The drawbacks are that is still a lot of travel in atmosphere, the friction losses consume fuel, and it may take a while to get up to speed. On the surface of the Earth escape velocity is about 7 miles a second, 11.2 kilometers a second, "at least" ten times the speed of a rifle bullet and 34 times the speed of sound. That is a lot of stress on the craft, so it would be best to get very high up to start. A "gee" is 32 ft a second squared [ft / (sec)^2], it would take about 19 and 1/4 hours to reach escape velocity. Rockets as currently used are hard on people but clear atmosphere quickly, getting to where the lower friction is. It would take a good bit of number crunching running many different scenarios to figure out whether space planes or rockets would end up using less fuel.

Now getting between stars or even to our outermost planets, that will be a challenge. There will be years of travel. To avoid the problems mentioned above, a common proposal is continuous acceleration of a craft, as that will act like gravity for the passengers. At the halfway point you turn off the engine, flip the craft around, and fire off the engine (now pointing the other way) to slow down. Very Major Drawback is speed kills, a tiny rifle bullet does equivalent damage to a handheld much heavier pike. With enough speed even microscopic particles are deadly, stray gas molecules can be dangerous, and space is far from being completely empty, even between stars.

So, we go relatively slow, no continuous acceleration. Option one, sleeper ships, if we ever get the technology right. If we can ever completely trust automated systems for that long a time, under what could be emergency conditions. Option two, people are awake. For short trips like in our solar system, there will be the expected problems. For much longer like between stars, generational ships, make your own crew replacements. Currently, no one even knows what a human will end up looking like if raised without gravity, whether they will end up eleven feet tall with limbs no thicker than an egg roll, or if with exercise involving pushing massive things they will be somewhat stronger and closer to "normal." If the effect of gravity is generated with revolving ship sections to about a gee, it might not be so bad. Otherwise, when we get to whatever final destination there is, whether a new planet to colonize or heading back to Earth after an exploratory mission, the current space-born will stay there while they will first have to raise those who can survive the gravity. That could be simulating gravity with centrifugal force, or on the "dark end" dropping "seeder craft" loaded with embryos for artificial wombs, with children given birth by and raised by machines of some sort for the first generation.

In many ways we have the technology right now for space exploration, even between stars, just not much of a safety margin. Safer ways for ordinary people to get to and work in space, not that far off, if you do not mind the complications. The ease of Star Trek, never, not without discovering a brand new kind of physics and loads of other monumental discoveries into super-strong materials and more. But, we can get there, and that is the important part.

And if we want the human species to continue regardless, and seriously considered how a solar hiccup without warning could completely trash our technology and civilization and even all life on Earth, including us and possibly even the bacteria in the deepest depths of the ground and seas, let alone the Hollywood favorite of planet-killing stray asteroids and meteors, we must get off this rock and disperse, as soon as we can do so with the assurance of future generations to come.

now, maybe there is a case to be made that establishing a permanent presence on the moon has economic benefits. I'd like to hear such arguments.

I can also see how such a mission could be an unequaled folly and, well, I do not see either the Chinese or Indians doing that. Its more within their character to politely say: "US, please, after you…"

now, maybe there is a case to be made that establishing a permanent presense on the moon has economic benefits. I'd like to hear such arguments.

I can also see how such a mission could be an unequaled folly and, well, I do not see either the Chinese or Indians doing that. Its more within their character to politely say: "US, please, after you…"

Actually we already have all the energy we could ever need for many tens of thousands of years, under our feet. We live on the solidified scum on top of a ball of molten rock and metal, the energy we could draw out of that is immense. Now tapping it, that is the issue.

I find geothermal heat pumps to look most promising. Check out the "Open Loop" systems, "Standing column well." If you will be drilling a well for water anyway, it could save money to get a second one drilled at the same time, there are costs involved getting the drilling rigs on site and set up, you could get a break for getting another on the other end of the property at the same time. It could also serve as a temporary drinking water source if the other gives out, if installed that way. The payback time is short, the technology proven, the lifetime savings are a great incentive.

The only drawback affects practically all heating, you need electricity to run it. Perhaps in time with advances in thermo-electric materials, this "free energy" can generate enough current to run a geothermal system without needing any connection to the grid, only a start-up battery to get the system running. With additional wells or similar, perhaps then you could run your entire house as well.

This is far closer to providing our energy needs now then fusion from a trace gas mined from tons of moon rock. And no need for government intervention with punitive taxation to force its adoption, capitalism alone dictates this is a great thing to get into, right now, period.

While some of this may be offset by simulated gravity, such as centrifugal forces in very large rotating space stations, as well as vigorous extended exercise, such is no substitute for 24/7 normal gravity. Part of why candidates for long-term missions must be in such great shape is so they have more of a "reserve" to lose before returning. Babylon 5 aside, there are no realistic plans for a station large enough spinning fast enough to get a full gravity even at the inside of the outermost wall, which would still leave lots of space being used at less apparent gravity. Likely the grandest plans would be far less, and on the Moon there would be the expected one-sixth gravity. While I doubt there would be "irreversible biological changes" as posited in The Moon is a Harsh Mistress, it would still be a very long recovery for anyone returning to normal gravity. I also doubt there will ever be drugs that can properly compensate. For example, while there are now drugs that can increase bone mass, increasing the body's uptake of calcium, without proper gravity to "direct" the calcium to the bones there can be calcium deposits built up where they are not wanted, such as within blood vessels.

Otherwise, the major reason astronauts have to be so fit is to merely get into space, the very high gee-forces experienced getting thrust into space on rockets is very stressful. In time with the development of "space planes" that will more slowly ascend into space, or the hoped-for "space elevator," many of the less-fit will be able to go into outer space and even stay there for extended periods like a month or so.

One thing to note, as part of "colonizing" space there will be children born and raised in low-gravity environments. Here on Earth we grow thick skeletons to deal with the gravity. When rebuilding bone mass after a long stay in space, we are merely "filling in the holes" of the existing structure. Without a need for such a massive structure, it seems unlikely those who grow up in a low-gravity environment will ever develop one and have thin yet solid bones. Even if the skeleton could somehow "bulk up" enough, those coming from the Moon to Earth would still have problems with joints sized for handling one-sixth the load. Also the cardiovascular system may also have problems from not being grown to the relatively high pressures needed to combat gravity. The children born and raised in space will stay in space. Since that puts the kibosh on "evacuating to Earth," if we ever go out there with a permanent presence we will have to do it right because we will have to be there to stay, there will be no coming back.

Rockwell wasn't _bad_ in Heist, for example, and I was about to the point where I could tolerate him (although it was a weaselly character) … but then he had to help stink up Hitchhiker's Guide …

In any case, I'll probably go see this.