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Could enough surface area be created with a blimp to shed speed using Mars' atmosphere to have a controlled soft landing to minimize the need for retrorockets? Runway would need to be in place. While floating on Earth it would have to behave as a high speed glider on Mars.

The heat shield bellow in the 2nd picture is a high tech balloon made by NASA. Could it be added to the nose of a hybrid Airship built or inflated in space work for descending from orbit without the need heavy heat shielding?

With a stratospheric launch could a blimp like the 1st picture achieve orbital speeds as a rocket?

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https://www.newscientist.com/article/dn10288-inflatable-cushions-to-act-as-spacecraft-heat-shields/ enter image description here enter image description here

https://www.nasa.gov/centers/ames/orgs/exploration-tech/entry-systems-div/hiad.html

https://www.newscientist.com/article/dn10288-inflatable-cushions-to-act-as-spacecraft-heat-shields/

Muze
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    The blimp couldn't be in orbit in the first place, because the internal pressure would cause it to rupture in the vacuum of space. – Phiteros Dec 24 '16 at 22:31
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    The pressure outside the blimp in space would be ~0. So you would be lowering a giant, empty airbag. If you were trying to do this on Mars, the pressure there is 0.6% of Earth's air pressure, so trying to fill it any more would cause a rupture. You can't do this without a rigid shell to protect the blimp from rupturing. And then it wouldn't exactly be useful as a blimp. – Phiteros Dec 24 '16 at 23:55
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    If your aim is to create a large structure on Mars, I do not understand why you need to go through the rigmarole of having a blimp. The blimp itself serves no useful purpose, and setting such a large structure down on Mars would be much more difficult than just constructing it there in the first place. – Phiteros Dec 25 '16 at 06:06
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    How do you intend to lower it? – Daniel Jour Dec 25 '16 at 16:29
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    If it is not intended to have significant buoyancy maybe it would be easier not to name it "blimp" – Antzi Dec 25 '16 at 20:37
  • @Antzi what should it be named? – Muze Dec 25 '16 at 21:31
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    @Muze You didn't get my point, I fear. How, without constant rocket firing, do you intend to get that blimp down from geosynchronous orbit to the ground? Without some support structure (space elevator like) you wouldn't stay "geosynchronous" as the blimp gets lower. – Daniel Jour Dec 26 '16 at 16:23
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    You have added a lot of material to the question that makes it harder to answer. This is now an entire transport and habitat system proposal, yet you are unclear about a lot of the physics behind it. To learn from this site you need to ask specific questions, and to consider the answer well before asking related questions. – kim holder Dec 27 '16 at 04:40
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    You need to slow down. You are trying to design entire systems before learning the science and math behind all this. That is really the thing you need to accept. Your imaginative visions won't amount to anything unless you learn the science to make them realistic. It's difficult but worth it. The system has held you back because that is the adjustment you need to make and it is trying to get you to do it - that is why you can't ask new questions right now. That happens automatically when you get enough downvotes. – kim holder Dec 27 '16 at 17:15
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    Those votes are because the questions don't show research, tend to be very broad, and also unclear because you often don't know enough about the science involved to express yourself clearly. It may be hard for you to be methodical about this when your head keeps filling with ideas, but that is what would really help you here. Ask about the smallest piece you can identify as a question instead of expanding things. Really try to check things on your own first, learn where and how to do that. Then give it time. Designing systems takes many years of training and there are no shortcuts. – kim holder Dec 27 '16 at 17:24
  • That's not a blimp in the first picture, It's the Reaction Engines A2 concept for the LAPCAT project. –  Feb 19 '18 at 16:05

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Unfortunately my answer won't contain the crucial "yes" or "no" - for the simple reason that one hinges upon fine parameters and would likely require a good NASA study for actual answer. But the answer I can give without that currently is "Quite likely so."

1) matter of sustaining the blimp in void. That one's easy "yes". If the blimp's envelope rated pressure differential is 500Pa, inflate it to 200Pa and it will stay inflated in void. Any risk of bursting can be handled through a dumb passive safety valve. And the pressure can be provided from pressurized gas tank - let me say if your target pressure is 0.006 bar, then a small pressure tank inflated to (pretty standard) 100 bar can fill a huuuge volume. Never mind storing liquid or even solid fuel and diverting cooled combustion products into the envelope.

2) Lowering it into the atmosphere. This is the one where I can shrug helplessly and say "maybe". We know that objects light enough (surface area to mass ratio high enough) can reenter from LEO into atmosphere without burning up. How light? What ratio? Where to draw the border? The reentry profile would probably involve insertion into a relatively high orbit, where the blimp would lose most of its orbital velocity due to atmospheric drag, even before falling below low orbit altitude - and maintaining buoyancy, reduce descent rate to such degree, that ram rise heating would be low enough due to the medium being sparse enough that the envelope wouldn't burn up. This is the crucial point - having the drag high enough at altitudes high enough that adiabatic compression of the medium can't damage the envelope before it slows down to terminal speed. And this is a calculation for a good paper by professional scientists, not for a post on a Q&A site.

3) Atmospheric descent. Absolutely doable; heating the contents of the envelope would regulate buoyancy allowing to fine-tune the descent speed and allowing for a soft touchdown.

