Let’s start the year with a look back in time to 1957, a time when nuclear bombs were being tested underground for the first time at the Nevada test site some 105 kilometers northwest of Las Vegas. If this seems an unusual place to launch a discussion on interstellar matters, consider the story of an object that some argue became the fastest manmade artifact in history, an object moving so fast that it would have passed the orbit of Pluto four years after ‘launch,’ in the days of Yuri Gagarin and Project Mercury.
I’m bringing it up because the tale of the nuclear test known as Plumbob Pascal B is again active on the Internet, and it’s a rousing tale. Operation Plumbob involved a series of 29 nuclear tests that fed the development of missile warheads both intercontinental and intermediate. The history of such underground nuclear testing would make for an interesting book and indeed it has, in the form of Caging the Dragon (Defense Nuclear Agency, 1995), by one James Carothers.
But let’s narrow our focus to the nuclear devices known as Pascal A and B, the former used used in the first nuclear test below ground. This would have been the first such test in history, as the Soviet Union did not begin its underground program until 1961.
Image: The scene following the detonation of Ranier, an underground nuclear test similar to Pascal B. Credit: Plane Encyclopedia.
The key player here was Robert Brownlee (Los Alamos National Laboratory), who supervised the detonation of Pascal A and duly noted the fact that the yield was much greater than anticipated, so that a column of flame shot into the sky. The blast was not remotely contained. Pascal B was partially an attempt to fix that problem by lowering a 900-kilogram, 4-inch thick iron lid over the borehole. It seemed sensible to at least some at the time, but Brownlee himself evidently did not believe it would work to contain the blast, as indeed it did not.
The detonation of Pascal B caused the blast, like its predecessor, to climb straight up the borehole and escape. The interesting part is that the lid was never found. The only camera footage of the event caught the iron plate in only one frame, and that fact seems to be the source of the current interest. For Brownlee, extrapolating from the speed of the filming (one frame per millisecond) attempted a calculation on the speed of the object. He wound up with something on the order of six times Earth’s escape velocity, which would be 241,920 kilometers per hour, or 67.2 kilometers per second.
That’s an interesting figure! Voyager 1 is moving at about 17.1 kilometers per second and is more or less the yardstick for our thinking about where we are today in achieving deep space velocities. So what is commonly being described as a ‘manhole cover,’ which is pretty much what this object was, is conceivably the fastest moving object humans have ever produced.
Brownlee, recalling these events in 2002, described the iron cap as requiring a lot of ‘man-handlng’ to get it into place. And he goes on to say this:
For Pascal B, my calculations were designed to calculate the time and specifics of the shock wave as it reached the cap. I used yields both expected and exaggerated in my calculations, but significant ones. When I described my results to Bill Ogle [deputy division leader on the project], the conversation went something like this.
Ogle: “What time does the shock arrive at the top of the pipe?”
RRB: “Thirty one milliseconds.”
Ogle: “And what happens?”
RRB: “The shock reflects back down the hole, but the pressures and temperatures are such that the welded cap is bound to come off the hole.”
Ogle: “How fast does it go?”
RRB: “My calculations are irrelevant on this point. They are only valid in speaking of the shock reflection.”
Ogle: “How fast did it go?”
RRB: “Those numbers are meaningless. I have only a vacuum above the cap. No air, no gravity, no real material strengths in the iron cap. Effectively the cap is just loose, traveling through meaningless space.”
Ogle: And how fast is it going?”This last question was more of a shout. Bill liked to have a direct answer to each one of his questions.
RRB: “Six times the escape velocity from the earth.”
Image: Los Alamos’ Robert Brownlee (1924-2018). Credit: American Astronomical Society.
According to Brownlee, the answer delighted Ogle, who had never heard of a velocity given in terms of escape velocity from the Earth. Brownlee himself notes that because the object was only caught in one camera frame, there was no direct velocity measurement. He could only summarize the situation by saying that the ‘manhole cover’ was “going like a bat!” But he also notes that neither he nor Ogle believed that the cap would actually have made it into space. And the story doesn’t end just yet.
