What If Humans Could Survive A 4000 G Explosive Launch?

A guest article by Joseph Friedlander

This is a longer article giving an overview of what happens if Gershom Gale’s theory that people with fluid filled interiors can survive 1000 G and better is workable. If so, what new opportunities for manned space operations are opened?

There are so many launch system ideas that have great promise for reaching space at lower cost than present, but a distressing number of them subject cargoes to extreme acceleration.

Let’s focus on explosive launch for a moment.   This can be gas guns or direct explosive launch.

Reader Paul 451 made the following comment on one of the Wang Bullet articles.

Joseph, I had a random thought. A nuke is a largely unshaped blast wave. (The drill-hole will cause some innate shaping of the wave, but I suspect that would be behind the leading edge, so irrelevant to the launch itself.) Is it possible to simulate the effects on the reaction mass (the water beneath the payload) by using conventional explosives. I was thinking something like ringing the entire length of the drill-hole with shape-charges, timing the explosions to simulate the speed and force of the nuclear blast wave. It’ll take a painful amount of explosives, but it won’t take 150,000 tons of HE to simulate a 150kt nuke. And it’s much politically safer than a nuke, so easier to actually be allowed to do it.

And indeed that is one scenario we consider in the article.

Brian Wang’s coverage of explosive launch

 The Blast-Wave Accelerator:
* is of Russian origin
* is a concept that has been verified by NASA studies
* is state-of-the-art technology
• Estimated launch cost: $200 – 2,000/kg of payload, depending on construction and refurbishment options
• 15 m barrel generates 300,000 g acceleration
• 40 m barrel generates 100,000 g acceleration
• Longer barrel generates lower launch acceleration
• Russian experiments indicate that Mach 27 projectile/payload velocity is achievable
• Payload mass fraction is 70 – 95%
 it has artillery-like operations, complexity and cost
* it can be based anywhere
* it possesses excellent stealth (i.e., it has no exhaust plume)
* it has affordability, ferocity, and quick reaction time

Projectiles are accelerated by a series of hollow explosive rings that are detonated in rapid sequence causing a near-constant pressure to form at the base of the projectile, thereby generating a near-constant and large acceleration 

The amount of explosives used can be very large and stacked in rings each conceivably as high yielding as the picture below for a conventional Wang Bullet kind of explosive launch of the kind Paul 451 suggested. I am guessing ear protection might be a good idea. Particularly when the thing goes supersonic. Note that ANFO may not be the quick triggering explosive you need for the above technology; illustrative only. 

Minor Scale fireball immediately after detonation. The F-4 Phantom aircraft in the foreground is 63 feet (19 m) long.
4.8 kilotons of ANFO explosive (ammonium nitrate and fuel oil),equivalent to 4 kilotons of TNT,[4] were used to roughly simulate the effect of an eight kiloton air-burst nuclear device. With a total energy release of about 1.7 ×1013 joules (or 4.2 kilotons of TNT equivalent), Minor Scale was reported as “the largest planned conventional explosion in the history of the free world”
Some future explosive launch systems might be analogous to this conventional explosive shock wave guide:

 Sandia National Laboratory’s “Thundertube”. The “Thundertube” was a conventional explosive shock wave guide which consisted of a steel pipe about 5.8 m (19 ft) in diameter and about 120 m (400 ft) long. Small scale HML design concept models were placed on a soil sample (about 5m x 5m x1.5 m deep) intended to represent Western US desert soils. Soil sample preparation was quality assurance verified using a 1 cm diameter ultra-miniature Cone Penetration Test penetrometer (tip and friction sleeve) developed at the Earth Technology Corporation (Long Beach, CA) in 1984. The CPT soil test system and sample preparation (soil surface planner) equipment was designed by Andrew Strutynsky PE,CPT Group Leader at Earth Technology 1982-1985.

But explosive launch systems aren’t the only way up at high  G:  pulsed quenchguns are an transient release of electrical energy to kinetic energy:


We are talking  two seconds to escape velocity. 

 Here is an excerpt from the 1980 L-5 News announcement of Dr. Kolm’s work. Read the whole thing here:



By Henry Kolm
From L5 News, September 1980

Mass Drivers were proposed by Professor Gerard O’Neill in 1974 as the logical means for transporting lunar raw material to L-5. As all but perhaps a few of the newest L-5 members know, mass drivers are electromagnetic launchers which accelerate payloads in recirculating buckets with superconducting magnet coils at a repetition rate of about ten per second. These buckets are levitated, guided and driven by a synthetically synchronized linear motor derived from the Massachusetts Institute of Technology (MIT) Magneplane. The magneplane is a cylindrical high-speed train which floats twelve inches above an aluminum trough. The mass driver ultimately evolved into a line of pulse coils surrounding a barrel of aluminum guide rails within which a stream of cylindrical buckets is accelerated and decelerated without physical contact.

