Manned Space Flight and the Planet Killer

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?

(G EddieA95) wrote in message ...
So what would it be, robots or people, or maybe both together to save
the Earth?

Both. Robots function in space much better than our bodies do, and they can do
the physical work, but you still need human minds locally. So you send 50
robot ships, and 2 following manned missions to supervise and fix what needs
fixing.

Yes I think that too. It is a matter of time scale. If time were very
short like a year, it might have to be robots only, if five or ten
years, might want a human supervised effort. One thing, it would have
to be international and with a lot of redundancy.
I did notice it manned, in a silly way in Armageddon, more seriously
in DEEP IMPACT.

JRS: In article , seen in
news:sci.space.policy, Cardman posted at
Sat, 26 Jul 2003 00:13:23 :-

So you just blast off two or three ships built mostly from a few tons
of really hard metal.

As you come up to this asteroid in question at high speed (thousands
of km a second) and go whack straight into it.

Due to the masses involved our probe is obviously the loser, but
thanks to Newton's second law of motion, the asteroid is hit with the
same high energy that moves it very slightly.


It would help if you knew some facts - for example, that it is quite
difficult to get a few tons up to 10 km/s, and that the difficulty rises
exponentially with the speed. Thousands of km/s, for anything
substantial, is impractical with foreseeable technology.

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.

Obviously the impactor has to be strong enough to hold together while it
is being accelerated. But in an impact at a relative velocity greater
than about the speed of sound in the material - i.e. greater than a few
km/s - the strength of the impactor is of no importance, since it cannot
be enough to hold the impactor together. If thousands, or even tens, of
km/s could be achieved, water would be as effective as steel.

A compact impact at that sort of speed would punch well into the
asteroid, somewhat like a bullet into a glass of water; the energy would
be deposited deep into the material, blowing out a large crater.
Actually, this would add to the desired effect; but the solid parts of
the ejecta would be potentially dangerous too.

A good approach is to cause the surface layers of the asteroid to be
ejected, at a speed not much greater than escape velocity, and in pieces
sufficiently small to be harmless.

A better is to cut the asteroid in two, and to push the parts apart so
that both halves just miss us.

--
© John Stockton, Surrey, UK. / ©
Web URL:http://www.merlyn.demon.co.uk/ - FAQish topics, acronyms, & links.
Correct = 4-line sig. separator as above, a line precisely "-- " (SoRFC1036)
Do not Mail News to me. Before a reply, quote with "" or " " (SoRFC1036)

Cardman wrote in message . ..
On 25 Jul 2003 06:21:16 -0700, (Al Jackson) wrote:

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.

Most unlikely, when just yesterday I was reading about how asteroid
impacts are less likely then first thought. This was even to the point
of considering if it is worth looking for them in the first place.

Check out this page:

http://impact.arc.nasa.gov/

Well actually that news came out in March,
in "Tsunami Hazard from Sub-Kilometer Impacts ".
Check this web site. From what I read the risk is NOT something
to be totally ignored!
Read also:
"OECD Report on NEO Hazard" on that same page.

For mitigation find a copy of :

Hazards Due to Comets and Asteroids (T. Gehrels, editor), University
of Arizona Press, (1994)

and look through the references on that page.

What I see is that we go into space, around the orbit of the asteroid
belt, and build a sphere of sensors to not only track asteroids to give u=
s
as much time to deal with asteroids and other threats, but also to be use=
d
as bases for asteroid mining, to act as the largest artificial array radi=
o
telescope ever, as well as start building a real dyson sphere..

Mike


Al Jackson wrote:

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 =91failure 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?

Dr John Stockton wrote in message ...
JRS: In article , seen in
news:sci.space.policy, Cardman posted at
Sat, 26 Jul 2003 00:13:23 :-

So you just blast off two or three ships built mostly from a few tons
of really hard metal.

As you come up to this asteroid in question at high speed (thousands
of km a second) and go whack straight into it.

Due to the masses involved our probe is obviously the loser, but
thanks to Newton's second law of motion, the asteroid is hit with the
same high energy that moves it very slightly.


It would help if you knew some facts - for example, that it is quite
difficult to get a few tons up to 10 km/s, and that the difficulty rises
exponentially with the speed. Thousands of km/s, for anything
substantial, is impractical with foreseeable technology.

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.

Obviously the impactor has to be strong enough to hold together while it
is being accelerated. But in an impact at a relative velocity greater
than about the speed of sound in the material - i.e. greater than a few
km/s - the strength of the impactor is of no importance, since it cannot
be enough to hold the impactor together. If thousands, or even tens, of
km/s could be achieved, water would be as effective as steel.

A compact impact at that sort of speed would punch well into the
asteroid, somewhat like a bullet into a glass of water; the energy would
be deposited deep into the material, blowing out a large crater.
Actually, this would add to the desired effect; but the solid parts of
the ejecta would be potentially dangerous too.

A good approach is to cause the surface layers of the asteroid to be
ejected, at a speed not much greater than escape velocity, and in pieces
sufficiently small to be harmless.

A better is to cut the asteroid in two, and to push the parts apart so
that both halves just miss us.



Oh yeah John, get up there with a hot butter knife and cut it in two.
Your talkin about changing it's tragectory of .01 degrees is
implausible, then suggesting to CUT IT IN HALF??? oh yeah, I did see
that one, it was called armaggedon with bruce willis. What a freakin
retard.


-Slick

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.

--


Regards,
Mike Combs
----------------------------------------------------------------------
We should ask, critically and with appeal to the numbers, whether the
best site for a growing advancing industrial society is Earth, the
Moon, Mars, some other planet, or somewhere else entirely.
Surprisingly, the answer will be inescapable - the best site is
"somewhere else entirely."

Gerard O'Neill - "The High Frontier"

Mike Combs wrote:

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.

To move the asteroid, you have to add a certain amount of impulse
(that is, momentum) to it. By conservation of momentum, you do this
by ejecting reaction mass with the same but opposite momentum.

If you need P units of impulse, you need to eject m units of mass
at speed v = P/m. The total kinetic energy of this mass is 1/2 mv^2 =
P/(2 m). Therefore, the more mass you eject, the less total energy
is required.

(This has ignored the rocket equation, assuming the mass expelled
is small compared to the mass to be moved.)

Paul

(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

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...

--
simberg.interglobal.org * 310 372-7963 (CA) 307 739-1296 (Jackson Hole)
interglobal space lines * 307 733-1715 (Fax) http://www.interglobal.org

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