As passed along by my ever-reliable buddy Al Jackson (Centauri Dreams readers will know of Al as astronaut trainer on the Lunar Module Simulator during the Apollo era, and as the author of numerous papers on interstellar propulsion), I point to a set of calculations by one R. Finden titled “The Fastest Object Ever: The Manhole Cover,” evidently sent in response to an article in a magazine called Business Insider in 2016. The note appeared originally on a Reddit thread. Finden notes that his or her work should be considered as a rough estimate because “flight at a mach number upwards of 200 has not been studied and may never be.” Good point.
Finden’s calculations show that the cover would have reached temperatures five times its melting point before it could ever escape the atmosphere. And then this:
If the steel plate were magical and did not burn in the atmosphere, it would have escaped the upper stratosphere (50km) at 53 km/s just 934ms from launch. This not only means it would have made it to space, but it would have eventually escaped our solar system (depending on the time of day at launch). What likely happened was the plate was initially launched parallel to the ground and rotated with oscillation into the upright position, and by that time the drag from the first second of flight decreased its speed enough to prevent it from entering the upper stratosphere.
Conclusion: No manhole cover in space. It’s worth recalling, the Finden note adds, that the Chelyabinsk meteor was moving at only one-third the speed and had 13,900 times the weight of the flying cover, and even this mass was unable to survive Earth’s atmosphere. I dislike this result, as the idea of an object ‘launched’ in 1961 escaping the Solar System while we were still trying to get to the Moon is utterly delightful. And because R Finden’s math skills are well beyond my pay grade, I can’t reach a definitive conclusion about the result. So maybe we can still dream of flying manhole covers even if the odds seem long indeed.
This is one of your most surprising and interesting blogs. Wonderful!
I think a plate hunt should be organized. What were its dimensions? It weighed about 900kg or about 2000 lbs and with density of about 500lbs/cf it was about 4 cf. Since it was 4″ thick it was of dimensions 12sf, say 3ft x 4ft. Did it land edge on??? That would make it hard to find…but it might be radioactive….
>but it might be radioactive….
it was an time of experimentation and unknown in terms of materials and reactions ; the objective was above all to gain power to dominate the world and space. Atomic energy now “mastered” by man was not perceived as a danger but as a tool, because of its power (see the crasy project “Plowshare” the same year) The global context and scientific thinking was different.
It was the prehistory of the nuclear era and they did not yet care about radioactivity on organisms. Remind that in 1957 had just drawn the first [secrets] conclusions of the effects of Hiroshima.
Today in France, on our old 50-year-old nuclear power plants, no one can really say how long the period materials will resist in the core of the reactor subjected for decades to radioactivity …
A very rough calculation suggests that the “manhole cover” experienced an acceleration of better than 5000g.
This is survivable by hardware and electronics.
This suggests that such a Jules Verne “gun” approach, but in the Moon, could theoretically reach these high velocities, given protection from melting with insulation between the object and the blast.
Apart from the high-velocity probe, there is seismic data to be collected on the Moon to help map the interior, as well as a commemorative new crater to mark the event. Drilling the “gun barrel borehole” would also provide core samples that could reveal more of the Moon’s history. Doing this on Farside would be especially useful to help determine the correct theory of the Moon’s formation.
There’s nothing theoretical about that approach! Check out SpinLaunch, which uses a giant centrifuge to reach very fast velocities. Apparently the viability of the full-scale approach is still “up in the air” (see Big Think‘s article) – it comes close to the maximum accelerations we see from centrifuges in any setting – but it would certainly be far more ecologically sound than any rocket launch, reusable or not.
