100 megaton bombs atop Saturn V rockets

Hop David wrote




I'd guessing we'll find quite a variety of different creatures
when we learn more about the comets and asteroids.

Which, ob policy, I wish we'd put more effort into. Having a
half-dozen surveyors wandering among the asteroids at any one
time seems about right.

In sci.space.policy Pat Flannery wrote:

would keep them warm and ice-free in winter. And the Atomic Powered Tank
was also stillborn; which is a pity, as it probably wouldn't have even
needed armor, due to the fact that no one in their right mind would dare
shoot anything at it, for fear of what might happen if they actually hit
it. :-)

Its always fun seeing things designed by peopel to whom "diverse terrain"
means "praire followed by slightly different praire"...


Pat


--
Sander

+++ Out of cheese error +++

In article ,
Revision wrote:
A recent paper on the asteroid population of our neighbor Tau Ceti
suggests that any planet in the solar system would receive a bio-killer
impact every couple of thousand years, making evolution problematic.

I thought Tau Ceti was supposed to have about 10x the number
of small bodies the solar system does. That would reduce the interval
between 10^24 joule impactors from 100 million years to 10 million.
Annoying, and it might well discourage large non-omnivores, or at
least cull their numbers on a regular basis but not animals below
5 kg who aren't picky about what they eat.

Impacts that can briefly alter climate to the extent a nuclear
winter could would go from once every 500 thousand years to once every
50 thousand years. That might not even stop civilizations from springing
up, if they did it in the interval. Tunguska scale events would happen
once a decade but happily even planets as populated as Earth are mostly
empty and the odds of a city being under such an object are slim.

World killers (big KBOs) would go from one impact every
trillion years to one impact every 100 billion years, which is
still about 20 times more time than the sun has left on the main
sequence.

Interestingly, giant KBO impacts on Jupiter would go up
from 10 to 100 times since the early days of the solar system to
100 to 1000. These sort of impacts are energetic enough to melt
and vaporize a considerable (although negligible compared to the
mass of the moon) depth of moon surface, at least 20 meters on
Europa.

--
"The keywords for tonight are Caution and Flammable."
Elvis, _Bubba Ho Tep_

Paul F. Dietz wrote:

Scott Lowther wrote:

Well, now, that's not strictly true, is it? Take it to an unlikely, yet
not wholly impossible extreme: an asteroid broken into chunks the size
of houses. This will be an interestingly large shotgun blast... absorbed
to a large degree by the atmosphere. Think of it this way: if you were
wearing a full-body Kevlar suit, which would you rather... to get struck
with a shotgun blast composed of two ounces of birdshot, distributed
over your chest... or a two ounce deer slug? The atmosphere serves as
the kevlar, absorbing much of the impact energy, if the cross-sectional
area of the impactor is greatly increased.


And mo while much will make it to the ground, the damage will be
spread out over a wider area... which is actually *good*.

No, it's bad, if the asteroid is sufficiently big. A good fraction
of the energy dissipated in the atmosphere gets radiated as heat,
and for a sizeable asteroid this would flash heat anything under the
impact region (of size up to an entire hemisphere) to ignition.

Since we're talking about impactors big enough to try to do something
about... that was going to happen *anyway*. What has it bought you to
save the heating rate to the impact flash and re-radiation of the
impactor debris raining down? better to have the heat flash in the upper
atmosphere... where much of it simple radiates away from Earth. plus,
radiation is a ****-poor way to create mass life-destroying
devestation... shock waves are more destructive.
--
Scott Lowther, Engineer
Remove the obvious (capitalized) anti-spam
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OM wrote:

On Thu, 08 Jul 2004 07:02:54 GMT, Scott Lowther
wrote:

OM wrote:

...And while it may be fun to take Missile Command to its ultimate
extension, I tend to agree with Henry that the only sane solution to
any real asteroid thread is deflection without breaking the damn
things up.