Mass driver
Cutaway of a mass driver model: the current in the drive coils makdes a magnetic field which pushes on currents in the bucket coils, producing acceleration.
Mass driver
The mass driver on display at the Princeton Conference in 1979. Photo by Charles Divine.

Mass driver development has been pursued by a dedicated group, first at two NASA Ames summer studies in 1976 and 1977, and during the intervening academic year, while O’Neill was a visiting professor at MIT. Out of this collaboration came Mass Driver One, built by a group of MIT students on a shoestring budget in four months, in time to be demonstrated at the May 1977 Princeton-American Institute of Aeronautics and Astronautics (AIAA) Symposium on Space Manufacturing. It was also featured in the NOVA documentary “The Final Frontier,” and was flown to California to be exhibited and nationally televised at the festivities surrounding the first piggyback flight of the Space Shuttle orbiter Enterprise in 1977.
It is now believed that a lunar mass driver several kilometers long, designed conservatively with present technology, should be able to deliver 600,000 tons a year to L-5, or more easily to L-2, at a cost of about $1 per pound, assuming only ten years of operation. Smaller caliber mass drivers could also be useful as reaction engines to propel large structures or asteroids by ejecting waste matter as reaction mass. Such devices are not as straightforward as lunar launchers since certain stability problems of long, flexible structures in space need to be solved.
I am often asked what, if anything, has happened recently. An update is about due, particularly since exciting new possibilities have emerged.
Mass Driver Two
In the fall of 1978, O’Neill and I shared a university-level NASA grant for the development of Mass Driver Two. It is to operate in an evacuated, four-inch caliber tube at an acceleration of 500 gee, with a superconducting bucket and an oscillating, push-pull coil system. It is close to an actual lunar driver, but more complicated due to the need for a vacuum tube between drive coils and bucket. ...it may be possible to build mass driver reaction engines which are only several meters, rather than several kilometers, long and eject reaction mass in the form of small rings or washers (easily made of lunar aluminum, for example) without the use of superconducting buckets. Normal metals will carry even higher current densities than superconductors for very short periods of time. On the other hand, conventional mass drivers with recirculating superconducting buckets can be improved drastically by using superconducting instead of normal-conducting drive coils, and storing the launch energy inductively in the drive coils. This would eliminate the need for capacitors and feeder lines, thereby reducing the system mass, cost and complexity. The most exciting thing we learned is that mass drivers can be used to launch space cargo from Earth!
The Era Of Earth-Based Mass Drivers
Electromagnetically launched space vehicles are an old dream. Arthur C. Clarke and Robert Heinlein have used them for decades, and a Princeton professor named Northrup proposed them in the Twenties. The Germans attempted electromagnetic launching unsuccessfully during World War Two, before they embarked on the development of rockets. Actually the most successful catapult launch was achieved by chemical means in the Sixties when a passive missile was almost accelerated to orbital velocity from the Barbados Islands by welding together two large naval guns. It would be nice to be able to launch pure payload, unaccompanied by over 100 times its mass in expensive rocket engines and fuel. Nevertheless, space technologists never took direct Earth-launching seriously. After all, consider the ablation problems we face when entering the atmosphere from the top, where it is very dilute. Imagine the energy and ablation loss when a vehicle enters at full speed from the Earth’s surface, where the atmosphere is very dense. Even if a vehicle could be launched at escape velocity of 11 km/s, or even at a lower orbital velocity, it would certainly burn up before traversing the atmosphere, right?
Wrong! At least one dreamer refused to accept this extrapolation: Fred Williams has talked about Earth-launching ever since the days of the Magneplane Project. The question is: just how large would an Earth-launched vehicle have to be to survive its passage through the atmosphere? The first time this question was considered seriously in a quantitative way, to the best of my knowledge, was at the 1977 NASA Ames summer study. The theory of ablation in a dense atmosphere had received recent attention in connection with the outer planet probe program, and two members of the Ames team applied the resulting software to the problem of the Earth launcher: Chul Park and Stuart Bowen. They found, much to everybody’s surprise, that an Earth-launched vehicle would not have to be prohibitively large to survive: a vehicle the size and shape of a telephone pole could be launched out of the Solar System with a loss of only about 3% of its mass, and 20% of its energy to the atmosphere. There are two reasons for this result. First, the atmospheric transit is short and vertical rather than long and tangential (as required for astronauts to survive the deceleration); and second, the high atmospheric density leads to highly opaque ablation products which reduce radiation heating from the hot air to the projectile’s surface.
A reference design telephone pole launcher would have the specifications shown below.

