Manned Space Flight and the Planet Killer

JRS: In article , seen in
news:sci.space.policy, Mike Combs
posted at Thu, 14 Aug 2003 12:59:54 :-
Dr John Stockton wrote

It would help if you knew some physics - for example, that you want to
hit with high momentum, rather than with high energy. Therefore, for a
given propulsive energy, you want to use as large a mass as possible
rather than as large a speed as possible.

That's something I've had a hard time wrapping my brain around. I happen to
favor mass-drivers for asteroid diversion. And I've heard it said from others
who also support this method that a mass-driver which could eject a greater
quantity of mass with less speed was better for this task than a higher-speed
but lower-throughput design.

I guess it's just something I have to accept on the word of others unless you
happen to know an approachable analogy good for the
mathematically-disadvantaged.


Perhaps you can see that, if energy is expensive, there is no point in
giving any portion of the body more energy than is required for that
portion to just miss us - with a little fine tuning to ensure that its
orbit after it has missed us is such that it will not hit us in the
foreseeable future.

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Mike Combs wrote:

Dr John Stockton wrote

It would help if you knew some physics - for example, that you want to
hit with high momentum, rather than with high energy. Therefore, for a
given propulsive energy, you want to use as large a mass as possible
rather than as large a speed as possible.

That's something I've had a hard time wrapping my brain around. I happen to
favor mass-drivers for asteroid diversion. And I've heard it said from others
who also support this method that a mass-driver which could eject a greater
quantity of mass with less speed was better for this task than a higher-speed
but lower-throughput design.

I guess it's just something I have to accept on the word of others unless you
happen to know an approachable analogy good for the
mathematically-disadvantaged.

Momentum is what you need to hit the target with (actually you probably
want impulse, but it works out to the same thing). Momentum is
proportional to velocity. Kinetic energy is proportional to the square of
velocity. For a fixed amount of energy, momentum is maximized by
minimizing the velocity and maximizing the mass.

h (Rand Simberg) wrote in message ...
On 15 Aug 2003 08:05:26 -0700, in a place far, far away,
(Slickwater) made the phosphor on my
monitor glow in such a way as to indicate that:

while I get to continue my life of dangerously heavy
boozing

This explains much, if not all...


Yeah, but nobody didn't say my idea was brilliant. All you can attack
is my lifestyle. The world needs more brash guys willing to take you
guys down a peg. Might actually get you to get somethin done.


-Slick

(Slickwater) :

h (Rand Simberg) wrote in message
...
On 15 Aug 2003 08:05:26 -0700, in a place far, far away,
(Slickwater) made the phosphor on my
monitor glow in such a way as to indicate that:

while I get to continue my life of dangerously heavy
boozing

This explains much, if not all...


Yeah, but nobody didn't say my idea was brilliant. All you can attack
is my lifestyle. The world needs more brash guys willing to take you
guys down a peg. Might actually get you to get somethin done.

This from some-one who as far as we can tell has done nothing.

Earl Colby Pottinger

--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp

Hum, Fetal Alcohol suffer? Or parents were way to much into illegal drugs
that damaged his chromesomes .

Aka a TROLL.

Okay, do you know the mass of the asteroid?
What is its center of gravity?
What is its orbit?
How much thrust would be necessary to deflect the asteroid.
How do we detect it far enough out, so that we can act on things, and even think about a course of action.

I know one thing, just deflecting an asteroid is not easy, as well as what you can do to take care of the
asteroid or asteroids. As well as it is a nice sci-fi topic, but often using an asteroid as a reason to
party until you puke. Or hump until you drop.

On other forms, might work on your grammer and spelling, it helps you look a bit less than a troll. And
more like a sentient being!?

