8 ms·

Would von Braun's Mars landers have worked?

112 points by Fred34 3y ago

Sparkyte 3y 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.
- Fred34 3y 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.
  - zizee 3y ago
    This says it's possible: https://space.stackexchange.com/questions/8016/is-a-railgun-up-olympus-mons-possible https://space.stackexchange.com/questions/8016/is-a-railgun-... Note: I cannot vouch for its correctness.
    - Fred34 3y ago
      I'll add that stack-exchange page to my bookmarks thanks.
  - colechristensen 3y 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)
    - rtpg 3y ago
      Wikipedia says there are prototype railguns that can shoot at 3km/s now (wording: "can regulary exceed 3km/s")... are we at a point now where I could put a rail gun and a bunch of solar panels and batteries on the moon and just shoot (tiny) stuff into orbit? Not like the rocks on the moon are that useful for anything, but....
      - Fred34 3y ago
        Apparently there is helium-3 on the moon which could be used as a fusion reactor fuel. https://en.m.wikipedia.org/wiki/Helium-3 https://en.m.wikipedia.org/wiki/Helium-3
- nickff 3y 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 3y 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.
    - nickff 3y ago
      I don’t think you can spin the blades much faster, as Earth-bound helicopters already have issues with blade tip speeds approaching the speed of sound. Short blades are less efficient anyway, and I’m not sure why pushing larger blades will require more power; that would have to do with the balance between density of atmosphere and its viscosity.
      - consp 3y ago
        As a bonus the speed of sound on mars is usually quite a bit lower than on earth, since it's usually colder. Or you'd have to wait for warmer weather at the right spot at the right time.
  - colechristensen 3y 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.
Animats 3y 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.
- Fred34 3y 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 3y 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.
    - Fred34 3y ago
      Within the decade? I wish I was that optimistic. There are only so many windows in the next decade where it's economical to send/receive rockets to mars. The planets have to literally align for it can be economical to send/receive people. https://earthsky.org/astronomy-essentials/close-and-far-martian-oppositions/ https://earthsky.org/astronomy-essentials/close-and-far-mart...
pugworthy 3y ago
If you are a fan of the Von Braun idea, you might find this interesting… https://youtu.be/ozkl1OvNvEc?si=B5ZQ3dWO2gFqlaoA 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 https://feoamante.com/Movies/Movies/Man_Conquer_Space.html
- Fred34 3y 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.
LuciBb 3y ago
[dead]
codeflo 3y ago
[flagged]
- hoseja 3y ago
  As opposed to all the other red-blooded purebred American murderers.
- RCitronsBroker 3y ago
  i agree. separating the man from his work is kind of hard after the man made a name for himself by hanging the slowest of his Jewish indentured servants "employed" in his German factory.
- Fred34 3y ago
  There is also a tendency, especially in America, to reduce everything to discussing the baddies of ww2, or at the very least, to not separate scientific discussions from political discussions.
- malermeister 3y ago
  "The Elon" is the Führer on Mars in an old timey Nazi book? Man, reality sure is strange sometimes.
  - defrost 3y ago
    The text on archive.org has both Elan and Elon ... there may be an OCR issue here: The Martian government was directed by ten men, the leader of whom was elected by universal suffrage for five years and entitled “Elan.” Two houses of Parliament enacted the laws to be administered by the Elon and his cabinet. The Upper House was called the Council of the Elders and was limited to a membership of 60 persons, each being appointed for life by the Elon as vacancies occurred by death. In principle, the method was not unlike that by which the College of Cardinals of the Roman Catholic Church is appointed. Usually the Elon chose historians, churchmen, former cabinet members or successful economic leaders who could offer lifetimes of valuable experience. https://archive.org/stream/ProjectMars/MarsProject_djvu.txt https://archive.org/stream/ProjectMars/MarsProject_djvu.txt ADDENDUM: It's Elon !! The first appearance as "Elan" was an OCR glitch:- https://archive.org/details/ProjectMars/page/n179/mode/2up https://archive.org/details/ProjectMars/page/n179/mode/2up
albertzeyer 3y 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.
- inquirerGeneral 3y ago
  [dead]
- Aachen 3y 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 3y 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 3y 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.
sspiff 3y 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 3y ago
  Which part is offensive to you?
  - deleted 3y ago
    [deleted]
  - sspiff 3y 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 https://tfaz.xyz/articles/toxic-femininity [1]: https://jacobwsmith.xyz/stories/build_fix_grow.html https://jacobwsmith.xyz/stories/build_fix_grow.html
Simon_ORourke 3y ago
What sort of knowledge did he have of the Martian atmosphere back in the 1950's?