Vehicle: Telephone Pole Shaped, Mass of 1,000 kg
Launch Velocity: 12.3 km/s
Velocity at Top of Atmosphere: 11 km/s (escape velocity)
Kinetic Energy at Launch: 76 x 109 joule
Ablation Loss, Carbon Shield: 3% of mass
Energy Loss: 20%
Acceleration: 1,000 gee
Launcher Length: 7.8 km
Launch Duration: 1.26 second
Average Force: 9.8 x 106 newton = 2.2 x 106 pound
Average Power: 60 x 106 kilowatts
Charging Time From 1,000 MW Power Plant: 1.5 minute

This launcher is about as long as the deepest well hole ever drilled, and therefore represents the longest launcher which can be installed vertically by present technology. If it were made longer to decrease the power requirement or increase the payload size it would have to be installed up a mountainside at an inclination of perhaps 30 to 45 degress. This would increase mass and energy losses due to the lengthened path through the atmosphere.
The cost of the launcher itself in terms of installed copper, steel and concrete would be only 24 million dollars. But a device to store 76 gigajoules by conventional technology (generators and capacitors) would cost 11 billion dollars. This estimate may not be very meaningful, because it is based on cost estimates for quantities of capacitors which have never been manufactured before, but even at half the price, the investment would be formidable. The energy cost of the launch would only be about 65 cents per pound, but amortization of capital would add 10 to 20 dollars per pound, even if the launcher were used continuously, day and night, every 12 minutes.
Actually, it is more useful to think in terms of power compression rather than energy storage. The reference launcher could be operated by storing energy from one single large (1,000 megawatt) power plant for 1.5 minutes, and releasing it in 1.5 seconds, a 60-fold compression. Perhaps sixty power plants could be tapped simultaneously during off-peak hours by using superconducting transmission lines. On the other hand, if the power requirement were reduced by a factor of 60, there would be no need for energy storage at all. This could be done either by making the launcher 60 times longer (468km), or by making the vehicle 60 times smaller (17kg). Neither alternative is reasonable. A compromise might be to apply a factor of the square root of 60 to each: a 60km long launcher with a 129kg vehicle. Unfortunately this launcher would be too long even for installation up a mountainside, and the payload ratio of such a small vehicle would be very poor.
There does, however, appear to be a solution to the energy storage problem. If the entire drive coil system of a mass driver is made superconducting, as well as the bucket coils, enough energy can be stored inductively by charging the system with current. It is then merely necessary to quench the current in each individual drive coil as the bucket passes. This loses some of the energy efficiency of a push-pull capacitor system, but the loss is more than offset by eliminating capacitor feeder line losses. A preliminary calculation indicates that a “quench gun” of this type of 12-inch caliber, only 1 km long, would store enough energy to launch a 20kg vehicle to 10.5km/s at an energy conversion efficiency of 80%, at an average acceleration of 5,600 gee.
There are technical problems to be solved, of course, but not any of a fundamental nature. The benefit-to-risk ratio of the enterprise certainly justifies an immediate, serious study. The possibility of launching cargo into space at a cost approaching about one dollar per pound by using off-peak electric power has mind-boggling consequences. To name only the most obvious: we could dispose of nuclear waste by launching it out of the Solar System; we could begin constructing solar power satellites; and we could establish fueling stations in low Earth orbit where Shuttle travellers would take on fuel and reaction mass for the trip beyond: to geosynchronous orbit, to the Moon, and to L-5.

Henry Kolm Henry Kolm


Friedlander here again. For reference we will talk about a Kolm Launcher later in the article. That is the above postulated system for a quenchgun scaled up by a factor of 100-1000 for a 2-20 ton launch vehicle but barrel lengthened to keep it down to 4,000 G. Why the upsizing? This has to be high G resistant and if manned the manned part has to be fluid filled thus the scale up. 
 If not manned you can make the capsules smaller sized like Quicklaunch (below) but you have cargo subdivision problems (many things cannot fit in a small capsule without total redesign and segmentation)  and you have packing problems (custom G proofing) and you have capsule rendezvous problems (instead of 1 self sufficient lunar surface rendezvous lander you have a bunch of little things that need gathering or orbital collection and assembly) It’s a mission architecture problem you can play with. Many new insights are possible.

When I say no evacuated spaces in the launch article I don’t just mean in the astronauts but the whole ship —
 literally there were no void spaces –electronics potted with epoxy,  tanks filled with no air at all, inflatable tanks in flat bag form, and no hard drives or other vacuum containing systems that can’t be fluid filled and pumped down later. Open spaces completely filled with fluid.  Combined with the stoutness of the ship that is a substantial weight penalty. The flip side is you have a lot of scrap material and chemicals you can use on the Moon. Unopened inflatable flat rolled tanks can take the outgassing as you de-liquid the ship on the Moon; later the base can do that for you.

This excerpt from the link below is by Dr. David P. Stern and I recommend you see the page he wrote to get a good look at the gas gun. Note his calculation yields a 4000 G value for launch, consistent with many cannon calculations as well.


