Please create an account to participate in the Slashdot moderation system

 


Forgot your password?
Close
typodupeerror
×
Space

Flying on Mars 149

Posted by michael from the taking-off-shoes-not-necessary dept.
jimharris submitted a bunch of links about flying on Mars: "X-Plane's author Austin Meyer is working out the details of flying on Mars. Meyer has taken his system and adapted it for the conditions on Mars and has discovered a lot about what it would take to fly on Mars, where the atmospheric pressure is 1 percent of Earth, and gravity one third, but laws of flight remain the same. Flying becomes difficult, and landing almost impossible. Other people are working with NASA to create Entomopters engineered to meet Mars conditions. More ideas about the concept can be found at PBS's Scientific American Frontiers. A quick search at Google will reveal many people are thinking about flying on Mars." It's a beautiful challenge - how to fly in a situation where everything you "know" about flight is wrong.
This discussion has been archived. No new comments can be posted.

Flying on Mars More

Flying on Mars

Comments Filter:
  • I always wanted to get a Flight Sim with accurate physics (and of course landscapes.) for the solar system planets and satellites. I hope that a game with this theme will show up one day. Maybe hacking XPlane would work?

    PPA, the girl next door.
  • Wouldn't helicopters work best on mars? Mars is smaller (I forget by how much).. so I doubt anyone's gonna need a 747 up there any time soon :P
    -Rob

    • Re:Idea! (Score:2, Insightful)

      by The Gardener ( 519078 )

      Helicopters aren't fuel efficient, nor are their rotor "wings" good for lifting in a one percent atmosphere. A plane like the U-2 would be the obvious choice, except for the horrendous storms on Mars.

      The Gardener

      • No, no, no. All we need is jet-packs.

        Remember those things from the 60's?
        They'd be 3 times as efficient on Mars!

        Seriously, it just doesn't make sense to fly on mars like it does on earth, It's like trying to push a boat down the highway. The martians will either have to thicken the atmosphere or just put down some tracks for the high speed trains.

        I could imagine 6000 MPH trains on mars, less gravity no pesky animals and hicks to run into, long flat stretches, _very_ little atmospheric drag.... At that speed would you really miss the airplane?
    • Helicopters wouldn't work in such a low-density atmosphere.

      I suppose planes would need huge wings in order to work, because they need to cover a much bigger area to get lifted.

      • Ohh, ok.. I thought they meant 1% oxygen, and not 1% pressure. Shoulda thought about it more :P
        At any rate, Mars still has low oxygen. I'd like to see how they work out using (hydrocarbon) fuel :P
        • At any rate, Mars still has low oxygen. I'd like to see how they work out using (hydrocarbon) fuel :P
          That's easy. Same way as the astronauts (or marsonauts if you prefer) will breathe, which means probably with oxygen bottles (liquid if the quantity is important and the temperature is not, else gaseous but at high pressure). Heck, the rockets that sent all the Apollo missions used liquid oxygen! It's some additional weight to carry on a plane, but since flying on Mars is inefficient to begin with...

          Now, the real kicker is how do you get that oxygen. The problem needs an answer anyway because of the humans that will probably be sent over there in the next couple years (or century). There's a couple ways. Ever wondered why Mars was red? Rust. And what is rust? Iron + oxygen. So you only have to separate them, either with a chemical reaction or with enough energy (electricity), which can come from the Sun or a nuclear reactor.

          If Mars is ever colonized (which flying vehicules on it implies, in part because of the costs involved) rather than visited as the Moon has been, there will probably be a power grid, a water grid and an air grid, as long as the outside is too harsh without a suit.

    • Re:Idea! (Score:3, Informative)

      by einhverfr ( 238914 )
      Wouldn't helicopters work best on mars? Mars is smaller (I forget by how much).. so I doubt anyone's gonna need a 747 up there any time soon :P

      RTFA. The basic problem is that you indicated airspeed is 1/10th the acutal airspeed, which means that your lift is 1/10th what it would be if you were on earth.

      So of your main rotor is moving at a very conservative 200RPM providing enough lift for takeoff, then that same rotor would have to move at 20,000RPM in order to take off on Mars. This won't work very well because it will be very inefficient and probably make it difficult to keep the body of the helicopter stable.

      Designing a helicopter to fly on mars would be a very interesting and difficult task indeed.

  • Landing (Score:3, Funny)

    by Waffle Iron ( 339739 ) on Sunday December 30, 2001 @05:14PM (#2765667)
    Flying becomes difficult, and landing almost impossible.

    Actually, landing is always easy. For example, NASA has landed several spacecraft on Mars in the last few years.

    The difficult part is managing to keep your vehicle in one piece as you land.

    • It seems that you have a problem with the definition of the world "land".

      You can only use the word "land" for a successfull landing. Anything else should be called a disaster.

      Despite all this, I think your comment should have been moderated funny instead of flamebait. Well, whatever.
      • By your logic, a "crash landing" would be a "successfull crash."

        A more appropriate definition for "landing" would be "controlled crash."
        • A more appropriate definition for "landing" would be "controlled crash."
          which is exactly what you do when you "land" an airplane... you stall it 3 feet over ground.
          (When the air flow around your wing rips off your plane falls like a stone... but you are only 3 feet high so it is very likely that you land (!) on the gear)
    • OK, given that you can't rely on reverse thrust, parachutes or brakes to slow you down.

