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February 25, 2009

In Praise of Large Payloads for Space by Joseph Friedlander Part 1

Hi, everybody this is Joseph Friedlander, in a guest article series on Nextbigfuture.

In this series I hope to discuss first some of the largest systems proposed to reach orbit with big payloads, and then why it’s a lot better (for equal cheapness) to have one big payload than say a million 30 kg payloads launched for a given project—and then some discussion of what those projects might be!

UPDATE: Pointers to critique and debate about this article.

The launch systems of huge size are
• LIBERTY SHIP
• ALDEBARAN
• SEA DRAGON
• ORION and SUPER-ORION



Without cheap prices per kilogram orbited and without huge mass throughput to space, the only business models so far that have made large-scale financial sense are data gathering and relay through satellites. This series will consider other business models as well.

• Brian has previously written of the LIBERTY SHIP, --1000 tons to orbit, 1000 tons coming back too—long life because huge weight margins with 29 km/ sec exhaust velocity of hydrogen and actually can retro down to decelerate, not burning via atmospheric braking, for far less stress on its reinforced ship-like structure—leading to long life.













Similar performance but much greater size both of ship and payload for the
• ALDEBARAN












The Aldebaran concept by Dandridge Cole, ca. 1960
Aldebaran vs Ocean Liner—50000 tons at takeoff

























Cost data on Aldebaran






60 million pounds (30000 tons to LEO or 45 million pounds 22,500 tons to lunar surface)

3000 isp (specific impulse) 29419.9 m/sec gas core reactor exhaust velocity
Could also be 22500 tons to a Near Earth Asteroid, since many of them have less delta-v than the 6-6.3 kilometers per second from Low Earth orbit to the Moon’s surface and the surface of Mars.

For comparison, delta-v for transferring from low-Earth orbit to rendezvous
with the Moon and Mars:
Moon: 6.0 km/s
Mars: 6.3 km/s
Delta V for many near earth asteroids by order of ease:

Delta V for many near earth asteroids by order of apparent size:

(H is the symbol of absolute magnitude, so a ranking by this makes dark large asteroids possibly underranked relative to true sizes, because they reflect less light and are dimmer as if small)

Delta V calculator for isp-m/sec conversions, mission analysis


pdf containing Cole’s design pictures and colonization ideas—also colony concepts by him and Kraft Ehricke

Paper by Kraft Ehricke

Wikipedia on Dandridge Cole, space visionary

Roy Scarfo’s artwork illustrating Dandridge Cole’s Macrolife concept of colonizing asteroids: (in his own words) the “Inside-out World,” the external view; the other of the set was the “Inside-out World,” the internal view.



Art by the great Roy Scarfo illustrating Dandridge Cole’s Concepts-- Philosophy Inc scans from Beyond Tomorrow (great out of print Cole Book, art by Roy Scarfo)]
Mention of Cole’s ideas about blow-molding molten asteroidal material to giant colony hulls-- the "nomadic pseudo-earth," as Cole and Cox called their conception, would be the hollowed out space inside a captured asteroid. The result would be a "gigantic geodesic interior chamber," created "in much the same way as a glassblower shapes a small solid lump of molten glass into a large empty bottle."

600 square miles of land in an asteroid--











Outside view—note the motors--












Also the unique lighting system without the vulnerable windows of O’Neill Colony designs—TWICE the land surface, too!



Notice that engines could be fitted on the colonized asteroid, as well as a mass driver for accelerating with man-tolerable G forces —over many kilometers small ships and capsules for delivery to Earth with but small effect on the massive colony’s trajectory.

5 Gs will accelerate to 3 km second over 60 seconds--- length determined by
.5 * (50 meters a second acceleration) * (number of seconds squared—to determine this, you divide desired final speed by tolerated acceleration so 3000/50=60 seconds)
.5 * 50 * 60 squared
25 * 3600 = 90 kilometers = length of accelerator—about 54 miles. Kind of like a rocket sled but can be propelled electrically or by other means.

Such an accelerator on the Moon could throw you to Earth or on a trajectory to Venus or Mars orbit.

On an asteroid it could throw you (depending on the asteroid) back to Earth orbit with net payload in a retro capsule built from materials on the asteroid itself. Theoretically as long as you have a locating device, it can reenter and float in the ocean, it can be as cheap as a sewer pipe—it’s up that’s expensive in space, not necessarily down. And with cheap downward shipments you can make money back. In other words, exports would pay for the program over time.



