volume, to punch through the atmosphere. One nice thing about having multiple packages, is that when you finally master the method, you should be able to replicate it endlessly.

Any successful Mars lander to date, it's methods, could be considered. They are small, but they get something there.

But I will discuss the possible variations of "Mule Ship", and then later something really silly, a lander which is a child of a bell ship I suppose I could say. I am bored. Tolerate me please.

So, what kind of a "Mule Ship"? There could be variations.

One I am not so comfortable with would be that it serves as a booster for a collection of packages to send to Mars, then it tucks tail and heads back to Earth. In that case though there is no guiding parent for the packages. You have to make them collectively or separately competent to navigate to Mars. So, I set that one aside.

Another type would carry the packages to Mars, and release them in a timely fashion, before the brutal aeroburn(s). It would then land, but with no cargo. Each package would have to land itself. Maybe this is OK, if you intend to gently tip it over and convert it's propellant tanks to habitat. Jury is out on that in my silly universe.

I think that their could be some variations of a Mule free return. That is the parent, the "Mule Ship" would escort the packages most of the way, and then release them to land if they can. The free or semi-free "Mule Ship" would then return to Earth, with sort of a free return method. (Maybe )

I love multiple options. Just the way I am. I try to think of all of the variations. It entertains me.

So, do you use gravitational swing around? Do you partially aerobrake in the Martian atmosphere? Do you do a so called "Free Return" to Earth, maybe a discount return to Earth. If so do you land? Or do you aerobrake into Earth orbit. Maybe the Mule never lands again. Don't know. What are the real options, and what are their values?

I think I will stop defining it now, so as not to restrict possibility.

Aluminum then then on broken legs, Fluorine.

A little break.

Later, got to crash a bit.

Last edited by Void (2020-04-08 11:52:08)

Void · 2020-04-08 16:08:04

So, the Aluminum thing is no great deal. Just a way of heat-sinking aerobraking energy.

In one version it would simply be a metal sandwich. Say two layers of stainless steel, and Aluminum as the peanut butter between them.

To make it simple, you melt the Aluminum, while atmospheric entry. Then before impact/landing, you quench it with a cold fluid. Say liquid Hydrogen, or Methane.

Then you hope not to blow up, until you want to. Hopefully you pop a cork and do an explosive boiler landing. Have not yet felt entirely secure about how to control that. But it would definitely deliver some Aluminum to a location.

Maybe it is useless. But I think that Aluminum will be wanted for reflective coatings for Heliostats, and for electrical conductors, before it can be manufactured on Mars. So, if delivered, in such a way might accelerate the growth of the community established on Mar.

There are other sandwich combinations which could be considered, different materials.

An explosive boiler landing would be exciting if it did not explode you.

Ideally the stainless steel would be made useful by repurpose as well.

Another break.

Last edited by Void (2020-04-08 16:16:56)

Void · 2020-04-09 18:21:48

Resting for contemplation again I am afraid.

Void · 2020-04-12 11:53:10

Fluorine then, as far I as I got. Not too satisfied with any methods, but who knows, maybe somebodies mind will spark to a method I could not conceive of.

Robert Dyck has some responsibility for this. Fluorine in plastics apparently survives rather well, in very hostile conditions, perhaps at locations of Mars.

I am going to think of ETFE for now unless corrected by the membership.
https://en.wikipedia.org/wiki/ETFE
Quote from the above reference:

ETFE has an approximate tensile strength of 42 MPa (6100 psi), with a working temperature range of 89 K to 423 K (−185 °C to +150 °C or −300 °F to +300 °F).[3]

So, do not burn it.

Fluorine is going to be a mean task to accomplish on Mars. Some day....But to deliver some could be of value. But it is just a nasty stuff, except if not overheated, and being bonded to Carbon, as ETFE seems to be.

In a "pixie" world, I would just like to dump bubbles of the material out of a Mule ship, inflate them and wish they could survive atmospheric entry, and tolerate the harsh situation. In the real world, almost certainly that is not going to work.

See post #357 for "Mule Method".

But I am going to play with the Pixies for a while, and so at least define better what the problems might be with such a method.

Obviously if you just wanted to put some ETFE into a Starship hold, that is a reasonable counter proposal. However, I wish to try a different way.

