IBS Agamemnon
Total ΔV	280,000 m/s
Specific Power	39 kW/kg (39,000 W/kg)
Thrust Power	1.1 terawatts
Exhaust velocity	220,000 m/s
Thrust	10,000,000 n
Wet Mass	100,000 mt
Dry Mass	28,000 mt
Mass Ratio	3.57
Ship Mass	8,000 mt
Cargo Mass	20,000 mt
Length	400 m
Length spin arm	100 m
T/W >1.0	no

IBS Agamemnon (Interplanetary Boost Ship) masses 100,000 tons as she leaves Earth orbit. She carries up to 2000 passengers with their life support requirements. Not many of these will be going first-class, though; many will be colonists, or even convicts, headed out steerage under primitive conditions.

Her destination is Pallas, which at the moment is 4 AU from Earth, and she carries 20,000 tons of cargo, mostly finished goods, tools, and other high-value items they don't make out in the Belt yet. Her cargo and passengers were sent up to Earth orbit by laser-launchers; Agamemnon will never set down on anything larger than an asteroid.

She boosts out at 10 cm/sec², 1/100 gravity, for about 15 days, at which time she's reached about 140 km/second. Now she'll coast for 40 days, then decelerate for another 15. When she arrives at Pallas she'll mass 28,000 tons. The rest has been burned off as fuel and reaction mass. It's a respectable payload, even so.

(ed note: in reality, the maximum amount of thrust a single ion drive could put out is about 10,000 newtons, not 10,000,000 like the Agamemnon is cranking out.)

The reaction mass must be metallic, and it ought to have a reasonably low boiling point. Cadmium, for example, would do nicely. Present-day ion systems want cesium, but that's a rare metal—liquid, like mercury—and unlikely to be found among the asteroids, or cheap enough to use as fuel from Earth.

In a pinch I suppose she could use iron for reaction mass. There's certainly plenty of that in the Belt. But iron boils at high temperatures, and running iron vapor through them would probably make an unholy mess out of the ionizing screens. The screens would have to be made of something that won't melt at iron vapor temperatures. Better, then, to use cadmium if you can get it.

The fuel would be hydrogen, or, more likely, deuterium, which they'll call "dee." Dee is "heavy hydrogen," in that it has an extra neutron, and seems to work better for fusion. We can assume that it's available in tens-of-ton quantities in the asteroids. After all, there should be water ice out there, and we've got plenty of power to melt it and take out hydrogen, then separate out the dee.

(ed note: 1,100 gigawatts requires burning about 0.014 kilograms of deuterium per second. For 30 days total burn time this will require about 36 metric tons of deuterium.)

If it turns out there's no dee in the asteroids it's not a disaster. Shipping dee will become one of the businesses for interplanetary supertankers.

• 

MAYDAY MAYDAY MAYDAY. THIS IS PEGASUS LINES BOOSTSHIP AGAMEMNON OUTBOUND EARTH TO PALLAS. OUR MAIN ENGINES ARE DISABLED. I SAY AGAIN, MAIN ENGINES DISABLED. OUR VELOCITY RELATIVE TO SOL IS ONE FOUR ZERO KILOMETERS PER SECOND, I SAY AGAIN, ONE HUNDRED FORTY KILOMETERS PER SECOND. AUXILIARY POWER IS FAILING. MAIN ENGINES CANNOT BE REPAIRED. PRESENT SHIP MASS IS 54,000 TONS. SEVENTEEN HUNDRED PASSENGERS ABOARD. MAYDAY MAYDAY MAYDAY.

---

The other screen lit, giving us what the Register knew about Agamemnon. It didn't look good. She was an enormous old cargo-passenger ship, over thirty years old—and out here that's old indeed. She'd been built for a useful life of half that, and sold off to Pegasus Lines when P&L decided she wasn't safe.

Her auxiliary power was furnished by a plutonium pile. If something went wrong with it, there was no way to repair it in space. Without auxiliary power, the life-support systems couldn't function.

---

I switched the comm system to Record. "Agamemnon, this is cargo tug Slingshot. I have your Mayday. Intercept is possible, but I cannot carry sufficient fuel and mass to decelerate your ship. I must vampire your dee and mass, I say again, we must transfer your fuel and reaction mass to my ship.

"We have no facilities for taking your passengers aboard. We will attempt to take your ship in tow and decelerate using your deuterium and reaction mass. Our engines are modified General Electric Model five-niner ion-fusion. Preparations for coming to your assistance are under way. Suggest your crew begin preparations for fuel transfer. Over."

---

The Register didn't give anywhere near enough data about Agamemnon. I could see from the recognition pix that she carried her reaction mass in strap-ons alongside the main hull, rather than in detachable pods right forward the way Slinger does. That meant we might have to transfer the whole lot before we could start deceleration.

She had been built as a general-purpose ship, so her hull structure forward was beefy enough to take the thrust of a cargo pod—but how much thrust? If we were going to get her down, we'd have to push like hell on her bows, and there was no way to tell if they were strong enough to take it.

---

The refinery crew had built up fuel pods for Slinger before, so they knew what I needed, but they'd never made one that had to stand up to a full fifth of a gee. A couple of centimeters is hefty acceleration when you boost big cargo, but we'd have to go out at a hundred times that.

---

They launched the big fuel pod with strap-on solids, just enough thrust to get it away from the rock so I could catch it and lock on. We had hours to spare, and I took my time matching velocities. Then Hal and I went outside to make sure everything was connected right.

---

Slingshot is basically a strongly built hollow tube with engines at one end and clamps at the other. The cabins are rings around the outside of the tube. We also carry some deuterium and reaction mass strapped on to the main hull, but for big jobs there's not nearly enough room there. Instead, we build a special fuel pod that straps onto the bow. The reaction mass can be lowered through the central tube when we're boosting.

