Alternate BFR (Big Falcon Rocket)

tahanson43206 · 2020-04-18 06:32:40

For elderflower re #375

Thank you for adding this set of factors for consideration for planning Void's concept in practice.

A mission planner (on Phobos for example) will have (I am predicting) a computer program able to accept the inputs for a given flight, so the factors you have identified will (surely) be included before a computation is performed.

If a customer can accept some delay before shipment, then (I would expect) the mission planner would seek a time when the optimum conditions would exist so that the payload delivered can be maximized. Thus, the altitude of the customer site, the temperature of the atmosphere, and perhaps wind flow levels would be entered into the program.

The mission planner would (presumably) be able to control the time of launch of the Dead Stop mechanism, but (assuming Phobos as the launch site) the orbit of Phobos itself would constrain the options available to some extent. However, there is no reason (I can think of right now) why the launch has to be directly astern of Phobos. There could be some inclination North or South of the orbit, and the amount of momentum imparted to the carrier/payload package could be varied, to achieve some level of flexibility in meeting customer requirements.

At this point, in the absence of someone knowledgeable about and skilled in application of calculus, let alone computational fluid dynamics, and (I must point out) in the absence of Void himself, I am trying to puzzle out a reasonably workable solution to how to estimate the potential payload that might be delivered to the surface of Mars using this method.

The NASA web page shown in Post #374 seems (to me at least) to point the way forward.

I found a YouTube video in which a professor of a university whose name I recognized offered a whiteboard solution of the calculus needed to find the velocity of a sphere moving through a fluid in a gravitational field. The result of the session was an equation that purported to show the velocity of the sphere at a point in time (t), given input of the various factors applicable in the situation.

For elderflower, I'll point out that the professor's solution included all the factors you've identified in a single term (D) drag. The actual mission planner in the situation we are discussing here would (presumably) need the ** exact ** factors in play at the proposed moment of deployment of the package.

However, what I am imagining might be possible while we wait for an engineer to show up, is to compute a series of points using the professor's equation, using a simple loop that iterates over the time of descent of the package.

The Drag factor might be estimated from the elevation of the package over the surface of Mars at time (t). The size of the sphere would be varied in an outer loop, if the checkout of the first loop passes muster.

A factor which applies in this situation which the professor's solution did NOT consider was negative Drag ... ie, buoyancy if the gas being delivered to the surface is hydrogen. Hydrogen would be a highly salable commodity on the surface of Mars for quite some time, if not forever, and the vendor who can deliver a required quantity at the best price will (all else being equal) win the contract.

In another topic (comet harvesting) it was reported that a rich potential harvest of valuable materials passed within 85,000 miles of Mars in 2014. There was no one there to take advantage of that opportunity, and there is no way (that I know of) to predict another such potentially attractive opportunity will occur.

Edit#1: There ** were ** a number of spacecraft in orbit around Mars at the time, from several nations, and a concerted effort was made to extract as much scientific data as possible from this fortuitous circumstance. What ** this ** post is about is ** harvesting ** the actual comet material.

Void has been talking about delivering other valuable gas payloads to the surface of Mars. His most recent focus was Fluorine.

It might be possible to deliver the gas itself to the surface of Mars in a suitable enclosure. However, another way to approach the problem is to deliver fluorine to the surface in a package composed of one of the solid compounds made from fluorine, and then perform the chemical reactions on Mars needed to produce the desired end product.

From the stand point of a shipper, sending a payload of a solid compound of fluorine in a package delivered by a hydrogen balloon would require a ** lot ** less hazard pay for workers. Every part of the delivery package would be salable, as discussed earlier in this topic.

For elderflower, thanks again for pointing out some of the factors that go into the (D) Drag component of the velocity equation!

(th)

Last edited by tahanson43206 (2020-04-18 06:37:06)

tahanson43206 · 2020-04-18 14:11:45

This is a follow up to the caution posted by elderflower regarding the variability of the Martian atmosphere.

