3
$\begingroup$

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?

enter image description here

enter image description here

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/

Improve this question
$\endgroup$
11
  • 4
    $\begingroup$ 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. $\endgroup$
    – Phiteros
    Dec 24, 2016 at 22:31
  • 4
    $\begingroup$ 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. $\endgroup$
    – Phiteros
    Dec 25, 2016 at 6:06
  • 3
    $\begingroup$ 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. $\endgroup$
    – kim holder
    Dec 27, 2016 at 4:40
  • 7
    $\begingroup$ 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. $\endgroup$
    – kim holder
    Dec 27, 2016 at 17:15
  • 4
    $\begingroup$ 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. $\endgroup$
    – kim holder
    Dec 27, 2016 at 17:24

1 Answer 1

Reset to default
9
+50
$\begingroup$

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.

Improve this answer
$\endgroup$
14
  • 2
    $\begingroup$ ...although why would you ever want to put it in Mars synchronous orbit is beyond me. Completely pointless "twist". $\endgroup$
    – SF.
    Dec 26, 2016 at 1:19
  • 3
    $\begingroup$ #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. $\endgroup$
    – SF.
    Dec 26, 2016 at 2:17
  • 1
    $\begingroup$ 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. $\endgroup$
    – SF.
    Dec 26, 2016 at 2:23
  • 1
    $\begingroup$ @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. $\endgroup$
    – SF.
    Dec 26, 2016 at 2:26
  • 1
    $\begingroup$ 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. $\endgroup$
    – SF.
    Dec 26, 2016 at 2:35

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.