Boost cargo goes on forward of the fuel pod. This time we didn't have any going out, but when we caught up to Agamemnon she'd ride there, no different from any other cargo capsule. That was the plan, anyway. Taking another ship in tow isn't precisely common out here.

Everything matched up. Deuterium lines, and the elevator system for handling the mass and getting it into the boiling pots aft; it all fit.

---

Ship's engines are complicated things. First you take deuterium pellets and zap them with a big laser. The dee fuses to helium. Now you've got far too much hot gas at far too high a temperature, so it goes into an MHD system that cools it and turns the energy into electricity.

Some of that powers the lasers to zap more dee. The rest powers the ion drive system. Take a metal, preferably something with a low boiling point like cesium, but since that's rare out here cadmium generally has to do. Boil it to a vapor. Put the vapor through ionizing screens that you keep charged with power from the fusion system.

Squirt the charged vapor through more charged plates to accelerate it, and you've got a drive. You've also got a charge on your ship, so you need an electron gun to get rid of that.

There are only about nine hundred things to go wrong with the system. Superconductors for the magnetic fields and charge plates: those take cryogenic systems, and those have auxiliary systems to keep them going. Nothing's simple, and nothing's small, so out of Slingshot's sixteen hundred metric tons, well over a thousand tons is engine.

Now you know why there aren't any space yachts flitting around out here. Slinger's one of the smallest ships in commission, and she's bloody big. If Jan and I hadn't happened to hit lucky by being the only possible buyers for a couple of wrecks, and hadn't had friends at Barclay's who thought we might make a go of it, we'd never have owned our own ship.

When I tell people about the engines, they don't ask what we do aboard Slinger when we're on long passages, but they're only partly right. You can't do anything to an engine while it's on. It either works or it doesn't, and all you have to do with it is see it gets fed.

It's when the damned things are shut down that the work starts, and that takes so much time that you make sure you've done everything else in the ship when you can't work on the engines. There's a lot of maintenance, as you might guess when you think that we've got to make everything we need, from air to zweiback. Living in a ship makes you appreciate planets.

Space operations go smooth, or generally they don't go at all.

---

When we were fifty kilometers behind, I cut the engines to minimum power. I didn't dare shut them down entirely. The fusion power system has no difficulty with restarts, but the ion screens are fouled if they're cooled. Unless they're cleaned or replaced we can lose as much as half our thrust—and we were going to need every dyne.

---

His face didn't change. "Experienced cadets, eh? Well, we'd best be down to it. Mr. Haply will show you what we've been able to accomplish." They'd done quite a lot. There was a lot of expensive alloy bar-stock in the cargo, and somehow they'd got a good bit of it forward and used it to brace up the bows of the ship so she could take the thrust. "Haven't been able to weld it properly, though," Haply said. He was a young third engineer, not too long from being a cadet himself. "We don't have enough power to do welding and run the life support too."

Agamemnon's image was a blur on the screen across from my desk. It looked like a gigantic hydra, or a bullwhip with three short lashes standing out from the handle. The three arms rotated slowly. I pointed to it. "Still got spin on her."

"Yes." Ewert-James was grim. "We've been running the ship with that power. Spin her up with attitude jets and take power off the flywheel motor as she slows down."

I was impressed. Spin is usually given by running a big flywheel with an electric motor. Since any motor is a generator, Ewert-James's people had found a novel way to get some auxiliary power for life-support systems.

---

Agamemnon didn't look much like Slingshot. We'd closed to a quarter of a klick, and steadily drew ahead of her; when we were past her, we'd turn over and decelerate, dropping behind so that we could do the whole cycle over again.

Some features were the same, of course. The engines were not much larger than Slingshot's and looked much the same, a big cylinder covered over with tankage and coils, acceleration outports at the aft end. A smaller tube ran from the engines forward, but you couldn't see all of it because big rounded reaction mass canisters covered part of it.

Up forward the arms grew out of another cylinder. They jutted out at equal angles around the hull, three big arms to contain passenger decks and auxiliary systems. The arms could be folded in between the reaction mass canisters, and would be when we started boosting. All told she was over four hundred meters long, and with the hundred-meter arms thrust out she looked like a monstrous hydra slowly spinning in space.

---

The fuel transfer was tough. We couldn't just come alongside and winch the stuff over. At first we caught it on the fly: Agamemnon's crew would fling out hundred-ton canisters, then use the attitude jets to boost away from them, not far, but just enough to stand clear.

Then I caught them with the bow pod. It wasn't easy. You don't need much closing velocity with a hundred tons before you've got a hell of a lot of energy to worry about. Weightless doesn't mean massless.

We could only transfer about four hundred tons an hour that way. After the first ten-hour stretch I decided it wouldn't work. There were just too many ways for things to go wrong.

"Get rigged for tow," I told Captain Ewert-James. "Once we're hooked up I can feed you power, so you don't have to do that crazy stunt with the spin. I'll start boost at about a tenth of a centimeter. It'll keep the screens hot, and we can winch the fuel pods down."

He was ready to agree. I think watching me try to catch those fuel canisters, knowing that if I made a mistake his ship was headed for Saturn and beyond, was giving him ulcers.

First he spun her hard to build up power, then slowed the spin to nothing. The long arms folded alongside, so that Agamemnon took on a trim shape. Meanwhile I worked around in front of her, turned over and boosted in the direction we were traveling, and turned again.

The dopplers worked fine for a change. We hardly felt the jolt as Agamemnon settled nose to nose with us. Her crewmen came out to work the clamps and string lines across to carry power. We were linked, and the rest of the trip was nothing but hard work.