The issue is a concern now for anyone trying to calculate the potential viability of Void's bubble gas delivery idea, and it would certainly be a concern for a shipper trying to find the optimum solution for delivery of a particular cargo to a particular customer on the surface of Mars.

https://planetary-science.org/mars-rese … tmosphere/

Atmosphere
Mars lost its magnetosphere 4 billion years ago, so the solar wind interacts directly with the Martian ionosphere, lowering the atmospheric density by stripping away atoms from the outer layer. Both Mars Global Surveyor and Mars Express have detected ionised atmospheric particles trailing off into space behind Mars, and this atmospheric loss will be studied by the upcoming MAVEN orbiter. Compared to Earth, the atmosphere of Mars is quite rarefied. Atmospheric pressure on the surface today ranges from a low of 30 Pa (0.030 kPa) on Olympus Mons to over 1,155 Pa (1.155 kPa) in Hellas Planitia, with a mean pressure at the surface level of 600 Pa (0.60 kPa). The highest atmospheric density on Mars is equal to the density found 35 km above the Earth’s surface. The resulting mean surface pressure is only 0.6% of that of the Earth (101.3 kPa). The scale height of the atmosphere is about 10.8 km, which is higher than Earth’s (6 km) because the surface gravity of Mars is only about 38% of Earth’s, an effect offset by both the lower temperature and 50% higher average molecular weight of the atmosphere of Mars. The atmosphere of Mars consists of about 95% carbon dioxide, 3% nitrogen, 1.6% argon and contains traces of oxygen and water. The atmosphere is quite dusty, containing particulates about 1.5 µm in diameter which give the Martian sky a tawny color when seen from the surface.

The first observation I would make about the text above is the note that the highest density on Mars is comparable to that found on Earth at 35 km. The height of Mount Everest is given (by Google and friends) as about 9 km.

A quick check with Google regarding the greatest elevation achieved by hydrogen balloons on Earth revealed:

High-altitude balloon - Wikipedia
OverviewHistoryUsesAmateur high-altitude ballooningGeostationary balloon satelliteSee alsoExternal links
High-altitude balloons are manned or unmanned balloons, usually filled with helium or hydrogen, or in some cases methane, that are released into the stratosphere, generally attaining between 18 and 37 km (11 and 23 mi; 59,000 and 121,000 ft) above sea level. In 2002, a balloon named BU60-1 reached a record altitude of 53.0 km (32.9 mi; 173,900 ft).

The figure of 53 km given in the quote above suggests (to me at least) that in the atmosphere of Earth, a balloon can achieve neutral buoyancy at an altitude well above the Mars equivalent of 38 km. How the density of Earth's atmosphere compares to that of Mars at an altitude 15 km is a question to be answered. However, assuming for a moment the two are comparable, then the implication is that a hydrogen balloon would begin to experience buoyancy 15 km above the lowest point on Mars.

A computer model of the situation would be a nice piece of work.

Edit#1: This Google search was productive: how to compute drag at various altitudes

One of the citations (from NASA) warned that trying to compute drag is complex.

Interestingly (to me at least) the search yielded citations about balloons in the first page top-tier result set.

(th)

Last edited by tahanson43206 (2020-04-18 14:46:58)

Void · 2020-04-18 19:08:46

"E" and "T", enjoyed your thinking.

Um... Mostly going to let this rest, but I do make the observation per Elderflowers comment, that yes northern hemisphere, and perhaps Hellas in the south, may be the most promising hope. I do consider seasonal effects as well. Probably cold air is better, and even though CO2 Snow is not as soft as our water snow, it may give some cushioning. It probably would keep the bubble from being damaged by rocks.

Thanks for all the research "T".

tahanson43206 · 2020-04-19 05:56:54

For Void re #378

In these worrying times, it is good to see your post in the lineup this Sol.

Thanks for the support for elderflower's observations. Your creative thinking is evident throughout the many posts you have authored in this forum. At least one deserves to be brought from inspiration to perspiration, and this one looks like a strong candidate.

The discovery yesterday of the similarity between the stretch of Earth's atmosphere between 53 km high, and 38 km low, and the atmosphere of Mars is helpful, because it leads to the practical option of sending a test article straight up, loaded with radio equipment and sensors of various kinds, to test the hypothesis that a well chosen mixture of gases and envelope material can safely deliver a payload to the 38 km destination. If all goes well, after a vertical descent from well above 53 km, the capsule would settle into a steady float state at 38 km, simulating a successful landing on Mars.

That would be a demonstration of principle that should lead to (at least serious consideration of) an experiment for trial at Mars, whether by NASA, ESA, or by any of the other national space organizations that exist today or will come into being.

I will attempt to recruit the kind of person (talent, education, positive motivation, available computer hardware and software) who can make short work of the theoretical aspects of the current study. However, in the absence of such a person, I will continue trying to puzzle out how to build a theoretical case for the idea. While your participation will be limited, your moral support will be welcome, and if something comes of your idea, you will be able to take a modest bow for your preeminence in the field of Bubble Package Delivery.