      So whats wrong with retro rockets 1/3 gravity should help here.

      slashnik

      • > So whats wrong with retro rockets 1/3 gravity should help here.

        Lower gravity doesn't help with retrothrusters. Think mass, not weight. That said, retrorockets would work quite well, but they're very inefficient in terms of vehicle weight and cost and such. Arresting gear (his suggestion is a simple tailhook) is cheaper, less prone to failure and easier to maintain, which is why it's a better choice.

        Virg
        • It does so help. There are two masses in the gravitational force equation: that of the object and that of the planet. In this case, the planet's mass is smaller, so there is less gravitational force. Lower gravitational force means you need less force to counteract it.
          • > Lower gravitational force means you need less force to counteract it.

            Since the original discussion was arresting forward motion after landing (this is a plane, so we're not talking about deorbiting), I'm not sure how you feel that a change in gravitation applies.

            Virg
            • Hmmm. My bad I guess. I'm trying to figure out where in the parent chain it specifically talks about horizontal motion and planes (a retrorocket arrests forward motion, but that forward motion can be vertical), but breaks were mentioned and they are pretty much only good for horizontal motion.
        • Yes and no, the retro thrusters wont help in couneracting the high speeds required for conventional flight but they will help in couteracting the force of gravity. Think perhaps of a hopper rather than than conventional plane.

          slashnik

          • Well, if they're used for lift then they're not retrothrusters, now are they (BFG)? That's actually not a bad idea for moving on the surface of any low-grav planet, and jump jets were proposed for Moon vehicles back in the '70s. They are still too expensive in terms of fuel at this point, but for navigating rough terrain without flying (on the Moon aerodynamic flight is, of course, impossible) the designs look very promising. One of the best designs I saw involved a treaded vehicle with jump jets to hop over big obstacles, in much the same vein as the Battletech mechs. That way, you don't need as much fuel but you can get out of (and into) some very tight spots if need be.

            Virg
  • What about that document, eh? Some fun RANDOM CAPITALIZATION. Looks like the entire document was written by Zippy the Pinhead, but without the random statements. An interesting document. Perhaps we're going to have to use slow "zepplins" on Mars. It could acutally be a better idea. The zepplin is floating about 60m above the surface, and it has four thrusters. The one the the back is the most powerful. They are arranged so that the thrusters are at right angles from each other (or maybe a "peace-sign" arrangement is better?).

    Just a thought. Flames will be used to save on energy bills.
    • You would have to use a gas with a lower density than the Mars atmosphere. And you'd need a huge volume of gas...

      Zeppelins probably wouldn't work, because they'd be far to big to be useful, IMHO.

  • We have large lifting craft that require almost no runway for takeoff and landing.. they are they relatives to the blimp.

    Same laws apply.. sure there is less of an atmosphere.. but you also have one third the gravity to contend with. The main problem with such craft on the martian surface would be the fact that 1) they are huge, and 2) they are light. With the storms that have been witnessed on mars recently, storing such a craft would be a nightmare if you didn't collapse it and store it. Lets not forget the possibility you COULD be in the air when such a storm kicks up.. nothing could save your arse if that happened..

    I think this will be the way we go.. because a dirigible could be packed into a small payload area for transport to the martian surface. The added bonus is that Mars has VERY little oxygen in the atmosphere.. so it becomes safe to fill the dirigible with hydrogen as opposed to helium, giving you much more lifting power.. the problem comes with storing compress hydrogen when you deflate these behemoths.. wouldn't want to store the tanks near an oxygen rich environment like say.. in the living structures or greenhouses.. =)
    • Hmm. In fact this would not be so easy I think.

      The highest-altitude balloons ever flown on Earth topped out at 100,000 feet. That's the altitude where Earth's atmospheric density finally drops to the point where it reaches Mars' at "sea level".

      By comparison the x1/3 lower gravity will not be that much help - you will need a huge, thin balloon to carry any weight at all, and (a) collecting the necessary quantity of gas; and (b) inflating it safely both become major challenges.

      I think this is why we don't see mention of balloons / zeppelins on the NASA webpages.

      -Renard

      • Who said we'd inflate the balloon? mars has a 1/100th of the air pressure, using a few stiff wires and the thinnest mylar you can find, I bet that you could hold a vaccuum in that sort of pressure.
        interestingly, since you need only a 100 times more volume, which equates to 100^(1/3) times as much volume on earth, it won't really have to be as big.
        I think about 4-5 times as large in a single dimension.
        Heh, it would probably still be as big as the queen emeraldas!
        • The reason i posted this idea is based on a few simple laws.

          First, you have gas laws, such as PV=nRT. Since all gasses in the martian atmosphere are going to follow that law, as temperature is constant as is pressure for localized areas (surrounding the dirigible). Also R doesn't change.. So the volume that the gas will occupy doesn't become a huge challenge like one would think.

          The other thing to take into account is the composition of the martian atmosphere.. its what, 95% CO2? (MW 44) compared to Earth's 79% Nitrogen and 20% Oxygen (MW 28 and 32 respectively).

          The point is that for a given cubic meter of atmosphere on Mars (if compressed to 1atm) it would be more dense than a cubic meter of earth's atmosphere at the same pressure.

          Sure there is going to be an altitude limit imposed on such a craft in martian atmospheric conditions, but for doing work at low altitudes I think this is much more than feasible.

          I don't have the desire to do all the fun math stuffs to actually test the validity of this argument, i was hoping someone would try to disprove this point mathematically then realize that it is possible.. =)
          .

