Would von Braun's Mars landers have worked?

https://raypatrick.xyz/blog/2023/11/24/would-von-brauns-mars-landers-have-worked/

by Fred34 • 2 years ago

112 100 2 years ago

Sparkyte• 2 years ago

Mars doesn't have a thick enough atmosphere for lift, you can fly a copter, but it needs a lot of power to do so and it needs to be light enough to do so.

On the otherhand you probably could get away with a space elevator on Mars where you couldn't on Earth.

Fred3412• 2 years ago

I wonder what's the math on trying to use a huge rail gun on Mars to shoot things into orbit. I know that people have talked about using rail guns on the moon to shoot and other materials ore back to earth (or even to mars) -- but the moon has less of an atmosphere and less of a gravitational pull than mars.

zizee2• 2 years ago

This says it's possible: https://space.stackexchange.com/questions/8016/is-a-railgun-...

Note: I cannot vouch for its correctness.

colechristensen2• 2 years ago

The escape velocity for Earth is 11 km/s. The escape velocity for mars is 5 km/s. The situation for a ground launched projectile is of course worse because of air resistance losses.

It's still really difficult to accelerate something to 5 km/s. (It's 2.5 km/s on the moon)

nickff4• 2 years ago

Honest question here; why would you need more power to fly a helicopter on Mars than on Earth? You’d likely need proportionally larger blades, but less power, as the power goes into providing thrust, which is used to counter gravity (that is lower on Mars). Likewise, conventional aircraft would require longer wingspans, as they’d be flying in lower density air, but they’d also be lighter (less weight).

In case it’s not obvious, I suspect that larger wings are required because of the lower density of Mars’ atmosphere, which would increase the stall speed relative to Mach number of any given aircraft.

samplatt• 2 years ago

You're not countering gravity, you're countering the mass of the helicopter vs. the mass of the air moved. Thus, since the air is thinner: to push larger blades going at the same speed, OR the same sized blades going at a faster speed, you'd need more power.

colechristensen2• 2 years ago

Aerodynamic forces are proportional to density.

Mars' surface gravity is 1/3 that of Earth's.

Mars' surface air density is 1/60 that of earths.

So to use lifting surfaces on Mars to fly, the situation is 20x harder.

It's roughly equivalent to flying at 40,000 ft on Earth with an electric helicopter. The world record for highest helicopter ever flown is 42,500 ft on Earth.

Flying on Mars is like flying more or less at the service ceiling of all but the most specialized aircraft can on Earth, and most of those are air breathing engines.

The structural weight required to make equivalent lift to weight ratios (L/W) is very much harder and the lower gravity doesn't make up for most of the difficulty.

Animats2• 2 years ago

Von Braun lived just long enough for the first Viking lander. So he got to hear the bad news.

Landing heavy objects on Mars is not quite as bad as an airless landing, but it still takes a lot of fuel. Von Braun probably would have wanted to build a large space station orbiting Mars, with rockets shuttling back and forth from Earth orbit for supply. Then, with enough fuel accumulated in Mars orbit, a soft landing on rocket power would be possible.

Fred3412• 2 years ago

I really doubt that humanity will make trip to earth from mars in the next 50 years. It already takes a huge amount of fuel to land on Mars -- its not economical to launch enough fuel for a return trip (even if some of the fuel could stay in orbit like with the moon landings). Much better idea to find the few people that are fine living and dying on mars. Humanity has not returned a single sample from mars even though we've been landing spacecraft on mars for 50 years.

cryptoz• 2 years ago

What’s missing from your calculation is the current Mars plans from SpaceX or others. They plan on building a colony of millions of people. In order to do that, costs must be dramatically lower and return trips must be possible.

So all the current Mars-capable rockets are being developed with the idea that there will be return trips every synod.

Maybe those ideas will fail. But there are billions of dollars going toward this goal today, and more in the future. So I would bet very much that a return trip is likely within a decade.

nickff4• 2 years ago

Are you familiar with Mars Direct? I don’t think any current plans to go to Mars envision bringing all their return fuel with them to Mars orbit (much less to the surface).

dotnet00• 2 years ago

It's only not economical with our current mostly disposable rockets and lack of experience with ISRU and long term management and transfer of cryogenic fuels in space. Luckily we're working towards gaining experience on all those fronts.

While generating sufficient Methane is probably too big of an ask without involving extensive infrastructure, in methalox rockets (which many next gen rockets are), the larger mass is the LOX (iirc ~75% of propellant mass on Starship is LOX), which is a lot easier to devise automated methods for ISRU. Thus the problem becomes a lot more solvable. You send ahead a system to collect and store LOX, then you bring enough Methane for the return trip, and you also spend the 2 years till the return window collecting LOX.

Although, if you're sending stuff ahead of time and have the expected economics of Starship (ie down from hundreds of millions per ton to the Martian surface to millions per ton), you really can afford to just send ahead enough propellants for at least a round trip.

ffgjgf113• 2 years ago

Much better idea to find the few people that are fine living and dying on mars

What would be the point, though? Besides live streaming someone slowly dying from radiation poisoning?