Mike


Slickwater wrote:

(Al Jackson) wrote in message . com...
There is one thing I have thought about lately. What if finally we
observe (within the next 20 years) an Earth-killing asteroid that will
definitely zonk us in 5 or 10 years? I mean it is calculated dead
smooth sure to be the case.
Here is a case were ?failure is absolutely not an option'.
What do we do? Prepare a fleet of robot ships to do the thermonuclear
nudge thing? (You sure are not going to send just one!)
Or do you send people to do the job? Maybe even several ships for
redundancy. People brains have , so far, been able to 'expect the
unexpected' better than solid state brains , and this is a case where
there is NO margin for error.
(Or at least errors that cannot be corrected.)
Then I see manned space flight , no matter how seemingly quixotic ,
important, even if its just going to LEO and mucking about with the
ISS. The experience gained would be valuable.
Up the line , maybe 50 years or so, we may have robot ships we could
trust for such an important mission.
So what would it be, robots or people, or maybe both together to save
the Earth?

I don't mean to sound incredibly smarter than you guys, but I really
ahve no choice. Never have I been amongst such retarded neandrathals.
The key is easy, yet you idiots bitch and moan in a manner trying to
sound smarter than the next. Your all dumb as dogfood, so just think
pragmatically. The key is, lemme break it in an intelligible way for
you degenerates, lots of mass + lots of speed = deflected asteroid.
"OH oh oh but slick, we can only get so much mass up into space, whaaa
whaa" sob, whine "oh ooh but slick!, we can concentrate on either
mass or speed, its impossible to get alot of both!" SHUTUP! It is
insanely easy to get both which is why I want to punch everyone who
says it can't in the face. Think you numbskulls, think. If we can't
put the tons we need into space, we have to consider alternatives. In
other, more clear words, USE WHATS ALREADY UP THERE. I'll be that
simple conclusion that none of you could come to just smashed your
depleated egos like a high school kegar. Oh wait, your all reclusive
losers to begin with so you never went to those for fear of getting
your glasses broke and your face stomped in. Anyway, we send the
thrusters up necessay to push one from our asteroid belt at the threat
and yeah, you guys have the displeasure of living in misery a few
years longer, while I get to continue my life of dangerously heavy
boozing, macking chicks and nihilism in general.

-Slick

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Abrigon Gusiq wrote in message ...
Hum, Fetal Alcohol suffer? Or parents were way to much into illegal drugs
that damaged his chromesomes .

Aka a TROLL.



hahaha, you have an incredibly homoerotic name


-Slick

In article ,
Abrigon Gusiq wrote:

On other forms, might work on your grammer and spelling

Heh. Pot, meet kettle.

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(Slickwater) wrote in message . com...

O man!
There is a better idea!

Build many 'decoy' Earths around the Earth's orbit, then the Asteroid won't
know which one to hit!

{{Date: Sat, 26 Jul 2003 00:13:23 +0100
From: Cardman
thanks to Newton's second law of motion, the asteroid is hit with the
same high energy that moves it very slightly.}}

You're confused: There's no law, by Newton or anybody, that distributes
energy equally between two colliding bodies. What one of Newton's laws
says is that MOMENTUM (not energy), or equivalently force integrated
over time, is conserved, such that for any momentum change on one
object there's an equal and opposite momentum change on the other
object.

So if the projectile merges with the asteroid, no debris thrown out,
all the momentum originally in the projectile now is distributed in the
combined asteroid+projectile object, so that object is diverted
slightly compared to the oroginal asteroid orbit (and greatly compared
to the original projectile path).

But you can do better: If there's a big explosion that throws out
debris at high speed back the way the projectile came, i.e. momentum
opposite to the original momentum of the incoming projectile, then the
change in momentum of the remaining asteroid is even greater than if a
merge-without-debris had occurred. My idea has long been to blast a
hole into the asteroid with the first projectile, then slam the second
projectile into the bottom of the hole to explode there, boring the
hole deeper, then a third into the bottom of that hole, each projectile
blasting more debris out and thereby diverting the asteroid more. Of
course you have to arrange that the asteroid doesn't rotate too much
between blasts, either by blasting it so quickly that it doesn't have
time to rotate more than a few degrees, or blasting it once per
revolution, or stopping it from rotating by arranging that the first
impact is very off-center.