    • Re:I think people are making this more difficult.. (Score:5, Informative)

      by SurfsUp ( 11523 ) on Sunday December 30, 2001 @06:28PM (#2765888)
      Same laws apply.. sure there is less of an atmosphere.. but you also have one third the gravity to contend with. The main problem with such craft on the martian surface would be the fact that 1) they are huge, and 2) they are light. With the storms that have been witnessed on mars recently, storing such a craft would be a nightmare if you didn't collapse it and store it. Lets not forget the possibility you COULD be in the air when such a storm kicks up.. nothing could save your arse if that happened..

      Fortunately, the laws of rocketry also continue to apply. The .38g gravity of of Mars really helps - landing vertically should be a cinch.

      As for structural lightness, remember, the air is very thin. What looks like a huge storm on a satellite photo just isn't going to going to blow anything over on the ground. It's true, Martian winds can pick up small particles, and researchers are still trying to figure out how that happens - vortices maybe, and the oarger particles probably don't get very far off the ground. Global dust storms would contain only the finest particles.

      Blimps/dirigibles on the other hand... with less than 1% atmosphere, you have less than 1% of the bouyancy. In the end your balloon will have to be 30 times bigger to lift the same mass. This means that, while a balloon might work, a dirigible won't. Too much structure required.
      • Blimps/dirigibles on the other hand... with less than 1% atmosphere, you have less than 1% of the bouyancy. In the end your balloon will have to be 30 times bigger to lift the same mass. This means that, while a balloon might work, a dirigible won't. Too much structure required.

        On the contrary.... here's a little math..

        Size of balloon for dirigible (and volume..)
        Volume of ellipsoid (a=semimajor, b= semimean, and c=semiminor axes) = (4/3)*pi*abc.
        A=100m B=40m C=30m

        V=5.03x10^5 M^3
        V=5.03x10^8 L

        Now for temperature and pressure...

        Assuming Tmars to be avg. -50C = 223K
        And assuming we inflate to 2atm(mars) = 0.02atm(earth)

        PV = nRT
        n = PV/RT = (0.02atm * 5.03 x10^8 L) / (0.0821 L atm/mol K * 223 K)

        n = 2.75x10^5 moles within balloon...

        M(H2)=2 g/mol * n = 5.5x10^5 grams

        yeah, that's a LOT of hydrogen.. but lets continue

        For the atmosphere this hydrogen is displacing...
        Which, BTW, is over 95% CO2, unlike earth which has a much lighter atmosphere for a given pressure..

        PV = nRT
        n = PV/RT = (0.01atm * 5.03x10^8 L) / (0.0821 L arm/mol K * 223 K)
        n = 1.38x10^5 moles of atmoshpere displaced
        M(CO2)=44 g/mol * n = 1.21x10^7 grams

        Taking the difference, we find that there is 115.5x10^5 grams or...
        11550 kg of lifting force here...

        Of course we might need to put more H2 into the balloon to have it hold it's shape.. for each martian atmosphere of additional pressure we inflate the craft with, go ahead and reduce the lift by 275 kilograms. Double the local atmospheric pressure should be sufficient.

        Now, can we build an airship of that size and keep it's weight under 10000 kg?
        (Mind you that IS 30000kg here on earth)...

        I think it is safe to say it is more than easily accomplished.
        .
        • I hate to nitpick, but this is so wrong I had to point it out.

          Taking the difference, we find that there is 115.5x10^5 grams or...
          11550 kg of lifting force here..
          ...
          Now, can we build an airship of that size and keep it's weight under 10000 kg? (Mind you that IS 30000kg here on earth)...

          I'll assume based on the rest of the post that you know the difference between mass and weight... ;) 10000kg on earth is still 10000kg on mars.

          Other than that and the fact that some of the calculations you show have the wrong answer (but strangely the right final answer, where'd you pull that out of?), you're right, a blimp should work ok on mars.

  • In response to others... (Score:3, Informative)

    by Fortuna Wolf ( 191194 ) on Sunday December 30, 2001 @05:27PM (#2765704) Homepage
    Helicopters won't work well on mars, you'll need to have your props spinning 10 times faster to get the same lift, which will be somewhat diffucult, no?
    It might work actually, but AFAIK there aren't any easily manufacturable materials that will stand up to the centripetal forces, since there will be 100 times as much force on the end of the prop (centripetal force is the square of velocity). You might be able to do this by increasing the surface area of the prop (longer blades, or more blades).

    Also, nasa's probes once they get into the atmosphere still use parachutes and rockets to slow down to a decent speed and then giant inflatable bubbles to bounce along, but you only use that when you're below a few hundred knots. In the article, it says, that you'll be going 400 mph in a well designed plane, there's no way you're gonna just bounce around if you hit the ground like that... Same inertia, right? imagine that its like having 10 times more inertia...

    also, I've seen a few articles, he mentions red sky on mars.
    I've seen no good proof to believe the sky is red, if its because the ground is red, think about the earth, in the middle of a desert, or forest, is the sky yellow or green? looking at that, you'll often think they'll be bluer than at the beach (where it tends to look grey, I live at a beach town).
    Because the colour of the sky is caused by Raleigh scattering (or other scattering effects), the effect (based on the size distribution of particles in the atmosphere) is the same on Mars as it is Earth.
    Somewhere, if you hunt around for photos from the surface of mars, and correct using say, photoshop, for the colour (look at the parts of the probe you can see in the picture and return them to their original colours, usually white or metal, unless its an american flag), the sky will be blue.
    • Helicopters won't work well on mars, you'll need to have your props spinning 10 times faster to get the same lift, which will be somewhat diffucult, no?
      It might work actually, but AFAIK there aren't any easily manufacturable materials that will stand up to the centripetal forces, since there will be 100 times as much force on the end of the prop (centripetal force is the square of velocity). You might be able to do this by increasing the surface area of the prop (longer blades, or more blades).