Well, now, that's not strictly true, is it? Take it to an unlikely, yet
not wholly impossible extreme: an asteroid broken into chunks the size
of houses.

snip

...The problem there is twofold:

1) You have to make sure that the impactor is broken up into fragments
much smaller than houses. IMHO, about the size of a Yugo might be the
max size I'd deem acceptable. This would ensure that what comes down
doesn't make it all the way down.

It would be nice to make sure that it is all absorbed in the atmosphere,
but if the intent is to save the planet from destruction, surface
impactors are perfectly allowable.

2) And while not trying to sound like one of those antinuke
treehugging hippie radical perverted poofters, there is the issue of
all that irradiated debris winding up in the atmosphere. A

Horsepucky. An impactor would not be more radioactive than fallout from
shallow-subsurface nuke tests; and that fallout was pretty lame as a
danger on the planetary scale.

And that assumes that the impactor wa nuked from within, and not from
without. Given a bit of warning, such that something more than an "Oh,
****!" mission could be launched, Casaba Howitzer-style nukes would be
the preferred type to use, and they would not activate the impactor
material *at* *all.*

--
Scott Lowther, Engineer
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Paul F. Dietz wrote:

It is not at all obvious that heating up the comet's surface with X-Rays
is the way to do it. Think Casaba Howitzer.

... which would deliver less total impulse than vaporizing a thick layer
of asteroid surface.

*Maybe*. But vaporizing a thick layer of asteroid surface, especially a
layer that is vaguely evenly distributed, using Xrays, gamma rays and
neutrons from a bare nuke is a very iffy proposition. Using a dedicated
propellant will save a hell of a hard step, and make each nuke far more
reliable. A Casaba Howitzer nuke will run much the same every time you
pull the trigger, while asteroids and comets will not only respond
differently from nukes from impactor to impactors, they'll respond
differently form location to location on an individual impactor.


--
Scott Lowther, Engineer
Remove the obvious (capitalized) anti-spam
gibberish from the reply-to e-mail address

Scott Ferrin wrote:

What is it with this f*cking infatuation with nuclear bombs!!! Why do they
keep wanting to blow up things when it has been shown many times before that
this is the wrong kind of solution. In fact, it could make things even
worse!



What would you suggest?(snip) A feather pillow?(snip) Or
maybe that dumbass solar-sail idea like the guy in
Armageddon?(snip)

Solar sail and nukes aren't the only two ways to move an asteroid.


--
Hop David
http://clowder.net/hop/index.html

"Scott Lowther" wrote in message
...
much snipped - sorry
And that assumes that the impactor wa nuked from within, and not from
without. Given a bit of warning, such that something more than an "Oh,
****!" mission could be launched, Casaba Howitzer-style nukes would be
the preferred type to use, and they would not activate the impactor
material *at* *all.*

Forgive me if I missed this earlier. Do you have an online cite or
explanation of what exactly the "Casaba Howitzer-style nukes " is, Scott?

And why is it better?

Sounds very interesting, but dangerous, and I'd like to know more.

If you've already provided said cite, curse my name and refer me to
Groups.Google.



--
Scott Lowther, Engineer
Remove the obvious (capitalized) anti-spam
gibberish from the reply-to e-mail address



Thanks and regards
Frank Scrooby

Scott Lowther wrote:

Well, now, that's not strictly true, is it? Take it to an unlikely, yet
not wholly impossible extreme: an asteroid broken into chunks the size
of houses. This will be an interestingly large shotgun blast... absorbed
to a large degree by the atmosphere.


On a lark, I went over to the Impact Effects Website (
http://www.lpl.arizona.edu/impacteffects/ ), and entered the criteria
for a stony meteorite the size of a house (I went with 15 meters)
hitting the earth at a 45 degree angle and impact speed consistent with
an asteroid; and then had it calculate the effects as seen from a
distance of ten kilometers.
The effects were surprisingly moderate:


Your Inputs:

Distance from Impact: 10.00 km = 6.21 miles
Projectile Diameter: 15.00 m = 49.20 ft = 0.01 miles
Projectile Density: 1500 kg/m3
Impact Velocity: 17.00 km/s = 10.56 miles/s
Impact Angle: 45 degrees
Target Density: 1000 kg/m3
Target Type: Competent Rock or saturated soil


Major Global Changes:

The Earth is not strongly disturbed by the impact and remains intact.
The impact does not make a noticeable change in the Earth's rotation
period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.


