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#51 2004-04-29 07:14:52

quasar777
Member
Registered: 2002-05-05
Posts: 135

Re: Land propulsion - Tracks, or tires?

www.sea-bow.ca     bear in mind i`m not suggesting an exact duplicate of this vehicle. but the angle of the wheels interest me.

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#52 2004-06-04 07:25:28

Shaun Barrett
Member
From: Cairns, Queensland, Australia
Registered: 2001-12-28
Posts: 2,843

Re: Land propulsion - Tracks, or tires?

Sorry to butt in. Is it just me who can't access the posts at 'Simple Mars Vehicle' here in Planetary Transportation?
    Even Cindy's trick of pressing the Add Reply button doesn't seem to produce the goods.
                                                sad


The word 'aerobics' came about when the gym instructors got together and said: If we're going to charge $10 an hour, we can't call it Jumping Up and Down.   - Rita Rudner

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#53 2004-06-04 07:53:23

Palomar
Member
From: USA
Registered: 2002-05-30
Posts: 9,734

Re: Land propulsion - Tracks, or tires?

Sorry to butt in. Is it just me who can't access the posts at 'Simple Mars Vehicle' here in Planetary Transportation?
    Even Cindy's trick of pressing the Add Reply button doesn't seem to produce the goods.
                                                sad

*Just answering Shaun's question:  Looks like that thread is busted.  Even clicking on "Review the Complete Topic (launches new window)" option (which appears at the bottom of the screen after pressing "+Add Reply" and scrolling down) produces no results. 

Back on topic here...

--Cindy


We all know those Venusians: Doing their hair in shock waves, smoking electrical coronas, wearing Van Allen belts and resting their tiny elbows on a Geiger counter...

--John Sladek (The New Apocrypha)

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#54 2004-06-04 08:07:17

Dook
Banned
From: USA
Registered: 2004-01-09
Posts: 1,409

Re: Land propulsion - Tracks, or tires?

The first post of that topic somehow got borked, now the second post froze as well.  Maybe I made too many edits of the post, not sure.  I think it was a really simple but capable design but it still had some kinks to be worked out.  The fuel cells would have gone through the carried hydrogen in a few hours and not provided the range I originally thought it would have so I was looking at the only other option, small nuclear reactor towed behind it. 

I guess I could post it again but I kind of get the feeling the forum is trying to tell me something.

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#55 2004-06-04 12:42:26

mboeller
Member
From: germany
Registered: 2004-05-08
Posts: 53

Re: Land propulsion - Tracks, or tires?

The first post of that topic somehow got borked, now the second post froze as well.

Hi Dook;

I still have the old thread "Simple Mars Vehicle" saved on my computer. I can open an new Thread with all the old posting's inside as the first posting if you like.


Manfred

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#56 2004-10-14 03:23:16

sethmckiness
Member
From: Iowa
Registered: 2002-09-20
Posts: 230

Re: Land propulsion - Tracks, or tires?

Just thinking about tracks over tires again...  I was thinking about some of the advertisements for Mat-Tracks..  would be a nice simples track system, that would reduce the chance of getting stuck, and also do nicely over rough, rocky terrain..  Also.. a tread with a built in warmer might work well too.  I really like the handling properties of rubber.  I think it would work a lot better.  There is also some much better compounds, plus multi compound tires that have come out in various sports that could be an idea.  Dual tread compound bike tires due well, With a harder compound in the center and softer on the sides.  I think it would be hard to simulate wear.  Also, UV breakdown may be an issue.

The other thing is suspension..  Some sort of spring and damper system would be good.  I don't like the idea of bouncing up and down like the lander, especially if any speed over 10 pmh is to be achieved.  even something simple would work.  But once again, temperature and pressure could play hell with a standard oil emulsion shock.. 

Just trying to think it through..


Also...  I know the Marines use hover crafts...  I don't know what kind of terrain they can go over...  also, threoretically, the more air you can push, the higher you can suspend yourself..  But I think a wheeled or tracked vehicle is more feasible, more simple, less expensive, lighter, more versatile..  etc...


We are only limited by our Will and our Imagination.

