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Race To Space: Exploration, Commercial or Tourist Driven?


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Posted on Mar 24, 2010 4:23:07 AM PDT
M. Helsdon says:
Virgin's tourist space rocket has completed its inaugural test flight over the Californian Mojave desert.

The spaceship was strapped to the mother aircraft for the three-hour test flight and reached an altitude 45,000 ft.

Tests will continue on the VSS Enterprise until 2011, before the first commercial flights take place.

http://news.bbc.co.uk/1/hi/technology/8584134.stm

Posted on Mar 24, 2010 12:20:25 PM PDT
The further VG gets, the better I like it. Thanks for posting.

In reply to an earlier post on Mar 24, 2010 4:48:05 PM PDT
I kind of like the idea that cargo travels slow and cheap, while people travel fast and expensive (just not too expensive).

Now if we can just work in a rotovator... ;)

In reply to an earlier post on Mar 24, 2010 6:15:04 PM PDT
TO: M. Helsdon

Thanks for the link. More power to 'em!

Posted on Mar 25, 2010 11:56:37 AM PDT
http://www.russianspaceweb.com/ppts.html

Since at least the Russians are continuing to pursue government-sponsored, manned space-flight, here's a picture of their Next Gen Manned Spacecraft. It is intended to eventually replace their workhorse, the Soyuz.

Posted on Mar 25, 2010 2:51:59 PM PDT
http://mmbenya.com/jules-vernes-space-cannon-by-john-hunter/

Physicist John Hunter, at the Lawrence Livermore National Laboratory, thinks Jules Verne's "space cannon" is do-able. Still needing a half-billion dollars to complete it, the completed space-cannon could reduce the cost of sending supplies to the ISS to $250/pound, from the current $5,000/pound.

Posted on Mar 26, 2010 6:34:39 AM PDT
John Hunter's Space Cannon is very cool, and thanks for bringing it up. He's also got a YouTube video about it (about an hour, lots of talk, unfortunately no video of the cannon in action). He's also mentioned at the site "Technovelgy."

http://www.youtube.com/watch?v=1IXYsDdPvbo

http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=2741

In reply to an earlier post on Mar 26, 2010 6:30:10 PM PDT
TO: Marilyn Martin

Thanks for the link re the Russian spacecraft.

In reply to an earlier post on Mar 26, 2010 6:49:35 PM PDT
TO: Marilyn Martin
RE: "This will increase the pressure to 500%, when fired, the half ton payload will be sent off at a respectable 13,000/mph!" [quoted from the article]

I have two questions right off. The author says, "This will increase the pressure to 500%..." Well, 500% of what? The way the phrase is written, it's not a pressure but a comparison. What is he comparing it to?

Also he implies that the projectile's initial speed will be 13,000 mph. Well, orbital velocity for low earth orbit (LEO) is 17,000 - 18,000 mph, depending on the altitude. Of course, the orbital velocity for higher altitudes is less. However, the projectile will encounter fierce friction from the atmosphere (remember the space shuttle Columbia?). At the very least, friction will cause it to lose velocity. Will the projectile be equiped with onboard rocket engines?

Posted on Mar 27, 2010 6:52:37 AM PDT
That 13,000 number struck me too. Fortunately, nothing struck me at 13,000 MPH.

It's going to need a rocket to circularize the orbit, so we can be sure it carries one. I guess it also provides that last 5,000 MPH? It would've been nice to be told.

It'll need a heat shield of some sort, but it won't be spending much time in the atmosphere, for the very reason that you don't want to lose speed/gain heat from friction. A reentering spacecraft spends a lot of time undergoing as much friction as they can get away with, specifically to slow down.

I hope he's thought of all these things that weren't explained to us.

Posted on Mar 27, 2010 8:09:26 AM PDT
Here's a better article on Hunter's Space Cannon:

http://www.popsci.com/technology/article/2010-01/cannon-shooting-supplies-space
"Heat the hydrogen in a confined space and it should build up enough pressure to send a half-ton payload into the sky at 13,000 mph."

In reply to an earlier post on Mar 27, 2010 8:36:17 AM PDT
M. Helsdon says:
"Heat the hydrogen in a confined space and it should build up enough pressure to send a half-ton payload into the sky at 13,000 mph."

