Can current ballistic missiles target asteroids?

[mlorrey]

Don't take my word for it: research for yourself what altitude explosive bolides detonate at typically, and what altitude asteroidal/cometary dust meteors burn up at. This is the altitude range in which the vast bulk of the heat will be expended in. Then look at the altitude of the ozone layer, and the distribution of CO2 in the atmospheric column. Then look at where the top cloud layers are. If the heat is expended mostly above where the substances are that reflect sunlight and other energy back into space, then that heat will also be reflected back into space.<br /><br />As for me, I know the answers to these questions, so it is obvious to me. It may not be so for you, so I suggest you go and research the topic, get the facts for yourself. Google it up.

 

[josh_simonson]

>And build the launch platforms in the movie? Could you build them so the missiles could not be targeted at Earth by some crazed dictator? If so, you could have them in an orbit outside Lunar Orbit waiting to be called on.<br /><br />Sure you could, just build the warheads so they can't re-enter the earths atmosphere intact. That way the worst they could do before becoming inoperable would be to create a high altitude EMP burst.<br /><br />As pointed out earlier, a tiny nudge early enough is enough to make an asteroid miss the earth. A penetrating nuclear weapon would have more of an immediate effect and hence be useful with shorter warning. If the NEO can be broken up with a weapon, then this method would be useful on fairly short notice. Blow up the asteroid a few days before impact and most all of the fragments would miss the earth.<br /><br />Deep impact and hayabusa demonstrated the ability of small spacecraft to accurately intercept such bodies, and the same technology could deliver a weapon.<br /><br />I believe people mostly try to dismiss the nuclear bomb approach to meteor deflection because they don't want there to be any legitimate use for nuclear weapons. There is a lot of bias here.

 

[meteo]

Well eventually it would be reradiated to space, and the atmosphere would return back to a regular temperature. The stratosphere takes a long time to respond though so with a large initial perturbation it could take months to return to equlibrium. Those were just "back of the envelope/order of magnitude" converting the kinetic energy directly into thermal energy. <br /><br />"All of the heating that occurs above the ozone layer and CO2 concentrations will be reflected back to space."<br /><br />Were talking about a pulvized asteroid which is heating the stratosphere and above. The layer absorbing the kinetic energy of the pulverized asteroid is going to be emitting mostly in the infared, visible if were talking about a fireball. CO2/water vapor will absorb the infared, and even if there is UV from the fireball, ozone absorbs UV it doesn't reflect it so UV will heat the ozone layer. The atmosphere will be transparent to the visible radiation (if there is a fireball) some will go back to the earth some to space.<br /><br />I can't calculate a better approximation using radiation transfer because I don't enough about the initial conditions and it would be way too hard. <br /><br />This site will tell you where asteroids of certian conditions will burn up.<br /><br />http://www.lpl.arizona.edu/impacteffects/

 

[spacefire]

it's better to have smaller pieces impact earth as they would have burned up more during entry (total surface area of multiple pieces is larger than total surface of intact asteroid).<br />certain phenomena associated with asteroid impact will be of reduced magnitude: tsunamis, earthquakes, volcanic activations and clouds of ejecta.<br /> <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[willpittenger]

How about theoretical warheads? Could someone have figured out how to build a larger weapon -- and just never built it due to something like treaties or international concern? If so, how quickly could it be built? If we are resorting to nuclear weapons, we would not have much time. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[willpittenger]

Certainly this would be true somewhat. Some of the debris would miss Earth entirely. A solid rock is either going to hit or miss. However, the gray area would be if the rock merely penetrated deeply into the atmosphere -- and then left. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[vogon13]

Even back in the fifties, weapon designers realized the largest yield for a fission bomb is ~500 kt due to the maximum size of a crititical mass that could be assembled.<br /><br />It was also realized that fusion bombs have no fixed upper limit in size, maximum yield is up to the designer and budget.<br /><br />IIRC, Dr.Teller felt that yields above 100 mt were undesireable because of a lack of targets of sufficient size (100 mt will devestate something the size of Arizona), and due to wasting a large portion of the bomb energy in simply heaving atmosphere upward.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[chriscdc]

Was that the maximum size that could be built in the 50's?<br />I remember that us brits built one massive fission nuke, IIRC 800KT. In order to trick everyone else into thinking we had a fusion bomb in case the real fusion bomb (that was to be tested later) didn't go off. It did go off, so we did what we always did in the 50's and 60's, mainly show that we can do it then buy american designs as we couldn't finance a program ourselves.

 

[drwayne]

800 kT is kind of small....to be considered large.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[willpittenger]

I heard that Dr. Tellar was always demanding the opportunity to build bigger and bigger warheads. It would appear that he even personally told Reagan there is no such thing as a warhead that was too big. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[henryhallam]

<font color="yellow">800 kT is kind of small....to be considered large. </font><br /><br />I thought it was pretty big for a pure fission warhead.