We could still transfer no more than four hundred tons an hour, meaning bloody hard work to get the whole twenty-five thousand tons into Slinger's fuel pod, but at least it was all downhill. Each canister was lowered by winch, then swung into our own fuel-handling system, where Singer's winches took over. Cadmium's heavy: a cube about two meters on a side holds a hundred tons of the stuff. It wasn't big, and it didn't weigh much in a tenth of a centimeter, but you don't drop the stuff either.

Finally it was finished, and we could start maximum boost: a whole ten centimeters, about a hundredth of a gee. That may not sound like much, but think of the mass involved. Slinger's sixteen hundred tons were nothing, but there was Agamemnon too. I worried about the bracing Ewert-James had put in the bows, but nothing happened.

Three hundred hours later we were down at Pallasport.

• 

Their first impression was of a bundle of huge cigars. Those were the big fuel tanks almost a hundred meters long. They were so large that they dwarfed the rest of the ship, and ran the entire length of midsection. Behind the "cigars" was a solid ring that held three rocket motors. Then at the end of a spine as long as the main body of the ship was the nuclear reactor and another rocket motor.

This was the real drive. The three chemical rockets were only for steering and close maneuvering. Wayfarer's power came from her atomic pile. The cigar-shaped tanks held hydrogen, which was pumped back to the reactor where it was heated up and spewed out through the rear nozzle. A ring of heavy shielding just forward of the reactor kept the pile's radiation from getting to the crew compartment. The rest of the pile wasn't shielded at all.

Despite the large size of the ship, the crew and cargo sections seemed quite small. There were some structures reaching back from the forward ring where the control room was. Two of those were passenger quarters. The other was another nuclear power unit to make electricity to run the environmental control equipment, furnish light for the plants, power to reprocess air, and all the other things the ship and passengers and crew would need. There was a big telescope and a number of radar antennae on the forward section.

The scooter pilot was careful not to get near the reactor in the ship's "stinger."

---

The ship had been designed for sixty passengers. She carried twice that number plus eight crew.

---

The internal space was constructed in a series of circular decks. Each deck had an eight-foot hole in its center, so that from the forward end, just aft of the separately enclosed control cabin, Kevin could look all the way aft to the stern bulkhead. Although there was a long and rather flimsy-appearing steel ladder stretching from aft to forward bulkhead, no one used it.

---

"F deck," the crewman said "A deck is the bridge. B is the wardroom. C, D, and E are the three aft of that. E happens to be the recreation and environmental control. Yours is the one beyond that. They're marked."

---

Finally he reached F deck, which he found to be sectioned into slice-of-pie compartments arranged in a ring around the central well, fifteen of them in all. He found the one marked "12" and went in.

His "stateroom" was partitioned off with a flexible, bright blue material that Kevin thought was probably nylon. The door was of the same stuff and tied off with strings. It didn't provide much privacy.

Inside the cramped quarters were facilities for two people. There were no bunks, but two blanket rolls strapped against the bulkhead indicated the sleeping arrangements. It made sense, Kevin thought. You didn't need soft mattresses in space. "Sleeping on a cloud" was literally true here. You needed straps to keep you from drifting away, but that was all.

One viewscreen with control console, a small worktable, and two lockers about the size of large briefcases completed the furnishings.

---

The incident reminded Kevin that he was in free fall, and his stomach didn't like it much. He gulped hard. "I'll be glad when we're under way," he said. "It won't last long, but it will be nice to have some weight again. Even for a day or so."

Norsedal frowned and rolled his eyes upward for a moment. "Not that long, I'm afraid," he said. "Let's see, total velocity change of about five kilometers a second, at a tenth of gravity acceleration—five thousand seconds." He took a pocket computer off his belt and punched numbers. "An hour and a half. Then we're back in zero-gravity."

---

Weight felt strange. The ship boosted at about ten percent of Earth's gravity, but Kevin found that quite enough. All over the ship loose objects fell to the decks.

---

Ninety minutes later the acceleration ended. Wayfarer was now in a long elliptical orbit that would cross the orbit of Ceres. Left to itself, the ship would go on past, more than halfway to Jupiter, before the Sun's gravity would finally turn it back to complete the ellipse and return it to its starting point. In order to land on Ceres, the ship would have to boost again when it got out to the orbit of the asteroid.

There would also be minor course-correction maneuvers during the trip, but except for those the ship's nuclear-pile engine wouldn't be started up until they arrived at Ceres's orbit. Then the ship would accelerate to catch up with the asteroid. That wouldn't happen for nine months.

---

The heart of the system was a series of large transparent tanks filled with green water and tropical fish. Once Wayfarer was under way the crew erected large mirrors outside the hull. The mirrors collected sunlight and focused it through Plexiglas viewports onto the algae tanks. A ventilation system brought the ship's air into the tanks as a stream of bubbles. Other pumping systems collected sewage and forced it into chemical processors; the output was treated sewage that went to the algae tanks as fertilizer.

---

Wayfarer had two airlocks. One was right in the bows, a large docking port that allowed smaller space capsules to link up with the ship, and could also be used to link with an airtight corridor connecting the ship with the Ceres spaceport, or even with another ship. The other was a smaller personnel lock on the side of the hull just aft of the bows. Kevin and Ellen went out that way. There was a small ladder leading forward. It wasn't needed as a ladder, but it provided handholds.

---

The telescope was large, over a foot in diameter, with flexible seals that let it pass through the ship's hull and into the control bridge.

---

The ship's engines started. There was no sound and no flame. Hydrogen was pumped from the tanks and into the nuclear pile on its sting at the end of the ship. The nuclear reactor heated the hydrogen and forced it back through nozzles. The ship drove forward at a tenth of a gravity.