An approach to the problem is to ignore the complexity of the atmospheric density changes, and simply interpolate from the low density at 53 km on Earth, and the 38 km level on Earth. If that were done, then the density could be increased by some small amount for each meter of descent, and the Drag(D) value could be derived from the density and other factors to permit computation of the velocity(V) available from the professor's YouTube presentation.

A factor that should come into play is the beneficial effect of heating the gas inside the balloon as it descends, due to heating of the atmosphere encountered by the descending object. The transfer of thermal energy into the interior of the balloon will inevitably increase internal pressure, and deliver a more rounded shape, so that at the time of maximum density of the atmosphere (ie, 38 km) the balloon itself will be fully expanded to a near perfect sphere and toasty warm with Hydrogen gas. The heating, of course, will increase the buoyancy of the package, just as it is most needed. On Mars, the package would have reached the surface, and a handy robot or teleoperation machines will secure the tie down lines. On Earth, the balloon will cool down, and hydrogen will leak out of the envelope, and the package will slowly descend after a random voyage of many miles in the caress of winds aloft.

(th)

Last edited by tahanson43206 (2020-04-19 09:41:33)

Void · 2020-04-19 12:14:26

That seems encouraging. Heated Hydrogen.

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

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]
ETFE resins are resistant to ultraviolet light. An accelerated weathering test (comparable to 30 years’ exposure) produced almost no signs of film deterioration.[4]

I know that Robert has other candidates, and that is completely fine. I am just familiar with the above one, so feel more comfortable that some of my assertions are close to right.

While it appears to me that you might be intrigued by the "Naked" balloon going into the atmosphere without assistive protection, I will say that I think I can see a partnership between the balloon and a protective shell to achieve what we may desire.

It can be a game of getting the "Mostest" for the "Leastest" Perhaps fun for some.

Think of this as a picture of a way. There could be many other ways as well.

Dr. Robert Zubrin has said that there are chances that a starship landing on the Moon might make a crater and so push projectiles also into Moon and even Earth orbits. For Mars, he says that this would not be such a problem. I am thinking "Sand Dune" again. He also says why do you want to bring back a Starship, when it is the size of an apartment building. Of course I think that there can be many options.

So, what if you worked out a way to harness the problem to suit your needs?

I have mentioned what I would call a "Mule Ship". This would be a starship that is virtually all propellant tanks, engines, AI, and whatever else is needed. No cargo holds. When it has completed it's estimated service life, can we use the crater method to poke it into a sand dune partway. It would not need legs. I think it would be tricky business, but entertaining.

Could the ship have also carried several balloon containing capsules on its back in it's journey from the Earth/Moon subsystem?

Each capsule would separate at some point before atmospheric entry, or just maybe during it.

The capsules may have an Steel/Aluminum/Steel sandwich portion which temporarily captures some of the heat of atmospheric entry, and energy supply to inflate the balloon within them with heated Hydrogen.

Think Viking lander system (Sort of). But maybe no engines.

Somehow these things take themselves apart in mid air, and eject the balloon, with heated Hydrogen.

There could be included a parachute method involved, especially if the parachute can be a useful to be retrieved after the "Landing".

Parachute might be seriously damaged, so I don't know about that.

The metal shell(s) drop to the ground at serious speed, but are still retrievable scrap metal (We hope).

The Balloon(s) ejected, survive impact (We hope).

Then we have the balloons, scrap metal of Aluminum and Steel, maybe the parachutes, and a "Mule" style Starship poked into a sand dune, and so partially protected from radiation, and perhaps not likely to topple.

I am going to take a walk now.

Last edited by Void (2020-04-19 12:57:32)

tahanson43206 · 2020-04-19 20:13:26

For Void re #380

in this post you have shown a material that seems (to me at least) quite interesting for the Bubble Delivery application.

Our visions are still far apart.

I pointed out that during descent, under acceleration by gravity, a balloon would experience some heating due to the compression of air molecules in the path of the balloon. However I have tried to eliminate the force of lateral motion, by proposing that all lateral motion with respect to the surface of Mars would be eliminated before the balloon is released. Thus, the ONLY velocity component to be managed is the vertical velocity as the balloon approaches the surface under the influence of the gravity of Mars. The velocity would be constrained by drag, which itself would be a function (primarily) of the density of the atmosphere and the size and shape of the balloon.