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#57 2004-10-14 22:29:09

Austin Stanley
Member
From: Texarkana, TX
Registered: 2002-03-18
Posts: 519
Website

Re: Land propulsion - Tracks, or tires?

I think there is some misconception as to how a hovercraft actualy works.  It does not blow out so much air that it supports itself by that lift alone, that would be more like a VTOL vehicle.  A hovercraft works by containing a region of high pressure air within a curtain of high pressure air that is being blown out through the skirt around the vessel.  The skirt only puts out enough air to maintain a region of higher pressure around the edge to contain the inner area.  The craft is actualy supported by the high-pressure air inside.

I don't see any reason why it could not work on mars (or anywhere else for that matter, even in a vacume).  But I don't think it would be very efficent.  Certianly drawing in enough low-pressure martian air to support the craft would be a problem.


He who refuses to do arithmetic is doomed to talk nonsense.

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#58 2004-10-15 15:26:13

Dook
Banned
From: USA
Registered: 2004-01-09
Posts: 1,409

Re: Land propulsion - Tracks, or tires?

By looking at the pictures there are some areas of mars where the land is entirely covered in basketball sized rocks.  I don't think a hovercraft would work so well there.

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#59 2004-10-18 06:28:23

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,828

Re: Land propulsion - Tracks, or tires?

The question on tracks or of tires are difficult to answer until other details of the vehicle are hashed out.

Some topics have talked about the need for speed and of duration of time but these are both affected by terrain, vehicle and consumables volume as well as weight for the crew size using the rover. Then we have also had discussions on the vehicle fuel type or power source or multiple fuel and power combinations in addition to the engine type or though use of electric motors and of multiple motors as well. Things that affect the vehicle overall size, shape, weight, are basically consumables either directly by the crew or by the vehicles use for a given duration of time and not truly distance. Differing fuel sources are developed from insitu materials, solar cells, nuclear and save by storage devices such as batteries or even compressed air. Of these some require cooling to remain liquid while others need large tanks on the vehicle or towed behind on a trailer or by a separate vehicle for safety. Other thoughts are to provide remote refueling stations to allow for extended range and for time duration of use to stretch beyond a few hours to maybe a day or to hundreds of miles possibly even measure by the kilometers.

The need for a goal oriented rover is a must since there are no roads and to make such would ruin the chances for science in any form. There is no need for high speeds but to shorten the time for a second vehicle to reach any crew in need of help if while out on a mission that damage should keep them from coming back to the base. Even on the smoothest of terrain top speeds are 30 to 40 miles an hour at best while most of the mission will be in stop and go mode on the first few times out. Features for best use while in stop and go mode would be to provide external vehicle movement controls for operations, platform for astronaut to stand on while in motion, external consumable port hook ups to replenish power, water and O2 for there space suits. The cab would serve not only as primary but as a secondary atmosphere for the astronauts depending on the conditions of there space suits which is the primary shield from the Martian conditions that they will face.

Yes, some redundancy is a must for crew protection but also for safe rover operations. We must not forget that if any part fails while out beyond a safe walking distance to the base that they will only have a few options due to consumables at that time remaining not only in there space suits but on board the rovers.

Looking at the rover the main goal is to collect samples, plant or install remote sensing equipment some of which would be to monitor the atmosphere, mars quake studies and even drilling for deep core samples. I feel that all samples are analyzed back at the base camp and or for packaging and return to more advance earth labs.

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#60 2004-10-18 09:03:44

Dook
Banned
From: USA
Registered: 2004-01-09
Posts: 1,409

Re: Land propulsion - Tracks, or tires?

Why would you need explorers on a platform outside the vehicle as it moves?  Much too risky and completely unnecessary.

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#61 2004-10-18 09:54:25

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,828

Re: Land propulsion - Tracks, or tires?

One to save on inside the rover contamination and on use of inside rover oxygen air lock function.

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#62 2004-10-18 10:49:50

Dook
Banned
From: USA
Registered: 2004-01-09
Posts: 1,409

Re: Land propulsion - Tracks, or tires?