• 

• 

• 

(ed note: the Medici Explorer is basically the Pilgrim Observer with the NERVA solid core NTR swapped out for a gas-core NTR)

The Medici Explorer was fifty-six meters in length, from the gunmetal-grey nozzle of its primary engine to the grove of antennae and telescopes mounted on its barrel-shaped hub module; at the tips of its three arms—which were not yet rotating—the spacecraft was about forty-six meters in diameter. Pale blue moonlight reflected dully from the tube-shaped hydrogen, oxygen, and water tanks clustered in tandem rows between the hub and the broad, round radiation shield at the stern. Extended on a slender boom aft of the shield, behind the three gimbal-mounted maneuvering engines, was the gas-core nuclear engine, held at safe distance from the crew compartments at the forward end of the vessel. Although the reactor stack in Arm Three was much closer to the hub, it was heavily shielded and could not harm the crew when it was in operation.

The Medici Explorer was already awake and thriving. Two days earlier, it had departed from Highgate, the lunar-orbit spacedock where it had been docked since the completion of its last voyage six months ago. During the interim, while its crew rested at Descartes City and the precious cargo of Jovian helium-3 was unloaded from the freighters and transported to Earth, the Medici Explorer had undergone the routine repairs necessary before it could make its next trip to Jupiter. Now, at long last, the giant spacecraft had been towed by tugs to a higher orbit where it was reunited with its convoy.

The shuttle made its final approach toward the vessel’s primary docking collar on the hub module. On the opposite side of the docking collar, anchored to a truss which ran through a narrow bay between the outboard tanks, was the Marius, a smaller spacecraft used for landings. The fact that the ship’s boat was docked with the larger vessel was evidence that the Medici Explorer’s crew had returned from shore leave; more proof could be seen from the lights which glowed from the square windows of Arm One and Arm Two (in model kit, Arm 1 windows are square, Arm 2 windows in hydroponics are circular).

Red and blue navigational beacons arrayed along the superstructure illuminated more details: an open service panel on the hub where a robot was making last-minute repairs; a hardsuited space worker checking for micrometeorite damage to the hull; the round emblem of Consolidated Space Industries, the consortium which owned the vessel, painted on the side of the hub. Then the shuttle slowly yawed starboard, exposing its airlock hatch to the docking collar, and the Medici Explorer drifted away from its windows.

---

So on and so forth, barely pausing for breath, as we dropped down the hub’s access shaft to the carousel which connects the hub to the ship’s three arms. Since the arms were not presently rotating, we didn’t need to make the tricky maneuver of reorienting ourselves until the appropriate hatchway swung past us. The carousel’s hatches were aligned with their appropriate arms, so all we had to do was squirm through the upward-bending corridor—passing the sealed tiger-striped hatch which led to the reactor stack in Arm Three—until we reached the open hatch marked Arm 1.

• 

The arm’s central shaft resembled a deep well, fifteen meters straight down to the bottom. Although I consciously knew that I couldn’t fall in zero-gee, I instinctively rebelled at the thought of throwing myself into a neck-breaking plummet. While I paused at the edge of the hatch, still visually disoriented by the distance, Young Bill dove headfirst through the hatch, scarcely grabbing the rungs of the ladder which led down the blue-carpeted wall of the shaft. I shut my eyes for a moment, fighting a surge of nausea, then I eased myself feet-first into the shaft, carefully taking each rung a step at a time.

There were six levels in Arm One, each accessed by the long ladder. Still babbling happily about rain forests and South American Indian tribes, Young Bill led me past Level 1-A (the infirmary and life sciences lab) Level 1-B (the Smith-Tate residence), Level 1-C (Smith-Makepeace) and Level 1-D (Smith-Tanaka). The hatches to each deck were shut, but as we glided past Level 1-D, its hatch opened and a preadolescent boy recklessly rushed out into the shaft and almost collided with Young Bill.

Young Bill shut the hatch, then led me down one more level to Deck 1-E, the passenger quarters.

He opened the hatch to Deck 1-E and pulled himself inside, hauling my duffel bag behind him. The deck was divided into four passenger staterooms, along with a common bathroom; not surprisingly, it was marked Head, retaining the old nautical term. The small compartment Bill led me to had its own foldaway bed, desk, data terminal and screen, along with a wide square window through which I could see the Moon.

Don’t bother making yourself at home,” he said as he stowed my duffel bag in a closet. “After we launch, you won’t see this place again for nine months.”

I nodded. “The other passengers… they’re already in hibernation?”

Yep. I helped Uncle Yoshi dope ’em up a few hours ago. They’re zombified already. You’ll be joining them after we—”

Although there are three decks to the ship’s hydroponics bay (in Arm 2), one can enter the section only through the hatch at the top level; the idea is to contain the humid environment of Hydroponics as much as possible.

---

• 

The Medici Explorer’s command center was shaped like the inside of a Chinese wok. Located on the top deck of the hub, Deck H-1 was the largest single compartment in the vessel: about fifteen meters in diameter, the bridge had a sloping, dome-shaped ceiling above a shallow, tiered pit. Two observation blisters, each containing an optical telescope, were mounted in the ceiling at opposite ends of the pit; between them were myriad computer flat-screens and holographic displays, positioned above the duty stations arranged around the circumference of the pit. In the center of the bridge, at the bottom of the pit between and slightly below the duty stations, was the captain’s station, a wingback chair surrounded by wraparound consoles. On one side of the bridge was the hatch leading to the hub’s access tunnel; on the opposite side was a small alcove, a rest area furnished with three chairs and a small galley.

It may sound claustrophobic and technocratic, but the bridge was actually quite spacious and comfortable. The floors were carpeted, allowing one to comfortably walk on them provided that one was wearing stikshoes, and the holoscreens provided a variety of scenes from outboard cameras as well as the main telescope, giving the illusion of cathedral windows looking out upon the grand cosmos.