Such a flight could be simulated by dropping a properly equipped balloon from a sounding rocket which has reached the altitude of interest, 53 kilometers above the surface of the Earth. The interaction of the balloon with the atmosphere that is of interest is the 15 kilometers from 53 km down to 38 km. The design objective would be to arrive at 38 km with a residual velocity that falls to zero as the buoyancy of the hydrogen is matched by the pull of gravity. This would coincide with the surface of Mars, if the drop were made above that planet.

As pointed out in an earlier post, references give the altitude of 38 km on Earth as equivalent to the densest atmosphere on Mars.

The amount of heating that would be experienced by the balloon during the proposed flight is probably knowable by calculation.

It appears that the amount of drag is knowable, and the velocity of the balloon at various points in the descent can be calculated, given the mass of the balloon, its diameter, the density of the air, and perhaps another factor I have forgotten.

I would presume/hope that temperature can be computed at the point where the velocity is established, and that would be helpful in knowing what kind of material should be selected for the skin of the balloon.

I am hopeful that nothing more than a plastic skin will be necessary, and the material you have shown in Post #380 looks promising. The applications of this material on Earth would imply that if a balloon full of hydrogen delivers a payload to the surface of Mars, then the hydrogen can be drawn off and the shell of the balloon collected for use in all sorts of habitat applications.

Edit #1: the New Shephard vehicle already performs a flight operation that is very close to what would be needed to test the Bubble Delivery concept.

From Wikipedia, the free encyclopedia
On 23 November 2015, after reaching 100.5 km (62.4 mi) altitude (outer space), the suborbital New Shepard booster successfully performed a powered vertical soft landing, the first time a suborbital booster rocket had returned from space to make a successful vertical landing.[6][7] The test program continued in 2016 and 2017 with four additional test flights made with the same vehicle (NS2) in 2016[8] and the first test flight of the new NS3 vehicle made in 2017.[9]

A concern I've had in thinking about finding an equivalent test on Earth, to simulate the drop from Phobos onto the surface of Mars, is altitude.

The gravity on Earth is greater, so in that sense, a drop above the Earth would be a stress test for a Mars planned delivery system.

On the other hand, the elevation from which the package would be dropped on Mars would be much greater, so the acceleration of Mars' gravity would have longer to run before the package encounters the atmosphere of Mars.

Ideally, simulation software will be able to compensate for the differences, to insure that a test on Earth meets or exceeds the challenges to be encountered on Mars.

(th)

Last edited by tahanson43206 (2020-04-21 07:52:29)

Void · 2020-04-19 21:44:06

I have enjoyed your materials (th)

In my world also there is room for various options and attempts at accomplishments.

I should have done it sooner.....Queried for "Mars Balloons. There seems to be a lot of material by creative thinkers. Its late, so I will just start such a process.

https://www.bing.com/search?q=balloons+ … US&plvar=0

https://www.bing.com/images/search?q=ba … &FORM=IGRE

Some of them are for dropping a payload, which is OK, but as you must know I am simply hopeing to drop a Fluorine containing plastic possibly spherical product to the settlers. Of Course I am also interested in Aluminum for them.

Looks pretty promising after.

Although I support the idea for insitu for things for Mars, I think that there are certain materials for a time should come from outside of Mars.

That would accelerate the development of hard to do insitu.

And I am beginning think Louis correct that Mars would have things to offer back. We know of those, but I am beginning to think that Mars may indeed have valuable elements from all the asteroids that have smashed it. They are not certain, but some think that instead of a Magma ocean in early days, melting from an impact(s) was relatively less than for Earth. So, possibly the cores of small impactors may have stayed shallow, and mining for that is a possibility. I know that is off topic, but to bring it back on topic, we could emphasize that the materials to be distributed to Mars, is a stimulant for growth, if you can deliver balloons, and yes also Aluminum.

Last edited by Void (2020-04-19 22:00:06)

tahanson43206 · 2020-04-20 06:35:14

For Void re #382

Thank you for adding links to related discussions! Those surely deserve review.

Today I have re-joined your topic to set a corner stone or two, for an article that might be submitted to a physical (printed) journal read by (real) people who like the texture of finished paper,

SearchTerm:ConjectureOfVoid
SearchTerm:VoidsConjecture

In thinking about a terrestrial proof of concept for a Bubble Package Delivery system on Mars, it occurred to me that we have a durable, reliable, pedestrian and ** very ** common test platform available .... the ubiquitous weather balloon!

It is ** certainly ** feasible to lift a deflated weather balloon to an altitude well above 53 km on Earth, inflate the balloon with Hydrogen, and release it to fall back toward's the center of the Earth, obstructed only by interaction with air molecules who are minding their own business when rudely pushed aside.

