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Horizontal landing on other planets

Posted by: Ekkehard Augustin - Wed Oct 20, 2004 10:32 am
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Horizontal landing on other planets 
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Post    Posted on: Thu Oct 21, 2004 7:44 am
Ekkehard Augustin wrote:
Could horizontal landing on Mars be assisted by the concept of JP Aerospace? Can that concept solve problems in keeping sufficient altitude as long as the vehicle is too fast?

Keeping altitude while going fast is (probably) not the problem. The problem is going slow near the ground, because going fast near the ground makes it dangerous and takes a huge, flat space to perform your landing. Again: if you need to use thrusters, rockets, etc. anyway, what is the advantage of having a horizontal speed?


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Post    Posted on: Thu Oct 21, 2004 7:53 am
At a given speed landing vertical may cause a greater damage than landing horizontal at the same speed.

Keeping altitude at a given speed is more difficult in thin atmosphere than in thick atmosphere I suppose. This is the reason why I'm thinking of the JP Aerospace concept.



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Post    Posted on: Thu Oct 21, 2004 8:33 am
Problem is: you can't just substitude the vertical speed for the horizontal one. For a save landing, you want to minimize both. Assuming you can't fly (aerodymicly, that is), there is nothing to gain with a horizontal landing I think, as you'll need to actively control your vertical speed anyway using thrusters or the like, while horizontal speed will only increase your total energy as well as the risk of hitting something while landing.

What is the "JP Aerospace concept"?


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Post    Posted on: Thu Oct 21, 2004 8:52 am
Concerning the problem speed could be reduced slightly by braking rockets in the sense of bidirectional thrusters. The braking thrust could be changed depending on current speed and current altitude. Expressed by mathematics I want to control the vector resulting from vertical forces and horizontal forces - the vector should be as far from the vertical force and as close to touching the horizon as possible.

JP Aerospace is developing an infratstructure for orbital flights consisting of Zeppeline-like crafts. The first is going to 140,000 feet, the second is at that altitude as a kind of "space" station and there will be launched another Zeppeline-like craft that using an ion engine will go to orbit.

These crafts are using the updrift of gas like Zeppelines do. They will go the opposite direction to leave orbit for the "space" station and to leave the "space station" for the surface.

In the case of Mars the horizontal landing craft could contain Zeppeline-like elements to prevent it from going down too fast (refer to ballon concepts and ARCHIMEDES especially too). As a consequence horizontal speed could be less or at least it could focussed on.



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EDIT: I have to add that for Titan - whom I didn't list as destination for horizontal landing vehicles - a Zeppeline-mission is under development. But the Zeppeline will not land.

JP Aerospace says at in an .pdf-document at its homepage that the third vehicle could leave its initial orbit for higher orbits, geostationary orbit and - if I remember right - for the planets too. So it might be possible to dock it to a manned spaceship going to Mars.


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Post    Posted on: Fri Oct 22, 2004 11:15 pm
Ekkehard Augustin wrote:
What about deceleration by a course going spirally around the planet down to the surface? Might it be possible to reduce the velocity at touch down this way? Or are there any braking rockets?


This probably isn't what you meant, but could be a cool idea to solve the Mars landing debacle. A while back (about five decades) they did some experiments out at Ford's automotive proving grounds in Arizona, which incidentally I've flown over several times in my family's Piper Cherokee. The main feature of the complex is a giant circular track a mile in diameter with about 10 degree banking on its outmost regions. One day some guy got asked a brilliant question; why not land a plane there! The idea was that you could approach the runway from any angle, regardless of traffic patterns or wind, and then have an infinate amount of runway in front of you provided you could turn at the same rate the track did.

In the experiment (gosh, it feels like I'm writing a lab report), they tried landing several different kinds of planes, including an F9F Pather (a jet fighter dating to the paleolithic age with a stall speed of around 150 KIAS) and a large cargo plane. It worked out marvelously, even the bulky cargo aircraft were able to manuver in to land and the F9Fs were able to keep up with the turn very close to their stall speeds. Not much has been done with the idea since, but it could be adapted for our purposes here.