This sounds suspect:

* This is achieved by "causing a 500 percent increase in pressure" this is only five times whatever the original pressure was. Sounds incapable of generating the necessary force to propel the projectile at "13,000 mph". The pressure will also rapidly drop off as the projectile goes up the barrel.

* Hydrogen will burn on contact with air; I doubt that an "iris at the end of the gun closes, capturing the hydrogen gas to use again" will work: the hydrogen will have been contaminated, and will escape very rapidly from the barrel.

* To survive the g force any cargo such as a 'hardened satellite' would need to be incredibly robust. Simply building something that tough would offset the apparent launch cost savings.

Posted on Mar 27, 2010 9:49:03 AM PDT
500%
I have no idea. Either Hunter and his cannon are a sham, or we are really missing something. I hope we are really missing something.

Hydrogen
If you're not burning the hydrogen, why can't you just use nitrogen, extracted from the surrounding air? No need to recapture, and less concern about contamination from the air (which is mostly nitrogen) if for some reason you do. I don't know; maybe there's something about nitrogen that makes it unusable for this purpose.

G-Forces
The military hardens electronics against thousands of Gs. So has NASA. I'm not sure how big a problem this is. I could see it being expensive, impractically so, for large, complete satellites. But it probably isn't a problem for very small satellites or for components shot up and assembled in orbit.

In reply to an earlier post on Mar 27, 2010 10:03:50 AM PDT
Last edited by the author on Mar 27, 2010 10:04:39 AM PDT
M. Helsdon says:
Sailor,

"I have no idea. Either Hunter and his cannon are a sham, or we are really missing something. I hope we are really missing something."

Superguns are feasible, though the methodology of this one looks suspect. However, superguns are better at firing a projectile in a sub-orbital trajectory, as a weapon. Saddam's Project Babylon supergun (based Gerard Bull's earlier Project Harp study in the 1960s) is an example. Bull was assassinated either by Mossad or VEVAK because such a weapon was a threat to Israel/Iran. There's evidence that Bull intended Harp as a means of launching satellites.

"The military hardens electronics against thousands of Gs."

Only against shock of very brief duration, not the sort of acceleration this supergun would generate.

In reply to an earlier post on Mar 27, 2010 8:05:42 PM PDT
TO: Sailor Barsoom
RE: "It'll need a heat shield of some sort, but it won't be spending much time in the atmosphere, for the very reason that you don't want to lose speed/gain heat from friction. A reentering spacecraft spends a lot of time undergoing as much friction as they can get away with, specifically to slow down."

True, the projectile wouldn't "be spending much time in the atmosphere," but, unlike a re-entering spacecraft, it would be encountering the densest part - from sea level up to, say, 100,000 feet. By the time that the Shuttle gets down to that altitude, it has lost most of its speed. Ever since the Columbia disaster, we know what an encounter with the atmosphere at high Mach munbers can do. And that was at high altitude - around 400,000 feet. Another point that was new to me is that the majority of the re-entry heating is caused by supersonic compression of the air and not by friction. Please see: http://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaster#Destruction_during_re-entry

According to the timeline, it took about 11 minutes for the Columbia to be destroyed. But, again, that was in the upper atmosphere. How much faster would the process happen in the lower atmosphere?

The bottom line is, given the information that was (and was not) in the article, I'm still dubious.

In reply to an earlier post on Mar 27, 2010 8:18:37 PM PDT
TO: Marilyn Martin
RE: "Here's a better article on Hunter's Space Cannon:..."

I'm sorry, Marilyn, but it's basically the same article. No significantly illuminating information is there.

In reply to an earlier post on Mar 27, 2010 8:33:38 PM PDT
TO: Sailor Barsoom
RE: "...why can't you just use nitrogen..."

Nitrogen is an inert gas. Interestingly enough, magnesium will burn in nitrogen. Nitrogen is used in many explosives, however.

RE: "The military hardens electronics against thousands of Gs."

Thousands of Gs? A couple of dozen, maybe. Maybe even a few hundred Gs for air-to-air missiles that would have make high-G turns at high velocities as it closes in on a manuevering aircraft.