It is my understanding of "Void's Conjecture" that a bubble can deliver useful material to the surface of Mars.

I have tried to imagine a real world application of this idea, and have made some progress in moving toward a theoretical proof. However, a practical, real world proof of feasibility is necessary.

This is an "open source" undertaking. Anyone is welcome to run with the ideas under discussion here, and any contributions individuals might care to make to the collection of related knowledge or insight would be welcome.

The caveat is that this ** is ** Void's topic, so if he has any rules for content submitted to this topic, he may let you know.

Void, if you would be willing to explore your fluorine plastic idea a bit further, I would be interested to know if anyone on Earth has used the material to make a balloon. It is clear from the article at the link you provided, that the material can be and is being used for roofing applications, where durability and translucent qualities are valued.

(th)

tahanson43206 · 2020-04-20 07:56:28

This is a follow up to Void's post #382

Montgolfiere Balloon Concept Button Montgolfiere Ballon Testing Button 100 px spacer
Solar Montgolfiere Balloon Concept Montgolfiere Balloon Testing Activities
Balloon Development Challenges for Mars
Ballooning in the Martian atmosphere is complicated by the fact that the Martian carbon dioxide atmosphere is very cold (200 K or -73 degrees C), and it is very thin at 0.006 bar, where 1 bar = 1 atmospheric surface pressure on Earth. In order to fly balloons at Mars, the balloons must be made of very lightweight material.
However, a number of balloon robots, or aerobots, have been proposed for Mars. One simple type is a helium balloon that carries a rope-like snake. During the day, the balloon would be heated by the sun and rise to some altitude above the Martian surface. At night, the balloon would cool, and land on the Martian surface when the landed snake reduces part of the effective mass of the balloon system. Although this type of balloon was proposed in the 1990's, it has never flown due to problems incurred during atmospheric inflation testing and due to fears that the snake might entangle, thus endangering the balloon.
Another type of balloon is a helium superpressure balloon that would fly at a nearly constant altitude for both day and night. The balloon's internal pressure would be higher during the day than at night, although the balloon volume would remain the same. This type of balloon has great potential for long duration flights, possibly several weeks, but a strong, lightweight, leak-proof material must first be developed and successfully tested in a system where the balloon inflates while falling through the Martian atmosphere.
A third type of Martian balloon is known as a solar Montgolfiere, or a solar-heated hot air balloon. This simple, lightweight balloon system shows great promise for long-duration balloon flights over Mar's polar regions during summer, as well as for soft-landing payloads on the Martian surface.

Dr. Jeff Hall is shown as the Technical Reference for this page on the JPL site. I have written to Dr. Hall, but it should be kept in mind that the link may not work, or Dr. Hall may no longer be available, or Dr. Hall may decline to respond.

However, all those caveats out of the way, Dr. Hall appears to be the kind of person I am hoping to invite to assist with the gradual accumulation of knowledge and insight carried on by forum members over nearly two decades.

Edit#1: It turns out Dr. Hall's interests in balloons (and specifically balloons on Mars) is more than superficial:

https://www-robotics.jpl.nasa.gov/people/Jeffery_Hall/

(th)

Last edited by tahanson43206 (2020-04-20 08:05:54)

Void · 2020-04-20 09:38:13

(th)
Good. No problem with looking at balloons.

But remember, in my case I am just trying to deliver a Ball of ETFE or Roberts version.

Therefore, a bit of bouncy ball action can be OK. Particularly if there is a less rocky surface. CO2 snow or a sand dune.

And beyond bouncy ball, I don't mind it is designed to pop in a controlled manner, to dissipate energy.

Therefor, I anticipate a greater tolerance for a heavier ball, one suitable to be converted into greenhouses, or solar collectors.

If that is not enough to deliver a useful product to the surface of Mars, then I have already suggested the possibility of using various schemes to help. Parachutes, steam rocket landing, and then if necessary chemical thrusters to assist.

-----

I have just thrown this lower section in for mental exercising.

I think you are enjoying this subject, so I will mention this different thing, that sort of interests me:
https://www2.jpl.nasa.gov/adv_tech/ball … olfier.htm

Again in my case, I am not so interested in dropping a payload to the surface other than the Balloon/Ball.

For this case, what I would be interested in would be to have a small rocket inside of it to emit heat and thrust. Of course you would need to keep the temperatures relatively low. But if you did have a relatively small rocket engine in the bell, then I would hope it could be capable of suctioning in Martian atmosphere to cool the exhaust to reasonable limits, and to add volume. For the pump, I would look at a venture method.

