Space Travel

Republican_Man · **Mon Mar 06, 2006 7:54 pm**

Well, the hunger and development issue is a different story entirely. I don't think that's really relevant to this discussion (did a whole unit in AP Human Geography on development and agriculture).
But yeah, we're gonna weaponize space, no doubt about it. And so long as we're ahead of the game, I'm fine with it

webtaz99 · **Mon Mar 06, 2006 8:58 pm**

I don't mean that we should stop trying to end hunger, poverty and war. But we should shift to new ways - that work. Use the money instead of wasting it. That's called an investment. So is space development. Many of the technologies and techniques needed for colonizing space will help mankind overall.

Republican_Man · **Mon Mar 06, 2006 9:07 pm**

I agree on all fronts. For instance, our problem with ending world hunger isn't supply but rather distribution. If we fix that problem, we fix world hunger.
And space. There are numerous benefits of moving into space and I agree that we should really put more focus on it.

PrankishSmart · **Tue Mar 07, 2006 3:19 am**

webtaz99 · **Fri Mar 17, 2006 8:56 am**

This is hard for me to explain.

Yes, fuel makes up most of the mass of a "heavy lifter". And yes, fuel represents a large portion of the cost of a vehicle, sitting on the ground and ready for take-off.

However, fuel is a minor portion of the total cost of given "launch system". What makes the Shuttle expensive to fly is not the fuel, but the tremendous load of parts and labor to get one ready to launch again. And the only thing that makes the Shuttle more expensive than an equivalent set of throw-away launches is the inefficient refurbishment. Things that were expected to give trouble gave more than expected, and lots of things that were expected to give no trouble gave much. For instance, when Columbia landed after the first flight, the techs looked at the tiles. They expected to see a few messed up or missing, but their jaws dropped when they saw the truth. And replacing tiles became much more involved and expensive than the designers ever envisioned.

And people should give the Shuttle program some credit, because it has taught us some lessons about how not to make a reusable vehicle that we simply wouldn't have learned without trying.

Space development is like that. We can't really simulate or test for most space activities - we have to try and learn. And along the way people will be hurt, and even killed. But this is true for nearly all human progress.

What commercial space development will provide is cheaper "turn-around" on reusable vehicles. For instance, NASA uses liquid hydrogen and liquid oxygen as fuels, becuase they offer high ISP from relatively easy-to-handle chemicals. But the pipes and pumps to provide LOX to the engines are incredibly expensive and difficult to maintain. So commerical space companies will probably use less-efficient techologies. This means the vehicles will have to be bigger for the same payload, but they can be made cheaper and maintained cheaper.

webtaz99 · **Fri Mar 17, 2006 9:25 am**

One major problem with reusables, and tourists, is reentry.

The vehicle needs some way to slow down. The fuel to slow down would be almost as much as the fuel to reach orbit. So the current process is based on loosing velocity by friction with the atmosphere. This is inherently dangerous, but if all goes well, it works.

If cheap Lunar-materials-based retro-rockets could be provided, reentering vehicles could be slowed down significantly before entering the atmosphere, and could brake on the way down, eliminating the "fireball" style of reentry, and possibly even benefit from a power-assisted landing. The same techniques could allow large upper stages (which are usually alowed to burn up) to be either boosted into a stable orbit for space use or de-orbited safely for reuse.

There is a concept called a ballute that is being developed which will make reentry a little less "fireball"-like, but in the long run we need to provide true orbital braking.

WeAz · **Sat Mar 18, 2006 1:57 am**

One of those focus fusion reactors might get a rocket into space. Or a nuclear reactor for in system travel.

stroppy · **Sat Mar 18, 2006 9:05 am**

I'm sorry, you'll probably hate me for this post...me being a newbie and all, but I don't think we're going to see any major improvements in spaceflight in our generation. The reasons are complex and have a lot to do with money, border control and nationalism. Here we are in the 21st century and we can't even return to the moon. The only lifter capable of doing so is lying on its side at the Space Flight Center rusting as a museum piece.

Think through the political implications of easy access to space flight. Before anyone lambasts me for this post please know that I dearly love the philosophy espoused by Roddenberry about his vision for the future. I just don't have any faith in our current crop of world leaders who seem more intent in creating friction around the world instead of unifying us with a shared vision, much the way Kennedy did in the 60s. If the world's leading industrial nations spent a tenth of what they do on space flight technology as they do on armanents we'd already be a full space-fairing species.

Republican_Man · **Sat Mar 18, 2006 12:41 pm**

I agree and disagree with you here, Mr. Stroppy. See, what you're saying revolves around the government, and the government only. I see space as becoming more and more a private industry, and therefore disagree with you.
It is my belief that, with all the private industries getting involved in space travel we'll have more of a chance of getting farther out into the final frontier than we already have, because of all the private investment.
If it was just government you'd be right. But it's not. It's becoming less and less a government monopoly.

stroppy · **Sun Mar 19, 2006 3:41 am**

At the moment private interests in space travel revolve around satellite launch and near-earth orbit excursions for very rich people. By and large the companies involved use ex-Nasa technicians / technology. Republican man, I understand your faith in private industry moving us forward but the reality is, for the present, the great amounts of time, money and research required for an extensive space program are still the province of national governments. What I hope for, and what is possible (look at the cooperation on Space Station Freedom) is that nations begin to work together on a united space program. The model for this already exists in the aircraft industry...look at the Airbus program, which incorporates many nations in Europe.

