New Mars Forums

It's actually not a bad idea, here's why: Venus has a very very thick atmosphere meaning that you can float at about 20-40km. Launching from such a high altitude with a rocket means the rocket can be smaller. You can float higher up in Venus with smaller balloons.

But back to the topic of balloon on Mars. For the last 3 days I have been grinding away on spreadsheet, AI and google. Here is what I found out. We can use balloon on Mars for large payloads but they have to resemble a wide shape such as a short cylinder of a wide oblique. The reason is because we have to minimize the vertical pressure gradient that forces us to thicken the skin of the balloon as Calliban correctly pointed out. Yes we can put limits on climb rate on sphere shape airships but there is another very compelling reason to go wider with a ratio of 5 to 1 for iexample 280m height cylinder/oblique with 800m radius. The reason is we can join the top and the base with structural beams that will further reenforce the integrity like a honeycomb. And this also optimizes human condition for walking around a flat surface with maximum real estate. With 0.18mm carbon fiber skin(obviously not the bit where we walk on which will be thicker and counted as useful payload) the ballon can lift 100 tons of useful payload to the tip of Olympus Mons. 7000 tons at datum and 15,000 tons at Hellas planitia. Now the internal pressure at Hellas must be 10% higher than the external pressure for redundant structural integrity, 15% higher at datum and 25% higher at 20km(Mount Olympus).

Altitude (km)    External Pressure (Pa)    Internal Pressure (Pa)    Percentage Higher (%)    Pressure Differential (Pa)
20    40    50    25    10
0    610    702    15    92
-8    1,200    1,320    10    120

Yes I know this is a giant flying saucer, but it's only giant because it is designed for all ground levels of Mars incluing Olympus Mons. We can get away with much smaller 250m radius cylinders with about 60m height for performance below the volcano but above datum.

UPDATE: I think oblique is better or a cylinder with rounded edges. But I prefer oblique because its more aerodynamic all around. With cylinder there might be too much stress on the top or bottom because it's perfectly flat and will hit head on to airflow generating stress.

I think ID4 and V got it right!

First of all I want to thank everyone especially Calliban for getting me a head start on the design process and getting me educated on the structural aspects of a balloon which is valid.

But even after all the structural considerations please realize that Mars as less gravity as a smaller planet that actually in signficant ways compensates almost completely perhaps exceeds the advantage of balloons on Earth too.

Your most recent chart only goes up to 25 meters and shows a illustration of such a balloon size.

However if you will refer right back to the chart I sent you before you will see that with the reduce Martian gravity when you go above 160m radius you get back some significant gains. I would encourage you to extend your chart all the way to 200 meters radius and rerender your AI inspired illustration to show what the new balloon would look like at that scale. The only disadvantage with Mars is the minimum radius. Once you go pass 160m radius you can catch up to Earth abilities. Lift force too strong for balloon structural integrity? No problem, what you then do is set limits for the descend and ascent (climb rate) rate. Have a no exceed limit for climb. Then the extra mass needed for internal skeleton is much reduced and you still have your exponential gain.

Remember a larger balloons means higher altitude of lift and higher force of lift but we can control the lift force but controlling how much hydrogen is in the bags. We can carefully keep the amount of gas controlled so the balloon radius is in practice less than what it physically is.

M A R S  H A S   L E S S  G R A V I T Y = Scale Height is elongated meaning also the max altitude is much higher than that on Earth because the air density changes are likewise stretched farther out into space. Because Mar's scale height is 11km vs Earth's 8km Mars atmospheric layer is actually thicker but the air density is not. Mar's atmosphere reaches farther out into space, this is true, while Earth's atmosphere is "thinner" it's denser. This is a tricky play on symatics that you might not be normally familiar with for Mars because the of media portrayal.

Below: Factoring in balloon mass which looks like it has a linear relationship after a certain point on the cart still gives no significant problems when you go to 200m, here after subtracting balloon mass you still have 385 tons of useful payload. I would design the balloon so that both structure and cabin spaces are integrated into the balloon material for further optimizations and to strengthen the skin, more of this integration into the balloon skin would be at the bottom to keep the ship/balloon (their both the same in this scenario - look at my picture) upright. Keep more mass on the bottom.

Pros and Cons of Martian Airships:

Cons:

1. Rise and Fall of airship is going to be limited due to weak Martian Gravity which actually cancels out the problem of structural integrity brought up by Calliban. However because of limited climb speed control of the airship wont be as great vertically compared to Earth airships which can climb and fall much quicker. However we can compensate with propulsion systems such as high RPM rotors or better still ion wind systems - ionowind propulsion. This works better on Mars due to laminar nature of atmosphere.

2. Ship has to be at least 160m in radius.

Pros:

1. Mars has low gravity cancelling out the low density atmosphere problem to a significant extent.

2. Mars has large scale height of 11km vs 8km of Earth. Enabling higher possible altitudes since the drop in air density is not as fast as that on Earth as you rise.

3. Because of low Martian Gravity Structual integrity issue brought up by Calliban is less of an issue. The balloon climb rate is going to be weaker and the disadvantages outlined in part 1 of cons.

UPDATE: Also NASA is doing this, here is an updated graphics that will cheer up Calliban as now he is included in it with association with NASA
https://www.everand.com/article/5624454 … n-Airships
https://www.spaceanswers.com/futuretech … pacecraft/

Ok because you cannot scroll up this image I'll explain what was discussed with AI before the screenshot.
Basicly when you double the radius you 8 times the volume, 4 times the surface area and you 2 times the balloon material to compensate completely for the increased forces experienced. However 2 times the material mass is only a fraction of the 8 times in lifting ability. And that fraction reduces each time you double the radius!