      Sounds like another potential use for carbon nanotubes. After all, if they're strong enough to build a space elevator (see earlier /. article) they're probably strong enough to make a helicopter, right?
      • true, but show me how to manufacture nantubules in large enough quantities to do that :), heh, and I'll just show you how to manufacture diamond blades...
        But yeah, that's what they said about carbon fiber,
        I think also that diamond is strong enough to build the space elevator.
      • Sounds like another potential use for carbon nanotubes. After all, if they're strong enough to build a space elevator (see earlier /. article) they're probably strong enough to make a helicopter, right?


        A quick disclaimer. I am not a physisict, however, I am a pilot. :)

        The problem isn't with the strength of the blades so much as it is with the rotor tip (linear) speed.

        The forces on the blades varies with the square of the RPM, so, for an increase of 100x, you get an increase of 10000x in 'centrifugal' forces on the blades. [Ref: Aerodynamics For Naval Aviators, pg 113 and 148 ] [amazon.com]. (or a Canadian Source) [aviationworld.net]

        Long before we design a rotor that is strong enough to do this, the tips of said rotor will exceed the speed of sound on Mars at whatever density altitude you are at. The onset of compressibility effects and eventually shock wave propagation will adversely affect the lift generated by the rotor.

        More likely would be a LARGE, slow, rotor. This is where the nano-tube technologies might have an opportunity to shine.

        You can read lots more about rotor-wing principles at this location. [aerodyn.org]

        Disclaimer: I am not a rotor-head. I fly a fixed wing.
    • Oh yes, one more thing,
      I'm curious as to whether an Ekranoplane would work better (plane that uses the surface pressure effect to lift, like a cross between a hovercraft and plane),
      hum, come to think of it, it probably won't, the wings probably would probably have to be too high off the ground for safety to be able to compress the thin atmosphere to the point where it provides lift off the ground.... assuming the speed of sound is less on mars than on earth.
      If the speed of sound was faster (which I'm thinking it is now), it might work.

      Does X-plane simulate ekranoplanes?
    • You can see the color of the sky on Mars by looking at photographs taken from the various crafts that have landed there. I'm not 100% sure, but I think you might find some on space.com.
      • Trying to Jump into the chatter.....NASA produced a dull if approximate tape on "Landing on Mars" ISBN 1-55541-026-x {1987 SSC{MA. }Personally the Whoopee cushion ride that used to be a moon ride and is now a Mars Tour at an older Disneyland was more fun. My favorite Mars Tour would have to be the TV show special on how we got there. Recently the Landing aspect was humorously dealt with in the Val Kilmer "Red Planet" bounceing ball. A game would indeed be fun something like the 80's moon lander mayhaps. Cheers ,I'll go read some Carter Mars now....
    • Helicopters won't work well on mars, you'll need to have your props spinning 10 times faster to get the same lift, which will be somewhat diffucult, no?

      One other problem mentioned in the NASA pages: because of the thin atmosphere your rotors will have to be moving at supersonic speeds before they provide sufficient lift! The resulting shockwaves (sonic booms) are severely disruptive of typical rotor airflow patterns.

      -Renard

    • Re:In response to others... (Score:5, Insightful)

      by jackal! ( 88105 ) on Sunday December 30, 2001 @06:34PM (#2765897) Homepage

      I hope this doesn't sound like a flame (famous last words!)

      I've seen no good proof to believe the sky is red, if its because the ground is red, think about the earth, in the middle of a desert, or forest, is the sky yellow or green? looking at that, you'll often think they'll be bluer than at the beach (where it tends to look grey, I live at a beach town).

      Go to a desert during a dust storm. The sky WILL be brown/sand coloured. That's part of the idea behind the red Martian sky: high amounts of red/orange/yellow dust in the atmosphere because of those storms that are always happening somewhere on the planet.

      Because the colour of the sky is caused by Raleigh scattering (or other scattering effects), the effect (based on the size distribution of particles in the atmosphere) is the same on Mars as it is Earth.

      The same on Mars as it is on Earth? If the colour of the sky is dependent of the atmosphere and its contents, then the Earth and Martian skies should be completely different, just as the atmospheres are.

      Somewhere, if you hunt around for photos from the surface of mars, and correct using say, photoshop, for the colour (look at the parts of the probe you can see in the picture and return them to their original colours, usually white or metal, unless its an american flag), the sky will be blue.

      I don't even know where to begin with this one. It's as if O.J. Simpson took pictures of his poor victims, and photoshopped away stab wounds to prove that they aren't in fact dead. Sure you can prove that the Martian sky is blue with one Photoshop filter, and I can prove that I'm 50 pounds thinner with another...