 Let us assume that the shell inside the cannon accelerates at a constant rate ofa (meters/sec2). From the equations of motion with a constant acceleration (developed earlier for falling objects, whose acceleration a equals g ≈10 m/sec2), if t (in seconds) is the time spent accelerating, the final velocity (m/sec) is

v = at

and the distance covered, in meters

s = at2/2

From the first equation, t = v/a. Substituting this in the second equation gives, after a few steps

v2 = 2as

    Suppose the barrel of the cannon is a mile long (≈1600 meter) and the final velocity v, the one with which the shell emerges, is the escape velocity from the surface of the Earth

v = vesc. = 11,300 m/sec
v 2 ≈ 128,000,000 (m/sec)2

Then a quick calculation yields:             a ≈ 40,000 m/s2 ≈ 4000 g

    The force on the shell and on any passengers inside it would be 4000 times stronger than gravity. A suitably supported person, such as an astronaut in the space shuttle, flat on his or her back, can endure accelerations of up to about 6 g. Doubling the figure can bring loss of consciousness, and any accelerations much greater than that can rupture organs and blood vessels. 

Friedlander here again.
At 4000 gs one would expect strawberry jam on the couch. In  one long ago science fiction story I read  of someone who endured 30 G accelerations on a water filled couch which failed and he was extruded out a hole in the back or some equally horrible fate.

But 4000 g?  If we could survive that—the cosmos would be open to us, and for cheap.

By the way, if you recall THINGS TO COME by H.G. Wells, a key plot point was a crowd of rioters rushing a space gun (smooth move, dudes) trying to abort a launch. I am guessing the overpressure didn’t do them any favors. 

 However being younger then I was disgusted by the fact that they did not explain how they could survive the high Gs (At the time being naive I thought it was merely 1000 gs or so. As shown, it’s probably closer to 100000 (short barrel) But that is fiction.

Nice page below….guns… lots of guns... it will give you a feel for many possibilities in this field. Nuclear gun launch of course includes the Wang Bullet concept. (links further  below)

A fact company that has been covered by Brian Wang in this blog is Quicklaunch.


Friedlander here. The picture is not from Quicklaunch but illustrates how easy it is to get to high velocities with simple hydrogen oxygen mixtures– superhot hydrogen allows even greater velocities.

Sander Olsen writes there–

basic idea of Quicklaunch is that you launch a projectile from a cannon at 6 kilometers per second using compressed hydrogen gas. On a conventional rocket, the payload fraction is about 3%, whereas with our concept the payload is more than 20%. So we could get propellant into orbit for about a tenth the cost of using conventional rockets. 

Question: So QuickLaunch could be used to launch propellant canisters to orbiting depots? 
Answer:Yes, these depots will serve as orbiting gas stations. For most space missions, 90% of the cost is getting propellant into orbit. Each launch could lift 1,000 pounds of payload into orbit, and we are capable of about 5 launches per day, every day. So we could reasonably expect to be able to transfer 30,000 pounds of fuel to an orbiting depot within a week, if so desired. 

…if we try to send a single human to mars and back using only conventional rockets, the cost is $5 billion per person just for the fuel. By using our Quicklaunch, the cost would be only $500 million per person for the fuel. ….

We did G-tests in the 1990s on ruggedized satellites using the High G Test facilities at National Test Systems in Largo Florida. It turns out that many items, such as electronics, can be hardened to withstand high gs. Most cellphones are already hardened to withstand 1000 gs. 
Hardening surface mount electronics to withstand 3,200 gs only adds 2% to the weight of the object. 

Question: How much would it cost to assemble and prepare a Quicklaunch system? 
Answer: To get a system capable of launching 1,000 pound payloads to orbit into operation might cost $500 million. But constructing a proof of concept system that could hurl 100 pound payloads into orbit would cost only $50 million. Such a system could be quickly developed. 

Question: How long would it require to get the QuickLaunch system up and running? 
Answer: The main component – the cannon – is based on well understood principles and should not be difficult to perfect. There are four proposed development stages, and each stage should take two years. Phase 3, where we are actually launching payloads in the 100 pound range, would be in about the fifth year. The system would require roughly $500,000 per payload pound to develop, amortized over thousands of shots. So for example when amortizing over 10,000 launches, the capital cost is only $500,000/10,000= $50/lb. Naturally one must fold in the time value of money as well as the vehicle costs and the O&M. 

Question: Wouldn’t wear and tear on the cannon barrel be a major concern? 
Answer: Yes, really good preventive maintenance on the barrels is required. The barrel will have a liner which will need to be periodically replaced. That process would require about a week. We would also need to be very careful to get proper payload alignments. We will also do maintenance between every launch, which would probably limit the number of launches to 5 per day. 


