18-01-2004 11:05									#271
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quote: Originally posted by JellyBean I don't think it would enter orbit. If you hit it at anything less than lunar escape velocity (2.4 km/s, iirc) then it will enter a path that is not an orbit because it intersects the surface of the moon at some point. If you hit it faster than that, then it escapes entirely. It should be possible to circumvent this by hitting it exactly horizontally from the top of a mountain, then kicking off the top of the mountain before the ball comes around and hits it.

but you still need to be at least at exact escape velocity for this to work....
If you are at less than escape velocity than the trajectory is an ellipse and will intersect the Moon.
2.4 km\s seems a lot but, its much less than on Earth, and is about MAch 2. I think some bullets travel at that speed dont they?
And with almost no air resistance, this theoretical escape velocity is almost exact to the practical one.

eidt: well as krazyhorse said...

	18-01-2004 15:32									#272
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Why is it not possible to boost things like the space station to a higher orbit where they might be more useful? Seems like a waste to abandon all that stuff that has already been boosted a lot higher than sea level and has a lot of rocket fuel's worth of momentum.

	18-01-2004 18:24									#273
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Because, I believe, it might not be built for it.

There's a big difference between the radiation levels you encounter in LEO, inside the Van Allen belt, and beyond the Van Allen belt. The ISS may simply not have the shielding for it.

	18-01-2004 21:26									#275
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--"shoulda coulda woulda"

This isn't hindsight. Several other plans were preffered technically at the time. But the beancounters had their way.

--"The space station is affording us the opportunity to evaluate how componets made by different agencies than NASA can all work together with the NASA based product."

Heh. It did show us which of the other agencies can't be trusted to hold their own payroll monies... ^_^ I'd be against any joint international Mars venture simply because of what the international ISS effort showed. There's some out there we just can't justify working with again, but they'd be cheesed off if we worked with some but not them.

--"any step means we can learn alot of valuable information"

It's a cost-effectiveness problem, though. The ISS is essentially worthless for any real research, as the crew spends most of their time just performing basic maintenance on the station. It was supposed to house a much larger crew, but budget cuts killed that. Right now it isn't worth much at all.

--"Why is it not possible to boost things like the space station to a higher orbit where they might be more useful?"

Because the Space Shuttle can only reach LEO, which means we aren't going to be able to place any manned structure above LEO until it's replaced.

Wraith
If space is warped, time is all that's weft

	18-01-2004 23:17									#276
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quote: Originally posted by LulThyme 2.4 km\s seems a lot but, its much less than on Earth, and is about MAch 2. I think some bullets travel at that speed dont they?

2.4 km/s = mach 7 or 8

No bullet in the world travels this fast, afaik

	19-01-2004 01:21									#277
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I found this, have no clue on the accuracy but the number was about the same on three different sites with three very different topics:

quote: FASTER THAN A SPEEDING BULLET. Ballistics experts at the Los Angeles Police Department say that the fastest bullet is fired from a .223 caliber rifle and travels at 3,500 feet per second, more than three times the speed of sound. So Superman is even faster.

Take it for what it's worth.

	19-01-2004 01:24									#278
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I had that exact number in my head for some reason, but did not bother checking it with a source.

	19-01-2004 01:59									#279
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Wraith, if you know, when the original design objectives of the space shuttle and laid down in 1969, did they include the ability to go to the moon? If they didn't, what was the plan, if any, to continue exploration of the moon?

	19-01-2004 03:58									#280
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Unfortunately it's been a while since I've dug into early Shuttle history (I did a detailed report on it in school on one of the Challenger anniversaries). The main objectives were for a lower cost (per pound launched) reusable method than the then current Saturn Vs et. al. They weren't really meant to go above LEO and get to the moon, although it would certainly have been a bonus if it could launch something there. Note that the Shuttle has a secondary boost system to get satellites into higher than LEO orbits, but I don't think it can push very much out of orbit.

Originally it was meant to be a completely reusable system, pretty much the Spaceplane type that NASA has been looking at again recently. The eventual design, with expendable fuel tank and SRBs with limited reuse, ended up after the typical budget cuts (also getting rid of a proposed space station, which was supposed to act as a waystation for the start of a Mars mission, which was also dropped). It's a smaller capacity than was originally wanted, not to mention the horribly cost-inefficient heat tiles (every single one is different, so no mass production cost benefits).

If you read some of Richard Feynman's talks, he brings up some interesting things about Shuttle design as well. He's impressed with the bottom-up nature of the software (he was involved in the Challenger investigation), but found the engine design ludicrious. Although the Shuttle Main Engines have lots of thrust for the size, the way it was designed was top-down, which means any alterations (to fix problems) are extremely expensive. Individual components that were supposed to last the life of the engine get replaced every launch, things like that. They've got ongoing problems (like cracked turbine blades) that get classified as "no problem" because it hadn't caused major problems before.
Note that this was brought up after Challenger, but it's pretty much the same thing that destroyed Columbia. NASA's upper management is the biggest problem right now.

