[SeaGypsy]

Google 'foamed glass reentry shield- nada. There ain't much I don't know about glass. In theory a pyrex type super pure silicate glass could be 'foamed' whether by injection with the right amount of bicarbonate at the right temperature (somewhere between 2150- 2300 Celsius) then precision controlled annealing might yeild some kind of interesting shield material. I have never heard of it any more than Mr Google has- with glass in my blood.

Ordinary Pyrex is not 'cheap'- for 3 reasons-

the purity of silica required is ultra fine- tiny deviations in the original sand can and do wreck whole batches of product.

The working temperature and melt temperature being almost double ordinary glass- uses approximately 4 times as much energy on a finished weight basis.

The refractories involved are at the highest spec available- 4 times the price of ordinary ceramic kiln, pot, furnace lining etc. Even the best gear has a maximum working life in months before needing rebuilding.

Believe it or not- glassblowers talk about some wacky shit while we're spinning bubbles of magic red honey- including any way we could do away with the need for contact surface refractories- including theorizing making glass in zero gravity. Nobody despite wanting the same thing since the Egyptians built the first glass furnaces 3500 odd years ago- has worked out how to do it.

Rail guns look safe for a lump of plasma. I aint riding on one, thanks.

[vision-master]

We look at space as something we must overcome by force, what if we rediscovered levitation like our ancient ancestors used instead? Maybe we already do, secret space program perhaps?

[AgentR11]

KJ, you aren't getting my point. There are all kinds of "known" and "proposed" concepts for getting stuff into and out of orbit. Of the ones that have been built and used, they are uniformly, hideously expensive. Of the ones that have not been built, I suggest you put your own money on the line to build the magic device and then smile bravely while you watch it not work in practice. There's a reason we tossed the shuttle. There's a reason we are replacing it with a stack of chemical rockets. Its tech that actually works and won't bankrupt us in the process.

If railguns worked and were really cheap enough to beat rockets, the Chinese would build it. Its right up their alley, they have sufficient native production of metals and power; sufficient currency they are looking to spend on long term infrastructure, and no regulatory niceties to get in the way of a top level decision. But guess what they use to put stuff in orbit. Chemical rockets.

The physics and economics of delta-V are brutal. There is no magic. No warp drives. No transporter beams. Just ejecting propellant out the bottom of a cylinder.

[vision-master]

$this->bbcode_second_pass_quote('', 'T')he physics and economics of delta-V are brutal. There is no magic. No warp drives. No transporter beams. Just ejecting propellant out the bottom of a cylinder.

[Timo]

$this->bbcode_second_pass_quote('vision-master', '')$this->bbcode_second_pass_quote('', 'T')he physics and economics of delta-V are brutal. There is no magic. No warp drives. No transporter beams. Just ejecting propellant out the bottom of a cylinder.

[vision-master]

$this->bbcode_second_pass_quote('Timo', '')$this->bbcode_second_pass_quote('vision-master', '')$this->bbcode_second_pass_quote('', 'T')he physics and economics of delta-V are brutal. There is no magic. No warp drives. No transporter beams. Just ejecting propellant out the bottom of a cylinder.

[John_A]

$this->bbcode_second_pass_quote('vision-master', 'W')e look at space as something we must overcome by force, what if we rediscovered levitation like our ancient ancestors used instead?

[vision-master]

$this->bbcode_second_pass_quote('John_A', '')$this->bbcode_second_pass_quote('vision-master', 'W')e look at space as something we must overcome by force, what if we rediscovered levitation like our ancient ancestors used instead?

[Timo]

$this->bbcode_second_pass_quote('vision-master', '')$this->bbcode_second_pass_quote('Timo', '')$this->bbcode_second_pass_quote('vision-master', '')$this->bbcode_second_pass_quote('', 'T')he physics and economics of delta-V are brutal. There is no magic. No warp drives. No transporter beams. Just ejecting propellant out the bottom of a cylinder.

[KaiserJeep]

The description "foamed glass" came from one of my IEEE publications, as in "The newly re-designed Orbiter heat shielding used inexpensive flexible sheets of foamed glass in place of the labor-intensive ceramic tiles." ("Reliability-centered maintenance on the Space Shuttle Program", IEEE Annual Proceedings of the Reliability and Maintainability Society, 2000).