Brian writes there–
Quicklaunch will cost $562 million to develop over 4 phases and 8 years
* One thousand pound payloads.
* 10-28% payload fraction (full scale system will have 28% payload fraction)
* the donuts around the tube are for bouyancy and for rigidity and precision alignment

* 97+% recapture of the hydrogen gas to recycle the gas
* Cellphone electronics are G hardened, just replace the transformers
* Bigger systems can be built
* Neutrally buoyant barrel made out of composite, so no gravitational sag

Quicklaunch designs shows that all of the high-g issues of my nuclear cannon design can be resolved. If larger projectiles have issues then can launch many smaller projectiles at the same time. The nuclear launch system can achieve the 9km/sec speed so no booster is needed. The nuclear cannon can have a deeper hole to allow reduced g-forces even when accelerating to 9 km/sec instead of 6 km/sec.


Friedlander here. As you can see, an ocean-suspended hydrogen gas gun which has the longest barrel length practical without building expensive land based structure– and it’s aimable given time, and can theoretically be towed to a near equatorial location for maximum trajectory choice.

A sabot is ejected at launch, an aeroshell is jettisoned at 100 km, a solid rocket uses most of the boost weight, but after all that cost to orbit is still a fraction of today. However if direct to escape blast were feasible the payload fraction would be far higher. 

Brian refers above to the Wang Bullet concept  This is nuclear explosive launch from below the ground or ocean with a single round, no airbursts like ORION.


Supportive posts with nuclear data for Wang Bullet Studies

This article was inspired by the speculation of Gershom Gale who  “introduced Dr. Tom Shaffer of Temple University (who had perfected liquid ventilation, which he had intended to employ in order to save premature children) to Dr. Henry Kolm, who had left MIT to found a company called Electromagnetic Launch Systems (which promised to put a two-ton payload into low Earth orbit in 1.9 seconds). 

Gale’s about page:  http://www.angelfire.com/my/theory/gale.html
BTW Gale’s interesting idea on why time flows ‘forward’ http://www.esek.com/jerusalem/timetrav.html
Gale says: It was my idea (subsequently favored by these two men) that filling an astronaut’s lungs with the breathable liquid developed by Dr. Shaffer and floating him in a similarly liquid-filled capsule (i.e. neutral density encapsulation) would make it possible to withstand the 1,000G forces generated by Dr. Kolm’s launch mechanism.”
This is Gale’s idea in his own words (shortened, whole thing at link)

Surviving 1,000G

One of the first problems that must be solved by any group planning to colonize space is getting there. Rockets are likely to be too slow, too dangerous, and far too expensive when substantial numbers of people, animals, and plants are involved.

Perhaps there is a better way. The electromagnetic launch system designed by Dr. Henry Kolm (formerly of MIT) offers the possibility of putting two-ton payloads into low-Earth orbit in less than two seconds, and with no risk of explosion. Furthermore, it may be able to do so at a rate of up to six payloads an hour at a price of about $10,000 a payload. The cost of developing such a system, says Kolm (who has formed his own company, Electromagnetic Launch Systems), would be considerably less than what has already been spent on the shuttle program.

Attaining escape velocity in two seconds, however, generates acceleration stress of close to 1,000 gravities. Up to now, there has been no way for human passengers to survive such stress. Neutral density encapsulation might make it possible.

Some years ago, Dr. Tom Shaffer of Temple University developed a liquid hydrofluorocarbon 

that can carry enough oxygen into the lungs to support mammalian life. His original purpose was to save severely premature infants, whose lungs are not able to handle gaseous oxygen. In this, he succeeded. Extensive animal studies and preliminary experiments with human infants show that his new liquid makes it possible to bring fetuses to healthy term after as little as 12 weeks in the womb.

Liquid Breathing Interview with Thomas Shaffer

 But the substance has other applications, one of which is to neutralize almost all the effects of acceleration stress.

Consider: What kills human beings at acceleration much over 30 g is not the acceleration itself, but the fact that the vehicle accelerates at a rate different from that of its passengers, and the different parts of the passengers’ bodies also experience different rates of acceleration. This is because of the differences in density between the astronauts’ bodies and the environment within the capsule, and differences in density between the lungs and the surrounding body tissues. So an unprotected human in a capsule accelerating at 1,000 g would be killed instantly for two reasons. First, in an air-filled capsule, the more dense human body, even if placed on an acceleration couch, would slam against that couch with bone-shattering force. Secondly, the relative density of the ribs and chest muscles compared to the air pockets in the lungs would cause the ribs to crush the lungs.

Neutral density encapsulation could perhaps solve both problems. The overall density of the human body is nearly the same as that of Shaffer’s liquid. By floating an astronaut in a capsule completely filled with the hydrofluorocarbon, and then accelerating the whole capsule, the first source of stress has been removed, since both the capsule and its occupant would now be accelerating at the same rate.

To better understand this point, remember the high-school science experiment with a raw egg. Placed loose inside a tin box which is then thrown against a wall, the egg shatters. If the box with the egg in it is filled with water, however, so that egg and box accelerate and decelerate at the same rate, the egg can survive the throw unbroken. The same principle was applied to living bodies during a rather cruel Italian experiment conducted in the 1960s. The researchers slammed a pregnant rat against a wall at 10,000 g. While the mother rat was killed instantly, the fetuses — floating as they were in sacs totally filled with amniotic fluid — survived.