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

This could suction in Martian atmosphere. The rocket engine would have to have the proper tubular curves, but if you could do it, it would be a bit like a hybrid between a rocket and a jet engine. CO2 is not a very good Oxidizer for many things, in fact I am not sure it can combust with Hydrogen. Maybe at a high temperature. Combustible metals might help. But just adding the Mass from the Martian atmosphere, could be useful, provided the rocket engine had enough power.

And of course this is going to be like a hot air balloon, except the exhaust is pointed out of the bottom of the balloon, but if done right you would have a hot air balloon, and yet not burn the balloon. Tricky. I think their could be room to dump some Hydrogen into the bell of the balloon. I think the landing would likely be so fast, that it might help lift. If fact "I think", you might have a standard rocket engine and then through a venture effect have an afterburner, where a Mix of Hydrogen and Martian atmosphere are suctioned out of the bell of the balloon Maybe helping in the landing. Of course some of the Hydrogen would be lost to the atmosphere, if the interior of the balloon was too turbulent. If you could keep the Hydrogen layer in the top of the balloon relatively stratified, with Martian air below, then perhaps we could get away with it.

This material can withstand a higher temperature I believe, so who knows, what that could lead to. Maybe something, maybe nothing.

http://inflatableductplug.com/high%20te … lloon.html

Last edited by Void (2020-04-20 10:06:46)

tahanson43206 · 2020-04-20 10:53:06

For Void re #385

Thank you for providing this link: http://inflatableductplug.com/high%20te … lloon.html

That is a most interesting material, and the scale of the products is definitely interesting.

What is needed is a way to perform a mathematical analysis that allows all the parameters to be input to determine the optimum set of factors for a given landing request. While no customer exists for any of these ideas at present, a successful demonstration of feasibility could stimulate interest.

Your vision (as I understand it) of a tough-walled sphere able to deliver a significant quantity of some gas to the surface of Mars seems plausible, but I would like to see a demonstration of performance in the comparable regime on Earth, between 53 km and 38 km. In that 15 km stretch, your proposed bubble must be able to survive heating in the atmosphere as it descends, and it must be able to slow to the velocity it can survive without bursting when it arrives at the surface of Mars.

If the bubble bursts, the customer will not be satisfied, and you will not receive full reimbursement for the costs of the shipment, even if the shell of the bubble can be salvaged. I recommend planning for a successful deployment, and a satisfied customer.

(th)

Void · 2020-04-20 11:26:58

(th)

I never intended to deliver a type of gas inside of a bubble. I intended to deliver Fluorine as a bound chemical in a plastic, that plastic comprising the bubble. So, a proper kind of bursting might be ok.

The bubble itself is the product. Not what is inside of it.

Last edited by Void (2020-04-20 11:28:05)

tahanson43206 · 2020-04-20 12:41:04

For Void ... This is your topic, and your preference will determine the flow of conversation.

My misunderstanding of what you were trying to do has been fruitful, but I NOW understand that you are NOT interested in delivering the CONTENTS of the bubble to the customer.

The computations I am pursuing for the track I was on should still prove useful for your purposes.

The bubble you would like to deliver to the surface must still survive passage through the atmosphere of Mars.

It would appear this is a good time for us to part company. I am grateful for your inspiration, and look forward to seeing more ideas as you come up with them.

(th)

Last edited by tahanson43206 (2020-04-22 09:29:01)

elderflower · 2020-04-22 08:40:36

Your bubble might be filled with Sulphur Hexafluoride, as well as being made from fluorinated plastics, Void. Two birds with one stone!

tahanson43206 · 2020-04-22 09:20:51

For elderflower re #389

Bravo! Thank you for your support of Void's initiative!

Google search: sulfur hexafluoride uses

en.wikipedia.org
Products & applications of Sulphur hexafluoride (SF6)
• Application as dielectric gas. Gas insulated high voltage circuit breakers and other switchgears. ...
• High Purity Grade Application. Etching agent for the plasma processing.
• Foundry Applications and metal casting. Component of inert atmosphere during the primary casting of Aluminum and Magnesium.
Products & applications of Sulphur hexafluoride (SF6) - EFCTC

OK Void! Can you/would you pursue validation of your concept?