“I’ll leave you to Wendy’s tender mercy,” Young Bill said as he gave me a slap on the shoulder. He then pushed off the floor, floating upward to grab a ceiling rung. “Captain, may I watch the launch from the blister, please?”

It didn’t seem as if Montrose could hear anything from within his thick VR helmet, but the captain circled a thumb and index finger, giving him the OK sign. “Thank you, sir,” Young Bill said, then worked his way along the ceiling rungs, hand over hand, until he reached the observation blister between the engineering and communications stations. With one free hand he tapped the control panel next to the hemispherical bulge; the blister’s hatch slid open, briefly revealing a tiny compartment with a single armchair mounted in front of a binocular eyepiece. Young Bill glided feet-first into the blister, then the hatch shut behind him.

---

“Three… two… one and mark.…” Now the vessel’s three arms began to slowly rotate around the hub, gradually running up to the two RPMs which would induce one-tenth gravity within the habitation areas. There was an initial sense of swerving movement through the hull until the main computer automatically fired RCRs to compensate for the torque, then the rocking motion gradually faded.

---

The major technological breakthrough which made Jupiter reachable was made in 2028 by a joint R&D project by Russian and American physicists at the Kurchatov Institute of Atomic Energy and the Lawrence Livermore National Laboratory: the development of a gas-core nuclear engine, resulting in an impulse-per-second engine thrust ratio twice as high as even the thermal-fission engines used by Mars cycleships.

(so instead of a specific impulse of 825 seconds or so, the gas-core has about 1,650 seconds or so. This probably means a closed-cycle gas core NTR aka "nuclear lightbulb." Which is a good thing, it doesn't spray radioactive death in the exhaust.)

(ed note: Actually, now that I look more closely, I'm not sure I understand what "impulse-per-second engine thrust ratio" means.)

At the same time, four new deep-space vessels—the Medici Explorer, as well as its drone freighters—were being built in lunar orbit. The Medici Explorer (named after the Medici family of Renaissance Italy, the patrons of Galileo Galilei’s research) was essentially a sister-ship of the Tycho Brahe, with upgraded engines and more spacious crew and passenger compartments. The freighters were simplified versions of the same design, each substituting a massive payload sphere for the hub-and-arm configuration.

---

Twenty minutes later, I had managed to climb the long ladder up the Arm Two shaft, negotiate the rotating hatches of the hub carousel, and make my way up the second ladder to the bridge.

Besides the number of ladder rungs I had to conquer, it took me three attempts before I figured out how to duck through the carousel hatches without bashing my head against a bulkhead… and I had to make the transition from one-tenth gravity to the microgravitational environment of the hub without losing my dinner. Fortunately, my nausea passed before I pushed open the top hatch of the hub shaft and glided, albeit clumsily, into the command center.

The ceiling fluorescents had been lowered to an almost twilight level; the sharpest glow came from the myriad red, green, blue, and silver displays from the vacant duty stations. Most of the holoscreens had been switched off, but on the ones which were still active, distant Jupiter shined like the beacon of a faraway lighthouse on a midnight sea. Some of the flatscreens displayed rotating, three-dimensional images of the planet’s rings, its plasma torus, the vast curving network of its vast electromagnetic fields, and the orbits of its fifteen moons. Yet Jupiter itself dominated even the most complex of these computer-enhanced images, as if the giant planet was the sun it could have once been, dominating a miniature solar system.

I paused in the foyer to study the holo displays. The ship’s position was marked by a blue oval, gliding through the dense silver strands of Jupiter’s radiation fields; other screens depicted the orbits of Elara, Lysithea, Himalia, and Leda. While I slept, the Medici Explorer had passed through the second belt of moons; dead ahead were the orbits of the Galilean satellites. Callisto itself was a tiny, slate-grey orb, less than a million nautical miles from our present heading, and Ganymede was magnified on one screen as a tiny, brightly spotted replica of Mercury.

• 

He went out in the ship’s service bug, a tiny gumdrop-shaped vehicle with double-jointed RWS arms, used for in-flight repair operations. Bill had been thoroughly trained and checked out for the bug; indeed, this was the third time he had piloted it during a flight. While Betsy, his dad, and Saul monitored from the bridge, he took the bug out from its socket on the hub, jetted around the ship’s rotating arms, and gently maneuvered the little one-person craft until he reached the maneuvering engines behind the radiation shield.

This thing rulz. Period.

It can stomp both the Michael and the Thuktun Fishithy into the dirt and still have enough firepower left over to blow the Soviet Union into the Stone Age.

But we could have been so much farther along. After the publication of George Dyson’s book Project Orion, and a few specials, a lot of people know that in the early 1960s DARPA investigated the possibility of a nuclear-pulse-detonation (that is, powered by the explosion of nuclear bombs) spacecraft.

Preceding but also concurrently developed with Apollo, this extremely ambitious project had unbelievable payload capability. Where Apollo at 3,500 tons could only put two tons on the Moon, the smaller Orion (about the same total mass, 4,000 tons) could soft-land 1,200 tons (600 times as much) on the Moon, and the larger (only three times as heavy as Apollo, or 10,000 tons) could soft-land 5,700 tons (nearly 3,000 times as much) on the Moon, or take 1,300 tons of astronauts and consumables on a three-year round-trip to Saturn and back!¹ The fission powered Orion could even achieve three to five percent the speed of light, though a more advanced design using fusion might achieve eight to ten percent the speed of light.

Most assume the program was cancelled for technical problems, but that is not the case. Few know how seriously the idea was taken by the top leadership of the US Air Force.