OK, so in the Pixie engineering world, you can inflate the ETFE bubbles, enter them into the atmosphere at high speed, they survive, and if you were extremely capable, they reach a survivable terminal velocity, impact nice ground such as a sand dune, and bounce, or even pop in a planned way. And so something of use survives. I can certainly see how this will be impossible to extremely hard. Still, that is the reference point opposite to landing ETFE in a Starship.

Assuming it is even worth a try, then the first problem is when to inflate the bubbles. I do not think you want to do it early because Micrometeorites may easily put holes in an inflated bubble, and also U.V. in the raw space environment will reduce the life time for the materials, or so I suppose.

Last edited by Void (2020-04-12 12:34:43)

RobertDyck · 2020-04-12 12:37:52

Sorry, what is this about?

I started looking at plastics for an inflatable greenhouse. In Robert Zubrin's book "The Case for Mars", he suggested an inflatable greenhouse for Mars Direct, including the first science mission. Makes sense. After some more reading, I found a paper about inflatable greenhouse in the "Case for Mars" papers, before the founding of the Mars Society. Author was Dr. Penelope Boston of the Ames Research Center. So I spoke to her at a Mars Society convention. She said she didn't think there was a plastic film that could survive the UV conditions in Utah much less Mars. Ok, I took that as a challenge, work to find one that would work. Brought samples to show her at the following year's convention.

ETFE is the obvious choice, because it's the "premium" film used for greenhouses on Earth today. But specs from actual manufacturers said the service temperature only went down to -80°C. Temperature on Mars gets colder than that at night in winter. Wikipedia is a great start, I use it all the time, but you have to look deeper. I wasn't able to find a manufacturer who made ETFE with a service temperature range as cold as Mars. Second problem was UV endurance. One manufacturer tested it outdoors for 20 years in Florida, but that's Florida. Florida is low altitude, on the ocean coast, with high humidity to block UV. Dr. Boston reported it wouldn't survive at MDRS in Utah. Then there's gas permeability, which means gas and moisture just passing through the film. ETFE is pretty good, but not perfect.

Then I found PCTFE. Technical document from the manufacturer says service temperature -240°C to +132°C. It's the most impermeable to water or moisture of any polymer known to man. (um, humans) It's highly impermeable to oxygen; so much so that the only polymer film I've found more impermeable to oxygen become brittle at -60°C or warmer. It's extremely UV durable. One reason it's so durable to UV is that UV just passes right through.

Of course one technique you can use with any polymer film is to metalize it. A metal coating will clog the pores, making it more impermeable. You will have to add a spectrally selective coating to any greenhouse, whether polymer film or glass. Mars has such a thin ozone layer that for all practical purposes it's not there. On Earth the ozone layer blocks all UV-C and most UV-B, but on Mars they get right down to the surface. UV-C will sterilize; can cause severe sunburn and skin cancer. Plants react just as badly to UV. NASA developed a spectrally selective coating for spacecraft and space station windows: a very thin, vacuum deposited layer of gold, nickel, and silver oxide. Only silver is oxidized. The silver oxide mostly reflect IR light, for radiant heat control. The result transmits 85% of visible light. There are other newer coatings, but the metal coating has the added benefit of clogging polymer film pours.

ETFE is a co-polymer. A polymer of TFE is known as PTFE: Poly-Tetra-Fluoro-Ethylene. TFE is ethylene with all of the hydrogen atoms replaced with fluorine. Regular ethylene is C2H4, TFE is C2F4. ETFE stands for EthyleneTetraFluoroEthylene (capitals added to show the acronym); it alternates ethylene and TFE. Molecule looks like this:

PCTFE is made from only one monomer, so a simple polymer. It's monomer CTFE is similar to TFE but one of the hydrogen (or fluorine) atoms is replaced with chlorine. It looks like...

Yea, don't burn it. Fluorine is nasty.

Void · 2020-04-12 12:46:16

Thank you Robert. Yes, I appreciate having some defining of limitations. Essentially, when I imagine sending something to Mars, I see it as hopefully more than it's end use, but to be capable of helping to get itself there. So, yes, I will venture into stupid here. It is pixie engineering after all. Then later I will try to tighten up to some hope of a plausible method.

Nice to see you again sir.

Last edited by Void (2020-04-12 12:51:38)

Void · 2020-04-12 12:54:30

The next problem for the bubbles is atmospheric entry. The material(s), have some heat tolerance, but I fear, not enough, even with an ideal ratio of surface area to volume and mass. Problem is if you add protective devices, then those protective devices have mass as well, and will then need to have their inertia successfully dissipated. After all what we would want is the delivery of some useful article to the surface of Mars.