Inside contamination?  From what?  Carbon dioxide?  Mars atmospheric pressure is quite low, I don't think that is a reasonable concern especially with an air lock.  And a little bit of dust getting inside shouldn't be a big deal either.  Certainly neither makes stranding someone on the outside of the vehicle necessary.  If they did then the rover shouldn't be pressurized anyway.

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#63 2004-10-18 16:13:44

Grypd
Member
From: Scotland, Europe
Registered: 2004-06-07
Posts: 1,847

Re: Land propulsion - Tracks, or tires?

Inside contamination?  From what?  Carbon dioxide?  Mars atmospheric pressure is quite low, I don't think that is a reasonable concern especially with an air lock.  And a little bit of dust getting inside shouldn't be a big deal either.  Certainly neither makes stranding someone on the outside of the vehicle necessary.  If they did then the rover shouldn't be pressurized anyway.

Martian Regolith dust appears could be one of the most dangerous materials we have to deal with on mars. It will be unlike the dust we have commonly on earth and may well be similar to asbestos in its nature causing scarring and damage to peoples lungs. Even if it is not as bad as that it will pose health threats to astronauts who will have very rare opportunity to wash. Dermatitus and lung disorders and eye infections being commen. Tell you I can see petroleum jelly being one of the most popular items on any Mars mission.


Chan eil mi aig a bheil ùidh ann an gleidheadh an status quo; Tha mi airson cur às e.

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#64 2004-10-18 18:21:30

Dook
Banned
From: USA
Registered: 2004-01-09
Posts: 1,409

Re: Land propulsion - Tracks, or tires?

Martian Regolith dust appears could be one of the most dangerous materials we have to deal with on mars. It will be unlike the dust we have commonly on earth and may well be similar to asbestos in its nature causing scarring and damage to peoples lungs.

Where did you get the information that mars regolith may be like asbestos.  I've never heard of anything other than it seems to have a strong oxidizer and salt in it.

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#65 2004-10-18 19:09:13

RobS
Member
From: South Bend, IN
Registered: 2002-01-15
Posts: 1,701
Website

Re: Land propulsion - Tracks, or tires?

There is persistent professional speculation that Martian dust, because of its extremely fine size (smaller than terrestrial dust) could cause lung cancer and other lung disorders because it can work its way into the tissues. We won't be sure it is dangerous for a while. The issue isn't unusual chemistry, just known chemistry (silicates) and extreme fine particle size.

         -- RobS

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#66 2004-10-19 05:53:40

Dook
Banned
From: USA
Registered: 2004-01-09
Posts: 1,409

Re: Land propulsion - Tracks, or tires?

To be breathable is must become airborne.  I don't expect the crew to go outside the vehicle during a dust storm so I think this isn't something to worry about.

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#67 2004-10-19 06:23:16

Grypd
Member
From: Scotland, Europe
Registered: 2004-06-07
Posts: 1,847

Re: Land propulsion - Tracks, or tires?

Dust is always airborne is it not, Mars has wind and weather. Our problem is to ensure it does not get into where we move it about while not wearing a suit. In short, we have to find a way to filter out all the dust before it comes inside the vehicles or habitats.


Chan eil mi aig a bheil ùidh ann an gleidheadh an status quo; Tha mi airson cur às e.

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#68 2004-10-19 07:43:44

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,828

Re: Land propulsion - Tracks, or tires?

Well in the airlock in addition to filtration of air you will also need a shower to rinse what dust has become stuck to the space suit as well. That is why I had proposed being able to drive the vehicle from the outside while in a stop and go mode of exploration. Otherwise they are in the protective cabin of the rover.

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#69 2004-10-22 01:17:34

MarsDog
Member
From: vancouver canada
Registered: 2004-03-24
Posts: 852

Re: Land propulsion - Tracks, or tires?

Hexavalent Chromium might be a serious concern.
-
Even after home base is secure and comfortable, long trips will not be made due to safety concerns. A few Kilometers is all that an astronaut could be expected to walk or pedal back, after a breakdown.
-
The rovers used solid metal wheels. Before large rubber tires, farm tractors used large steel wheels. On Mars, the arrivals could spend their time smelting metals, to bolt or weld into wheels. Steel wheels reshaped Earth, Mars is next ?