      • Because the colour of the sky is caused by Raleigh scattering (or other scattering effects), the effect (based on the size distribution of particles in the atmosphere) is the same on Mars as it is Earth.
        The same on Mars as it is on Earth? If the colour of the sky is dependent of the atmosphere and its contents, then the Earth and Martian skies should be completely different, just as the atmospheres are.
        I don't think that's the case. AFAIK, the scattering effects don't depend on the atmosphere's contents: shorter wavelengths are always scattered more.
        I don't even know where to begin with this one. It's as if O.J. Simpson took pictures of his poor victims, and photoshopped away stab wounds to prove that they aren't in fact dead. Sure you can prove that the Martian sky is blue with one Photoshop filter, and I can prove that I'm 50 pounds thinner with another...
        I think you need to read your parent post again. He's saying that the colour of the spacecraft can act as a control sample. Correct the picture so the spacecraft looks right, and everything else should also look approximately right.

        I'm not sure it's as easy as that, but it's certainly not as stupid as you make it sound.

        • Wow, this is really silly. How can the spacecraft act as a control sample if it's being lit in the same way as the rest of the landscape?

          To have a control sample, you'd need to take a picture with the camera of some known colours, under controlled lighting conditions.
          • You should be able to account for that. I'm no expert, but it seems to me that if you have a picture containing the spacecraft and the sky, and you know that spacecraft is lit by that sky, you should be able to get a good approximation of the real colours involved.

            Regardless, I still think it's not as stupid as you made it out to be. He wasn't proposing that you can just fiddle with the colours until the sky looks any colour you want.
      • seems reasonable... if the sky is red because of
        dust, then the ambient light is also is also
        going to be reddish, casting a shade on the
        probe/etc. Filter that ambient color cast out,
        using a control sample of known color (well,
        somewhat known... after all, on Earth it should
        have a slight blue cast, though probably less of
        one) and what's left should be the wavelength
        scattering as seen right here on Earth (ie, blue).
        Shorter wavelengths bend more, that shouldn't change
        just because the atmosphere is thinner (though
        everything should bend less, so the color would be
        less pronounced)

        Not that the sky would be blue when you looked
        at it, but that effect should be there underneath
        the red dust.

    • Re:In response to others... (Score:5, Informative)

      by instinctdesign ( 534196 ) on Sunday December 30, 2001 @06:36PM (#2765901) Homepage
      I was able to find a few images of mars [marssociety.org], this one here [nasa.gov] is particularly good. In terms of color it seems fairly ok to me, though the other color references are a bit limited. Also, a basic overview of Raleigh Scatter for those who are interested can be found at www.people.cornell.edu/pages/eac26/RaleighScatteri ng.html [cornell.edu]. A quick quote from it, Have you ever seen a brilliant red sunset? After all of the colors have scattered out of the white light, we see the oranges and reds. Where on the horizon are the red colors found? The reds are found close to the horizon because the sunlight must pass through many particles before we reach the point that red is scattered out. So if the atmosphere of Mars is particularly dusty for instance then you'd get a more red hue (at least if I'm reading this right), making the Mars sky closer in hue to a reddish color.
      • I read an account written by a fellow who was in JPL when
        the Lander Pics were received.

        The NASA officials were estatic at the hue of the pictures
        which had been incorrectly rendered in colour from the
        original Monotone FITS standard.

        They were happy at the pink sky effect.

        When this individual Colour-corrected for the thin atmosphere
        and the US Flag on the Lander -- the sky came out Dark Blue at
        25 to 45 of viewing angle.

        He was howled down, and banned from the building. THIS was
        an ALIEN World, and it was going to stay that way!

        I can't remember WHO that individual was; but he is respected
        in Science and the field of Digital Rendering.

        .

    • White is the Bitch (Score:2, Informative)

      by mojotoad ( 78874 )
      Fortuna Wolf said:

      Somewhere, if you hunt around for photos from the surface of mars, and correct using say, photoshop, for the colour (look at the parts of the probe you can see in the picture and return them to their original colours, usually white or metal, unless its an american flag), the sky will be blue.


      In spite of this potential troll, I feel compelled to point out that the reflectivity of a surface will naturally reflect most electromagnetic components of its environment. This goes for white surfaces. So by "correcting" the color balance of such a surface, such as appendages of the mars probes, you have in fact only inferred the original environment from which your photo was based.

      Mojotoad
      • So by "correcting" the color balance of such a surface, such as appendages of the mars probes, you have in fact only inferred the original environment from which your photo was based.
        But if you went and stood on Mars long enough, your eyes would adjust to the hue, and the scenery would propably seem a lot less red.
    • Due to the Thin Atmosphere, and the Low Gravity...

      Maybe what is needed is a Giant Light-weight Mechanical Grasshopper with Even More
      Giant Wingspan!

      Of course, the take-off accelleration would be a bitch!

      --More seriously, what about aircraft similar to the Gossomer Series?

      Gossomer Condor, Gossomer Albartross, etc? Light weight and really big wingspan.

      Then there's the one that was the only aircraft to fly non-stop around the world.
      And the recently designed solar-powered circling Radio Platform design.

      --I recall that there was an engine design that carried self-'oxygenizing' fuel! That
      was featured in an article in Popular Science 18 or so years ago.

      .
  • .......but I would rather just *get* there.
    • Yes we all need to get behind Dr. Zubrin's plan Mars Direct. Everyone who is interested in Mars should read "The Case For Mars"

      http://www.amazon.com/exec/obidos/ASIN/068483550 9/ qid=1009753007/sr=8-1/ref=sr_8_3_1/002-3248067-676 8865
  • you take a box say about 5mx8mx4m attach short extenstions (wings) say 1mx1mx0.05m and put thrusters under them, now, put a big thruster on the back of the craft, a big fat reactor to power the thrusters (I know I know, but I like SciFi) and of you go.

    let me clarify, the box is the body of the craft, It is divided into 2 floors, the upper floor houses the crew, controlls, etc. the lower floor houses cargo, fuel, reactor, etc.