I have said before, that I am not too satisfied with my solutions for this problem, but I will continue to try.

I have very serious concerns about trying to bring a plastic bubble into atmospheric entry of Mars, I can suggest that the problem can be reduced by using a ballistic capture method, I think, maybe.

But I would like to set aside the atmospheric entry problem and consider the lower atmospheric process. In this case, just a bubble, what is its terminal velocity on Mars? You must know by now, I do not work with math that well. We have not defined the nature of the bubble, so there could be many variables. I hate to get down to precision math, before having a better definition of possibilities. It can likely be a somewhat waste of time. Coarse adjustments, then fine adjustments. Otherwise you will finish up far beyond chances.

I am thinking an impact at the terminal velocity, and a giant flatulence, if you could observe that. To dissipate energy of course.

So, if it is possible to land a complex instrument on Mars, in part using air bags, and if air bags can protect people to some extent in car crashes, can an air bag protect itself, if it has no other task? I am inclined to feel just a bit comfortable about this part. I think it could, even on Mars.

Last edited by Void (2020-04-12 13:21:50)

tahanson43206 · 2020-04-12 13:14:08

For Void re #363 and bubbles in general

Your idea is intriguing. As a thought experiment, could I offer a suggestion for your evaluation?

If the idea does not work (following your example) I will not be offended if it is discarded.

Suppose your bubble factory is on Phobos!

Phobos is my favorite location for just about everything relating to Mars, as my history in this forum will confirm.

Let your bubbles be accelerated in the wake of Phobos passage, so that the relative velocity of the bubbles with respect to the atmosphere is zero. Then (of course) the bubbles will be attracted to Mars, and they will accelerate toward Mars at whatever rate applies in that situation. I am confident the velocity (whatever it is) will be less than that of Phobos, and CERTAINLY less than the velocity if the bubbles were arriving from Earth (see GW Johnson calculations for details).

Thus, the bubbles would descend relatively gently into the already rarefied atmosphere of Mars.

Depending upon what they contain, the bubbles might even bounce upon arrival at the surface, where they could be collected by industrious robots or grizzled Mars prospectors out for a leisurely stroll.

(th)

RobertDyck · 2020-04-12 13:19:00

So what are you trying to do? Deliver bulk materials to the surface? You'll need an atmospheric entry vehicle of some sort. Any of the fluorocarbons will burn up in the heat of atmospheric entry. No parachute, just crash into the surface? Ok. Expect any film will get torn, and machined parts will get bent or broken. But if you want bulk materials that can be melted down, Ok.

One option is a heat shield with a traditional ablative heat shield. Another option is a metal heat shield: Inconel-617 or Rene-41. These two alloys are both nickel-chrome with cobalt, molybdenum, aluminum, and carbon. Only difference is a fraction of a percent more of this, less of that. Differences are so slight they're practically the same; different name implies different manufacturer. Rene-41 was the metal used for the outer hull of Mercury and Gemini capsules. Inconel-617 is the metal NASA considered in the 21st century. The advanced thermal blanket called DurAFRSI developed by NASA Ames has an outer surface of Inconel-617 foil.

Another option is a fabric heat shield that opens like an umbrella. The one chosen for Mars Direct was ADEPT, which uses a carbon fibre fabric and titanium alloy ribs. NASA was working on it in the '80s so was current technology at the time of Mars Direct. You could use Nextel-440, the fabric beneath the foil of DurAFRSI. It's a synthetic ceramic fibre spun as threads and woven to form a fabric. Carbon fibre can withstand more heat, but Nextel-440 is more durable for multiple uses. Of course if you plan to crash, reuse is not an issue.

Then there's HIAD. Also a fabric heat shield, but uses an inflatable to support the structure instead of metal ribs. Requires a thermal gel to separate the fabric heat shield from inflatable, to ensure the inflatable doesn't melt.

Void · 2020-04-12 13:24:39

Thanks guys (I presume). Um nasties have shown up on the site. I am going to take a brake. Not at all done.