We have the technology to do a good, solid, fully reuseable space plane (off the shelf, mostly; otherwise the X Prize would be happening). There's a number of designs out there, many being variants of a piggy-back style system, where a plane is used to get the actual orbiter into the upper atmosphere. NASA has been chasing much more extreme designs, and tends to run into problem when they've got sixty-eight major new things all roled into one. The (recently cancelled) X programs suffered from this. They need to put their focus behind getting a good, sustainable system before going on these evolutionary system hunts.

Hmm. I'm getting curious about this again. Have to dig out some of my old books and look at this stuff again.

Wraith
"Let's not tell anyone about the space shuttle sinking."
-- Arisa (All Purpuse Cultural Catgirl Nuku Nuku)

	20-01-2004 00:52									#281
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Wraith, any link to a contemporaneous 1969 article about the Shuttle would be appreciated. It is my understanding that the Shuttle was sold as a cheaper way of lauching sattelites into LEO. This seams ludicrous on its face and it turned out to be false in practice as well. NASA ended up with Challenger and Columbia trying to make the Shuttle into a reliable, schedule-wise, launch platform.

I think the Shuttle was an excuse to continue manned space operations when they had no mission beyond Apollo.

	20-01-2004 03:37									#282
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I'm with the US administration 100% on this, but still I just can't help posting this.

Attachment: mars.jpg
This has been downloaded 34 time(s).

	20-01-2004 03:42									#283
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quote: Originally posted by Winston I'm with the US administration 100% on this, but still I just can't help posting this.

	20-01-2004 05:21									#284
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--"Wraith, any link to a contemporaneous 1969 article about the Shuttle would be appreciated."

Not on hand, but now that I'm curious again I'll try and make some time to look for them.
It was sold as a cheaper launch platform. To some extent that's true, but it wasn't near as much of a difference as had been claimed. If they had ever got the thing up to the full flight capabilities claimed, maybe, but there's no way NASA could ever have run that many missions a year with them.

It was actually originally sold as part of a package deal, including a space station and a Mars mission. As I noted in the last post, both of those ended up getting cut, leaving just the Shuttle. Unfortunately, NASA tried to game the finances and aligned itself with the military. The US military, being ever so much more experienced at gaming procurement, pretty much took over and dictated the cargo conditions, which didn't really help the civilian applications.

And yeah, with both the space station and Mars mission plans on permanent hold, it was pretty pointless. That's part of the reason NASA's never been able to actually get a decent manned program going. They saddled themselves with the STS, and once there was an entrenched interest in keeping it going (the maintenance contracts on those are big money) there wasn't any way NASA by itself was going to get rid of it. We just haven't had a President since JFK really push things. Hopefully this is more than just a stunt, but either way getting rid of the STS and ISS is a good thing. NASA could also use some upper management changes...

Hopefully we'll see in a good two-stage-to-orbit system up in a few years. The tech really is there, even if they decide to just go build off of one of the X Prize systems. However, the best bet would be to consolidate some of the good points of the recently scrapped programs, like VentureStar, and put them in a more traditional system. Coupling the linear aerospike engines with a two-stage-to-orbit system could get us a nice, cheaper-than-the-STS, reliable LEO+ system. Then they can go all out and work on a third-gen launch system, like the SSTO VentureStar.

Of course, none of this is strictly necessary for a Mars mission... but for a moon base or a an actual worthwhile space station (say, at Lagrange 4 or 5) that would be very helpful.

Wraith
QUARKBAR - the candy with flavour and charm.

	20-01-2004 05:48									#285
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quote: Originally posted by Wraith And yeah, with both the space station and Mars mission plans on permanent hold, it was pretty pointless. That's part of the reason NASA's never been able to actually get a decent manned program going. They saddled themselves with the STS, and once there was an entrenched interest in keeping it going (the maintenance contracts on those are big money) there wasn't any way NASA by itself was going to get rid of it. We just haven't had a President since JFK really push things. Hopefully this is more than just a stunt, but either way getting rid of the STS and ISS is a good thing. NASA could also use some upper management changes...

Yeah, I can see how a Shuttle could be part of a larger plan that would include a manned space station and a Martian mission. But just carrying cargo to LEO is not much of a mission, and could be done much more cheaply by conventional rockets.

Just a thought, but was the idea to refuel the Shuttle in orbit and have it go to Mars, conduct its mission there, and then return to Earth?