The Spin Launch idea is very novel, but it does mean that maximum velocity and maximum aerodynamic pressure difference (max Q) occur at the launch point. This suggests to me that the launcher should be sited at the highest point possible – e.g. from a high plateau. Even better would be a launch point in the stratosphere, say 20 km or higher, to reduce the air pressure to about 5% allowing for a potential SSTO vehicle. Even better would be to float it at 50 km at the edge of space where J P Aerospace plans to place their “Dark Sky” floating station, reducing air resistance to negligible levels.
I may have mentioned before that a Spin Launch system coordinated with a Sky Hook tether could launch capsules to be captured by the Sky Hook and thrown into orbit or escape velocity, no propellant is needed at all except for fine maneuvering to dock with the Sky Hook. Now that would be low-cost access to space for some cargoes. Conventional aerospace vehicles would carry passengers and delicate cargoes to the Sky Hook. This Spin Launch-Sky Hook approach would be great for robots to reach space as they could tolerate the high g’s from a Spin Launcher.
Peeking in at the JP Aerospace blog, it looks like they have a lot of fun ideas. I’m not sure about the practicality though, let alone the funding. How would they keep a balloon base 50 km in the air from drifting away away to China, or being destroyed by the weather if they instead have it take off and land repeatedly?
Alas, despite the very impressive prototype facility, I see Spinlaunch isn’t looking so good either now. Oddly, one launch site they proposed in Unalaska would been within sight of the ocean. Apparently there’s a problem siting the facility because it makes sonic booms and requires closing nearby roads for two hours each launch… because things could go sideways?
If I have understood correctly, the energy of the nuclear explosion channeled in the tube (or chimney) compressed the gases which gave a powerful accelerator effect on the plug (called “astroboy”) ? If theoretical calculations show ~5 times the earth release rate, I am a little skeptical about whether a material can withstand such pressure and heat stresses when it is ejected, which would have probably distorted (lid could have curled) it and thus impact its trajectory in the layers of the atmosphere but, why not, there is something to enjoy for ballistic calculation…
If the effects of the reaction were foreseeable, no one knew how much they would occur. Imagine now that the project was continued and the tube was fluted like a gun barrel ? How fast would the object have been propelled ? Could the experience be repeated in space with the Orion project ? Can such a moving object be guided at such speed for an interstellar journey ?
some info : https://nuclearweaponarchive.org/Usa/Tests/Plumbob.html
I’m not sure but may be we see this famous plug in this technical documentation at p119 :
https://www.dtra.mil/Portals/125/Documents/NTPR/newDocs/ANTHReport/1957_DNA_6005F.pdf
A movie about Plumbbob : https://ahf.nuclearmuseum.org/ahf/history/operation-plumbbob-1957/
AT orbital velocity only 5 miles a second, spacecraft burn up unless they enter the atmosphere at a very shallow, grazing angle. At six times escape velocity it would have completely disintegrated. If the atom bomb could be exploded in space any projectile would have a fast velocity. The only problem is that it is a one time thrust unlike project Orion. Even small atom bomb explosions make a lot of ionizing radiation.
I wonder if a solid metal projectile with a high melting point might make it into space from the ground. One would have an atomic space cannon. The underground radiation would be another problem with many shots.
The atomic cannon exists, it is the constraint of materials or their mass that prevents the sending of a projectile in space from earth. We have the problem of rockets: either they are heavy and require considerable energy to escape from the earth’s gravity or they are smaller but their possibilities are reduced. It is obvious that a weapon fired from space is now less expensive than launched from the earth’s surface.
Well, now imagine a lind of “tube” from the ground to space in which one could escape gravity…everything would be possible. (Paul has probably a short story from SF to propose on this subject ;)
https://archive.org/details/youtube-3ZhZ2ZWd0Ps
The first interstellar probe was a man hole cover!
Never let the facts get in the way of a good story ;-)
Even if this manhole cover didn’t make it into space, there is still the possibility that aluminum pellets launched by shaped charges from an Aerobee sounding rocket on October 16, 1957 escaped the Earth and went into solar orbit. For more details, see https://www.drewexmachina.com/2017/10/16/fritz-zwickys-solar-orbiting-pellets/