It’s not like a human can really do anything that a sufficiently complex robot wouldn’t be able to. Also I always assumed that the whole point of going there (or to the moon for that matter) was to show that we can successfully get humans there and back rather than anything else.

lukan• 2 years ago

"Much better idea to find the few people that are fine living and dying on mars"

A few? Over 200 000 payed a scammy company money, to maybe be considered a one way mars colonist.

https://en.m.wikipedia.org/wiki/Mars_One

This year was supposed to be the year they finally go, but surprisingly it did not work out somehow, maybe because the company only knew how to do good looking 3D models and no real hardware. But they did make the proof, that there is no shortage of willing people to make a one way trip.

And in general I am more optimistic, I am pretty sure there will be humans on Mars in the next 50 years. I am not a fan of the guy in general, but I do believe Elon Musk is serious about going there and I can imagine him still dreaming of being the first on Mars (and then build his kingdom there). And the chinese might start a new space race. Then there is India, Brazil, .. lots of ambitions and national pride and egos. Or crowdfunding goes really mainstream and we organize a pure scientific mars mission at some point? 50 years are a long time and the rate of change right is crazy. It does not have to go all in a bad direction. In either way, rocket starts became something very normal. At some point it is just about doing enough of then, for the fuel and supplies. And we can do that. Also robots have come far, who can be send ahead.

steveBK123• 2 years ago

We will.. in the metaverse, interacting with LLM chatbot alien avatars!

bookofjoe• 2 years ago

"I'd like to die on Mars, just not on impact."

Elon Musk, in his 2013 keynote address at SXSW

nojvek• 2 years ago

I agree with you.

The bigger question in my mind is that in 50 years, will we need to even land humans on mars, or will be able to build space-faring robots where we can upload our consciousness and send that instead.

Humans, or generally all complex life on this planet is well ... adapted to this planet. Space is very hostile to us.

There's a reason why Mars has had six rovers, with opportunity working for 15 years.

Distance to Moon (384,400km) is 0.0017 of that to Mars (225,000,000,000km).

Humans have spent barely a few days moonwalking.

krystianantoni• 2 years ago

To me the whole concept of this exploration is to first find good base building and fuel materials while lowering the cost of travel. Once that happens it will be very quick paced race to those materials.

Like in any other business venture this mars/interstellar is a bet, so doubts of success are natural.

pugworthy• 2 years ago

If you are a fan of the Von Braun idea, you might find this interesting…

https://youtu.be/ozkl1OvNvEc?si=B5ZQ3dWO2gFqlaoA

It includes a few scenes of Von Brauns Mars gliders.

This is from a long dead indie movie project called “Man Conquers Space” based on his ideas. More info at https://feoamante.com/Movies/Movies/Man_Conquer_Space.html

Fred3412• 2 years ago

Thanks for the links, it’s cool to see a video showing how the gliders could have looked liked if they were real. I haven’t heard of that film project.

albertzeyer• 2 years ago

Just as a side note, I'm currently watching "For all mankind", and of course Von Braun played an important role there as well (in the real world, working 1959-1972 for NASA). I can recommend this series if NASA, spaceflight, moon or Mars are interesting to you.

Aachen• 2 years ago

Mainly if NASA, spaceflight, moon, or Mars of that era are interesting to you. I found that it was as much a history lesson as fiction, and devolved into the usual drama rather than actually being about the topic they lured you in with

throwbadubadu• 2 years ago

Find it amazing that he assumed 8 times too much density, but still the design in regard to lift missed only 50%? Not too bad, likely had quite a margin planned as good engineer? ;)

totallyabstract• 2 years ago

Also have to take into account that number was at ground level where there is the highest air density. I’m not sure what the landing and takeoff profiles looked like in the design but presumably the wings are that size so it can operate at a higher altitude at a reasonable speed.

sspiff2• 2 years ago

Interesting read.

After having read this post, I noticed the page had an old school webring footer, how nice!

Clicking on it however, I was greeted by:

An invite-only discussion platform for Christian men. Christ is King!

Jikes...

matrixcubed• 2 years ago

Which part is offensive to you?

sspiff2• 2 years ago

Nothing in and of itself, other than "why would you want to limit a community to Christian men?". It signals a particular worldview and set of values, most of which involve excluding or degrading others.

Look around the webring. You'll find statements like:

"Feminism is without a doubt one of the key ideologies in perverting the Christian worldview. The rhetoric “patriarchy”, is a denial of spiritual fatherhood. I’d wager most feminists would admit they’d give up their man-like life in return for a loving father."[0]

And

"What would happen if we got rid of the lower education industry? Kids wouldn't have anywhere to go during the day so many mothers would probably be forced back into the home and fathers would be forced to stay with and support their families. This would actually be really great for society."[1]

So: jikes.

[0] https://tfaz.xyz/articles/toxic-femininity

[1] https://jacobwsmith.xyz/stories/build_fix_grow.html

Simon_ORourke• 2 years ago

What sort of knowledge did he have of the Martian atmosphere back in the 1950's?

Would von Braun's Mars landers have worked?

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