Asteroid with linear motor












SEA DRAGON 550 tons to low earth orbit
More Robert Truax data on Sea dragon and other vehicles (sea launched a Truax specialty—why pay for a launch pad?)

Look at the size of that thing—yet it is the smallest payload of any non-NASA system considered here—“only” 550 tons—because it uses regular chemical rockets, not nuclear. Note that Sea Dragon above could have orbited a preassembled equivalent to the 227 ton International Space Station-- and years of supplies in one whack, and a heavier cheaper version at that—under $1 billion versus $100 billion. More on mission architectures later in the series…



Saturn 5 to same scale as Sea Dragon. Saturn 5 on the right












I believe NASA should drop this Ares 1 and Ares 5 nonsense.

The proposed Ares I configuration has been criticized on several grounds. The production of a launch vehicle in the 25 tonnes (55,000 lb) payload class can be seen as direct competition with existing vehicles such as the Boeing Delta IV-Heavy. It can be argued that lower costs and improved safety are likely to result from the use of an existing vehicle, since it would have lower development costs, a proven track record, and would benefit from a higher flight rate…



a superior for less version would be the Direct scenario











The key program risk, according to DIRECT, is that NASA's Ares I is already over-budget, late and is lacking in performance, so when serious funding is required for the much larger and more expensive Ares V, Congress is not likely to be impressed. The risk is that Congress may pull the budgetary plug on the Heavy Lift effort before it is complete. This would leave NASA with a very expensive, yet small, Ares I launcher and no heavy-lift capability to enable any Lunar or Martian exploration programs in the future, but even Direct is still too expensive (but if Congress
is determined to save the Shuttle industrial base, it is a better way than the Ares vehicles) rather, for cheapest spaceflight, if NASA is really determined to build a non nuclear system-- build the Sea Dragon – for reasons to be stated later in this series but revolving around lower cost of development and per kilogram to orbit-- (the fact that from orbit with enough mass to play with radically cheaper spaceships are possible—of which more anon.)

• PROJECT ORION, which Brian has covered extensively on this site:
here and here and other articles.

Many have focused on the 40 meter diameter 4000 ton Orion but this is one concept that scales so well that the bigger (within reason) the better.



The Super-Orion we will consider here is the 8 million ton model. This alas is not 8 million tons to orbit but rather an extrapolation of the 4000-ton model—1/4 each payload, structure, pusher plate, and bomb units (fuel/reaction mass)
So in this case 2 million tons of each. Note that in most cases nearly all the ship and pusher mass would be usable in some way as construction materials or at least as shielding or reaction mass. So 2 million tons of payload, and 2 million tons of ship/station/base (the ISS is 227,267 kg as of last report) so the equivalent of 8800 International Space Stations—This implies the ability to drop colonies, outposts and miner’s settlements throughout a given area. Imagine a flight around Jupiter, stopping at each of the 61 moons (or multiple sites on the biggest ones) and putting a colony of 1000 people (including a small medical center) at each one. Resources could be identified and mined, all in one mission, and a trading economy set up in the Jupiter system. But more on mission scenarios later.

It is superfluous to talk about the Super-Orion or indeed the regular Orion without touching on the issue of nuclear contamination.

The problem about launching bomb-propelled ships anywhere in the magnetosphere, is that the thermonuclear bomb debris comes down to Earth, captured and sucked in along magnetic lines of force. Therefore you really want a polar exit through the doughnut holes of Earth’s magnetic field to escape velocity, then go to your desired target at a great distance.



There are other tricks that may be useful to limit fallout, but the key thing is minimizing the fission fraction of each bomb.
With a standard 5 Kiloton primary of a B-61 nuclear bomb,

(Using the Russian trick of NO sparkplug in the secondary, used for that 30 KT incremental Peaceful Nuclear Explosion sealed secondary unit of theirs –presumably at a considerable tritium cost, as in a neutron bomb--) you could get 99.9% fusion, better than 98% for Tsar Bomba.

So the total fission product fallout for 1000 bombs would be on the order of 5 megatons which is one bomb test in the old days of 1952-63.