Because internal budget discussions and internal memoranda are not generally released and some only recently declassified, almost nobody knows how close Strategic Air Command (SAC) was to building the beginning of an interstellar-capable fleet. Had the personalities of the Air Force’s civilian leadership been different in 1962, humanity might have settled a good part of the inner solar system and might be launching probes to other stars today. We might also have had the tools to deflect large asteroids and comets.

Recently declassified internal budget documents show that, in 1962, the US Air Force had plans to build entire fleets of giant Orion spacecraft, and was prepared to commit almost 20 percent of its requested space budget from 1963 to 1967 to its realization.

It is one thing to hear Freeman Dyson, the eminent physicist and Project Orion veteran, say that the “end result [of Project Orion] was a rather firm technical basis for believing that vehicles of this type could be developed, tested, and flown. The technical findings of the project have not been seriously challenged by anybody. Its major troubles have been, from the beginning, political.”² It is another to have that confirmed by Air Force internal memoranda.

America’s near-brush with Starfleet began with Donald Mixson and Fred Gorschboth, two young captains assigned to the Air Force Special Weapons Center at Kirtland Air Force Base. Their job was to investigate the military implications of Orion nuclear pulse propulsion technology, and wargame out a military concept for use.

They developed a plan for a three-tiered space force of dozens of Orion spacecraft deployed in either low, geosynchronous, or lunar orbit squadrons. This fleet would hold both nuclear surface attack missiles to provide a survivable deterrent without risk of being destroyed by a first strike, as well as space-based ICBM interceptors and mines (an early vision of the Strategic Defense Initiative) that could defend the United States from a Soviet attack in the event deterrence failed.³

In late 1959, Captain Mixon laid out the evidence for General Thomas Power, the commander in chief of SAC, and obviously convinced him. On January 21, 1961, General Power signed a SAC requirement for a “Strategic Earth Orbital Base” (SEOB) based on the Orion propulsion system and roughly following the space force deployment concept. The SEOB would be “capable of accurate weapon delivery” to “include the capability to attack other aerospace vehicles or bodies of the solar system occupied by an enemy.” The SEOB would also be able to orbit “extremely heavy useful payloads” on the order of 5,000 tons.⁴

General Power was not out there alone. He had the full support of the Chief of Staff of the Air Force, General Curtis E. LeMay. Writing in a 1962 letter to Power, he said, “I share your views regarding the potential of ORION.”⁵ Nor was it just talk: both the SAC commander and the US Air Force Chief of Staff were willing to put their money where their mouth was. In 1962, funding for the SEOB and Orion propulsion development together accounted for $1.36 billion (over $10 billion in 2014 dollars), or 18 percent of the total Air Force space development budget for fiscal years 1963–1967, as requested by LeMay in his Air Force Space Program.⁶

Just what was the capability SAC wanted? A ten-meter Orion ship could get a crew of eight men from Earth to Mars orbit and back in 150 days (chemical missions would require 300–450 days round trip at best) in a vehicle weighing just under 1,000 tons with a 100-ton payload. The SEOB, with a payload capability of 5,000 tons, was akin to the “Advanced Interplanetary Orion” design developed later during Project Orion, which had a gross mass of 10,000 tons and could take 5,300 tons to the same Mars orbit.⁷

So who killed Starfleet? Here is how it went down:

Secretary of the Air Force Eugene Zuckert approved LeMay’s space program but, contrary to his own support of it, refused to request funding for it from DOD, knowing that Secretary of Defense Robert McNamara would not be supportive.⁸

Upon hearing that Orion would not be funded, General Power wrote to the Defense Director of Research and Engineering, Dr. Harold Brown, and argued that “the capability to launch and maneuver truly large payloads [in space] could provide the operational flexibility… [that] could be a decisive factor in achieving scientific and commercial, as well as military supremacy.”⁹

Dr. Brown, the man responsible to McNamara for keeping Air Force research and development constrained to Kennedy Administration wishes, responded, “This development program would be a high risk one… If we accept the possibility that military operations will require large maneuverable payloads in space, it is still far from clear that substantial investment in ORION is warranted now.”¹⁰

And so, here we are in 2015. Fifty-three years later we still have nothing close to Orion. Rather than get to Mars and back in 150 days, with 5,000 tons, we can’t even contemplate a three-person capsule to Mars for another couple decades.

No doubt Dr. Brown was recommending what he thought was responsible at the time, and recommending spending-averse budgets to minimize risk over the advice of the capability-driven military minds. Perhaps he, like many modern voices, felt the need to fear or temper the perceived rapaciousness and expansionism of such men as LeMay and Power. With their vision would have come challenges to stability and perhaps increased risk of a nuclear conflict on Earth. We may have bought ourselves a little near-term stability, but it was not without cost.

Secretary McNamara’s and Dr. Brown’s conservatism and lack of vision has left humanity in a local minima, trapped in a gravity well, unable to access the vast wealth of the inner solar system, and left the life on our entire planet bare and defenseless against what has emerged as a credible threat: asteroids and comets.

We have traded the grand visions of 1962 for a much more tawdry reality, one where instead of going to space in ships with large crews that could roam the inner solar system in voyages measured in months, and would have laid the foundation for humans to reach other stars, our species has accepted small tin cans that may just be able to send a handful of specialists to Mars before the Apollo lunar landing centennial.

Had the US Air Force not been gelded in 1962, humanity would today be reaching for the stars.

