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So we are spending a lot of money to get things landed vertically. Its a challenge, and obviously tough too.

So here is the idea. Get to mars. land over there, no need to return to earth (if no human is there) Get the bots to build a long air strip. Maybe something that can be easily made and transported there and that can be quickly put up there.

Now you can have more ships sent out there with lesser risks. What would some of the challenges in this idea, and what would make this not feasible?

UPDATE: So assume at some point we do colonize and then does it make sense to have an air strip. Or would you rather have small shuttles that can take off vertically?

UPDATE: So we have concluded that due to atmosphere thickness, it would not be enough for present aircrafts to fly. What if your aircraft was 1/3rd lighter by the use of advanced materials or carbon fibre, nylon, or something meant only for mars takeoff to space only? Is there a possibility then?

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    $\begingroup$ Obligatory XKCD: what-if.xkcd.com/30 $\endgroup$ – Steve Nov 22 '16 at 21:17
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    $\begingroup$ Maybe à landing pad would make more sense $\endgroup$ – Antzi Nov 23 '16 at 9:31
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    $\begingroup$ Winged aircraft are simply impractical on Mars. The U-2 aircraft flies at an altitude of about 21km. Air pressure there is about 5% of sea level. To maintain any lift at all even with its enormous wings it has to fly at nearly 800kph. At Mars surface level you'd need 5 times the relative wing area if you wanted to do takeoffs and landings at that speed -- 80 times the area to manage it at a more-sane 200 kph. It's not quite theoretically impossible, but it's not gonna work. $\endgroup$ – Russell Borogove Nov 23 '16 at 19:48
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    $\begingroup$ Albseb: We could probably make an aircraft that would manage to fly on mars. But with the magnitude of mars atmosphere, it is EXTREMELY impractical, and no one in there sane mind would do that since rockets would be much more efficient. Very small and light drones have been considered for exploration tho. $\endgroup$ – Antzi Nov 24 '16 at 7:19
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    $\begingroup$ Building a landing strip on Mars was proposed by Wernher von Braun in his 1952 novel Das Marsprojekt, before the density of Mars' atmosphere was known. $\endgroup$ – LocalFluff Nov 24 '16 at 7:42
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On Mars, the atmosphere is thin enough (around 1% of Earth's) that it's impractical to use aerodynamic lift during the terminal phase of landing.

Therefore, a horizontally landing craft would be much less efficient than a vertical lander.

Even for Earth-returning spacecraft, where aerodynamic lift is relatively easy to get, the mass requirements for wings and control surfaces plus their thermal protection systems are such that they are only attractive if precision landing and reusability is required -- and even then, vertical propulsive landing SpaceX style is competitive.

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  • $\begingroup$ how would a lift off from mars be if there was an air strip? $\endgroup$ – albseb Nov 23 '16 at 12:52
  • $\begingroup$ No air means no lift means no reason to travel horizontally on the ground. You want a small flat pad for vertical takeoff and that's all. $\endgroup$ – Russell Borogove Nov 23 '16 at 19:33
  • $\begingroup$ correct me if I am wrong. The weight also depends on the overall lift. So if the wings and the body are made of things lighter would it not give be sufficient for lifting. $\endgroup$ – albseb Nov 24 '16 at 6:56
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The problem with a landing strip on Mars would be size. Because Mars' atmosphere is so thin you'd have to be going very, very fast (several hundred mph/kph) in order to get enough lift to arrest your descent enough to land safely. At that speed touchdown would be incredibly hard on the wheels, which would most likely pop instantly - a skid makes more sense I'd guess although that's still a big materials science problem. Say you did manage to get the wheels/skid on the ground, you'd then have to slow down and stop. The air is too thin for aerodynamic braking to matter much and the gravity is low so you wouldn't get the same traction, and would need to brake much more gently - again a skid would probably work better on Mars, but in either case it's going to take much longer to work because there's less gravity.

So because of these factors a landing strip would have to be many, many miles long. The very thin atmosphere also makes controlling an airplane challenging, and because of the high speeds involved an airplane's turning radius would be huge, so you would need a very wide runway as well to compensate. So you'd need a landing strip the size of Manhattan, or even bigger, to be able to land an airplane on Mars. That would be hugely costly compared to other alternatives.

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  • $\begingroup$ hmmm. so basically its friction thats killing the idea. Does this mean its easier to take off on an air strip on mars? $\endgroup$ – albseb Nov 23 '16 at 12:52
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    $\begingroup$ @albseb, no. Taking off has the same problem. You either need huge takeoff speed or very large, heavy wings. $\endgroup$ – Hobbes Nov 23 '16 at 13:04
  • $\begingroup$ @Hobbes At which point you are fighting gravity pulling those wings downward... $\endgroup$ – a CVn Nov 24 '16 at 8:47
  • $\begingroup$ starting runway wouldn't need to be so wide. Regardless, airplanes on Mars are a dodgy idea. With no atmospheric oxygen and air so thin you'd have trouble designing engines (other than rocket) capable of generating enough thrust to move the plane, never mind reach lift-off speed. $\endgroup$ – SF. Jul 18 '18 at 7:42
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Besides the extremely thin atmosphere on Mars and construction obstacles, there are two other reasons to not build a landing strip on Mars that I can see.

