According to a doctoral candidate in aerospace engineering at North Carolina State University. David French's novel approach to preventing an asteroid from impacting Earth is to attach a long tether and ballast to incoming objects - thereby changing the object's center of mass, effectively changing the object's orbit. Of course the tether would be astounding in length - in the order of 600 to 60 thousands miles!
Brings to mind the scale and scope of the proposed space elevator.
Read the complete Science Daily article
Brings to mind the scale and scope of the proposed space elevator.
Read the complete Science Daily article
18 comments:
Kim Stanley Robinson strikes again!
HA!! That's right! Damn, I didn't make any connection until you mentioned!
http://en.wikipedia.org/wiki/Bolas
Yeah, I gotcher space debris. I gotcher space debris right 'ere!
Okay, here's what we'll do. We'll gather up all that pesky CO2, get a steering wheel at the Auto Parts store....
On the other hand, any plan is probably better than mine, which involves (and is limited to) soiled pants.
"We need to evacuate!" "Way ahead of you, Kimosabe. Now what?"
LMAO Matt! evacuated and running too! Too damn funny.
But my point was that this idea is based on tech that isn't even in existence yet...if ever. Giving this any more than "hey, thats a clever idea" is a recipe for failure.
Heh. You don't have to tell me. I still get a rumble in the colon when people talk about space elevators. I don't even know what would happen if one of THOSE cables snapped. Makes me want to hop the first asteroid outta here. :)
You know Matt...if the cable did snap, I don't think we would have to worry about hitting the ground. Wouldn't that cable under that much tension have ferocious rebound? The end of the cable hitting the car at supersonic speeds would have the yield of several mega tons....
You misunderstand. D'you really think you could get me up in one of those things? I'm thinking more along the lines of being on the ground when the piece(s) of cable hit. There's some recoil for you.
Of course, as long as we're imagining space elevators, we might as well imagine some Heinlein-ian (i.e., magic) safety features so that wouldn't happen. It's really just a visceral thing. I flew in an airplane. Once. Perfectly safe, but I never want to look at the top of a cloud again.
At the same time, I'm the guy who wants his next apartment to be a space station. I'm not sensing any irony here, are you?
If I remember Arthur C. Clarke's space elevator correctly, the centrifugal force on the cable would just about equal its weight...so there would be just enough tension to keep the cable tight.
Boarder
That is my understanding as well. However as far as the elevator was concerned was the weight of the structure in a gravity field. Present materials can not maintain integrity over the distances needed. Now even though there isn't a "gravity field" pulling on the structure, it still has mass and spinning it would put it under load stresses. Now even though the counter forces have been canceled out, the cable would still fail as more length is added. Said failure would be equal to that observed in a gravity field.
Oh, yeah, that was Clark-ian, not Heinlein-ian, wasn't it? Oops.
lmao! None at all Matt! I wonder if we are looking at the size of the "elevator" wrong. Just the word alone brings claustrophobic reactions, however this device is going to be a heavy lifter and a large passenger load. Given that the transit time is going to be many hours then I suspect that there would also be onboard facilities for eating, entertainment etc. I would suspect something on order of one of the large ocean going ferries. I don't think there would be any of the triggers that haunt commercial flight (cramped, noise, crappy food, even crappier people etc) I don't think the transit would be any worse than a fairly boring cruise.
Jeez, I finally got the name right and still spelled it wrong. Man, Arthur H. Heinlein would be really irritated with me. :)
(Clarke-ian, not Clark-ian. Not that anyone cares about my foolish mistakes but me....)
About the only hope on the horizon right now for the space elevator is the research into carbon nanotubes. Remember, a lot of the stuff we use today was science fiction less than 30 years ago. You are correct about the length of the trip. The end of the elevator would have to be in geo-scyncranous orbit - 22,300 miles up. Even if the car/platform could reach 1000 mph, that would be a day each way...and in vacuum 95% of the time!
yeah well how bright does that make me then! I never caught it either! lmao Arthur H. Now there is a pseudonym for ya!
Border
Oh believe me, I am putting my money on the tech being solved for the use of CNTs. The barriers to their use are certainly not insurmountable. As it stands now, the process can produce a nano-tube that supports the stresses within a few percentage points of what is needed. But to be safe scientists are looking at a matrix that could handle 4x to 8x the projected stresses. Plus the manufacturing process still needs to be able to produce near 100% of all tubes in alignment. The reasoning there is that even at an infinitesimal small percentage of tube de-laminate, the very size of the structure means almost certain failure. Not insurmountable problems, just a level of QC that is not available yet. And that is the core of my caveat, planning a safety system around a tech that isn't fully expressed is leaving a bit too much to chance. Using proven tech in the short haul only makes sense as long as the plans are open ended enough to incorporate newer systems when they become viable.
Matt and Paul,
As I recall, similar devices were used in one of the Brin/Bear/Benford Asimov-Foundation spin-off books (i.e., on Trantor)
The original point in this thread was changing the course of earthbound asteroids. The space elevator, as I understand it, would require the maneuvering of an asteroid into GEO. Hmm.....
Steve
yeah, you got to ask yourself "exactly when did we go completely insane?!" Because we are not talking about a lightweight rock out there. Counter balancing the weight of the ribbon, the elevator and the acceleration of the elevators (unless they have one coming and one going at the same time...) That's going to be a big damn rock! It would be the initial installation that would freak me out. Once the counterweight is in place it would move away from the Earth should the cable break. But it is still the thought of a rock the size of several city blocks just hanging over your head.
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