The second source of stress — the difference in density (and hence rate of acceleration) between chest and lungs — can be neutralized by having the astronaut breath the liquid. The gag reflex can be overcome by adjusting the substance’s temperature and pH. Ethical considerations have so far prevented Shaffer from filling both lungs of a human volunteer, but one lung has been filled, and the liquid has been breathed and later coughed out without harm. Whatever was left in the lung was safely absorbed….
Neutral density encapsulation could thus permit the entire “package” — capsule, astronaut, chest, and lungs — to be accelerated or decelerated as a single-density whole. When the idea was presented to Shaffer and Kolm, they worked out the physics and concluded that, yes, floating a liquid-breathing astronaut in a completely liquid-filled chamber would offer full protection against up to 1,000 g.

Of course, if the ultimate goal is colonization of the galaxy, rather than merely the solar system, drive systems considerably more “potent” than Kolm’s may be required. A Swedish specialist in space medicine has speculated that, if the sinus cavities as well as the lungs are filled, it might be possible to survive even higher accelerations.

Friedlander here again.
Wiki is not so optimistic 

Acceleration protection by liquid immersion is limited by the differential density of body tissues and immersion fluid, limiting the utility of this method to about 15 to 20 G.
 Extending acceleration protection beyond 20 G requires filling the lungs with fluid of density similar to water. An astronaut totally immersed in liquid, with liquid inside all body cavities, will feel little effect from extreme G forces because the forces on a liquid are distributed equally, and in all directions simultaneously. 
However effects will be felt because of density differences between different body tissues, so an upper acceleration limit still exists.
Liquid breathing for acceleration protection may never be practical because of the difficulty of finding a suitable breathing medium of similar density to water that is compatible with lung tissue. Perfluorocarbon fluids are twice as dense as water, hence unsuitable for this application.

 Incidentally, if we could safety against a million G’s (We would need a nanotech infusion that would equalize body tissue densities)  we could heliobrake at the target star’s atmosphere so we would only have to pay for the outward trip which itself would be huge in terms of affording massive interstellar colonization. Combine that with an AB Matter tether at Jupiter as I have speculated on here 
and we would be able to do it with little net energy cost other than drawing down Jupiter’s rotational energy. 

But that is literally getting ahead of ourselves. Let’s focus on merely launching to earth escape velocity from the ground with some sort of high G launcher of 1,000-4000 Gs with humans aboard and surviving unharmed.

Brian Wang wrote about  the Johndale Solem Orion like asteroid interceptor that would have given a 1000 G launch a few years ago.

BTW, the original orion project had the design for an asteroid intercepter that would accelerate at about 1000 Gs. An unmanned Orion asteroid interceptor was designed. It would not need shock absorbers. Artillery arming, fusing, firing system for shells are regularly built to take 1000 Gs. There was a three page paper: Nuclear explosive propelled Interceptor for deflecting objects on collision course with Earth. Johndale Solem, Los Alamos, proposed unmanned vehicle. No shock absorber or shielding. The pulse units were 25kg bombs of 2.5 kiloton yield. Get to high velocities with only a few explosives and small shock absorbers or no shocks at all. Launch against a 100 meter chondritic asteroid coming at 25 km/sec. 1000 megatons if it hits. Launch when it is 15 million kilometers away and try to cause 10000km deflection. A minimal Orion weighing 3.3 tons with no warhead would do the job. 115 charges with a total of 288 kiloton yield. Launch to intercept in 5 hours. Ample time to launch a second if the first failed. https://www.nextbigfuture.com/2009/02/unmanned-sprint-start-for-nuclear-orion.html Sprinting out of the Magnetosphere Notice the unmanned high acceleration configurations would reduce the number of charges to go through the atmosphere to about 1-3 charges. Instead of 200 charges to go to orbit with constant lower acceleration. Kick it hard with 3 or fewer 100G force acceleration charges. (charges would go off every half second for fast acceleration instead of 1.1 seconds for human safe acceleration). It can head up at 100Gs. 980 m/s**2. So only 1-3 charges is enough to give escape velocity then coast. It is only a matter of containing the fallout from 1-3 low level charges. Plus 1-3 charges and that is it we have tens of thousands to millions of tons to start the space age. Some of the Orion configurations were for 1000Gs of acceleration. At 100G’s in 10 seconds it would be almost 50 kilometers up. 20 shots assuming one every 0.5 second. In 20 seconds it would be almost 200 kilometers up. Some more charges could be used to slow the Orion for a rendezvous with human passengers and acceleration sensitive cargo. They could then fly anywhere in the solar system at a leisurely pace without concern about fallout. Mars Express Another aspect of the fast acceleration that is possible is that an unmanned Orion go from earth or earth orbit to Mars (decelerate at halfway) and get to Mars in under one day going at 100Gs if Mars and Earth are in the close approach. If the unmanned version was going at 1000Gs (which was a design that is possible), then Earth to Mars could be done in a few hours. At about 300Gs and you would be looking at a Mars Overnight package delivery. Brian

A manned Soledale hotrod would give new opportunities to work on yelling Yahooo! through fluid filled lungs (could you even gurgle?)  But a manned Wang Bullet would give the same performance if it were possible to launch at 4000 Gs filling humans with fluid breathing liquid and with NO atmospheric nuclear explosions (just one underground or underwater) 

You will note that above Gale speculated on 1,000 Gs. Many systems need a bit higher than that so I am setting the bar at a nominal 4000 Gs in which encapsulated electronics can survive. 