There's definately no shortage of craters on Mars, many of which would have very smooth near-circular walls. All you have to do is find one big enough around the desired area, pull up to the wall and jently ease the plane down. There would be challenges of course, it would be difficult to maintain a turn when you have the inertia of a plane screaming in at 300 KTAS but with all the control capiblity of one clunking along at 30 KIAS, but if that could be negatied provided the plane has enough control surface area. A landing like this would obviously be too big a challenge for a dinky little probe running on less power than your average lightbulb and a processing unit that would make an electric typewriter seem cutting edge, but it could be a viable option on manned flights.

Another option would be to send a probe to land conventionally and then clear an area of rocks and create a future landing space for other probes. Of course, no matter what you're putting a lot of faith into that a robot can land a plane when Mars Polar Lander proved that just keeping an engine running all the way to landing is a challenge, but you would get pretty decent mass savings. NASA did some other experiments at Dryden a few years ago by dropping a plane with inflatible wings that popped out in a fraction of a second. Wings can be made light, strong, and compact, and can save you a lot of fuel that can then be used on other things (like, say, payload).

On the subject of airspeeds on Mars:
One might think at first that indicated airspeeds on Mars would be one-one-hundredth what they are on Earth at sea level, but that's not taking several factors into account. Density altitude is determined by two main factors, ambient air pressure and temperature, and Mars is very, very cold. Additionally, though that atmosphere is 1% as thick as that of Earth's by pressure, almost all of that pressure comes from carbon dioxide, which is far denser than the nitrogen that forms the bulk of Earth's atmosphere. Hence for the same unit of pressure, Mars' atmosphere has about ten times the density of Earth's atmosphere, and the speed of sound is actually around mach .6 at sea level. Landing horizontally on Mars is a challenge, but a doable one.

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Post    Posted on: Sat Oct 23, 2004 11:04 am
I think a landing strip made of sticky rubber would still be the best solution, with enough
wheels to brake the speed down.
Weight penalty will surely be there, so I assume this kind of ship only could operate outside earth atmosphere and never return to earth again...

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Post    Posted on: Wed Oct 27, 2004 12:13 pm
Mmmm! I've had a good read of everyones ideas here, but really (I'm my opinion), for a horizontal landing regardless of braking system, atmostphere, and gravity; the surface will need to be flat. Mars surface (or the moon for that matter) is anything but. It's a long way to go to make a school boy error. Once we've visited a few times, then perhaps a landing strip could be built, perhaps with cable arresting system similar to aircraft carriers. Rockets could control desent from orbit, aero braking would help, but the final deceleration by arresting gear already in place on the surface.

What do you think?

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Post    Posted on: Wed Oct 27, 2004 12:26 pm
The properties of the lunar and the martian surfce is the reason why I recently have begun to discuss the use of something like skids.

At least on Opportunity's images of the martian surface a wide area of dunes is to be seen. It seems to be not as rocky as the surroundings of Spirit.

Something LIKE skids - not real skids. Perhaps parts of them should be able to dig deep into the soil while landing releasing the craft but keeping it by a cable - could that be an idea for an arresting system that doesn't require a landing strip? Perhaps the craft should have at least four skids seperated - two in front and two behind the craft.

The skids might required to be flexible. And satellites orbiting Mars shuld be used to detect sites having the least amont of rocks and craters. The haz-cam, the nav-cam and the panoramic cameras of the rovers could be improved and used at the lander.

All this may be very silly - I say it only to stimulate thinking of it. Perhaps working ideas can be born.



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Post    Posted on: Wed Oct 27, 2004 12:34 pm
Actually, for a Mars mission, given the properties of the Martian atmosphere, I'd say a balloon descent would be quite useful. A slowly-deploying gas bag which acts both as a terminal brake and a buoyancy device in the thinner but heavier air would allow the craft to slow down, and fly to a desired landing location while consrving fuel. Vertical landing would also be supported.

Then, for the takeoff, the craft could use the gasbag to rise to a certain level in the atmosphere, and then begin accelerating while retracting/deflating the gas bag. As drag decreases, more conventional methods take over, perhaps a lifting body to maintain altitude while making the final deflation, and then a rocket powered escape acceleration...

Crackpot idea or workable plan?.

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Post    Posted on: Wed Oct 27, 2004 3:35 pm
André wrote:
Problem is: you can't just substitude the vertical speed for the horizontal one. For a save landing, you want to minimize both. Assuming you can't fly (aerodymicly, that is), there is nothing to gain with a horizontal landing I think, as you'll need to actively control your vertical speed anyway using thrusters or the like, while horizontal speed will only increase your total energy as well as the risk of hitting something while landing.