    The wings with thrusters are so that you can change the pitch of the vessel. the thruster on the back is the main thruster, you can change in which direction its facing (handy for liftoffs,etc.).

    maybe I've been watching to much startrek, corrections are welcome, also, I'm not sure if I used the right word for pitch, if you have better Ideas, please tell me ;)

  • Am I the only person... (Score:2, Interesting)

    by Snard ( 61584 )
    ... who read that article and thought "too bad they didn't call these vehicles 'ornithopters' "?
    • You probably are. Ornithopters are "mechanical birds" with flapping wings, like Da Vinci used to imagine. None of the proposed designs fits the name.

      Admit it, you're just a MTG junkie, aren't you?

      Virg
      • Admit it, you're just a MTG junkie, aren't you?

        Actually, I have no idea what "MTG" stands for. I just thought the idea of "life imitating art" was an interesting one (i.e. a real invention that was similar in concept to something from Herbert's "Dune" series).
        • My vision for a manned Mars flyer always went more toward the idea of an ultralight, in the same vein as the trip down the axis of the vessel in Rendesvous with Rama, since I figured a large span, ultralight airframe was about the only device capable of steering within any safe distance. Thrust is still an issue (props don't work very well in thin air, after all) and the airship is fragile but at least you don't need to be moving at an insane speed to get off the ground, and an ejection from a damaged or out-of-control craft could be affected with a simple jetpack (jump from the craft and use the jetpack to touch down on your feet, ideally).

          By the way, MTG refers to the game Magic: the Gathering from Wizards of the Coast. One of the cards in the game (a popular card when it was first printed) was an Ornithopter.

          Virg
  • Not only has Mars flight been a feature of X-Plane for ages, it even comes with two vehicles specifically designed for Mars, a rocket and a jet, [geocities.com] which somewhat resembles a U-2.

  • Recommended reading: Kim Stanley Robinson (Score:3, Interesting)

    by adamy ( 78406 ) on Sunday December 30, 2001 @06:13PM (#2765846) Homepage Journal
    Read Red/Green/Blue mars by Kim Stanley Robinson. Not only has he done an amazing amount of research into all the aspects of an initial effort to live on and terraform (aeroform) Mars, but he has written it as a very readable story. Some of the things he brings up:
    • Dirigibles to navigate
    • Dealing with Dust storms...and the everyday dealings with particles much smaller than earths dust (fines)
    • Water
    • Use of Robotics
    • Legal issues (When in the course of human events...
    • Political views. The Reds (Keep Mars as it is) VS The Greens (Terraform Mars)

    And more. For example...If you want to convert the surface of the planet to a temperature where you can stay outside without a space suit you need to heat upo the atmosphere. The best way to do that is to use Carbon Dioxide as it is a natural greenhouse gas. However, if your eventual goal is to make the atmosphere breathable, you need to do something about the vast quantities of Carbon Dioxide.

    How about a huge focusing lens positioned in a aerosynchornous orbit that collects those solar rays that woud just miss Mars and focuses them back toward the3 planet to heat it up.

    How about drilling huge holes in the surface to realease Geothermal energy into the atmosphere to heat things up.

    And so on. If you are interested in Mars, read the book. He addresses a lot of the major issues . Even if he is off on certain topics (it is a novel after all), it is a great step forward in Science Fiction
  • A name pops up in my mind, Dragonfly... ;-)
  • It's a beautiful challenge - how to fly in a situation where everything you "know" about flight is wrong.
    Everything we know about flight is wrong? Hardly!

    Did you even read the article?

    The laws of physics are the laws of physics -- and they're the same on Mars. Yes, you'll need larger wings, and will have to fly *much* faster than you would here -- but 1) we can easily calculate all these factors (like Austin did) and 2) we've already got planes here on Earth that fly in somewhat similar conditions (up at 100k feet -- not 1/3rd Earth gravity, but the same weak atmosphere (well, it's not mostly CO2, but there are realms where the Reynold's numbers are the same.)

    The only way that `everything we know about flight' could be wrong is if `everything we know about flight' corresponds to `Give it full power, wait a few seconds as it accelerates, and then pull back on the stick at 60 knots, and your Cub will take off'. Sorry, but we do know more than this. If we didn't, this article wouldn't even be here.

    Other /. posters have commented about the horrible `storms' on Mars. I'm not so sure they'd be a problem for anything but a blimp -- sure, the wind may be blowing at 200 knots -- but that's only 1/3rd of your cruising speed (and only 20 knots on your Earth-calibrated air speed indicator -- it wouldn't even faze a guy in a spacesuit walking on the surface.) Hell, a 400 knot headwind might allow you to take off and land in a reasonably short space :)

    What would be even neater than flying in Mars would be flying in Venus or Jupiter. As I understand it, Venus has a thicker atmosphere, so you could fly slower and turn quicker. Jupiter is a gas giant, so as you get deeper and deeper the atmosphere would get thicker and thicker -- of course, the pressure goes up too, and since it's mostly hydrogen, you're likely to have a much higher pressure than you'd find on Earth before the atmosphere would be as `thick' as it is here, but it would certainly be doable.