What would be the design rules for stuff going up?

Compact design. If fluid has to fill every void space there can’t be a lot of void space unless you have a huge system.  With the Wang Bullet this is not a problem but with the reference Kolm Launcher it is.

No evacuated spaces.  This is the biggest rule. Not only the lungs, the sinuses would be filled. Astronauts would literally wear wetsuits, fluid containing suits in which they had been sealed (I am not sure I am joking when I can envision a CAT scan directly after sealing in the suit just to be sure).  The early 60’s astronauts joked about spam (the meat, not the email) in a can– we are talking about spam in a beverage bag.  They get loaded in their ship and the ship itself filled with (possibly a different) fluid. Ideally the time from sealing in to direct to escape is so small that literally an hour later– they have been in space for half an hour.

(note that sanitary arrangements are assumed and can be discussed but not  here. The main concern being that you not only need to be able to take care of bathroom needs waiting for a launch but before a high -G landing. In other words, you may need to stay liquid-packed during the whole Earth-Moon run if you want to try for a high G-landing.)

 Yes, even though direct impacts at over 300 m/s tend to leave powder in their wake,   not whole ships, (see F-4 Phantom dispute with wall movie below)

 there might be ways to totally cut the mass ratio of payload up to payload down if you could take say 4000 gs deceleration as well as acceleration.) (actually even 50 to 500 Gs would be huge) The penalty is you need to stay in your G-suit for however much time to get to your destination) 

For example the Zond capsules of the USSR would have killed a cosmonaut if they had encountered the 20-30 G forces in certain possible return trajectories. 

All L1/Zond spacecraft made only unmanned flights from 1967–70, from (Zond 4 toZond 8), and four of these five Zond flights suffered malfunctions.
Test flights conducted around the Moon showed problems using their star sensors for navigation. These problems caused ballistic reentry due to the failed guidance. One direct descent re-entry was performed on a steep ballistic trajectory with deceleration of up to 20 Gs and splashed down in the Indian Ocean. Three others performed a maneuver known as “skip reentry” to shed velocity. One of those also performed an unsafe (for humans) descent of up to 20 Gs of deceleration, the other suffered main parachute failure, and only one flight – Zond 7 – would have been safe for cosmonauts.

For example again the Pioneer Venus Multiprobe 
they encountered 458 Gs in a very swift deceleration.  http://www.mrc.uidaho.edu/entryws/presentations/Papers/bienstock_pioneer%20venus%20and%20galileo%20probe%20history-final.pdf
Ability to take high Gs on demand would enable many exotic mission profiles and return trajectory profiles and probably someday save lives. 

I have a rotary tether in mind on the moon or something akin to but longer than an aircraft carrier arrestor system 
that could pull on the surface skimming (you need the right angle and incoming trajectory) capsule as it comes into the moonbase. (The first missions to build the braking base would be blasted up, retro-rocket down. But by saving the half your weight in fuel you’d need to retro each capsule up the capture system of the moonbase would rapidly pay for itself)
This would only work for many smaller loads such as the reference Kolm Launcher mentioned above. Imagine a 12 ton launched, losing a few hundred kilos of heatshield on the way up, rocketing down to the moon, and you will find maybe 6 tons lands dry, maybe less and most of that is salvagable structure (say 2/3–high G capsules are built sturdily) and void filling fluids (besides the breathing fluid, these could include water, propane, liquid ammonia (on unmanned flights) and other candidates– but they aren’t really payload unless someone on the base asked for them and will pay for them)  Net real payload might be under a ton and a half on a 12 ton launch.  My model of this is two people might launch simultaneously but it might only be  one. So if 6 shots an hour, 8 hours a day (the Earth rotates and not every trajectory up is ideal for a prompt Moon landing, only the best windows are for manned missions, the other payloads need to take their time down) you have 48 shots a day, a few of which might be manned, and maybe 60 tons net payload down.  The Saturn V system might have been rigged for a direct landing of the 3rd stage or with 3 bottom stage only lunar modules to give say 15-18 tons down. So the equivalent of over 3 Saturn Vs a day, or a thousand a year.  That basically can build a couple Skylab base modules a day, or a large Moonbase 2001 or Space 1999 style in a year.