RobertDyck · 2020-04-12 13:24:42

Terminal velocity: https://space.stackexchange.com/questio … ty-on-mars

Terminal velocity on Mars (from Scientific American):

Even though the surface gravity on Mars is only 3.7 meters/sec (compared to 9.8 meters/sec on Earth), the thin atmosphere means that the average terminal velocity hits a nail-biting 1,000 km/hour or so, compared to about 200 km/hour back home. That means you have to do a lot more work to shed speed.

RobertDyck · 2020-04-12 13:26:22

Nasties? Is this not a crash landing? Is this a bounce landing like Mars Pathfinder / Spirit / Opportunity? Not trying to be nasty, just trying to understand what we're doing.

tahanson43206 · 2020-04-12 14:56:19

For RobertDyck re #368 "Nasties" ... Void has had problems with his home system for as long as I've been following his posts.

It's not clear (to me at least) what he's referring to.

However, for your post #367 ... thank YOU for clarifying my incorrect understanding of what a fall from a fixed position over Mars would be like.

On Earth, where that experiment was tried, the experimenter (I'm working from memory) was lifted by a balloon to a significant altitude, so (as I recall) the bulk of the atmosphere was below. That experiment showed that it would be possible to survive such a fall, but (again as I recall) there were some stability issues that made the flight risky. The density of the atmosphere lower down provided the medium for a parachute (or two) to provide a happy end to the story.

On Mars, that happy result seems unlikely, unless Void's bubbles can withstand that 1000 km/hour bounce.

I ran a quick Google search looking for any research that might have been done on the subject of collisions of elastic balls, but didn't find anything that seemed directly applicable.

The bouncing "balls" used by NASA for one of the early probe landings had relatively slow velocity to contend with, after earlier measures had slowed the velocity of the package in the upper atmosphere.

As I was understanding Void's idea, a "ball" (bubble) of some material could (presumably) deliver a supply of ? gas ? to the surface of Mars.

The material comprising the shell of the ball would have to be able to withstand a collision at 1000 km/hour (using my theory of a drop from a dead stop), but it seems possible to me there may be a material with that kind of durability.

(th)

Last edited by tahanson43206 (2020-04-12 14:57:18)

RobertDyck · 2020-04-12 16:37:17

Mars Pathfinder was the first to successfully land using the bound-and-roll technique. Russia came up with the idea, but didn't get it to work. NASA found they had to surround the air bag with multiple layers of very tough fabric. A single layer no matter how strong or heavy would not survive their tests. They tested in a vacuum chamber, with a full-size test article dropped onto a board at an angle to simulate an angled landing, and with various rocks attached to the board. The vacuum chamber was filled with the same gas mix as Mars atmosphere, the same pressure and temperature. Inside the lander was a tetrahedron: 4 sided shape with triangle faces. It didn't matter which face ended on the bottom, when it opened it always end up facing the right side up.

If the goal is to deliver gas, then it doesn't matter of the lander survives. If you want to deliver raw material that will be melted and shaped, it doesn't matter if it gets bent or mangled. If you want to land machinery, impact force becomes relevant. Mars Pathfinder used an aeroshell consisting of heat shield and back shell for high speed atmospheric entry, then a parachute.

Mars Exploration Rover (Spirit/Opportunity) did the same. MER hit the top of Mars atmosphere at 12,000 mph. Surface of heat shield: 5,000 - 6,000°C, shell skin temperature 1,600°C, inside was room temperature. Parachute opened at Mach 2 = 1,000 mph. Retro-rockets on the back shell slowed from 150 mph to zero before cutting the bridle (rope) holding the lander. It dropped 15 - 20 metres above the surface. First impact: 40G.
https://youtu.be/Ij33yhdGn_g

tahanson43206 · 2020-04-12 17:28:52

For RobertDyck re #370 and the entire sequence about bubbles

Void has taken the topic seriously off in a new direction.

I went back and looked, and this topic ** was ** created by Void, and it was set up from the beginning to explore alternatives to traditional rocketry.

Interplanetary transportation seems the right Index level topic for Bubble Gas Delivery systems.

If such a topic were to come into existence, reasonable goals would be to find the range of options to turn Void's interesting idea into a practical delivery system. What I am imagining is discovery of a size of bubble (eg, 10 meters in diameter), mass (to be derived using Physics), and content (type of gas to be delivered) as well as shell material for optimum cost effective performance.