If you can find a vendor who would like to deliver fluorine to customers on Mars (thinking ahead obviously) then it would follow that a demonstration of a Dead Drop Delivery from above Earth's atmosphere would be a useful test. The velocity of the bubble at 38 km would be a measure of interest, since that is the point of equivalent atmospheric density to the surface of Mars (at the lowest point). However, if the bubble can survive all the way to the surface of the Earth, then (I would think) that would be an achievement of potential interest to Earth-side parties.

At an online meeting last night, I brought up your Bubble Delivery concept in the context of weather balloons, and one of the participants suggested taking a look at the abundance of weather balloon related videos on YouTube, to try to glean additional insights or possible contacts.

(th)

Void · 2020-04-22 13:10:00

Elderflower....Interesting.

(th) I will think about it.

elderflower · 2020-04-25 04:02:14

Sulphur Hexafluoride is a great substance if you want to warm the atmosphere, Void. If your bubble bursts the contents would go towards terraforming. Don't try this at home (earth)!
I do think it would probably be more economical to search the surface of Mars for a source of Fluoride, though.

Void · 2020-04-25 06:45:52

Elderchild said:

Sulphur Hexafluoride is a great substance if you want to warm the atmosphere, Void. If your bubble bursts the contents would go towards terraforming. Don't try this at home (earth)!
I do think it would probably be more economical to search the surface of Mars for a source of Fluoride, though.

I fear a bit that Sulphur Hexafluoride, would freeze out on the polar caps. But perhaps it would be retained in the atmosphere at small amounts, just as there is a small amount of water vapor in the air at Antarctica, and indeed on Mars. Not that much of Sulphur Hexafluoride is required in the atmosphere in order to make a change.

As for economics, I could twist what you said, and similarly say it would be more economical to make solar panels on Mars than the carry them to Mars in a space ship. When Mars is sufficiently developed, then it indeed might make more sense to make solar panels and ETFE there and to quit transporting them from the Earth/Moon to Mars.

Last edited by Void (2020-04-25 06:50:51)

Void · 2020-05-09 14:09:19

I hope you all, will appreciate that I will not clutter another topic with my utterances.

We can clearly see that Starship will now belong to several new families.

-Starship for Mars.
-Deep Space Starship (Per O.F. 1939, does not deal with atmosphere). Good for airless objects I presume.
-Point to point Earth, and maybe Mars Starship.

-Deep Space Starship could also be for the orbital Hill Sphere of Mars, if it used a Ballistic Capture method. Maybe it can even get back to the Earth/Moon subsystem, by the Ballistic Capture method as well. I don't know enough about it.

But I am going to speculate on a third option:

Aerocapture Method(s)

It seems to me that this version could be in variations which may overlap the other two.

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

Obviously this version must have some type of heat shield unlike the "Deep Space Starship". It may well require braking flaps such as the type that can land on Earth and Mars, but that may not be set in concrete.

It may be well suited to also land on Earth and Mars, or else, to land on airless objects. Probably not all three types of options, that would not be efficient.

The original instance of conceived Starship would have it just doing a "Sky Diver" maneuver, which was a brilliant idea. But then they discovered that they could do a hypersonic glide, to dwell in the upper atmosphere first to bleed off some of the speed. Then the "Sky Diver". This apparently allows, for less heat shield, which cannot be a thing to yes like as prudent.

Of the objects that you could glide in the upper atmosphere of are Venus, Earth, Mars, Titan, Jupiter, Saturn, Uranus, Neptune, and who knows, maybe at times Pluto.

But for various reasons, I only at this time, consider Mars and Venus, and perhaps Earth to be rational objectives for our presumed possible life period.

So, what are the fuel requirements to do a hypersonic glide in the atmospheres, of Venus, Earth, and Mars, maybe to skip off, and then to need to fire engines, to regularize an orbit. This is not necessarily a needed capability, but an interesting possibility, perhaps achievable, and maybe useful.

Don't know.

Done.

Last edited by Void (2020-05-09 14:26:05)

elderflower · 2020-05-11 14:20:18

Triton also has a bit of an atmosphere, Void, and is a very interesting object. It has been proposed as a captured Pluto type world, rather than a moon formed where it is currently located.

Void · 2020-05-11 16:41:33

Interesting point Elderflower.

Down the road, presuming fusion powered synthetic gravity habitats, the Nitrogen could be very important.

