Should we build armored spacecraft?

Great Debates
1

This is an issue, sort of, that was raised as we pondered things in this thread.

The design of the US space shuttles is more than 25 years old at this point. It seems reasonable to conclude that eventually, perhaps soon, America will need to replace them. When that occurs, it seems likely that a new design will be needed in order to better take into account any technological advances made since the last design.

The current shuttle design is very practical, but it doesn’t offer a lot of defense. A small piece of tile taken out while the craft is in orbit, a missle to the nose during a descent, or any number of small incidents could be (and have been) fatal to the crew on board.

In light of the United States’ recent awakenings concerning terrorism, would it make sense to design any new spacecraft with armor of some kind, in the hope that it would be able to withstand a direct SAM hit (or any type of missle, debris, etc.). Could we do it? What would the costs be in additional fuel needed to lift the presumably greater mass into orbit, and would those costs be self-justifying?

Or should we continue to build light-frame craft, and just hope that no one shoots at the shuttle?

My $.02: I think we could probably come up with a new design that was more along the lines of the stratosphere craft like SpaceShipOne that was both more maneuverable and better armored than the shuttles. I also think that with new materials technology and new weapons technology, we could make a craft with some serious offensive capabilites as well. I also think that it makes sense to do this, and even do this now, while we still have such a huge jump on the field compared to the rest of the world. It would offer the US a terrific advantage not just in military terms, but would make us the first truly space-faring people on this planet (or off of it, if you’d rather).

2

It would not be cost effective (in fact it might even make the whole mission impossible) if the shuttle had to lift heavy armour; it’s only (dubiously)useful for a very small part of the journey, yet it would have to be taken all the way to orbit and back.

Costly, reduces usable payload space, complicates maintenance, increases landing weight.

Much easier and cheaper just to enforce a large, strict exclusion zone around the launch and landing sites - large enough to put the shuttle out of range of SAMs.

3

ah, but the thing is, I think we’ll be wanting a new design of spacecraft. I agree we couldn’t retrofit the shuttles with armor, but a new ship could be designed with the armor already there.

If the new ship were a rocket plane, and the cost of a trip up and back was cheaper than a shuttle launch, it wouldn’t matter that the payload space was smaller; we could just make more trips.

4

Propulsion technology being what it is, I’m afraid you’re going to have to live with spaceships not being plated with any sort of armor that would stop a missile.

It’s telling that JET FIGHTERS, which actually do get into combat, aren’t armored. It just is not worth it. Spacecraft can’t afford the weight. Forget it.

5

What are you basing that statement on? TANSTAAFL in aviation or any other part of physics. This is why passenger planes are made of thin aluminum and not “the stuff the black box is made from.” Adding enough armor to significantly protect the exterior isn’t a matter of taking away a little payload but making it too heavy to fly at all.

SpaceShipOne worked exceptionally well for it’s mission because it was made of light but strong composites. It also didn’t get any higher than about a fourth the altitude of the shuttle. If you took one up in the shuttle then chucked it out so it could re-enter on its own it would be a trail of smoking debris because it doesn’t have the heat shielding the shuttle does.

6

Yes they are, but not in the way the OP is asking for. The F-14 has a canopy that 20mm bullets will glance off of but a few inches below the fuselage skin is thin enough one could probably pound a scredriver through it. There is armor inside the engine compartments to keep the fuel tanks above from being punctured by hot turbine blades if an engine should come apart from mechanincal failure or a missle hit.

7

It’s not just a matter of retrofitting the Shuttle versus building a new craft; extra weight becomes prohibitive. Your engine is built to put out such-and-such thrust and the SMEs are almost the most powerful engines in terms of thrust per weight, ever built. Additional thrust isn’t as simple as scaling up the engines or bolting on a couple of new engines; at some point, a vehicle becomes too heavy to lift, regardless of how many engines you carry, because the weight of the engines, extra fuel, and additional structure increase in a greater-than-linear matter. The Shuttle can barely manage to lift itself into Low Earth Orbit as it is.

