To roll or not to roll...

[jhwegener]

Perhaps some may find it interesting - or funny - to consider this: On some of the moon landing there followed a vehicle - or "moon car", seemingly extending the concept of "automobile industry" beyond earth.
Transport on wheels seems very effective - at least if You have a good infrastructure, smooth roads without too many "bumps". From my point of view, though I admit to be the very opposite of an expert, it seems that few extra terrestrial bodies fullfill such criteria, or will in the near future. So if some wheeled artifact is sent with the intention to be able to move around, problems arises every time the is a rock or perhaps even a stone - not to speak about Mons Olympus. So why not try something else, either entirely from our imagination or inspired by earthly creratures. The later usualy are non wheeled, but use legs, finns, wings, to walk, jump, dive, fly, creep, crawl or climb. Perghaps a bit more complex way of moving, but with lesser risk of completely stop by some obstacles in the terrain.

[JohnD]

jh,
A Martian probe to float around in its tenuous atmosphere has been studied: http://www.space.com/scienceastronom...on_000831.html
And a true aircraft, a parasail, too: http://www.space.com/scienceastronom...on_000831.html
But that will only work in an atmosphere.

Walking robots are still very experimental on Earth.
Wheels are astonishingly efficient, given a smoothish surface.
Tracks are very much less efficient, principally because of the steering, that requires one track to fight against the other.

Hopper probes have been described, which leap into the 'air' and land elswhere on the body being investigated. http://www.astronautix.com/craft/fobos1f.htm They have the advantage of allowing available energy to be stored for as long as it takes to have enough for another leap, but I imagine would be fairly random in where they came down!

The ill-fated Beagle II had a creeper, intended to burrow under rocks for evidence of life in thiei protection, but that had a very limited range.

Good subject for discussion!

JOhn

[jhwegener]

Wheels may be the best "given a smootish surface", but I cannot resist to ask the question "where in heaven (literally) do we find "smooth surfaces"? And then about the "randomness" of jumping "thing"erhaps there may be ways to control that? after all there is many creatures on earth that do exactly that - jumps. Do they all realy move randomly around(frogs, kangaroos, small insects etcetera)?

[captain swoop]

Well, the Rovers sent to Mars so far haven't had too many problems, neither did those sent to the Moon with Apollo.

[swampyankee]

The mechanisms involved in getting walking to work are a lot harder than getting wheels to work, even on crappy surfaces. That wheels don't exist in nature (at least macroscopically, and don't mention tumbleweeds) is because nature doesn't seemed to have evolved any macroscopic rotary joints that can carry fluids, at least on Earth.

[DrRocket]

Wheels may be the best "given a smootish surface", but I cannot resist to ask the question "where in heaven (literally) do we find "smooth surfaces"? And then about the "randomness" of jumping "thing"erhaps there may be ways to control that? after all there is many creatures on earth that do exactly that - jumps. Do they all realy move randomly around(frogs, kangaroos, small insects etcetera)?

If you have any experience with off-road vehicles you will recognize that "smoothish" need not be all that smooth. Going over a medium-sized log is not a problem. Neither are moderate-sized rocks.

[mugaliens]

What category of surface land animals has been on our planet many times longer than mammals and are yet still here?

Yes. You think you've seen this video, but this is the extended testing version of it. Watch from about 1:45 and on.

Now imagine how much more capable a six-legged version of this would be.

[novaderrik]

http://www.youtube.com/watch?v=lMrwe...eature=related


http://www.youtube.com/watch?v=2kdnmAWrr2U

the surface need not be smooth for wheels to do their job..

[HenrikOlsen]

Smoothish
Not even remotely smoothish for the scale.

[mugaliens]

Smoothish
Not even remotely smoothish for the scale.

Yeah, I'm sorry, Henrik, but even with a 40lb pack, he loses.

I win.

[HenrikOlsen]

Yeah, I'm sorry, Henrik, but even with a 40lb pack, he loses.

I win.

In vacuum? I'd like to watch. On video, not in person.

[mugaliens]

In vacuum? I'd like to watch. On video, not in person.

Yet brain surgeons manage micrometer accuracy with just their fine motor skills.

Are you saying it's not "humanly possible"? Ask Chrissy - sharpshooters crack 2 inches at 1,000 yds hands-only, no computers, all day long. Of course it's humanly possible.

Whether it's machine possible is simply a matter of time. I strongly suspect it's time in the past.

Getting back to 4-wheelin'... A nine-wheeled vehicle over rough terrain with the right adaptive wheel control/lifting mechanism could have made mincemeat out of that mindfield. I know that while riding enduro years ago that "obstacle course" was amateurish, at best. See: http://www.youtube.com/watch?v=5_pSb9S7JT8

[JohnD]

Hi, mius, me again.
Respect to your Iron Man, but he doesn't show the ability of two wheels to cross impossible obstacles as well as Danny McAskill: http://www.youtube.com/watch?v=Z19zFlPah-o.
John

[HenrikOlsen]

Yet brain surgeons manage micrometer accuracy with just their fine motor skills.

I think I have absolutely no idea what you've been talking about in the last couple of posts.

I posted a couple of clips showing wheeled performance in very non-flat terrain, in support of the idea that wheels are quite OK for exploration vehicles on other planets in up to very heavy terrain.
You start talking about out-hiking them with 40 lbs on the back, I comment that it's for use in vacuum because the OP was about exploration vehicles and you start talking about brain surgery and snipers.

You're quiet honestly not making any kind of sense I'm able to detect.

[mugaliens]

I'd like to see any wheeled vehicle attempt to navigate this terrain.

I asked a question earlier: "What category of surface land animals has been on our planet many times longer than mammals and are yet still here?"

The answer is two-fold: Avians and reptiles. The human form is wonderfully adapted for navigating a wide variety of terrain. Although it'll take decades to come up with a machine capable of duplicating our abilities, it'll eventually be done. If more stability is required, consider going with a four or six-legged machine.

[swampyankee]

It's easy to find cases where mechanism x is sub-optimal. Legs are not the best choice here, for example. An engineered, as opposed to evolved, mechanism for walking is much more complex than wheels, which means it will be more complex, more likely to fail, and likely to have more mass, which would mean it would require more fuel to get it to anyplace extraterrestrial.

[flynjack1]

Mars has low concentrations of methane. How about a device that has the abilitiy to collect methane and use it for propulsion? Something that could fly short distances, say a mile or two at a time and then explore while it re-collects methane for it propulsion. The thin atmosphere and low gravity would necessitate some thing more ballon like vice winged aeroplane.

[mugaliens]

Mars has low concentrations of methane. How about a device that has the abilitiy to collect methane and use it for propulsion?

Combusting it with what? Mars also has 95.32% CO2. We'd either have to bring our own O2 to the party, or make it from surface materials/minerals.

Also, methane is only 10 ppb. That's per billion, or 1 part per 100 million. Not likely to find any efficient means of extracting any useful amounts.

[swampyankee]

iirc, the two most likely fuel systems for Mars vehicles are solar (useful for ground vehicles and maybe aircraft) and hydrazine or hydrogen peroxide monopropellant engines (useful for aircraft, especially, but rather limited in range).

[flynjack1]

Correct me if I mistaken, but I thought the persistence of methane was one of the curious aspects of Mars. It implies some source of methane in the environment, which would suggest some areas of higher concentrations than 10ppb. Even at much higher concentrations my idea may be hair brained, but flying is the easiest way over tough terrain. Would a hot air balloon concept work in the Martian environment?