Btw, thanks for bringing this up and not giving up trying to call me out, because of this it got me thinking about this ahead of schedule and I didn't actually know about the doubling of material as a compensation which is something I was eventually going to tackle and find out anyways but thanks for speeding up the process of me designing an interstella Airship. It will probably be saucer shaped not spherical and most of the payload will be part of the enclosing material discussed to further enhance the ability of the ship to handle stress. The flying saucer is going to have most of its mass as part of it's outer protective shell - This is a potential future post "Interstellar HAPs"

Caliban, each time you double the radius you increase the volume 8 times and the surface area 4 times. So the larger the balloon the less material you need per unit of volume. If you're unfamiliar with the maths of volume of a sphere and surface area of a sphere you can google or ask AI to confirm what I say.

hint: Each unit of volume is what causes lift. THE BIGGER THE BETTER!

Keywords for this theme:

1. Economies of scale
2. Scale Effect

So why didnt those PhDs you quoted or NASA themselves figure this out? The one thing I realized about human beings is that they sometimes have a "failure of imagination". No matter how smart they are. Want proof? Go back to Apollo 1. That capsule that caught on fire and killed all the astronauts. How come all those smart guys at NASA and the PhDs didnt think that it would be dangerous to fill that capsule up with so much pure oxygen at high pressures? Pretty commonsense now right? Why wasn't it commonsense back then? This is why I don't focus on other people's research although I do think it's a good idea before one starts a project or research to do exactly that for papers that have similar theme. But there are soooooo many now and its very very very easy to get lost in other peoples opinions about this and that. I rather focus on the maths and the basic laws of physics. If people did that more often with their time instead of regurgitating other's ideas and opinions without even understanding it, it's a waste of time.

Please refer to this post:
https://newmars.com/forums/viewtopic.php?id=10762
Refernce Spreadsheet:
https://docs.google.com/spreadsheets/d/ … ue&sd=true

That's why an airship is perfect. No rockets used to land. We have to figure out how to enter Mar's atmosphere with an inflated airship which I imagine will remain inflated from it's journey from Earth to Mars. I do not anticipate a huge problem to the insertion of an airship into the atmopshere of Mars because Mars has a low gravity and a thin atmosphere, so what we think might be a turbulant ride entering Earth's atmosphere would not apply on Mars. The large surface area of an airship would help it aerobrake gradually in the upper levels of Mars and then it can free fall into the denser lower regions of the atmosphere before floating at a set altitude. We could use nuclear electric system to use ionwind propulsion which might be more efficient in thinner less dense atmosphere compared to props. I'm not saying the airship wont have rockets, sure it will, just not for landing on Mars. Any rocket burn will be in the upper regions of the atmosphere during gradual aerobraking. We might even use plasma drives in combo with combustion rockets. The regular rocket would rapidly drop the speed of the airship and then turn off leaving only the plasma drives to assist with reducing speed for a steep drop into the lower regions of the atmosphere.

BTW I think the ice is going to be kms thick above any possible water under. So I don't think landing a rocket on it will drill all the way to liquid water. But if I'm wrong about that the airship is a good solution to just land like a cushion.

I have taken the liberty of doing the calculations for you so there is no more room for confustion. Have a look at the following screenshots and the linked spreadsheet:

This is how much payload a certain sized balloon can lift on Mars at datum for varaous sizes in radius. Can you now see that there is an exponential increase in payload the larger the baloon radius? At a certain point at abuot 106m it starts to compound the benefits like as if 106m radius is a sweet spot or minimum size for the balloon to start to be beneficial.

https://docs.google.com/spreadsheets/d/ … ue&sd=true

THIS IS HOW BIG IT SHOULD BE:

NOT THIS:

Thanks for this advice!

Hello, kindly scroll up to post 12(upstream), there is a screenshot of my calculations and link to spreadsheet with said calculations. Many thanks in advance!

The renderings are unprecise arts to make the topic more entertaining and digestable however they are not to far off from the truth of the topic. But by all means focus on my numbers!

We don't have to do the operation as large as like in the illustration, it can at first be just a small fration of that scale. 1 bar of vapor preassure can be achieved by raising the temperature of the water below very slightly. Use the Ideal Gas Law to calcuate. With a submarine style nuclear thermal reactor this can be achieved. The air cavity can be a small fraction of the ice so the ice basicly acts like air tightbvolcanic veins that can hold an air cavity with preassure partly because of their weight, density and thickness combined. I woud love adding regolith inside the dome but will think about what you said. The edge of the ice at the crater rim should not be disturbed.

Please examine the equations as the numbers do not lie. If I have made an error in an equation let me know! And I didnt say doubling the pressure does anything much, I said doubling the radius of the balloon does!

Copy of my Spread Sheet here
https://docs.google.com/spreadsheets/d/ … ue&sd=true

Here is also an updated vision of what we can do instead of hugging the ground in Hellas Planitia in humiliation:

Just a brief response to both members above, I've run some numbers independent of AI:

From above numbers a balloon 200m in radius that is 400m diameter can lift up 90 metric tons to the height of mount olympus. Im surpised by this and kinda suspicious. Sounds too good to be true. Feel free to scrutinize these numbers.

I used both the equation of bouyancy and equation for volume of a sphere. Feel free to google and wikipedia.