Then there is the issue of this “armor”, which is presumably built to withstand impact weapons. The tiles and carbon-carbon leading edge caps on the Shuttle aren’t just their for decoration and aerodynamics; they’re specifically designed to absorb heat during reentry. (This is not due to “friction” as often asserted but owing to the pressurization of air that stagnates in front of the wing.) The tiles are a ceramic “foam” (actually, kind of a fiberous mass) that can absorb a great deal of heat and withstand high temperatures without melting, but they are fairly fragile. The carbon-carbon edge pieces are a combosite that can also withstand high temperatures. Normal metals, even high temperature metals, or high strength ceramics used as armor could not withstand reentry temperatures. It is a question of using the right material for the application. I guess we could build a vehicle with “disposal armor” which is ejected, revealing a heat shield, prior to reentry

As for armor that can withstand a direct SAM hit…it doesn’t exsist. Oh, you can make a steel or ceramic plate thick enough to withstand the blast and shrapnel from the (relatively small) warhead carried by a SAM, but you couldn’t protect fuel tanks or engine nozzles, which is where catastrophic failure will occur. Nor does there seem to be any compelling reason to do so; to date, no one has been shooting down our Shuttles, and if an advanced spacefaring nation decided they wanted to do so, there is little that we could do to stop them; a small, unguided projectile moving at orbital speeds would do damage that no reasonable amount of armor could withstand.

The problem with “just making more trips” is that there is a relatively fixed cost for ground operations. The reason the Shuttle was designed as a heavy lift vehicle (3 full sized communication satellites in bay) is that it is cheaper to launch one heavy vehicle than three smaller boosters, not only for the manufacturing and assembly cost of the boosters but all of the manpower and resources into supporting a launch. (Of course, the Shuttle has not turned out to be cheaper in that regard, but that is another political shaggy dog story entirely.)

Making more trips also opens the door to more opportunities to failure, especially when a launch is seen as being routine. Perhaps some day we’ll have a vehicle that is simple and mature enough not to be considered a prototype, but that ain’t going to be the Shuttle or it’s replacement (which is slated to be an Apollo-like capsule called the Crew Exploratory Vehicle).

Stranger

8

Wha??? You mean you don’t have one already??? :slight_smile:

9

This debate reminds me of this article. I really doubt that any amount of armor would have helped with the Challenger disaster. The space shuttle is already massively inefficient, so I doubt that the next shuttle, if there is one, will have it.

10

I cannot imagine this going down well with anyone outside the US. You have enough public relations disasters on your hands as it is without adding to them. Can you imagine what everybody else wuld say to this idea?

11

The bean counters are going to squash those ideas; why build one big expensive, heavy craft that requires more trips(this alone is a safety impactor), when you can build three lighter, cheaper, more capacious ones for the same money, or just build one of those and spend the rest of the budget on something else?

The USA has plenty enough land mass that it could set aside a launch and landing area with a very large exclusion zone with a secure perimeter, for a fraction of the cost of developing an entirely new, armoured shuttle to circumvent some risk that is probably quite fanciful in any case.

12

With chemical fuel sources, space vehicles need to be nearly all fuel on liftoff, and the structure has to be built ultra-lightweight just to reach orbit. If you start adding armor, you pretty soon won’t have any payload capability at all.

Defending against a SAM hit isn’t really a priority. The Shuttle is only withing range of a reasonably portable SAM for a very short time at the beginning and end of a mission, and it’s a lot easier to make sure no missiles are in the area it’s taking off from or landing in than to try and armor it. It’s not like we have a pressing need to fly spacecraft in and out of Kabul or something.

13

That would be a reasonable conclusion, but you’re wrong about the “perhaps soon” part. The US is planning to replace the shuttle with manned capsules launched on top of existing expendable rockets. Just google for “NASA Crew Exploration Vehicle.”

Designing spacecraft to survive missile attacks wouldbe as pointless as doing the same to airliners. It would be sufficient and probably more effective to improve security around the launch site.

You’re right about the tiles though, I think most people realize that the Shuttle’s thermal tiles are obsolete. There are newer heat shield materials available which aren’t as fragile, and presumably won’t be damaged by a piece of foam or a window cover falling on it. But as I said, there’s no spacecraft being planned that would benefit from this technology.