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#70 2004-10-22 10:59:02

RobS
Member
From: South Bend, IN
Registered: 2002-01-15
Posts: 1,701
Website

Re: Land propulsion - Tracks, or tires?

Various experts have proposed dust-off facilities that would use blasts of liquid carbon dioxide to blow and wash dust off of the outsides of spacesuits.

Even Apollo had this problem, and the moon doesn't have an atmosphere. The spacesuits got dusty and the dust got inside the LEM. The astronauts could either taste or smell it. If the stays on the moon had been lengthy there would have been problems of airtight seals not sealing tightly because of dust. This would have been true of space suit zippers and airlock doors. Lunar dust was also sharp enough to be gritty and damage things. Martian dust may have superoxides on it to corrode rubbers, plastics, and metals.

As for long (10-20 km) trips away from the landing site, I'd use all terrain vehicles able to carry one astronaut and send out three people with three ATVs. If one breaks, the other two could tow the ATV back to base and the astronaut could ride behind someone. Longer trips would involve at least two pressurized vehicles, maybe three, with a trailer to haul ATVs and robotic assistants. Maybe the ATVs could BE the robotic assistants, carrying various supplies and approaching the astronaut on command to deliver some instrument needed.

         -- RobS

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#71 2004-10-22 12:08:32

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,828

Re: Land propulsion - Tracks, or tires?

Then I guess our topic on compressed air use will come in handy even if not used to make a rover move.

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#72 2004-10-22 14:11:40

Rxke
Member
From: Belgium
Registered: 2003-11-03
Posts: 3,658

Re: Land propulsion - Tracks, or tires?

Rob, why liquid CO2? why not just blast the stuff away with filtered... Um... Yes... Filtering would be quite hard indeed.

OK, stupid question. big_smile


ExoMars' launcher's 2nd stage is probably en route to Mars. Unsterilised... yikes

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#73 2004-10-23 00:32:07

RobS
Member
From: South Bend, IN
Registered: 2002-01-15
Posts: 1,701
Website

Re: Land propulsion - Tracks, or tires?

I don't know why liquid CO2, I suppose because a tank of it can be stored at Martian "room temperature" easily, because it would make compressed gas quickly and easily, because it's compact.

         -- RobS

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#74 2004-10-25 10:48:28

Austin Stanley
Member
From: Texarkana, TX
Registered: 2002-03-18
Posts: 519
Website

Re: Land propulsion - Tracks, or tires?

Liquified CO2 would be neat, because it would evaporate quickly fairly quickly at typical martian temps and pressures.  The liquied would hopefully quickly wash off the dust, and then evaporate taking any remaining particles with it.

One of the problems with this is that liquid CO2 is obvioulsy fairly cold.

I would simply use an "air-currtain" or a blown wall of higher pressure air to block enviromental dust from getting into the airlock and to help clean the dust off of the suit.  I would then have use an "air-pick" to detail the suit, and blow off any remaining dust.  Of course, filtered CO2 would be used for the "air" in the system.

One of the problems with this setup is that it would be fairly bulky, since you would need an air-lock big enough to clean the suit off in.  It would probably be easy enough to do at the base, but more difficult on the rovers where space is a premium.

As for filtering CO2, that should be pretty easy.  Liquify it, the dust should settle to the bottow, and the evaporate CO2 off of the top.  Presto, filtered CO2.


He who refuses to do arithmetic is doomed to talk nonsense.

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#75 2004-10-25 13:05:15

RobS
Member
From: South Bend, IN
Registered: 2002-01-15
Posts: 1,701
Website

Re: Land propulsion - Tracks, or tires?

It may be that liquid CO2 would simply serve as a source of high pressure gas. If you spray liquid CO2 on a surface, the evaporation of the liquid would cool the surface. That could be quite dangerous for metals or even for suits. The dust-off units with liquid CO2 tanks were going to mass about a tonne each, I think (I saw a mass inventory) so they were designed for use at the base only.

       -- RobS

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