A guest post by Joseph Friedlander for Next Big Future
The reader known as Goat Guy is a regular in the talkbacks at Next Big Future, many have been entertained by his opinions, backed up by hard engineering calculations.
I had a correspondence with him about, among other subjects, the Wang Bullet and Tsar Bomba and the possibility of boiling off many meters of rock within a few moments. The Wang Bullet is a single pulse nuclear external pulse propulsion system. Freeman Dyson and Ted Taylor and others worked on the project Orion nuclear pulse propulsion system. The designs involved about 200 pulses to get out of the earth’s gravity and 600 more pulses to go to Mars or Saturn’s moon Titan. The single pulse propulsion system is to dig a large hole and use one pulse which is a nuclear cannon that could launch thousands of tons in one shot. In this article, the reports from past nuclear tests is used to consider if the blast size and the projectile could not be configured for a successful launch. They also consider nuclear blasts for excavation.
”THE thing that scuttles this isn’t the cost of the nukes, nor the added-load of nuclear fallout in the atmosphere (a political problem more than anything), but the consequence of the nuclear explosions to the payload. They would be positively drenched in neutrons with every shot. Now, one can go all yada-yada “boron”, etc … assuming that one might be able to absorb most of the neutrons.
Aux Contraire, me hearties. Neutrons, especially in “spikes” are really good at lighting up absorbers such as boron into resonant states that no longer absorb (on nanosecond time-scales) more neutrons.
What you’d get by the time the big tub got to space … is a highly radioactive wastebin of heavily transmuted “stuff”. Electronics would be fried. Metals would be permanently radioactive. This is not what would be “the point”.
Further, instead of wishfully thinking about using megaton-or-larger devices to get around the cost, please recall that if small-kiloton blasts (0.5 to 10 kT) could barely be sustained by the pusher-plate due to blast-spallation effects, then 100 MT is right out. There are no known materials that wouldn’t just vaporize to plasma in 10-meter-thick layers at modest proximity to such blasts. The 1 km wide, 100 m deep pit left after the air-burst of the Tsar Bomba at only 50-60 megatons wasn’t only “compressed dirt”. nearly half the mass was vaporized entirely. Instantly.
The whole idea is an intellectually stimulating thing, but a practical nightmare. And that’s the problem. Not to mention the elephant-in-the-living room.”
Thus far Goat Guy’s comment, I wrote back,
I wonder. First of all if you have a link to the mass vaporized under the Tsar Bomba fireball (and better yet the temperature incurred in process) I would love to see it. Darn, didn’t think about that but if it was vaporized you get fallout from an air burst– because the condensate (rock dust–what size? just visible 50-30 microns? Respiratable (1-5 microns?) 50 meters of rock gone– is that a bunker buster or what? And I am a Cold War amateur historian but never heard that one.
I note specifically I have seen a Ted Taylor quote that a very heavily built structure (topped with asphalt) could take within 100 meters of a megaton device and live. I think a Orion could take within 500 feet of a megaton device. (Opacity, sprayed with grease) Presumably there is a way to reconcile these data sets.
Second of all I would argue that the clever fact I totally didn’t consider
Neutrons, especially in “spikes” are really good at lighting up absorbers such as boron into resonant states that no longer absorb (on nanosecond time-scales) more neutrons.
has 2 workarounds– 1) I think on the H-bomb 5 megaton charge Super Orion they were planning to drop *fresh* boron encapsulation around each fresh bomb. 2) This boron invalidation scenario actually argues better for the Wang Bullet architecture because the *first* lightup presumably might be shielded with enough thickness (actual data welcome!)
Goat Guy replied,
[A1] – vaporization. Read it in a book 25-35 years ago. “Effects of nuclear blast” by government. They could be guilty of hubris, but the thermodynamics aren’t out of whack:
cu m (crater)
kJ/(kg*K) (sp heat, basalt)
Hv (J/g = kJ/kg) (entropy of vap)
delta T (to vaporize)
m deep vaporized
yield to vaporization
Couple of notes – 4.7 MJ/kg for complete vaporization is not terribly surprising.