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

Void · 2020-05-12 12:20:17

In light that SpaceX is going to be trying to make their own alloys, I might think that this article could be of use.

https://phys.org/news/2020-05-super-ste … rough.html
Quote:

Super steel project attains major breakthrough

Void · 2020-05-13 10:24:25

In his post #1, Index
» Planetary transportation
» Inter-settlement transportation on Mars

Louis sums up options for surface transportation. I want to also explore orbital activities, but don't want to pull him off topic. So, I will post here instead.

As for general types of Starship at this point, we have those that can land on Earth and Mars, so Atmospheric Starships.

O.F. 1939 proposed a more generalized class of Starships that can land on airless bodies. "Deep Space Starship".

Dr. Robert Zubrin has proposed, a Mini-Starship. Don't know if SpaceX will do that or not ever. Sound OK to me, but I don't run SpaceX, so have very little to no say on that.

Posts #394, #395, and #396 discuss Aerocapture Method(s) Starship.

In this case, I would think you would dispose of the need to do the Skydive and swoop landing. You would however likely want to be able to glide hypersonically, and to then skip and/or propel out of the Earth's atmosphere.

I think that if that ever shows up it is likely to be the last general category that would be created.

And yet it may have it's own characteristics which could be of value.

I could make a case for un-crewed, missions of this sort for both Mars and Venus.

In the case of Mars, the purpose would be to have very strong instrumentation on board, to analyze the surface and sub-surface of Mars.

But that does not currently seem to be in the plans of SpaceX.

But I am looking at the aerocapture method as possibly conserving energy.

If you could come in and just skim the atmosphere enough to achieve an elliptical orbit, that just stays bound to either the Earth or Mars, then you have conserved some of the energy of travel.

This however, isolates it from a situation where it can do useful work. Of course you could direct it to the Moon, and then it could lift things. But I am more inclined to speculate on a movable propellant depot, where Oxygen from the Moon, Methane from Earth, and useful technological devices would be stored. The "Depot would link up with the Aerocapture Starship, and a transfer would be made.

This would reduce the "Down Time" of that Starship as it could launch to Mars, fairly soon. But it almost surely would have to use Ballistic Capture, and perhaps also an Aerocapture at Mars.

This does not satisfy either Dr. Robert Zubrins notions or Elon Musk.

However Elon is thinking that eventually a Starship of some sort will be manufactured every 72 hours. But if they can do that why not have other facilities that can do that?

It would only be a matter of it being worth it per $$$.

Aerocapture Starship may never be built, but never say never.

What if it turns out that women cannot have proper pregnancies? We don't know now, but the Moon is likely to teach us about that in lab animals rather soon, maybe 5-10 years? (Maybe less).

So, never say never.

In such a case, if we wanted to "Occupy Mars", we will have to occupy its sky's also. At least until very advanced space medicine overcomes that potential problem. Of course that will mean the Jeff Bezos/Gerard Kitchen O'Neill dreams, curiously in the Elon Musk/Dr. Robert Zubrin dreams.

Done.

Last edited by Void (2020-05-13 10:51:59)

Void · 2020-05-27 05:27:21

Today, I have been wondering about Starship Light (Don't know if it is currently under contemplation or not).

Also, the dreaded SSTO, just for fun. Technically it would not be purely a SSTO.

And per O.F 1939, the Deep Space Starship.

And Space Stations.

Have begun to wonder if in the deep future, a version of Starship could hijack Space Shuttle and/or Vulcan tricks.

I don't think I will put too much time into this, but I was thinking that if you objective were to get a set of stainless steel, pressurized chambers into space, you might try the following.....

This presumes that some entity with some money would want to buy those Starship/orbital chambers. Or else, I guess it would not makes much sense.

The space shuttle had an external tank, and Vulcan will have expendable propellant tanks.

Point to point Starship will not use the Super Heavy. It is capable of going point to point, without the Super Heavy.

Some part of the value of that might be that you eliminate a largen number of rocket parts, saving money, and perhaps having better odds, of not having a cascade failure.

Adding an external tank(s), will be trouble. I recall that Elon Musk said that making the Falcon Heavy with a 3 part first stage was really trouble.

The engines should perhaps be hybrids, so that they can all fire at sea level. That will damage efficiency, but then there would be ~6 engines to get the thing started up.

No Heat shield, no landing legs to take with, most likely.

Probably no crew cabin(s), no cargo bay.

The shell is the cargo.

Done

Last edited by Void (2020-05-27 09:29:19)

Void · 2020-05-27 09:31:27

I am not thinking that the thinking from the last post would necessarily be done by SpaceX. I know that what it can do, is not in the main line for Elon's thinking.

But there will be others who eventually may rival SpaceX. Just not yet.

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