    • I guess that is everything we know about how a plane looks like is wrong. I don't thing anythig resembling a jet would work on mars; onot because it can't be designed, but other flight machine designs make more sense. Like a vast glider powered, when required, by rockets.
    • What would be even neater than flying in Mars would be flying in Venus or Jupiter.

      Flying on Jupiter would be an interesting concept.

      Just where, on a gas giant, would you land? (or take off from, for that matter)

      • You'd take off from space, of course. So you'd need some sort of rockets to get you back into space once you're done.

        And you'd better have a very reliable craft. If your engine were to fail, or you ran out of fuel, you'd be gliding. Which would normally be fine, but you'd be getting deeper and deeper into the atmosphere of the planet, the pressure would go up and up and up -- you'd be gliding better and better, but eventually the pressure would crush your plane. Oops.

  • Using jet engines to slow down in thin atmosphere (Score:3, Insightful)

    by BlowCat ( 216402 ) on Sunday December 30, 2001 @06:27PM (#2765883)
    From the article:

    Reverse thrust? NOPE!!!! With only 1% atmosphere, jet or prop engines can put out basically no thrust...

    I was surprised that Austin Meyer doesn't understand that the thrust of jet engines in either direction doesn't depend on the atmosphere density, unlike prop engines. Am I missing something?

    • You're thinking rocket engines.

      Rockets carry their own fuel and as such provide their own thrust.

      Jets and props require an atmosphere to provide the gas necessary to provide thrust.

      Sorta like... imagine outboard motors and water jets out of the water... not much thrust :)
    • I was surprised that Austin Meyer doesn't understand that the thrust of jet engines in either direction doesn't depend on the atmosphere density, unlike prop engines. Am I missing something?

      Disclaimer, I am not an aeronautical engineer.

      Actually, you are incorrect. The challenges for jet and prop engines are different in very thin atmospheres, but the basic problem is that with 1% of the earth's atmosphere, you cannot take enough O2 into your engine to get the engine running. OK. Crash course in turbofan engines:

      The engine containes a few parts:
      compressor->combustion chamber->turbine

      The turbine runs the compressor, often generates electricity and usually also runs a secondary compressor or fan ourside fo the combustion pipeline used for increased thrust.

      THe secondary compressor's thrust output, like a propellor's is purportional to the strength of the atmosphere (less air, less thrust). This is the first main problem. Unlike the propellor, the fan's thrust is mostly in the form of reaction mass and there is no real Bernouli's effect. Again, this reduces probably 10fold at 1% atmosphere.

      The second in in the jet pipeline. The turbine compresses air in the combustion chamber which is mixed with fuel and burns. The jet of hot gasses pass by the turbine which runs the compressor and produces thrust in the form of reaction mass (for each action...). The combustion is limited by the oxygen intake which goes down as the air supply goes down, but not as fast as it does for a propellor (assuming adequate O2).

      For take-off and landing, the turbofan engines also produce thrust in a third way. If you have been reading this so far and asked, "what about the shape?" I will answer this question. The shape is designed to produce a ducted fan effect, drastically increasing thrust at low speeds. Basically, as air gets sucked into the engine, it forms a low-pressure ring around the lip of the rim which means that the rim of the engine gains forward lift (similar in principle to the Hillard Flying Platform). This thrust would also be decreased 10 fold in the thin martian air.

      So yes, jet engines do depend on atmospheric density. Their curve is just flatter than that of a propellor (which are basically forward spinning wings similar to helicopter rotors, but with more fan and less wing).
  • Didn't we see this article [slashdot.org] before?

  • Three ideas.

    1.) "Mothership" based radiolocation beacon for the planes/copters to keep track of.

    2.) SunTracker, could help orient the planes locally; done with enough precision (both spatial and timing), could navigate to within decent low-power radiobeacon range of the 'mothership'.

    3.) We're already sending craft into orbit, how about a small fleet of GPS satellites?

    Just a few ideas...

    Jim Deane
    Physics
    Emporia State University

  • Would I be able to change the weather in the game too? Is the weather the same on Mars as it is on Earth. The article doesn't give too much details about this part. Is this an Hollywood to represent the Red planet weather as really tough? Thanks for the info.

    PPA, the girl next door.
  • i hadn't even seen a mention of visibility with flight on mars in the article(s).

    since mars has a thiner atmostphere (much more than earth's), viewing, navigation, and landing, etc. would be more difficult by the pilot's own eyes, and would have to rely more heavily on his computers to guide him. Telling the diffrence from something far away and close would be very difficult, since there is none, if few obscurities in the air to be able to determine depth.

  • Interesting article.


    He mentions the idea of a U-2 like plane, or high aspect-ration wing-design. Unfortunately, planes with this design have very poor performance with regards to turning, and they have a tendency to fail structurally quite easily. And as the guy pointed out, you're already moving pretty fast to generate the lift, so you already are not going to be able to turn very fast at all.

    What he didn't point out are the compressibility effects when you're going that fast. Since the speed of sound on Mars is roughly that of Earth (a = sqrt(gamma * R * T)), you are going to get big `ol shockwaves, which with those high aspect ratio wings--they're going to cause a very large amount of drag at those high speeds. Which means you need a bigger engine, yadda yadda more weight, thus bigger wings.

    And if you're going to do the stubby wing design, what's the point? It won't generate enough lift. You might as well strap rockets onto yourself to get off the ground.

