New Mars Forums

Hardly matters. What is your power source?

Engineering requires engineering the whole thing. So start there, and then think about what you can run using that power source. That's why Zubrin's hoppers are such a good idea.

All that is why I think it's a good idea. Mars will be where the next leaps can happen. It can be, given enough energy per capita, a true terra nova, where land taken is not taken away from someone already living there. It can be like the USA, except without the somewhat bloody past. (Though, to be accurate, 95% of all aboriginals in the USA died from disease, not war. But even so.) That, and having another, totally new planet for people is why for me.

I'm not exactly sure on population carrying capacity, but my WAG would be somewhere around 100 million - because of the resource problems and energy requirements.

Well, on the face of it, the claim that the USA is obviously more lit up is simply not true. Look here: [http://www.cs.hut.fi/~mox/world-at-night/]http://www.cs.hut.fi/~mox/world-at-night/ Scroll to the right and you see more light in Europe.

It's extremely irritating when people don't do the math or research and base their thinking only on personal anecdotes. Sure, personal experience is useful, but should be tempered by clear thinking and looking at the data.

For example, the aquifer that allows Chris to live in Arizona is archeological water. If he checks out how long it's going to last, he will find out that Phoenix is as good as dead as a city, as is the desert agriculture he refers to. It's just a matter of time unless a different massive source of water is found, then everybody has to leave.

Another little stat is that grain reserves are dropping worldwide. The green revolution gave us an increase in productivity equal to converting all the remaining forested lands on earth to farming. Now, after hitting the limits of that, we need to double or triple what the green revolution has given us. But even if we did, much, if not most, of the forested lands of the world are unfit for agriculture anyway.

We are almost certain to face inundation of roughly half the urban centers in the world over the next 15-100 years, perhaps faster, along with wild climatic swings. That is going to put incredible pressure on world population. Agriculture doesn't work without predictable weather patterns.
See: [http://www.commondreams.org/headlines04/0222-01.htm]http://www.commondreams.org/headlines04/0222-01.htm

Then let's look at Hubbert's peak and the decline of oil.

i.e. This ain't no party. This ain't no disco. This ain't no foolin' around.  ???

Having recently worked on design of farm machinery going over just this question of tracks versus wheels, I'd definitely say go with wheels!

Among other things, tracks are out unless manufactured in place because of weight. Tracks are quite complicated and have lots of things that can go wrong. They have few advantages over wheels, except for their average PSI value which can be extremely low. They are used in some farm machinery, and for certain types of heavy equipment because of that.

Tracks are terrible on energy efficiency. It requires a lot of power just to turn the tracks around their capstans.

Did a back of the envelope cut at whether or not a bike would get bogged down on Mars. Basically, the low gravity greatly improves wheels for use even in environments that would be difficult on Earth.

Let's see. At 38% of earth weight, with additional gear on board for suit, and miscellaneous carrying minus a few pounds because the bike would come from earth, let's compare weight.

On earth, a bike and rider is about 180 pounds. 150 for rider, and 30 for bike and stuff carried. (We are talking utility bike here. With standard Mt. bike tires, the contact patch is about 5 square inches per wheel, with about 70% of weight on rear. So, you have about 126/5 = 25 PSI on the rear, and about 54/5 = 11 PSI on the front on earth.

On earth, by creating dual front and rear wheels, riders in th Iditabike can ride through snow, which presents similar problems to sand. That would tend to indicate that the compression strength of snow/sand is on the order of 12 PSI. That correlates reasonably well with figures for ultra low pressure farm tractors which use special radial tires inflated to 6-8 PSI. That enables the tractor to be used on wet, soft, muddy ground without damaging the soil from compression or creating ruts.

So, multiplying those mountain bike figures by 0.38, one can establish a pretty reasonable guesstimate of whether a bike could be ridden on Mars over the surface.

Bike and rider + stuff total weight = 180 * 0.38 = ~70 pounds
Rear wheel PSI of ground contact = ~48 lb / 5 square inches = ~ 10 PSI
Front wheel PSI of ground contact = ~21 lb / 5 square inches = ~ 4-5 PSI

So I think the answer is yes - a bike would work very well on Mars for transportation with little or no modification.