To keep things reasonable, I propose the concept of dead stop drop be accepted as the mode of operation. The bubble (whatever it turns out to be) would be released at (effectively infinity) and allowed to fall toward Mars. In the descent, the bubble would experience deceleration and heating as it encounters the atmosphere. I suspect (without having read the reference you provided from Scientific American) that even though the atmosphere is tenuous, a sphere of sufficient size and the optimum mass (whatever that turns out to be) could bounce on the surface of Mars without bursting. Thus, useful gases could be delivered to a community on Mars without the expense of rocket systems and the fuel they require.

The material of the bubble (whatever that turns out to be) would itself have value in the Martian economy. A thin, extremely tough material would seem usable for pressure chambers. One option would be to cut the sphere in half to make two hemi-spheres which could hold pressure for habitat, work area or perhaps even for greenhouse areas.

***
I just noticed you are listed as a moderator. In the absence of SpaceNut, I notice that the spammers are testing the waters, to see if they will be evicted.

Depending upon the powers you have, you may (or may not) be able to deal with the spam folks.

(th)

Last edited by tahanson43206 (2020-04-16 06:48:25)

Void · 2020-04-15 19:59:24

I appreciate what you guys have done in my absence. You are not the nasties.

Give me a bit of a break though, today for my stupidity. I have been a bit sick I think my head is functioning somewhat well. It wasn't that last few days. I felt a bit off. Chills, disorientation, digestive system problems, vomited suddenly today, everything, down to a proper dry heave. But it could be just that my diet and life style has had to change with all the social distancing. I'm monitoring it. I will go to help if it turns out to be the big bad wolf.

What I was after is to deliver a Fluorine/Carbon bubble web to the surface, "T" is close. I have worked around Fluorine, and know it is nasty stuff. And getting transparent glazes is a tough deal. I know you have worked on glass insitu for Mars Mr. "R". And as (Almost) always I always would what to have whatever we could have.

I do understand some of the problems are horrendous, but I sometimes like a challenge.

Terminal velocity for Starship could be very large. For a bubble of your favorite plastic it could be less large. For this instance, we are not delivering a robot to the surface. The air bag is it's own air bag. (In this example).

A similar idea is a Starship "Mule". It will be it's own cargo, if it is decided to land it on Mars, after it's service life is concluded. No payload. Propellant tanks, engines, no cargo hold, AI, Else as needed. Therefore it should have more surface area for unit of mass and volume than a standard Mars delivered Starship. And so a more favorable terminal velocity.

A prelude to other things.
https://www.bing.com/videos/search?q=ji … &FORM=VIRE

Mule Ships might carry bubbles on their back and dump them off to inflate before impact/Mule ship landing. Of course the bubbles have to be protected during the heat of entry to the atmosphere of Mars, and then deployed appropriately and very quickly. Flopping them down on a sand dune would be a great preference, or onto CO2 Snow.

You would need a sufficiently sound landing pad for the Mule ship. Or maybe it enters the atmosphere of Mars, releases the bubbles, and somehow has enough fuel to rocket back out into space and have a return path to Earth (Maybe, depending on the price of fuel.

That seems like fun to think about. Levels of success??? Eh???

Anyway one of my more recent dream devices, would deliver Aluminum, and a Fluorine plastic film as part of a delivery ship carried to Mars by a Mule ship. Also included would be some steel shells, (Pica where required), maybe a super fast parachute, and a tank of Hydrogen or Methane (Liquid). And some AI brains, and a steam rocket engine(s).

This is a lot to play with. OK is the protective outer device like a Viking Aero shell? or like an Apollo capsule, (Er Dragon).?

I have previously mentioned metal melt sandwiches in earlier posts. In this case my best example might be two stainless steel walls with Aluminum to melt. That would be a "Heat Sink" heat shield (You would also use Pica or an ablative of transpire cooling as necessary).

In a pixie world, you would have the Mule Ship release these things before any of the items entered the atmosphere. The Mule Ship would be an escort up to that time. All the way from Earth. Then the Mule Ship behaves according to any on of several options, for itself. The released objects are then on their own. To enter the Martian atmosphere.

So, it has been a bit of a desire of mine to recapture some of the energy of travel from Earth to Mars, using a method.

In this case, I am imagining that the Aluminum sandwich melts during re-entry, and so stores some molecular vibrations taken from the friction of atmospheric slow down. That heat is then available for a propulsion device, if you were to "Squirt/Quench" a cold fluid on it. Such as Hydrogen or Methane. If you want you can forget the plastic film, but I am going to include it in this example. Once you have entered the atmosphere, you are free to slow the craft down with a parachute, if you value that. And you might consider thrusting with the steam vapors of Hydrogen or Methane, to slow down and aim the ship.

