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How does the human lifespan figure into the difficulties of traveling to Mars? We aren't talking Pluto here, Mars is only 8.5 months away from Earth using a Hohmann Transfer Ellipse.

http://www.phy6.org/stargaze/S...

Start with the space shuttle's tethered power generation experiments: http://www.phy6.org/earthmag/wtether.htm

Multiply the power generated by the many orders of magnitude that the elevator is longer than the tether was.

As the elevator swung through the magnetosphere on the aposol and perisol points of its rotation, it'd be generating billions of volts and conducting huge amounts of current down to the ground and out the top end of the elevator.

The ground equipment and probably a portion of the bottom of the elevator would be turned to plasma. Same at the other end. The rest of the structure would orbit free and crash. Enough of it would not be burned away that the remainder would wrap around the Earth several times.

Note that this scenario would require it be completely built before the effect started. This is, of course, impossible. It would be burning itself away as its length was increased. Note also that this is due to the structure only, not the dynamics of something going up and down it. Nothing would ever get the chance to make the trip.

It is at first obvious that generating power in this fashion would power the elevator. Less obvious but more important, is what to do with the 99.999% of the generated power that's surplus. It's just too much surplus, and we have no technology to carry that much power safely on such a structure.

Look at the details of the tether experiment. Less than 20 km of tether produced 3500 volts and burned the tether away from the shuttle. The elevator would be 4216 times longer. Also, the tether was not directly vertical, whereas the elevator would be. The amount of power generated would be more than the 4216 times the length.

A primary choice for the elevator structure is carbon fiber. When that stuff burns it puts out a cloud of random buckytube-like particles which pose a health hazard much like a cloud of equivalent mass of asbestos. The best choice of material for the structure would be pretty near the worst choice when it came to its inevitable self-destruction.

If the elevator burned away in the atmosphere, the carbon particulate would be a nasty pollutant. If the structure boiled itself away at higher altitude, outside the atmosphere, it would leave a trail of carbon particles that would become a hazard to spacecraft. Flying through that cloud would be like plowing into fine sand. A brief encounter would be very little trouble. But trying to fly at that same orbit for an extended time would erode away the spacecraft. If it were dense enough, it could also collect some charge in the manner of the tether, and discharge that into a spacecraft approaching it.

Because you need to deal with a much higher delta-V when landing on the pole compared to landing on the equator

Let's see... Mars diameter... sidereal rotation... carry the two... 240 m/s. Earth-Mars velocity difference 2649 m/s. The delta-V due to rotation is a tenth of what needs to happen to burn off the delta-v from getting to Mars in the first place. It's an extra handful of seconds behind the heat shield, plowing through the atmosphere. It's not really all that tough.

C++ likes to hide things from the programmer... There are so many cases of this, I won't even list them to prove my point. If you're a C++ programmer, you'll know what I mean.

If you're not a C++ programmer, then the best way to describe it is like this:

There was a Tom and Jerry cartoon where Tom finally catches Jerry in his hands. As he peeks into a hole made by his fists, he sees Jerry peeking into his own tiny hands. Tom is curious what is in Jerry's hands and tries to look, too. Jerry pulls his hand away and hides it out of Tom's view. Now Tom is really curious and has to kindly ask Jerry to show him what he's hiding in his hands. Jerry then gets his fist near Tom's eye and then gives him a big sucker punch in the eye and runs away.

Tom is the programmer (you) and Jerry is C++. You *think* you have control. But when you want to look very closely at things, then Jerry won't let you. You have to do a few things "against the spirit of the language" in order to get your work done (or else have a very costly rewrite for very marginal additional features.) After you have done this dirty deed, Jerry will sock you in the eye some time later. You don't know when, and you think you got away with it, but it'll happen... usually before a critical deadline because that's when the highest volume of code changes occurs. Of course, you feel kind of dumb that Jerry did this to you. But there are so many countless ways, you can always get caught by a new one, and then eventually he tries an old trick on you that you forgot about. An experienced programmer will sort of just accept that this abuse is part of why he gets paid so much.

C++ is like this Tom and Jerry cartoon where Jerry sucker punches Tom in the eye. Until we invent a language that doesn't do that, we will be stuck in this prehistoric age where future generations will look at our existing programming languages in puzzlement in the same way as we now look at doing math in Roman numerals as peculiar and unintuitive.

Whether the code itself is interpreted or native compiled is irrelevant to our progress in software development.

You would think that by now someone would have invented a better language to replace all of our existing ones. But then again, you would have thought that the Romans would have invented a numeral system that allowed them to progress in mathematics to a point where they could understand how their multiplication tricks worked:

http://www.phy6.org/outreach/edu/roman.htm

But that never happened, and similarly, Western civilization may expire before we have a competent programming language.

• The Space Tether Experiment -- I assume your solution would have been to build a spacecraft to handle this. Consider, also, that the tether broke on the mission. How would you have returned the unbroken end to Earth in order to determine what had happened?
• There's a neat article here on some of the experiments done on the Columbia mission. How would you duplicate those experiments without the Shuttle?

This differs from my main point (and so I don't want to get sidetracked), but I found a few links...

Funny, and very fitting to the topic at hand

A link discussing Newton's theory of Universal Gravitation

Things moving towards other things is an observed phenomena. "Gravity" is the name we gave to the force that causes this. Thus "gravity" is a theory.

Second, much of our electronic communications would be interrupted without this protection. For more information see this FAQ