14

That’s the whole thing in a nutshell. The main problem lies in how the shuttle works; it uses almost all its fuel get into orbit and at that point it’s moving 25000 miles per hour. The biggest problem is slowing down enough to land, and meanwhile, god knows what happens if it meets a screw going 25000 MPH the other way :eek:

15

Not to be snarky here, but…cite?

I know that there are some more advanced heat-absorbent materials (in fact, the tiles currently used on the Shuttle are most third-generation components) and the science of composite materials has advanced significantly in the last 25 years, but I’m not aware of any materials for those applications that could withstand a hard impact AND meet the thermal criteria of reentry environment. There are some ablative materials that could probably match the criteria, but then the idea of the Shuttle (and reusable spaceplanes in general) is to minimize parts that have to be replaced between flights. (Never mind that the SMEs are rebuilt every second flight, and that the damage to and loss of tiles during reentry is common.)

Survival during reentry has always been one of the biggest unpopularized problems of spaceflight; you are shedding an enormous amount of energy in a very short period of time while trying to keep the bulk of the craft intact and keep the vessel on track. The Shuttle tiles are actually a marvel of material science; you can hold one in your hand, red-hot, and feel only a slightly uncomfortable warmth coming from it. But drop one from shoulder-height, and it’s likely to break into pieces, or at crush at an edge. That’s part of the trade-off of engineering.

Stranger

16

OK, I’m not too sure about surviving hard impact, but the Shuttle uses ceramic tiles attached by an adhesive (RTV?), and is notoriously fragile. Pretty much anything would be more durable. Here’s one example of a more modern heat shield system -

http://www.nasa.gov/centers/ames/news/releases/1999/99_09AR.html

17

I say we should be building Project Orion type launchers, rather than messing around with dinky little craft like the shuttle. That way, we can move a lot more weight into orbit, and you can still slap large amounts of battleship armour on them.

And I would love to see the expression of any terrorist face who was trying to use a SAM near the launch site! :smiley: :smiley:

18

Interesting. I wonder how they attach the external skin to the insulation and to the spaceframe.

It’s the nasty little details that actually make for unfavorable design consequences; Shuttle designers have worked for years, both during the initial design and after deployment of Columbia and Challenger to figure out a better way to mechanically attach the tiles. The problem is that the tiles are, as you indicate, fragile and have very little structural integrity themselves, and any fastener that protrudes through the tile will act as a heat conduit that makes the tile irrelevent. The tiles are adhered on with RTV (I believe it is the DowCorning 6-1104 CV type), and frequently shake loose during reentry and sometimes during launch. This has always been considered marginally acceptible, but obviously isn’t a design condition.

The problem with Orion launchers, other than that the use a propulsion system that is tantamount to atmospheric nuclear detonation (though the amount of residual fallout from a properly designed and “lubricated” pusher unit is quite small) is that they suffer from economies of scale problems, but in the opposite direction from chemical rockets. With chemical boosters, increased payload becomes prohibitive, but with the Orion, you have to have a minimum (and quite large) reaction chamber and mass to make it efficient and controllable.

Dyson Freeman’s son, George, recently wrote a book about Project Orion; while it doesn’t get heavily into the technical details (some of which are still classified) of the propulsion system, it does provide a good overview of the conceptual feasibility and potential problems and hazards of a “nuclear pogo stick”. You could armor such a vessel, but again, it would be so massive that no handheld weapon is going to affect it except as a lucky shot.

Personally, I don’t think space travel is going to be “economical”, i.e. affordable by the average (or even above-average) person until we have the technology to construct some kind of space elevator…but to get there, we probably need to be able to exploit space resources.

Stranger

19

If one has to spend a gabillion dollars on space travel, better to put it into the space elevator project because we’ll get a lot of cool nanotech spinoffs from it and it’s a neat idea.

20

Or we could take a look at what sort of threats are reasonable to harden ourselves against, and take appropriate steps at the launch site we have:
NASA relaxes some shuttle launch security