 

[toymaker]

The biggest nuclear detonation was the Soviet Tsar bomb.<br />Actually using such big warheads is counterproductive-after a certain phase it will no result in bigger radius of the crater-its better to use more smaller ones IIRC. <br />http://nuclearweaponarchive.org/Russia/TsarBomba.html

 

[darkenfast]

First, a question: Do we have a reliable estimate of how many tons of material hit the earth's atmosphere every year? <br /><br />Second: The odds of a sizable asteroid "sneaking up" on us are rather...well...astronomical, aren't they? We should have plenty of warning if an orbit is going to intersect the Earths position in the furture. So, say an asteroid is discovered that will probably hit us in a few years. We get or build a 100mt or larger bomb (if the Russians haven't got one hidden away from those tests they did), and we launch it on the most reliable large booster we have (and in a few years the CLV/CaLV will probably fit that bill). This would have far more capability than even the largest ICBMs, and although it would require a maneverable upper stage, our experience with various probes shows how it can be done. If the asteroid is shattered hard enough so that most of the material attains escape velocity, that debris will now be in slightly different orbits and should miss Earth down the line.<br /><br />Personally, I'm more worried about crossing the street, but it's fun to speculate.

 

[darkenfast]

The Tsar Bomba was a rushed non-operational design for a political statement and was completed within 16 weeks. The US at that time was already making weapons much more compact and light than the Soviets. <br />This is an area I know little about. Perhaps there is a member here who could give us an estimate of what a current superbomb would weigh?

 

[chriscdc]

Asteroid yes, Comet nope. If a comet was on a collision course with earth then we probably wouldn't see it until it was venting and it would be too late by then. Plus a comet has a higher velocity than an asteroid and so would be far more damaging.

 

[willpittenger]

<blockquote><font class="small">In reply to:</font><hr /><p>using such big warheads is counterproductive-after a certain phase it will no result in bigger radius of the crater-its better to use more smaller ones IIRC<p><hr /></p></p></blockquote><br />Even in space where you only want to bombard a target with radiation? <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[drwayne]

Use against space targets has never really been a warhead design requirement.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[willpittenger]

That is the question of this thread though. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[drwayne]

I was just pointing out that the bulk of the work done to date has not been optimized for the role we are talking about, so it is possible that the design for such a role may in fact be different than what I might consider conventional design.<br /><br />(Or things that we have even though about)<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[qso1]

willpittenger:<br />Arthur C. Clarke's book The Hammer of God featured a gigaton warhead. How much bigger is that than anything built or theorized?<br /><br />Me:<br />The largest manmade explosion was a nuclear test conducted by the former Soviet Union in October 1961 (The Tsar Bomba test or monster bomb). The estimated yeild was generally reported to be between 57-92 megatons. According to the "Guiness Book Of World Records", the yield was reported to be 57 Mt.<br /><br />The largets seriously theorized bomb was also Russian and reported by Nikita Kruschev to be 100 Mt.<br /><br />1Gt would be 10 times the 100 Mt device and 20 times the actual largest bomb detonation. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[qso1]

darkenfast:<br />The Tsar Bomba was a rushed non-operational design for a political statement and was completed within 16 weeks. The US at that time was already making weapons much more compact and light than the Soviets. <br />This is an area I know little about. Perhaps there is a member here who could give us an estimate of what a current superbomb would weigh?<br /><br />Me:<br />You are right about the U.S. making more compact weapons. However, even a superbomb of the size tested by the Russians may not be enough to do actual damage to an incoming asteroid or comet if they get close enough to require significant power to deflect.<br /><br />A much smaller yeild warhead could theoretically deflect an asteroid or comet if launched years or decades in advance when the object is far enough away to require much smaller amounts of energy to deflect. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[nexium]

My guess is mlorrey page 1, 02-27-06 11:48 pm is nearest to correct, but we need to have the multi stage rockets already stacked and the detailed protocol in place pre need, to successfuly pulverise an asteroid or comet on short notice. Neil

 

[mlorrey]

You are correct, Neil. I know our ICBMs have the capability, and the idea of taking out a 3 or ten MIRV bus and replacing it with a single ground penetrating nuke with an upper stage motor is a good one. Our warhead could have zero velocity at the time it meets our incoming target, since the target will be going so fast, it will impale itself with the stationary warhead at the peak of its trajectory. If the intercept speed is too high, we might even launch it early so that the warhead is falling back when it is intercepted.<br /><br />Also, note that the MX missile, which is probably the most capable missile for this job in US inventory, is decommissioned under the START treaty. Its motor stages are being used, I believe, in the Minotaur launch system. There are similar ICBM conversion jobs in Russia, with the Cosmos, Dneiper, and Rokot launchers.<br /><br />What I believe is needed is an international organization, likely under control of the UN (as much as I hate to admit it) or a US/Russian treaty organization, which has a set of converted missiles held aside in launch silos just for this purpose, and under control of the international team, requiring launch approval from both US and Russian team members. This would prevent these missiles from being used as ICBMs against Earth targets. They may need to be housed in other countries as an additional security precaution. Perhaps Kourou, Malta, India, Fiji, and Okinawa would be good candidate sites, and would spread out launch sites to give fastest response from any angle.

 

[willpittenger]

I brought the gigaton warhead up in case we only had a couple years notice. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>