112 points by Fred34 3y 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.

Fred34 3y 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.
- zizee 3y ago
  This says it's possible: https://space.stackexchange.com/questions/8016/is-a-railgun-up-olympus-mons-possible https://space.stackexchange.com/questions/8016/is-a-railgun-... Note: I cannot vouch for its correctness.
  - Fred34 3y ago
    I'll add that stack-exchange page to my bookmarks thanks.
- colechristensen 3y 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)
  - rtpg 3y ago
    Wikipedia says there are prototype railguns that can shoot at 3km/s now (wording: "can regulary exceed 3km/s")... are we at a point now where I could put a rail gun and a bunch of solar panels and batteries on the moon and just shoot (tiny) stuff into orbit? Not like the rocks on the moon are that useful for anything, but....
    - Fred34 3y ago
      Apparently there is helium-3 on the moon which could be used as a fusion reactor fuel. https://en.m.wikipedia.org/wiki/Helium-3 https://en.m.wikipedia.org/wiki/Helium-3
nickff 3y 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 3y 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.
  - nickff 3y ago
    I don’t think you can spin the blades much faster, as Earth-bound helicopters already have issues with blade tip speeds approaching the speed of sound. Short blades are less efficient anyway, and I’m not sure why pushing larger blades will require more power; that would have to do with the balance between density of atmosphere and its viscosity.
    - consp 3y ago
      As a bonus the speed of sound on mars is usually quite a bit lower than on earth, since it's usually colder. Or you'd have to wait for warmer weather at the right spot at the right time.
- colechristensen 3y 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.

Animats 3y 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.

Fred34 3y 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 3y 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.
  - Fred34 3y ago
    Within the decade? I wish I was that optimistic. There are only so many windows in the next decade where it's economical to send/receive rockets to mars. The planets have to literally align for it can be economical to send/receive people. https://earthsky.org/astronomy-essentials/close-and-far-martian-oppositions/ https://earthsky.org/astronomy-essentials/close-and-far-mart...

pugworthy 3y ago

If you are a fan of the Von Braun idea, you might find this interesting… https://youtu.be/ozkl1OvNvEc?si=B5ZQ3dWO2gFqlaoA 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 https://feoamante.com/Movies/Movies/Man_Conquer_Space.html

Fred34 3y 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.

LuciBb 3y ago

[dead]

codeflo 3y ago

[flagged]

hoseja 3y ago
As opposed to all the other red-blooded purebred American murderers.
RCitronsBroker 3y ago
i agree. separating the man from his work is kind of hard after the man made a name for himself by hanging the slowest of his Jewish indentured servants "employed" in his German factory.
Fred34 3y ago
There is also a tendency, especially in America, to reduce everything to discussing the baddies of ww2, or at the very least, to not separate scientific discussions from political discussions.
malermeister 3y ago
"The Elon" is the Führer on Mars in an old timey Nazi book? Man, reality sure is strange sometimes.
- defrost 3y ago
  The text on archive.org has both Elan and Elon ... there may be an OCR issue here: The Martian government was directed by ten men, the leader of whom was elected by universal suffrage for five years and entitled “Elan.” Two houses of Parliament enacted the laws to be administered by the Elon and his cabinet. The Upper House was called the Council of the Elders and was limited to a membership of 60 persons, each being appointed for life by the Elon as vacancies occurred by death. In principle, the method was not unlike that by which the College of Cardinals of the Roman Catholic Church is appointed. Usually the Elon chose historians, churchmen, former cabinet members or successful economic leaders who could offer lifetimes of valuable experience. https://archive.org/stream/ProjectMars/MarsProject_djvu.txt https://archive.org/stream/ProjectMars/MarsProject_djvu.txt ADDENDUM: It's Elon !! The first appearance as "Elan" was an OCR glitch:- https://archive.org/details/ProjectMars/page/n179/mode/2up https://archive.org/details/ProjectMars/page/n179/mode/2up

albertzeyer 3y 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.

inquirerGeneral 3y ago
[dead]
Aachen 3y 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 3y 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 3y 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.

sspiff 3y 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 3y ago
Which part is offensive to you?
- deleted 3y ago
  [deleted]
- sspiff 3y 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 https://tfaz.xyz/articles/toxic-femininity [1]: https://jacobwsmith.xyz/stories/build_fix_grow.html https://jacobwsmith.xyz/stories/build_fix_grow.html

Simon_ORourke 3y ago

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