Would such a blimp be usable on Mars? Possibly so; while not really useful as an airship (with air so thin, the lift would be pathetic and the required size would make it a victim of extremely fast winds), but the envelope could be repurposed as a layer of shell of a colony dome, not a full 1 bar but a partial pressure to allow inner layers to have a lower pressure delta until the innermost one provides the full pressure. Also due to need to keep the whole thing very light (for airbraking) there would be nearly no payload - the envelope itself would be the actual payload, with only a minimal amount of active systems for guiding the descent.

But - providing we can make a blimp light enough and durable enough to withstand the aerobraking - this would be a very viable method of delivery of the dome construction material - likely way more robust than powered landers with deflated material.

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SF.
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    ...although why would you ever want to put it in Mars synchronous orbit is beyond me. Completely pointless "twist". – SF. Dec 26 '16 at 01:19
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    #2 you're assuming terribly wrong. There is absolutely no benefit of orbital insertion into geosynchronous orbit. You're losing opportunity both for airbraking and Oberth effect benefits of a low orbit insertion; you waste a lot of fuel for completely unnecessary circularization, and even more to deorbit the craft from there. Seriously, play some Kerbal Space Program to get the basic intuition of how that all works together. The synchronous orbit is a really awful place squat in the middle between any useful altitudes. – SF. Dec 26 '16 at 02:17
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    If the blimp was to slow down its descent as on Earth at 1% the air density, it would need to be sufficiently big and light that 100mph wind would affect it like 100mph wind affects a blimp on Earth. Same properties, same dependencies. If you make it dense enough to be immune to martian wind, you're making it dense enough to burn up on reentry or at best crash into surface at a very high speed. – SF. Dec 26 '16 at 02:23
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    @Muze: and #3: there's the matter of structural integrity and cost of delivering it into space and Mars orbit. Make it too thin relative to its size and it will be torn by aero forces. Make it thick enough and big enough and it will mass hundreds tons and there's no rocket to fly it to Mars. – SF. Dec 26 '16 at 02:26
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    First, slowing it down to such orbital speed that you have groundspeed of zero on touchdown would definitely wreck it on reentry; air density grows with exponent of altitude; your speed at the time you begin airbraking would be way too high to lose it before density grows enough to burn it up. And it would be very inefficient to try it from the synchronous orbit anyway. – SF. Dec 26 '16 at 02:35
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    Put it into orbit of Pe of some 200km. It will keep losing orbital speed with each pass pf Pe until it circularizes; then it will continue losing speed and altitude - hopefully losing speed fast enough and altitude slowly enough by the time it's about to enter thicker layers it's already below speed sufficient to burn it up. – SF. Dec 26 '16 at 02:41
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    Let us continue this discussion in chat. – SF. Dec 26 '16 at 02:46
  • I have answered some comments in my question. – Muze Dec 26 '16 at 19:05
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    @SF. The limit to this idea of losing orbital speed slowly on each pass is that there must be one orbit when you have enough speed to make it round the planet again (~ km/s) and then one when you don't. At that point, you're going to reach the surface within half an orbit, which gives you around 45 minutes to dissipate all that energy at best, and in reality much less time due to the rapidly increasing density. – djr Dec 29 '16 at 00:17
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    @djr: That assumes a classic, dense spacecraft. With Mars low orbit speed of 3361m/s, at a ballpark 100gram per m^2 of surface, 1m^2 will be dissipating 546kJ of energy over these 45 minutes. That's an average of about 200W/m^2. The craft must withstand LEO solar irradiation of about 1400W/m^2. And it has a large volume of convective coolant (buoyant gas) inside to deal with excess heat. – SF. Dec 29 '16 at 01:19
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    @SF. My comment was about orbital dynamics, and doesn't make any assumptions about the spacecraft. Even a "dynastat-type spacecraft" has to slow down from orbital speeds to near-stopped in a matter of minutes. It's possible that dissipating the energy is less of a challenge for this form, but as you've noted before, holding that shape and not turning into confetti will be a problem at hypersonic speeds. – djr Dec 30 '16 at 00:06
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    @djr: Matter of how many minutes. Typical plasma blackout lasts at most 2-3 minutes and energy dissipated goes into megawatts. This shape causes atmospheric drag to matter much earlier - at much higher altitudes and lower densities; distributing the energy dissipation over longer much longer time and at far lower air density - unlike reentry capsule depending on ablator and short timing not to allow heat inside, this one purposedly prolongs descent. It would stand no chance on Earth nevertheless, but 3.3km/s is not 8km/s and with the $v^2$ in kinetic energy this makes a world of difference. – SF. Dec 30 '16 at 00:22
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    @SF. You're right - peak heating matters for burning up, and that could be quite different for this type of body. What I was objecting to was something I read into your comment that wasn't actually there: you said "hopefully losing speed fast enough and altitude slowly enough by the time it's about to enter thicker layers it's already below speed sufficient to burn it up" and I interpreted this as meaning "losing speed slowly enough that it can enter safely". I was pointing out that this isn't losing 1 m/s on each orbit over months (as in aerocapture), it all happens in minutes. – djr Dec 30 '16 at 00:46
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    I guess you know all of that, the point was really aimed @Muze who possibly doesn't. – djr Dec 30 '16 at 00:47