But if you could snag the 12 tons coming in and not waste 6 tons of that in retro fuel you could probably quadruple the net payload. So first you rocket down, and build the landing base. Then you operate a lunar capture port and ship more people, livestock, plants and industrial equipment and start building and launching spacecraft on the Moon for tether launch to space (including a L-5 shipyard for large structures) 

How might we capture large payloads at high G on the Moon? Direct crashing won’t work unless we can build a retro tunnel in which to hit the incoming craft with gas streams of some kind in which it can retro. This gas need not be a permanent gas but could be sodium vapor for example that would not ruin the lunar vacuum.
Another approach would be a hovering capture hook.
The main idea would be a mass driver on the surface speeds up (on a hovertrack with magnetic suspension)  something akin to a rocket sled that lifts a hook up to the incoming spacecraft at something under 300 m/sec relative velocity. Only the capture eyelet on the spacecraft need be built superstrong. Hooked, and then the spacecraft can decelerate at at least hundreds of Gs if not thousands at quite a reasonable encounter length.

If that idea doesn’t work, Kraft Ehricke came up with an elaborate treatment of using lunar dust runways to slow down with 1/10th the fuel (for hover as you brake using skids)

If that idea doesn’t work, this rocket sled which is going better than lunar escape velocity  8,568 km/h is slowed down by liquid drag through liquid braking. 

So we can imagine a liquid runway of molten sodium metal as detailed here https://www.nextbigfuture.com/2016/01/the-future-of-canal-transport-take_3.html with a rocket sled brake accelerated to docking speed on a mass driver along side and the capsule hooking on and decelerating at high G sloshing liquid sodium in a great plume.

There are many other lower G ways to decelerate if you want to get out of the wetsuit right after reaching escape. For example hooking on to a lunar rotovator and enduring 8 Gs at 100 km radius as you are decelerated.  But the whole focus of this article is cool things you can do at high G so we are weighting it toward those scenarios.

I am assuming the astronauts would want to launch being awake. But if you want to keep consumption of oxygen to a minimum you could chill them and put them to sleep this way while liquid filling them.  I personally would want to be awake every minute during my first space mission but I am guessing there are a lot of people who just want to go to sleep on Earth and wake up on the Moon with no worries in between.

Which would you prefer? 19 hours-3 days in a wetsuit with waste filtering  awake or asleep?

There is a sweet spot on the trip duration and delta v requirements even if ANY launch speed is possible. If you go to bare escape velocity you take 5 days to get to the Moon and impact at the lowest possible speed.  If you up the launch delta v a bit, not much over 12 km/sec launch net speed would get to the moon not in 5 days or even 3 but 19 hours. 
New Horizons left at 16.3-5 km/sec (the first thing launched to solar escape directly IIRC) and could have reached (and impacted) the moon at 8 hours 35 minutes after launch. It passed the Moon’s orbit by.New Horizons went past lunar orbit in under 9 hours

But if you had to brake as you are retrofiring onto the moon’s surface you want a low incoming speed. So I am guessing the sweet spot is a bit over 12km/sec for explosive or high-G launch and as slow a landing as possible for under 3 km/sec delta V needed.  

There is a claim which I am not sure I believe that the very first thing to impact the Moon on September 1 1959 from the USSR retrofired by explosive charge to give its commemorative medallion a chance to survive impact.  

It also carried metal pendants which it scattered on the surface on impact, with the hammer and sickle of the USSR on one side and the launch date on the other. – See more at: http://www.historytoday.com/richard-cavendish/soviet-union-first-moon#sthash.AN79osgn.dpuf

Or at least a ghost of chance. Not sure if that story is real and no photographs from the surface have yet proved it.  But by dynamics, if not retrofired those medallions had this happen to them 

with 8 times the velocity and 64 times the energy.
Explosive deceleration would be tricky but might pay if for example aluminum/liquid oxygen charges were locally makable on the moon. But would detonation velocity be in the right range? It might be very hard to match compared to say a spray of liquid or gas in the path of the oncoming capsule.
For that reason I think explosive slowdown isn’t as likely as explosive launch. But the high-G deceleration capability for manned missions would enable astounding things.

One can imagine 1000G shielded astronauts surviving an asteroid aerocapture event as the successful return of a one-way manned asteroid mission. 
Go to the asteroid ALMOST in an encounter with Earth trajectory, 

nudge it a bit years in advance, stay with the asteroid working on it to form it into an aerocapture friendly shape, then ride it into a highly eccentric earth orbit (Low point is capture necessity, high point because you don’t want it circularizing at the low altitude circular orbit which would herald atmospheric reentry!)  With one mission Earth would have a literal new moon and a huge new space station possibly of kilometer scale. 
 IF the world community would ever permit it.

Some posts of mine that discuss problems of lunar landing and colonization, Lunar and Space  Industrial buildup—and what to do with it:

Some other articles on 





And other Wang Bullet collaborations:


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