Note: This essay is based in part on a presentation by Major Ziarnick given to the Tennessee Valley Interstellar Workshop at Oak Ridge, TN in November 2014. A video of the presentation can be found at: https://www.youtube.com/watch?v=gWYo7nfwEXw

The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Air Force, the Department of Defense, or the US Government

Endnotes

1. George Dyson, Project Orion (New York: Penguin Books, 2003), 55.
2. Freeman Dyson, “Death of a Project,” Science, Vol 149, No 3680, 9 July 1965, 141.
3. Captain Frederick F. Gorschboth, Counterforce from Space (Kirtland AFB, NM: Air Force Special Weapons Center, 1 August 1961) Original classification SECRET. Now declassified. Captain Gorschboth’s work is representative of the space force concept. Captain Mixson’s work is not yet declassified.
4. General Thomas S. Power, Strategic Earth Orbital Base, Strategic Air Command Qualitative Operational Requirement, 21 January 1961. Original classification SECRET. Document is now declassified.
5. General Curtis E. LeMay, Vice Chief of Staff, to General Thomas S. Power, commander, Strategic Air Command, 16 July 1962. Original classification SECRET. Document is now declassified.
6. Launor F. Carter, An Interpretive Study of the Formulation of the Air Force Space Program, 4 Feb 1963. Original classification SECRET. Document is now declassified.
7. George Dyson, Project Orion, 55.
8. Gerald T. Cantwell, The Air Force in Space Fiscal Year 1963 (Washington, DC: USAF Historical Division Liaison Office, December 1966). Classified TOP SECRET. Excerpt is declassified, 6.
9. General Thomas S. Power, commander, Strategic Air Command, to Dr. Harold Brown, Director of Defense Research and Engineering, 3 November 1962. Original classification SECRET. Document is now declassified.
10. Dr. Harold Brown, Director of Defense Research and Engineering, to General Thomas S. Power, commander, Strategic Air Command, 15 November 1962. Original classification SECRET. Document is now declassified. Emphasis original.

• 

• 

(ed note: this story occurs in an alternate future where both the US and the Soviet Union built and deployed Orion-drive warships. It is happening about the year 1989. A rogue Soviet Orion-drive Boomer, the Rokossovsky, ran away. It has been intercepted by the US boomer LeMay. A combat team from the LeMay is attempting to board and neutralize the Rokossovsky.)

      Strode decided to leave them be. According to Intel, the Russians booby-trapped all access to their boomers. Disturbing them while they were trying to crack the hangar controls would be what Colonel Klaus would call “inadvisable.”
     He glanced up through the top port as much as the helmet would let him. The hull of the Russian boomer curved far overhead, the point of one huge star visible to his left, a handful of Cyrillic letters to his right.
     Rokossovsky (Рокоссовский), they spelled out. Marshal of the Soviet Union Konstantin Konstantinovich. Hero of the Great Patriotic War. Order of Lenin, Order of the Red Banner, Order of Victory. Effective viceroy of Poland for nearly a decade after the war …
     … and throughout it all, under suspended sentence of death, courtesy of Uncle Joe Stalin.

     “Got it,” Cruz said.
     Strode lowered his eyes. Outside, the two suited figures were still huddled against the boomer’s hull, tools and parts floating beside them. “Got what?”
     Cruz raised his arm slightly. Within the gauntlet, Strode could make out a small white cube. “About five or six ounces of what looks like Semtex. Blow both your f*ckin’ hands right off.”
     Strode fought down an impulse to demand why they hadn’t told him they’d found it in the first place. “Good.”
     “Brace me,” Cruz told Kieran. He tossed the explosive in the direction of Cygnus and swung himself clumsily back toward the hull. “Gimme me some light here.”
     “No more cavities,” he said after a moment.
     Strode smiled. A dental mirror was a crucial part of their equipment.
     “Okay … we’ll crack this sucker in just a minute.”
     “Excellent.” Strode could see Morris standing behind him, reflected in the plexi. He’d been so quiet that Strode had forgotten he was there.

     There was a buzz in his earphones. He glanced at the board. A call from the LeMay. He carefully reached over and switched to the laser antenna. “Strode here.”
     “LeMay CIC here, Major.”
     Strode rolled his eyes. Who else would it be?
     “Ah, how’s it going?”
     “We just disarmed their welcoming present, Colonel. About ready for insertion.”

     “Awright,” Strode said. “Gogol? You ready?”
     “That’s an affirmative,” the assault team leader told him.
     “Okay. Questions … No? Let’s go for it, Micky.”
     Cruz bent over a small black box and manipulated it. Strode shifted his gaze toward the vast, closed hatch to their left. For a moment, nothing happened, then it started to slide open, moving upward like a garage door. He bit his lip when the lights inside remained off. But then they started glowing, softly at first, then brighter as the hatch slid up out of sight.
     Strode shifted against his seatbelt. Nothing. The hangar was completely empty, as far as he could see. Oh, there was equipment strapped against the bulkheads. But EVs, vehicles of any sort—not a sign.
     There was one section not visible from the EV. “Gog—is there anything in that right-hand corner?”
     “Nothing. Bupkus.”
     “Okay—we’re going in,” Gogol said.
     “Do it.” The team entered the hangar. Splitting up and drifting slowly across the thirty yards to the rear bulkhead, shotgun barrels high and rotating slowly as they went. They reached the bulkhead and Strode shifted the EV about twenty feet to the left, facing the open hatch.
     Cruz and Kieran were clambering around the hangar examining niches and equipment for any more surprises. “Clear,” Cruz called at last.
     Strode eyed the hangar, the assault team covering the airlock in the rear. He’d had a mild argument with Klaus about this—the colonel didn’t like the idea of the EV actually entering the ship. But Strode just couldn’t shake his mind of the image of the Rokossovsky taking off and leaving him with no way out. The colonel had at last told him to use his judgment.
     “Bringing her in.” He slowly slid into the hangar, coming to a halt about halfway to the bulkhead. Morris and Hinche climbed out to secure the EV. Strode unstrapped himself and grabbed for the case of claymores. At the hatch, he paused to glance at the bulkheads, the lock, the signs in Cyrillic, wondering if they’d find any answer to the question as to why a Soviet nuclear impulse vessel would head halfway across the solar system instead of parking itself at L5 as it had been ordered ordered to do.

