The Island Group still has the problem of launch costs.
VentureStar ultimately failed because the fuel tank design was not strong enough causing them to rupture during testing. It was moving along fairly well until then and then quickly cancelled. I thought they should have held on to it until a stronger fuel tank could be made or else use the next best thing.
Even with heavier tanks, the launch costs could have been greatly reduced form the shuttle's 10,000 dollars per pound.
There are those in the Government who would do away with NASA. 13.8 billion per year is nothing compared to the whole Federal Budget.

If some of these private launch companies can get off the ground, all those problems can be bypassed. A Canadian group just tested their launch engines and checked out well.

 

Rocket performance:
Isp is called Specific Impulse(the capital "I" will be a number).
Specific Impulse(SP) is a measure of efficiency, it also can tell you how fast the exhaust velocity of your rocket.
There are other factors at work including weight and fuel amount and such. But Isp is used as a basic referance.

To calculate a top speed the quick and easy way just multiply the Isp number by 21.7.(this is equal to one Earth gravity per hour.) The result is MPH of your exhaust.

The space shuttles Isp is 450. This means the exhaust from its engines travels at 9765.0 miles per hour. The shuttle can go faster than this because of the thrust of the engines. However, even though 450 is good for chemical rockets, it is a very low efficiency.

Ion propulsion engines have been designed around 2500 Isp. This is approx 54,250 mph. Meaning with a 1 to 1 fule to weight ratio the craft can get up to 54,250 mph.

There are three types of fission rockets: Solid Core, Liquid Core, and Gas Core.

Gas Core fission rockets would provide the highest Isp at upwards of 7000. This would provide a possible top speed of 151,900 mph.

A fusion rocket might get as little as 2500 Isp(54,250 mph) or as high as 200,000 Isp (4,340,000 mph, although this would take some GREAT tech to make).

An Isp of 30,000,000 would be required to go lightspeed. The best matter/anti-matter engine might get an Isp of 15,000,000 or half lightspeed.

Magnetic sails, solar sails, and laser push propulsion really can't be measured with Isp as they do not carry fuel.

 

The Island Group would only use the shuttles to use the tanks for their space stations. It's a shame NASA cancelled the aerospike research. IIRC, they said the research costs were too high. But they could have made that money back in cheaper and more frequent launches with the Venture Star, right?

 

Right,
The VentureStar would have dropped launch cost by a factor of ten.
With NASA's 6 billion a year set aside for those launches, they would either make 10 times as many launches, or save a lil over 5 billin to use in other areas.

 

And the atmospheres of Saturn and Uranus have an almost infinite supply of helium 3.

Uranus has gas? Who'd have guessed

 

lol

 

And the atmospheres of Saturn and Uranus have an almost infinite supply of helium 3.

Um, I'd like someone to back that statement up with a reference. The Jovian planets (Jupiter, Saturn, Uranus, Neptune) consist mostly of molecular hydrogen. Don't get me wrong - there is a lot of helium, too, but not necessarily He-3.

 

I got that from [link=http://www.space.com/scienceastronomy/helium3_000630.html]this site[/link]


Here's the paragraph:
While it's true that to produce roughly 70 tons of helium 3, for example, a million tons of lunar soil would need to be heated to 1,470 degrees Fahrenheit (800 degrees Celsius) to liberate the gas, proponents say lunar strip mining is not the goal. "There's enough in the Mare Tranquillitatis alone to last for several hundred years," Schmitt said. The moon would be a stepping stone to other helium 3-rich sources, such as the atmospheres of Saturn and Uranus

 

I was just wondering if there were a better reference than an unattributed Space.com sentence. My concern is that it should be relatively straightforward to process He-3 from the Moon, but I'm unclear on how to process He-3 from the gases on the Jovian planets. "Scooping" is probably not feasible. Any ideas?

 

Yea it probably would be pretty difficult to get it. Even if you got close enough the gravity might pull you in, especially in Saturn. Far in the future, if we still need helium 3 and run out on the moon, I guess we might find a way to get it from Saturn and Uranus. We probably won't need to though, since there is enough on the moon for thousands of years, and hopefully by then we have other sources of power.

 

Off the top of my head the only thing I could think of was an orbiting platform(or ship) that lowers a tethered "scooper" that can withstand the stresses involved.
I'm just guessing if/when we need it, we could create it.

 

Um, pleae correct me if I am worng, but it is going to be very hard to get the He3 from those planets. Yes, as far as i know, the gas planets are mostly hydrogen, with bits of other stuff, including he 3. However, here is another little problem. He3 (I am pretty sure, correct me if I am wrong) is heavier than Hydrogen. So you will have to go allot deeper to somehow get it. Just another little problem.

 

EnforcerSG: you are correct about He-3 being heavier than Hydrogen. Even more of a problem is that the clouds we see when we look at the Jovians are made out of other chemical compounds (like our atmosphere differs in composition from the soil). Temp and pressure increase pretty rapidly as you go into the atmospheres of the Jovians, making deeper excursions difficult.

Of course, we'd need nuclear-powered spacecraft just to get out there.

 

Hmmm, maybe we could make some type of "city" amongst the clouds to make the mining easier?