    I guess my point on this is that you should probably do away with this whole idea of winged flight on mars until we've terraformed it (ha!). My personal favorite is a big, fat, blimp. It's a bit more practical then any of those high speed deathtraps.



    -Rub a dub dub, thanks for the grub, yay god!

  • Bought the game back when the announced intention of a Linux game, but assume this will occur after the release of the OSX varient. Its a fun sim, with alledgedly more accurate flight dynmaics than MSFS (Microsoft Flight Sim), indeed flying on this sim seems smoother. MSFS does have a lot better scenery though.

    What is incredible is that Austin Meyer is the sole developer of this program, I thought development like this had ended since the early 90's.

    After flying on Mars, its very hard! Reality is certainly stranger than fiction in many instances. The scenry and effects on Mars are very alien indeed, definately worth a try.

    Matt
  • I have worked on physics models for atmospheric effects in a flight sim for the Kitty Hawk project. There are a lot of issues surrounding flying a plane on mars, but it is not much different.

    The biggest obstacle (and one in which I haven't read yet.. so I'm posting) is the differences in speed of sound. People say, "Get bigger wings" and "fly faster" unfortunately this doesn't work as well as would be expected. You basically have to design your plane to fly super-sonic when it is travelling roughly 180 knotts (Martial sea level vs. earth equiv is around 100K feet, reduction in speed of sound..don't remember the exact numbers -- this was years ago that I worked on the project)

    This isn't the easiest of tasks, but, they did it. [robotbooks.com] - the major obstacle the project faced (we did the sim, as show in the picture - CMEX did all the "real" work) faced was efficient fuel. The final engine was Hydrazine powered, as the whole plane had to be exceptionally light weight and cover a large stretch of valles marineris.

    Anyway, it's been designed for years now... hope you found my drivel interesting.

    And yes, it is cool to work at NASA.
  • This is 'old news' to me, but only because I have been following the greatest Open Source flight sim out there: Flight Gear [flightgear.org].

    IIRC, they also have a 'flying on Mars' flight model that was in development. Whether or not it was ever finished, you can find out by getting into the project.

    Having full source to an OpenGL flight simulator is really nice. In the early days, I would modify the flight model to allow super-jet properties out of my little Navion (small propeller) plane. It was a bit unstable at 400 knots, but a lot of fun anyway.

    In any case, you can hack a Mars flight model YOURSELF into this flight sim, and be happier for it.

    • You're right this isn't news at all. X-Plane has supported Mars environment almost for a year. Anyways, i find the shuttle reentry much more enjoyable :-)
  • One of the biggest problems facing us as far as flight on Mars is the fact that we have a somewhat trivial fanatacism with wings. With air pressure being 1/100th of that on earth, and gravity being 1/3rd, it is trivial to limit ourselves to the flying wings we see in our skys these days. Helicopters as well, for like a previous poster pointed out it would be difficult to provide the lift with rotors. IMOP, it would be much better to develop a flight system not reliant on air resistance. Rockets would come to mind, but a little too volatile for my liking. Air compression/decompression would be most effective, if we decided to place jets fore and aft on the vehicle. We've been using aeroplanes for little over 100 years now, why not try something different?
    Just my two sense
    • A jet engine wouldn't work. There is not very much O2 on mars. What would work is a device called an ionocraft.
      It works by having a few negatively charged spikes above a positively charted wire grid. The high-voltage current flows from the spikes to the wire grid, ionizing some of the air along the way. The negatively ionized air is attracted to the +charged grid. This causes air to flow out of the bottom of the craft, propelling it forward. It would work well to 300,000 feet on earth. At that altitude the air is much thinner that on mars.
  • Why would we need to fly there? Man made satellites are already in place that map the surface of the planet. There aren't any forests or rivers to block your path, why not just build the equivalent of a Jeep with ten meter tall balloon tires and drive wherever you want to go? I would guess that an engine that puts out sufficient torque to do that would still be more fuel efficient than, say, a rocket, and balloon tires ought to be easier to build than a hundred-meter wingspan...

    There aren't that many vertical cliff faces on Mars, are there?
  • You Americans all ways have had this big thing
    about flying being the only way to get from
    A to B. I am sure some type of high speed
    train would be the sensible choice on Mars.

    I have been to Japan a couple of times and there
    you can get almost anywhere by train and quickly!

    And people cann't smash trains into sky scrapers.
  • On mars, a plane is doable. It would have to have a large wingspan because of the thin atmosphere. What would really be great is a plane on titan.
    Titan's atmosphere (correct me if im wrong)is mostly nitrogen, with some methane and ethane. It's atmosphere is about 1.5 times as thick as our atmosphere. Also, it has 1/6 the gravity of earth.
    Titan's very thick atmosphere and low gravity would make it ideal for flight. Helicopters would work very well on titan.In fact, if we ever send a manned mission, we could even have human powered choppers!
  • Would some form of a plane like the harrier jet do the trick? If durring flight they just did not tilt the jets all the way to the horizontal that would reduce the ammount of lift the wings had to produce and thus reduce the speed at which it must travel to fly. Lower speeds should make for easier landings.
  • You guys love Google so much, why not form a proper query [google.com] for "flying on mars."
  • MarsLightning.jpg [airwindows.com]

    I'm of the 'with gravity that low, make a sailplane-like craft' school ;)

Slashdot Top Deals

If computers take over (which seems to be their natural tendency), it will serve us right. -- Alistair Cooke

Close