Well, actually a horizontal flight profile can make sense, even with a zero velocity landing requirement. If a glider is used during approach, you have much more time to select your landing area, and much more control over where you actually put down. On Mars, the glider would be high speed, but terminal velocity (the velocity that a wingless version of the spacecraft would fall) is even higher.

So, if you want to not splat (vertical landing) and you don't want to smear (horizontal landing), then you can use wings to get near the surface at a lower speed than falling - then you use retro-rockets to kill your velocity and land.

So, why does noone do it this way? Two reasons - transports can live with some impact velocity whereas horizontal velocity is very hard on equipment (tumbling is bad), and wings weigh too much.


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Post    Posted on: Thu Oct 28, 2004 7:46 am
Alright - but have the recent Mars vehicles been made out of light weight materials? And what might be miniaturized that isn't?

If someone finds a way to reduce weight, miniaturize more things and to smaller sizes and if he finds another way to organize and coordinate those things and their work - then there may be a point where the wings don't weigh too much no more.

...



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Post    Posted on: Thu Oct 28, 2004 1:02 pm
Hmm, I take it we're talking about landing humans on Mars here?

Personally, I don't see what's wrong with the good old parachute idea, although if you want to be able to travel around the planet some sort of zeppelin is probably your best bet. The problem with plane's on Mars is the fact that there is no Oxygen in the atmosphere, so you can't use a conventional air-breathing engine, which makes it very difficult to travel long distances. If you could float a zeppelin into an airstream, you could potentially travel large distances without the need for massive amounts of fuel.

Of course, then you still have the problem of getting back.

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Post    Posted on: Thu Oct 28, 2004 1:17 pm
I personally have in mind an orbital version of SS1 a little bit - if Rutan will construct something like that. If he will build an orbital vehicle landing horizontal one day it would be advantageous if it could be modified to land on Mars.

That's the initial idea only - such an SSx couldn't have wheels and has to handle an atmosphere that's a hundred times thinner. If it cannot be a manned vehicle it still could be advantageous to have an unmanned Mars-fit SSx.

It could use in-situ ressources.

Some XPRIZE-teams are working on SSTO-concepts launching and landing horizontally that launch at rocket-engines.

All this I have in mind a little bit. I'm interested in the question wether a private vehicle could be found that is working concerning earth and concerning Mars too. And SS1 is the only successful private vehicle today.



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Post    Posted on: Mon Nov 01, 2004 8:13 am
To extend this topic:

What about horizontal landing on Titan once Huygens has delivered its results next year and if these result show a landscape similar to Mars? In contrary to Mars the atmospheric pressure is 1.4 times the earthian and similar to earth the main share of the atmosphere is nitrogen. This might allow the landing of a spacecraft similar to SS1 - if it can be decelrated to a sufficient low entry velocity.

What abou a horizontal "landing" or better diving into the jovian atmosphere? In contrary to reentry into earthian atmosphere a spacecraft similar to SS1 won't be too fast because the jovian atmosphere has a diameter of 142,000 km and is rotating once in 10 to 11 hours which means a rotation velocity of 44,000 km/h or so.

These SS1-like vehicles would be unmanned robots and could be smaller than SS1 - it might be possible to find a concept that keeps them in the most upper regions of the jovian atmosphere, prevents them from collaps (other thread to be opened) and allows acceleration by scramjet using jovian gases.



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Post    Posted on: Tue Nov 02, 2004 4:09 pm
I can't see any need for horizontal landing on another planet. The landing method should be chosen to fit the mission. Aircraft need to land in a very specific location and then take off again. And they need to do it over and over again. And landing is a small part of the mission, which is rapid horizontal travel in the atmosphere. If a 747 could land and take off vertically but still cross the ocean like a 747, it would be great!

On the other hand, spacecraft only need to land once and never take off again. The exact location of landing is not critical, within a kilometer of target is more than good enough and sometimes 100 kilometers off target is close enough. And the landing method must not take up resources (weight, fuel) needed to accomplish the main mission, which is to fly through the vacuum of space to the target planet.

Now in the future, if we have cities on other planets we might build airports and use horizontal landing for the same reasons we do so on Earth, but in the initial exploration phase parachutes are still the best technology.


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