Why go to the same place twice?

Mars is big. It's not as big as Earth, but there's still a whole lot of unexplored terrain that would be of interest to study. By building a landing strip, even if you can build one and it's viable in the first place (which, given the other answers so far, appears highly doubtful), you commit significant resources to a single location. Just like you can't get a good idea of what the Earth looks like by studying only Manhattan or the Mariana trench, missions have deliberately picked highly disparate landing sites at least in part precisely to study different parts of Mars to get a better idea of the planet's overall geology.

NASA Mars landing sites

Landings aren't precise enough

Our Mars landings just aren't precise enough for a landing strip to make sense. You are probably thinking in terms of doing this:

Mars base

while reality is like this:

Mars landing ellipses

Look at that 2012 Curiosity landing. A landing ellipse of 12 x 4 miles, or 19 x 6.5 km, with touchdown 2.4 km from the centre, is far too imprecise for a landing strip to make any sense. Not only would you have to actually land on the landing strip in the first place; for a horizontal landing onto a landing strip to make any sense at all, you have to be going in just about exactly the right direction when you hit the ground, and hit very close to the correct spot on the landing strip. We aren't talking a few kilometers here; we are talking more like on the order of tens to a few hundreds of meters.

We simply aren't there yet, and I wonder if we will ever be there before we have significant human presence on Mars, at which point there's more productive things for those people to do than flatten and cover a large swath of Mars surface near their base where it is most accessible for study.

The Space Shuttle was able to do that kind of landing, but it did so on Earth (with an atmosphere hundreds of times thicker, with corresponding differences in aerobraking and lift capability), and it had significant constraints on landing. There's a reason why the deorbit burn was called a landing commitment.

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  • $\begingroup$ A landing craft that had wings would be able to steer. $\endgroup$ – uhoh Nov 24 '16 at 10:16
  • $\begingroup$ Sure, but that doesn't help much if you for example undershoot the runway (or whatever we want to call it; I doubt it would much resemble a runway of any contemporary Earth airports). Bottom line, by the time you reach ground level, your craft's attitude is a critical parameter in the success of the landing, and you still have sufficient horizontal velocity that you don't have much time to correct for any errors. And of course, you need the wings to be large enough to generate a sufficient amount of lift in order to be able to steer. As that was already brought up by others, I left it out. $\endgroup$ – a CVn Nov 24 '16 at 12:00
  • $\begingroup$ OK but you are using a landing ellipse for a (mostly) passively dropping spacecraft to answer a question about a winged aircraft. It's apples and oranges, or am I missing something? I agree the winged landing idea is really difficult to justify, but how does the landing ellipse relate? $\endgroup$ – uhoh Nov 24 '16 at 12:10
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    $\begingroup$ @uhoh space.stackexchange.com/questions/13981/… is relevant. I wish that would be captured in an answer somewhere rather than merely a comment, but I for one don't have the expertise to turn it into a decent answer. $\endgroup$ – a CVn Nov 24 '16 at 12:20
  • $\begingroup$ Ya you are right!! It had both thrusters, and ballasts it could eject to change it's center of mass in order to use the lift for coarse "steering" en.wikipedia.org/wiki/Mars_Science_Laboratory#Guided_entry . Wow that's amazing - thanks for your comments!! $\endgroup$ – uhoh Nov 24 '16 at 12:32
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Basically all the challenges of a mid-scale construction project, except done by remote control from several light minutes away, and you first need to land all the construction equipment on Mars.

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The weight reduction would not be nearly as much as 2/3. Carbon fiber has about twice the yield strength for 2/3 weight compared to aluminum, so theoretically this would mean a 2/3 weight reduction. In practice buckling becomes more likely, and carbon needs a higher safety margin for safe use. If you still don’t believe me compare weight in bike frames. Good high end aluminum frames usually weighs between 2.5 and 3 pounds while carbon is between 2 and 2.4 pounds. Carbon usually uses some 5 times safety margin vs 2 for metals. (Those vary wildly but they tend to be around that.)

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The difficulties would be significant after all you would need either the high wing surface area per weight or high landing speed that would be needed but I believe with proper care and lot of extra mass to make the needed structure it would be possible. Not sure why you would do that on a module with such weight penalties. The powered option would be my choice.

Something that might make more sense and contradict what people are saying is using a shuttle like shaped reentry vehicle with a small area to weight ratio. It would not have enough lift to actually land and therefore would need to have a powered landing. You would suffer a small weight penalty because of the shape versus ballistic but the advantages would be lower temperatures on reentry, lower G loads and a greater precision on landing place. it would not be able to correct gross reentry mistakes but would provide a far greater precision. And to correct the misconception presented on one other comment. A properly designed winged reentry vehicle would have no trouble reducing drag while increasing lift so undershooting would not be a problem. The space shuttle has this capability.

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