As for the practicality of electromagnetic catapults, 1/10th scale models have been tested in partial vacuums in underground tunnels originally constructed for particle accelerators. A full scale model needs a 30-km long site, with the muzzle as high as possible on a mountaintop, facing East so that the radial velocity of the Earth adds to the projectile's, and with open air between the accelerator magnets for the shock waves from the supersonic projectiles to spread. The nearer the equator, the better. A single fission power plant of 1000 mW should suffice and the waste heat can be used to keep the high altitude parts of the catapult free of ice and snow. The estimated tab for the whole thing is a few billion US dollars. The overall scale of construction is less than 1/10th the size of the Three Gorges Dam in China.

Such a project requires the participation of a large government, it is too big for private investors. The three possibilities are China, India, and the USA. But it's not yet a political priority, even though the projected cost is well below either the Apollo program or the Shuttle program.

====> Note however that this is an Engineering program, the R&D has already been done on the scale models, which were paid for by the US Department of Defense. There are no advances in material science or spacecraft design needed, we are basically using a railgun to accelerate steel cans (covered in heat shielding for launch) to escape velocity.

I'm actually hoping that the US does this instead of China. China might be tempted to use coal powered electricity, which would work but be tremendously polluting. However, a fraction of the hydro-power from the Three Gorges Dam would also work.

Appreciate however, the environmental consequences of this launching system. It should prove possible to launch one canister every 10 seconds at a minimum. There would be sonic booms emanating from the catapult every 10 seconds as long as it is in operation. Nobody would want to live within hundreds of miles of the site.

[SeaGypsy]

Your Geography is a bit off. The best location would have to be in Indonesian PNG- Irian Jaya.

http://en.wikipedia.org/wiki/Puncak_Jaya

[SeaGypsy]

Oh and there's another thing. The reason the projectile is 'plasma'. At the speeds generated, there are only 2 things an object can do- heat up and break up, or heat up and liquefy.

[AgentR11]

shhhh... don't mention physics. Its just thin air, surely it couldn't cause a problem for our launcher... /must wave hands faster!!!

[KaiserJeep]

Obviously, you gentlemen failed to note the term "steel cans (covered in heat shielding for launch)".

Your prejudices are showing. This is another useless conversation. An Engineer familiar with the material says this is doable, laymen unfamiliar with the material say NO.

Again, it is YOUR responsibility to educate yourselves. (Again I am plagued by the image of a mama bird regurgitating partially digested fish into the mouths of her cheeping chicks.) If you doubt this is possible, you have been reading BS on the internet.

But the one thing you did answer quite well is WHY we are not building this launcher already. Because space access is way down on our priority list below Obamacare and Ethanol crop subsidies and government grants to study the sex lives of <insert favorite species name>.

Then there are the "doubting Thomas's" such as yourselves, too prejudiced to even examine the rather far along plans for space access, and already cringing from the end of the Oil Age.

You doomers are indeed a downer.

[Keith_McClary]

$this->bbcode_second_pass_quote('KaiserJeep', 'T')his is a useless debate. I don't actually care whether it was pure iridium or iridium in stone.
...
All those elements are present in space. Metals, gases, water, hydrocarbons, and unlimited solar power.

[Keith_McClary]

$this->bbcode_second_pass_quote('KaiserJeep', 'B')ut the one thing you did answer quite well is WHY we are not building this launcher already.

[SeaGypsy]

There is no such thing as glass which will NOT LIQUEFY before reaching 2300 degrees C. Foamed or otherwise. The stuff would be peeling off like talcum at rail gun speeds. Then there is that danged plasma drive.

[vision-master]

The space program went from exploration to exploitation.

I'm seeing Google censoring more and more factual information.

Young people brought up on the Internet will be totally brainwashed.

More and more knowledge is being filtered out - we are borg.

[SeaGypsy]

Who's the conspiracy theorist now?

[vision-master]

$this->bbcode_second_pass_quote('SeaGypsy', 'W')ho's the conspiracy theorist now?