As you hope to aim at a sand dune, you may (Just maybe be able to inflate a balloon of a Fluorine plastic extending out of the top of the ship. (Door, hatches required). You might be able to inflate the bag to a significant pressure to be useful in a landing of the device. A sort of a boiler tank. And so the big hope is as you approach the sand, dune you expel a significant amount of gas to be useful. Directed downward towards the sand dune. As you approach, you might even get a hovercraft cushion under the device.

Ideally the exhaust would serve to fluidize the particles of the dune in a gas and particle slurry which I hope would further cushion the landing. That would be an ideal splashing down on a temporarily fluidized sand dune.

I think it might not be totally bad. Maybe others will add to it and shift to something better.

That would be great.

Last edited by Void (2020-04-15 21:14:10)

tahanson43206 · 2020-04-16 07:05:12

For Void re this new addition to the topic ...

I went back and looked, and "discovered" that this topic was created by you, and it was created (as I understand it) specifically to look at alternatives to traditional rocket transport, specifically as imagined by SpaceX.

In light of that "discovery", the new direction you are heading, toward finding a practical way to deliver substantial quantities of various gases to the surface of Mars in the most efficient, cost effective way possible, and (ultimately) with the least risk to passengers, seems quite promising.

I have not made time to study your most recent post closely (#372).

This purpose of ** this ** post is to inform you of my better understanding of the new direction you are looking in the context of the topic as a whole.

You had mentioned a few posts back that the "bubble" delivery system concept needs some math to back up the ideas you are exploring. I'd very much like to see some math developed to show that your basic premise (as I understand it) is valid, and that real-world gas delivery systems could be built in competition with traditional rocket transportation.

In broad brush terms, I am imagining a mass delivery system that employs the buoyancy of Hydrogen to deliver payload to the surface of Mars gently, after completing descent from at Dead Stop velocity, after departure from Phobos.

For a while, if you allow me to continue, we will be working in parallel without much overlap, but perhaps there will come a time when your exploration of this approach will increase in overlap with mine.

The first problem I am trying to address is how to find a computational solution to show that a hydrogen filled balloon would indeed survive a Dead Drop fall from the orbit of Phobos.

There is a robust field of computing that applies directly to this situation.

Scholarly articles for gas dynamics simulation software
Simulation and analysis of gas networks - Osiadacz - Cited by 557
… codes for the numerical simulation of the gas dynamics … - Van den Berg - Cited by 17
… of the direct simulation Monte Carlo method - LeBeau - Cited by 163
Web results
Computational Fluid Dynamics Simulation Software (CFD ...www.simscale.com › product › cfd
Computational Fluid Dynamics (CFD) is the branch of CAE that simulates fluid motion and heat transfer using numerical approaches. Our CFD software can ...
SimFlow CFD Simulation Software - SimFlow CFD Softwaresim-flow.com › download › cfd-simulation-software
SimFlow CFD Software for your everyday needs. Download simFlow for free (Windows and Linux). Powerful tool for Computational Fluid Dynamics simulation ...
Flowsquare | The free, handy, integrated, Computational Fluid ...flowsquare.com
Jun 6, 2019 - Above video: Room AC (heating) simulation simulated by up-to-date ... is a two-dimensional computational fluid dynamics (CFD) software for ...
How to use? · License Types | Flowsquare · Your first simulation | Flowsquare · FAQ
Computational fluid dynamics simulation ... - Autodesk CFDwww.autodesk.com › products › cfd › overview
Autodesk® CFD software provides flexible fluid flow and thermal simulation tools with improved reliability and performance. Compare design alternatives, and ...

A couple of years ago, when I last looked at the field, there was only one free package, and I found it sufficiently challenging to use I set it aside.

I found the name in the quote below: OpenFoam

The list above shows that there appear to be more offerings along that line, while the commercial field has grown significantly in capability.