The factor x^2.5 (not ^3) was used for figuring volume of vapor-layer. Yes, pulled it out of my tush, but it makes sense too: a radial heat-intensity profile at ground surface wouldn’t be unlike the same cone profile that defines the crater itself. Not as deep, not as wide. The final 15%-of-bomb-to-vaporize-rock seems pretty nominal. Most energy would dissipate outward, not downward. But clearly too, most downward energy would impinge on friable rock, which would rapidly (nanoseconds) vaporize, resulting in plasma, which turns out to be nicely transparent to infrared and optical energies … necessary to vaporize more rock. Speed-of-light gets in the way, but but there aren’t good scattering mechanisms. So, it gets absorbed. The IR/visible opacity (transparency) thing ensures that once vaporized the plasma doesn’t heat much more. Useful.
[A2] boron. “Fresh for each pop” isn’t a bad solution. The amount though has to be pretty convincingly large. All that extra mass … does Orion’s equations still work? And what of all that nuclear ash? Damned inconvenient. Let’s just get behind mass-throwers, shall we? No fallout, the same “nuclear power” [at small power stations along the launch site] gets the work done, etc. Use something reasonable [100G] for nonbiological launches and [8G] for bio. Or “water filled launches” (this works well, even up to 15G for people)
If true for the Tsar Bomba, say 1/3 heat, half downwards. 16%. Plausible…I think we’ve found a new way to mine, boys…ouch.
This strongly implies disturbing things. I am trying to remember other low airbursts (relative to yield.) Surely there should be a picture somewhere— however as I recall the US favored barge or surface shots until they favored underground ones.
This begs a question, what if a starship commander needs to tunnel down. Now you know my cynicism regarding an Star Trek Next Gen episode where they used the phasers to tunnel down faster than an elevator. Knowing actual tunneling rates of 25 meters a day I was laughing at the tunneling rate for my wife to hear.
This way–*whomp* *whomp* *whomp*—
If you did it in a string one supposes (if no fratricide) it would work.
Sequentially– how high would the plasma fountain reach (to get rid of the tailings? Low airburst in the crater, plasma fountain, wind, clear, do it again.
You might indeed be able to go down a kilometer within an hour. However the environmental impact statement probably would weigh more than the excavated dirt 🙂
Got to think about this.
Regarding getting behind mass drivers, yeah, I know. It’s definitely a sign of my immaturity that I like ships that can have a Captain, First Officer and Chief Engineer. Makes for good stories, I suppose…
Your correspondence was most gratefully received, sir 🙂 Other topics loom but so does naptime….
To our readers I should adduce the following exhibits–
from English Wikipedia, this caption and picture–note that it says the fireball did not touch ground.
Maybe the brown curtain like radiance in this movie still around the fireball is rock vapor boiling away? Doubtful but intriguing. The movie below shows a quick action view.
The Tsar Bomba’s fireball, about 8 kilometres (5.0 mi) in diameter, was prevented from touching the ground by the shock wave, but nearly reached the 10.5 kilometres (6.5 mi) altitude of the deployingTu-95 bomber. Although simplistic fireball calculations predicted the fireball would impact the ground, the bomb’s own shock wave reflected back and prevented this
It was an airburst, (so no fallout sucked into the radioactive fireball) and no contact of the fireball with the ground, but the publication Goat Guy recalls claims the fireball’s immense heat vaporized rock to plasma and boiled it away from right under the fireball. Is the area on the right in this picture this ‘rain-down’? (It’s possible the fireball expanded because of heat reflection from ground to which swelled it larger than otherwise naturally occurring.)
Note the behavior of the ground under the fireball live in this YouTube video: (before 4 seconds in) http://youtu.be/Pu88gb1EpmI Note that the Wilson Cloud Chamber Effect shocks atmospheric moisture into visibility so most of the clouds you see after that will not be candidates of interest for this study.
In closing I copy from Wikipedia data on the Tsar Bomba device for our readers’ benefit:
Any readers who run across data on the Russian internet
details on the ‘crater’ under it are more than welcome to post in the comments details about the condition of the surface under ground zero.
Any articles on Russian Internet of geology of this crater and debris nearby?
Favorite fact of Tsar Bomba—
windowpanes were partially broken to distances of 900 kilometres (560 mi).Atmospheric focusing caused blast damage at even greater distances, breaking windows in Norway and Finland.
The seismic shock created by the detonation was measurable even on its third passage around the Earth. Its seismic body wave magnitude was about 5 to 5.25. The energy yield was around 7.1 on the Richter scale but, since the bomb was detonated in air rather than underground, most of the energy was not converted to seismic waves.