Energy:

3.83 x 1014 Joules = 0.92 x 10-1 MegaTons TNT
The average interval between impacts of this size somewhere on Earth
is 17.4 years


Crater Size:


Transient Crater Diameter
http://www.lpl.arizona.edu/%7Emarcus/craterglos.html#transient:
431 m = 1413 ft
Final Crater Diameter
http://www.lpl.arizona.edu/%7Emarcus/craterglos.html#final: 672 m
= 2204 ft

The volume of the target melted or vaporized is 0 km3 = 0 miles3
Roughly half the melt remains in the crater, where its average
thickness is 0.01 micrometers = 0.00 thousandths of an inch
The crater formed is a simple crater
http://www.lpl.arizona.edu/%7Emarcus/craterglos.html#simple


Thermal Radiation:


Time for maximum radiation: 0.01 seconds after impact

Visible fireball radius: 0.1 km = 0.1 miles
The fireball appears 3.1 times larger than the sun
Thermal Exposu 1.70 x 102 Joules/m2
Duration of Irradiation: 0 seconds
Radiant flux (relative to the sun): 0.9



Seismic Effects:


The major seismic shaking will arrive at approximately 2.0 seconds.
Richter Scale Magnitude: 3.9
Mercalli Scale Intensity at a distance of 10 km:

III. Felt indoors. Hanging objects swing. Vibration like
passing of light trucks. Duration estimated. may not be
recognized as an earthquake.

IV. Hanging objects swing. Vibration like passing of heavy
trucks; or sensation of a jolt like a heavy ball striking
the walls. Standing motor cars rock. Windows, dishes,
doors rattle. Glasses clink. Crockery clashes. In the
upper range of IV wooden walls and frame creak.



Ejecta:


Most ejecta is blocked by Earth's atmosphere



Air Blast:


The air blast will arrive at approximately 33.3 seconds.
Peak Overpressu 5294.4 Pa = 0.0529 bars = 0.7518 psi
Max wind velocity: 11.1 m/s = 24.8 mph
Sound Intensity: 74 dB (Loud as heavy traffic)




The last thing the world needs is a massive asteroid strike that punches
through the crust. That will create worldwide devastation due to
geological upheavals and throwing teratons of molten rock into the sky.
If the blast is over a wider area, the penetration depths are much
lower, and *total* planetary damage is less.


There will still be a great deal of fine dust tossed up by a large
number of hits like this, but as you say- compared to large scale
vulcanism this is certainly the better of the two scenarios. If you
could the majority of the pieces to come down at sea, you could get off
even better, although you would probably wreak some havoc on the local
marine population from the shockwaves being transmitted through the water.
So if you were going to blast it to flinders, you probably want to do it
at a point of approach where the component parts end up falling into the
Pacific if possible. Too early and they will spread all over the place
(unless you want to hit it _really_ early, and have the majority of
pieces clean miss the planet, realizing that you may have to deal with
them later as they pass by again in their orbits.) Too late and they
won't be separated enough to dilute the effects much.

Pat

(Henry Spencer) wrote in message ...


If we do have to do a short-notice deflection before we have better
information, about all we can do is take our best guess, launch bombs --
smaller ones than the MIT study specified, because we no longer have a
Saturn-V-class launcher handy -- and pray that it works.

I wonder how yield per mass has improved since the study. Perhaps a
Delta Heavy can put in space the same yield as a Saturn V.

What should be improved is guidance. Small bombs could be much better
positioned than a few decades ago.

Also, is it possible to use a tungsten rflector to focus the
radiation? I appreciate the reflector will vapourise, but would it
have any effect.

Apart from that, rather than 100 M Ton boms, it might be better to
explode a 1 MT bomb every hour over several days.