Posted on Mar 28, 2010 8:36:51 AM PDT
Last edited by the author on Mar 29, 2010 1:09:31 PM PDT
Hi Walter!

I'm still trying to get you more specifics on Space Guns. Below are some related articles, that may help answer some of your questions:

http://www.vectorsite.net/tarokt_4.html
This is basically a historical article on Rail Guns. Some cool photos, tho'.

http://www.fas.org/man/dod-101/sys/land/docs/ordtech.pdf
This is an interesting Navy Ordinance Technology PDF on rocket/missile propellants and projectiles.

http://nextbigfuture.com/2010/03/dense-plasma-focus-dpf-fusion-systems.html
DENSE PLASMA FUSION FOR SPACE This is a new propulsion system or fuel for spaceflight, I think from/for the Air Force.

(URL corrected. Sorry!)

In reply to an earlier post on Mar 28, 2010 2:41:11 PM PDT
Last edited by the author on Mar 28, 2010 2:41:47 PM PDT
TO: Marilyn Martin
RE: Links

Thank you for the links. It seems that the article on dense plasma fusion was taken off of the Next Big Future site.

Posted on Mar 28, 2010 4:41:36 PM PDT
I'm pretty sure that there are artillery shells with electronics hardened to a few thousand Gs. Here's something on this (I notice that it's still in development). That something that can survive 5000 G for a hundredth of a second might not be able to survive 500 G for a full second didn't occur to me, but I don't think I can say that it isn't possible.

The thing with the thicker air is a serious consideration. How much of a heat shield would be needed, and much mass it would add, I wouldn't guess.

In reply to an earlier post on Mar 28, 2010 7:23:43 PM PDT
TO: Sailor Barsoom
RE: "I'm pretty sure that there are artillery shells with electronics hardened to a few thousand Gs."

Oh, yeah, you're right. I hadn't even thought of artillery shells. Those, though, generally contain only explosives - which are not acceleration sensitive. However, there is a new cannon under development (possibly deployed by now) that fires shells that have a terminal self-guidance capability. This means that electronic hardware and software must be inside the shell. If that's true, then you're exactly right.

RE: "That something that can survive 5000 G for a hundredth of a second might not be able to survive 500 G for a full second didn't occur to me..."

OK, maybe not 500 Gs for a full second, but, intuitively, one would think that the object could survive 50 Gs for a full second.

In reply to an earlier post on Mar 29, 2010 1:28:51 AM PDT
M. Helsdon says:
Sailor,

"I'm pretty sure that there are artillery shells with electronics hardened to a few thousand Gs."

The Rheinmetall 120 mm gun has one of the higher muzzle velocities, at 1,750 meters per second, which works out at about 179g. The initial velocity in the barrel is higher, but not by much.

In reply to an earlier post on Mar 29, 2010 8:45:57 AM PDT
Hi Walter!

Yes, I found the dense plasma article on nextbigfuture.com. But I had to hunt down the original article to post the URL.

All of you are talking about the feasibility of actually firing this Space Gun. But my question - IF this Space Gun ever works - is how is that "shot cargo" going to get to the ISS? Is there a guidance system in the tip of the projectile?

Posted on Mar 29, 2010 1:11:08 PM PDT
Corrected URL on Dense Plasma:

http://nextbigfuture.com/2010/03/dense-plasma-focus-dpf-fusion-systems.html

In reply to an earlier post on Mar 29, 2010 7:59:01 PM PDT
TO: Marilyn Martin
RE: "IF this Space Gun ever works - is how is that "shot cargo" going to get to the ISS? Is there a guidance system in the tip of the projectile?"

The projectile would have an internal guidance system and an onboard propulsion system. The propulsion system would be needed to give the projectile that extra 5,000 mph needed for it to attain orbital velocity, and for docking maneuvers at the ISS. The guidance system would be necessary for the maneuvers to be accomplished in order for the projectile to rendezvous with the ISS. The guidance system could either be totally automatic or be controllable from Mission Control or the ISS.
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Discussion in:  Science Fiction forum
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Initial post:  Jun 2, 2009
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