Republican_Man · **Sun Mar 19, 2006 12:36 pm**

You have, within the next two decades:
-Private industry working towards Mars
-Private industry working towards having 3-week trips to the moon and back
-Private industry working towards having Space Hotels
-Private industry working towards having trips to the International Space Station for ordinary citizens
-Private industry working towards a 62,000-mile elevator ride
-Spaceports
-Private industry investing in solar sail technology
-private industry investing in solar satellites
-Private industry investing in microsatellites
-Private industry working towards orbital labs
-Private industry working towards asteroid mining

Perhaps there are no long-distance space projects being planned for by private industry, but what is the unintended consequence of these things? Private minds, who are facing competition, working towards getting better technologies towards getting things done. What is the unintended result? New technologies that work governments and private industries alike can utilize for more long-distance space programs.
I�m not saying that the public industry couldn�t do a fine job with space and isn�t doing good things, and what you�re saying about international unity is a good and true thing, but I think that it is eminently clear that space is in the hands of private industry. Such things are better in the hands of private industry as well, as there is that drive for competition. Heck, that drive from the private sector could convince the public sector to step up and compete more.
Such is the beauty of capitalism. You bring an opportunity that breeds competition and you have remarkable things as a result. I�m banking on just that. I believe it�s in the hands, for the most part, of private industry, and that private industry will greatly help technology and governments alike when it comes to space travel, albeit private industry space travel is currently for the wealthy. But that will change.
Before you know it, private industry will be doing FAR more things than you said in that post, though I do see your point.
Good discussion

PrankishSmart · **Mon Mar 20, 2006 3:57 am**

^The thing with lifting cargo into orbit is it needs to travel around an orbit to stay up there (around 7.5-8km/sec). A lifting 'elevator' can't do that.

stroppy · **Mon Mar 20, 2006 4:50 am**

webtaz99 · **Tue Mar 21, 2006 9:11 am**

PrankishSmart · **Wed Mar 22, 2006 5:52 am**

A geostationary orbit is about all you could do though. I don't see how a tilted equator orbit or polar orbit would be possible.

webtaz99 · **Wed Mar 22, 2006 8:26 am**

Actually, I mis-spoke.

The orbital "anchor" for the elevator will actually be in geostationary orbit. And yes, that means the elevator must be on the equator.

Republican_Man · **Wed Mar 22, 2006 6:59 pm**

I'll read the article I have to see how they plan on doing it, but I'd think they'd figure out the correct way to do it. It's not your average elevator.

PrankishSmart · **Thu Mar 23, 2006 5:52 am**

PrankishSmart · **Thu Mar 23, 2006 5:55 am**

stroppy · **Thu Mar 23, 2006 6:43 am**

PrankishSmart, if this http://news.bbc.co.uk/1/hi/sci/tech/2157975.stm works, maybe the elevator may not be necessary. Read it and see what you think.

PrankishSmart · **Thu Mar 23, 2006 7:07 am**

^seen that before stroppy. It looked really promising but well into the future to consider for at least the next 50 years. A mechanical device at high rpm usually = high maintenence I think. Would be intresting to know what direction this goes though.

webtaz99 · **Thu Mar 23, 2006 9:17 am**

stroppy · **Thu Mar 23, 2006 11:02 am**

Prankish Smart. I agree, this concept may take time. Also this one is worth considering as well:
http://news.scotsman.com/scitech.cfm?id=16902006

The elevator concept is exciting and achievable but wouldn't it be susceptible to such things as geological problems, vulcanic disturbance and temperature stress...being that even the smallest heat expansion of less than a mm over many km of structure would cause the whole thing to go out of whack?

webtaz99 · **Fri Mar 24, 2006 8:07 am**

If the magnetic field/gravity/thrust thing held water, wouldn't we have observed it from astronomical objects, some of which exhibit truly staggering magnetic fields?

It also begs the question, is there a fundamental limit to magnetic field density?

Some of the given, yet often unmentioned assumptions conerning a "space elevator" are thermal stresses, vibrational modes, and weather effects. There will obviously have to be active stabilization built in or the thing would shake itself apart.

The space elevator also presents a "catch-22". To build it, you need cheaper access to space, but that's what it's for. It's much easier to build if you have access to extra-Terrestrial materials, but that's what it would help achieve.

I think we have a lot to learn about construction in space before we attempt a space elevator. We haven't even built the simplest rotating, "artificial gravity" habitat or space power station.

stroppy · **Fri Mar 24, 2006 8:13 am**