About 7,540,000 results (0.44 seconds)
Search Results
Web results
Comparing CFD Software — Resolved Analytics CFD ...www.resolvedanalytics.com › theflux › comparing-cfd-software
Comparing CFD Software. Part 1: CAD Embedded CFD Software Packages - Featuring SolidWorks Flow Simulation, Autodesk CFD, ANSYS Discovery Live and more. Part 2: Open-Source CFD Software Packages - Featuring OpenFOAM. Part 3: Semi-Comprehensive CFD Software Packages - Featuring COMSOL CFD, CONVERGE CFD and NUMECA OMNIS.
Comparing CFD Software - Part 4: Comprehensive CFD ...www.resolvedanalytics.com › theflux › comparing-cfd-software-part-...
Aug 7, 2019 - Part 4 of our series on Comparing CFD Software discusses two of the best in class “comprehensive” CFD packages out there: Siemens ...
Top Computational Fluid Dynamics (CFD) Software: List ...www3.technologyevaluation.com › category › computational-fluid-d...
Select the best computational fluid dynamics (cfd) software for your organization . Get reviews/ratings, cost, feature lists, comparisons and more.
What is a comparison of the major CFD software packages ...www.quora.com › What-is-a-comparison-of-the-major-CFD-software-...
10 answers
Sep 16, 2016 - While OpenFoam is a CFD program, ANSYS is a Computer Aided Engineering (CAE) Software Developer. Some of the Computational Fluid Dynamics (CFD) ...
Which is the best CFD software? - Quora 4 answers Oct 28, 2017
Which is the most accurate, easy to use and cheapest ... 3 answers Apr 18, 2019
Which is the best free computational fluid dynamics ... 7 answers Jan 29, 2016
Which is the best simulation software in the CFD ... 6 answers Aug 11, 2015
More results from www.quora.com

(th)

tahanson43206 · 2020-04-16 13:05:55

For Void re Bubble Gas Delivery system for Mars ...

Assuming for the moment we are the only folks working this problem, I decided to see what resources might be available.

I asked Google for help computing the drag of a ball in air. The result set is encouraging. The example of a soccer ball in air is comparable.

That is a light weight sphere which we can most certainly imagine dropping from a Dead Stop at the elevation of Phobos at Mars.

Lacking the sophisticated tools of "real" researchers, we might have to break the problem into sections.

The ball would accelerate toward the center of Mars at the theoretical rate until it reaches the first molecules of atmosphere.

The question to be answered is whether the light mass of the ball will protect it from the heat of impact at the various stages of the journey.

In the mean time, since you have reported having been exposed to computer languages in the past, here is the list of possible resources:

Search Results
Web results
Drag on a Soccer Ball - NASAwww.grc.nasa.gov › WWW › airplane › socdrag
Computer graphics of ball with the equations to determine the aerodynamic drag of soccer ball. As an object moves through the air, the air resists the motion of ...
People also ask
How do you calculate drag force in air?
How do you calculate drag?
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Feedback
Web results
Drag of a Sphere - NASAwww.grc.nasa.gov › www › airplane › dragsphere
Where D is equal to the drag, rho is the air density, V is the velocity , A is a ... flow past a sphere, but is a little easier to compute and understand because of the ...
Let's Study Air Resistance—With Coffee Filters | WIREDwww.wired.com › 2017/04 › lets-study-air-resistance-c...
Apr 4, 2017 - But if I look at something like a falling tennis ball, the drag force will just be too small to even notice. The solution is to drop something with a ...

I am guessing .... or perhaps we could say, my hypothesis is that "there exists a combination of sphere size, sphere mass and sphere buoyancy that would permit it to survive a fall from Phobos to Mars".

Edit#1: The payoff for success finding the "magic" combination is the opportunity to publish the results in a more prestigious location than the New Mars forum.

Edit#2: this NASA site addresses the specific situation under discussion:
https://www.grc.nasa.gov/www/k-12/airplane/falling.html

A factor which may not be addressed is buoyancy of the sphere.

Momentum will be gained by the sphere as it descends through the upper atmosphere of Mars.

At some point, if the design allows drag to equal the weight of the sphere, acceleration will hold not continue.

What remains to be computed is any potential benefit of buoyancy of the enclosed gas inside the sphere.

The ideal result would be for the package to arrive at the surface of Mars with a net zero velocity at the desired destination.

(th)

Last edited by tahanson43206 (2020-04-16 18:35:32)

elderflower · 2020-04-18 03:02:07

Another factor you will have to consider is the great variability of the Martian atmosphere from place to place and from time to time. A solution that works for a low terminal velocity at ~11mbar and 0-10C (daytime, Hellas) may not work at half the pressure applying at higher elevation, or at night.

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