 

I thought I had some litiature that showed cutaway views of Jupiter's atmosphere, and I do, but nothing saying which is heavier, helium or hydrogen.
I do believe you are right, that it is heavier.
However, Jupiter's atmosphere is never at rest. It churns and bubbles and swirls and I don't think the helium has a deeper, separate layer.
Jupiter is 95% hydrogen and helium, with 10% being helium. The helium3 makes up 45 parts per million.
Two books:Mining The Sky by John Lewis and Entering Space by Robert Zubrin touch on mining helium3 out of the giant planets.
Uranus and Neptune would be first as their escape velocity is lower and therefore easier to get helium3 out of, about 20km per second compared to Earth's 11.2 per second and Jupiter's whopping 60km per second.

Both books seem to suggest dropping a rocket powered "scooper" with wings that can go in and float though the atmosphere, gather the helium3, and then harvest the hydrogen as rocket fuel to escape.

Uranus has 16 million times the helium3 that the Moon does in the upper atmosphere. If 4000 tons per year were used this would last 4 billion years. And thats not even the total amount, just the upper atmosphere. And that still leaves the other three gas giants.

I still like the tether idea better, but whatever works.

EDITosted after dustchick's helium3 is heavier confirmation. Thanks.

 

Another thing to concider (i dont know, but just more fuel for the fire) is concentration. Is the He3 all spread out in the gas planets, or is it somewhat concentrated? That could be a problem in terms of "practical" minning, I dont know. Any ideas?

 

If it is, we could just scoop up huge amounts of gas and filter out the He 3. It's all spread out on the moon too, but that's a little easier to get to though.

 

Here's a nice site that is all about the [link=http://www.nuclearspace.net]topic[/link]

I think it's a new site, as it doesn't have very much material on it. There is a good article about NASA's need for a heavy lifter.

Here's a little snipit from the aricle:

Even by today's standards, Skylab was quite sizeable, at almost 13,000 cubic feet of habitable volume; it was well suited to the needs of its residents.

In light of the recent attempts at constructing the International Space Station (ISS), one fact remains clear- that Skylab was put into orbit with a single, solitary launch. There was no need for dozens of shuttle launches, the lapses of time associated with this method and cost overruns that undoubtedly are a direct result. As can be readily observed, the above problems have been very apparent with the construction of the ISS.


For comparison, the ISS when completed is supposed to have 43,000 cubic feet, and take 46 assembly flights.

 

Ramius, alot of good info can be found on that site. There is a sort of.....um....history concerning it though.

At Space.com there was a poster there by the name of Yales. If I'm not mistaken he is a working scientist, very knowledgable, and though he does listen to the ideas and opinions of others he is not a nuclear power in space advocate. All around, a nice guy.

About a year ago a new poster came to Space.com. His name was Projectorion. This guy was the complete oposite of Yales. If you disagreed about ANYTHING this guy had to say HUUUUUUUGE flame wars erupted from this guy. One day he spammed the entire message board area and messed it up for a day. All because people did not see things his way. If I have this right he is a security guard who is an EXTREME advocate of nuclear anything. He was banned.

A little time goes buy and nuclearspace.com pops up. Now, it does have good info to find there, and with a brief once over most of the posters seem level headed. If you look though, you will notice most of the threads are authored by Porjectorion(PO) I don't know if he put up the site himself.

Yales pops on those message boards from time to time and because PO can't stand him he has banned him many times. Yales being the computer engineer that he is can get back in without any hassle. Its like an internet war between these two. Yales goodguy, PO badguy.

This thread has been mostly Pro-nuclear, if Yales was here we would get an earfull since he does not want nuclear power in space. But it would be a well educated DISCUSSION from him, not an argument.

Just thought you should know.
I myself have had no talks with either of them since this is the only message board I post to.

 

That's funny about the two posters Yales and Projectorion. I had looked briefly through nuclearspace.com's forum and noticed that the two seemed to be bickering. It's too bad Yale isn't a member of the JC, it would be nice to have someone who is opposed to the issue here.

 

One point I remeber Yales making was on the creation of fusion power plants. If I remember this right a fusion plant makes alot of neutrons. Neutrons are bad for you.
I think they can be shielded to some degree but any fusion plant is basically a weapon that can harm alot of people.
Like any tech, they can be abused.

If you want an education on the possible pitfalls of nuclear power its not a bad idea to read through his posts.

 

Well, in space, what is the big deal? Once safely up there, how can it really hurt us? If it falls, most of it will burn up. And radeation made up there wont hurt us down here, so what is the big deal?

 

Between Yales and Prjectorion is the ideal of an old nuclear rocket design called Project Orion.

This was a vertical launch rocket that would explode nuclear bombs one after another while launching from Earth. This is nutso.

In space there would be no harm but it is not an efficent way to use nuclear power.

Still, even if used in space there is still the neutron shielding problem for the crew of said ship. I am not sure what the parameters are for such shielding.

Also I'm not really sure what the crew shielding difficulties are for the americium nuclear fuel I mentioned in an earlier post(It is a fission type).

 

Also I'm not really sure what the crew shielding difficulties are for the americium nuclear fuel I mentioned in an earlier post(It is a fission type).

Possibly no more than on a nuclear submarine. Maybe, I don't know.

 

Hehe, that would make sense, fission is fission.

The one major problem most anti-nuclear activists have is getting the nuclear material up to orbit from Earth to build it.

The solution is to be able to create it out in space where any materials needed are out there in spades.