If you could further mess with the design you might be able to get the total fission down to 1 megaton. The problem is keeping the units affordable (Tritium is $30000 a gram) and you need about $90000 worth for each primary, and who knows how much for each fission free secondary.

All of this totally neglects the problems of messing with a known to work primary configuration which would take many now banned weapons tests to recertify (one reason why DOE keeps 5000 old pits at Pantex for a ‘rainy day!’)

As for developing from scratch a new primary, it seems unlikely the people objecting to fallout would rejoice in new low yield primary development—historically they never have.

As Brian has written, Orion's propulsion units would be inert material such as polyethylene, or boron salts, used to transmit the force of the propulsion unit's detonation to the Orion's pusher plate, and absorb neutrons to minimize fallout

--that is to stopping neutron activation of Nitrogen-17 to become Carbon 14 which is not good for living things. It can directly become part of nucleus- DNA (DNA) in a given cell. It will be flushed out over time but meanwhile there is exposure. That is why you want to stop it before it starts, and boron very probably will do that. This was an idea by Freeman Dyson.

There remains the problem of tritium contamination.

Tritium Units where 1 TU is defined as the ratio of 1 tritium atom to 10**18 hydrogen atoms. As noted earlier, nuclear weapons testing, primarily in the high-latitude regions of the Northern Hemisphere, throughout the late 1950’s and early 1960’s introduced large amounts of tritium into the atmosphere, especially the stratosphere. Before these nuclear tests, there were only about 3 to 4 kilograms of tritium on the Earth’s surface; but these amounts rose by 2 or 3 orders of magnitude during the post-test period.

Lets just say that in the peak year 1963 of Tritium contamination, Kodak had to take precautions against slightly clouding the film when they made it according to a story I heard.

Each megaton of fusion is said to put out 1.5 kg of byproduct tritium, unrecoverable and dilute. Obviously you want to immobilize that.

I believe that bizarre as it sounds the best thing to do is take off in the largest polar blizzard of the winter so things are immobilized near the ground in the snow (where they can decay in peace). It is a mark of the power of the Super-Orion that you can plan to take off in any weather with absolute impunity- the weather has to be afraid of Super-Orion, not the other way around!

I am just remembering the reference to Antarctica Control in the 1979 movie Alien. That makes sense (Southern Ocean in storm into polar radiation doughnut exit hole) so you fly up the South Pole from the Southern Ocean. You tow to there from the shipyard.

The rule of thumb I am working on is that if a 4000 ton regular Orion uses one thousand 5 kiloton charges, then a 2250 times heavier Super Orion— (off the cuff design consistent with known facts) might approximate--
9 million tons gross weight
-2 million tons payload
-2 million tons structure
-2 million tons pusher plate
-3 million tons pulse units/charges (about 4 tons of bomb with about 3000 tons of plasma-generating and support material to be energized making up just one single working charge for a Super-Orion with the mass of a Saturn V! Per unit!)
(and you will be using 1000 of these to Earth escape velocity.)

Super Orion would take say one thousand 10-12 megaton charges. This is roughly equivalent to a W-53 bomb. or about half of a W-41 bomb

Note that these are not regular bombs but pulse devices with attached reaction mass to be energized and directed in a fan cone of not more than 22.5 degrees dispersal.

That is efficient fusion of around 120-140 kg of D-D or rather more 160-180 kg Li6D. That is to escape velocity, more for the home trip. So a few hundred tons of fusion fuel. Note the pulse units are 3 million kilograms, but the expensive parts are actually ‘small’ in mass. Note also that a few thousand tons heated to many tens of thousands of degrees will eat up megatons of energy—because it radiates by the fourth power of the temperature difference. (Just to melt rock, it would melt a perhaps a few million tons per bomb) Again, this bracketing logically puts us in the several to 20 megaton range. Between a W-38 and a W-41 but 5kt maximum fission content, please!

This also means that the 8 million ton Orion “only” has 2 million tons of payload. You’d need a 32+ million ton Orion for 8 million tons of pure payload.
Still one hundred thousand 20 ton Shuttle or Ariane V kind of payloads isn’t bad.

G. Harry Stine once wrote that a large thermonuclear device detonated in the geostationary arc would create trapped radiation that could destroy every satellite there, so you definitely want the Super-Orion to avoid that flight path!

This ends Part 1. In future parts we shall consider what we might do with such wonder ships…

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