---

     It took them a quarter hour to clear the hangar level. At six hundred feet long, the Rokossovsky had a lot of nooks, crannies, and corners that had to be looked at. Much of it on that level was parts storerooms, work spaces, and the like, large and packed with all sorts of stuff. Atmosphere was nominal, so they raised their helmet visors. This had the added advantage of allowing them to hear their surroundings unimpeded by the thermos-glass.
     Another problem lay in the fact that Russian boomers got a lot of modifications after they were constructed. Rokossovsky had been modified quite a bit. He could see a lot of differences on this level alone. It was a relatively old ship, as far as boomers went, launched in 1977, just three years after the Zhukov went up. It was likely that Strode had seen this very ship back when he’d been in college, maneuvering around cislunar space leaving a trial of white-hot nuclear fireballs behind it.
     He got the team back together and they headed for the next level, moving “up” toward the nose. The CIC ought to be located in that direction.
     There was no lack of doors on the next level. They stretched off a hundred, hundred twenty feet in each direction.
     “Personnel quarters,” Strode muttered.
     “Yep.” Morris slipped past him and drifted over to a slot beside the closest door. Morris was G2, and could actually read the godawful Cyrillic alphabet. “These are names.”
     “Okay.” Strode gestured up and down the hall. “Let’s clear ’em.”
     The first one he checked was the standard bunkie, larger than the ones on the LeMay but otherwise pretty similar. There were two bunks, unlike the singles on their ship, a couple of closets, shelves for books and whatnot. A battered map of Mother Russia on one wall, some personal photos, and that was it. As he was swinging around to leave, it occurred to him that they were doubled up, despite the size of the ship, so that they could keep an eye on each other.
     He glanced up and down the corridor as he swung himself out and gripped the rail. The boys were darting in and out, none with anything much to report, as far as he could see.
     Morris waved to him from the other side of the corridor. “You’ll like this one. Take a look.”
     Strode kicked off and halted himself at the doorway before swinging inside. It was the same setup as the other room, bunks, closets, and so forth, but on one side …
     For a moment, he was cast back to his own room on the LeMay. No maps of Russia here—the wall above the bunk to his left was covered with photos taken around the system. Valles Marineris on Mars, Pluto’s Plain of Dis, the ice fountains of Europa. And there, the exact shot he had on his own wall, one of the most famous photos of the late seventies: the rings of Saturn, taken by Dyson himself.
     A sense of something like kinship touched him as he regarded the photos. He thought he understood this guy, whoever he might be. Ah, ‘thought’ nothing; he knew he did. It was the same impulse that had caused him to join up in the first place. To drop his potential career as a Deadhead for the USAF, with the intention of riding the boomers to the edges of the system, to see for himself the sights preserved in these photos … Not that he’d actually seen any of them, spending much of the past four years on station in long, leisurely trajectories around the Earth-Moon system, on the front line of defense in the Cold War. “Somebody’s got some soul on this wagon.”
     By the time they cleared a dozen rooms, it was apparent they were going to find nothing. There were just too many rooms to search—not surprising on a vessel with a crew that could number anything from a hundred twenty to three hundred plus. They could easily waste the next two hours searching the rooms on this level and the next, which was also a personnel level.
     There was a mixed-use level above that one. Strode decided to check that out next.

---

     “Got the computer room here,” Cruz called out.
     “Looks like a f*ckin’ museum,” somebody said.
     That it did. A collection of big mainframes with tape drives and readouts, all of them dark now. Strode shook his head. The PC he had on his desk back in the LeMay probably had more processing power than this entire system.
     “I’m surprised they’re not using abacuses,” Cruz said. Strode waved at the mainframes. “This is all IBM equipment. Bought in false-flag operations. They don’t know d*ck about—”
     Morris had drifted in through the doorway, sheets clutched in his gloved hands. “How many nukes you think they’ve got aboard?”
     “Well, it better be twenty-five,” Strode said. That was the limit set by the Reykjavik Treaty.
     “No.” He raised the sheets. “They’re talking one eighty-five on this sheet and … two oh five on this one.”
     “Pills?”
     “Nope. Not kiloton yield. Fifteen, twenty megatons. They’re warheads.”
     “Holy sh*t.”
     Twenty megatons … those were city-busters. With two hundred of those, this single boomer could knock the US back into the stone age and go on to wipe out every Western installation in the solar system. Strode was beginning to get a vague picture as to just what the Rokossovsky had been up to. But it still didn’t explain why this bird was bobbing around just within the orbit of Jupiter.

• 

     Morris gestured at the papers floating around the room. “Look through all these, find me the ones that got this emblem on top. See it—the sword and shield?”
     Strode grabbed one himself, then another, wishing he’d taken the time at some point to learn Russian. There it was—a sword within a shield, star and hammer and sickle centered over all. The emblem of the KGB, the little friends of all things living.
     Cohn was floating above a big block of machinery in the corner, gazing at something just past it. Strode hoisted himself to a spot where he could see what it was. There was a fan of dark stains against the rear bulkhead. Blood spatter, and nothing else.
     “They had three warheads allotted for Moscow—”
     That actually made sense, if the theory Strode was turning over in his head was anywhere close to the truth. Kicking off, he headed over to join Cohn. The machinery he was floating above, half the size of a Volkswagen van, was apparently their printer. A block of paper remained in a hopper at one end, the top sheet fluttering in the air currents. There was a padlock hanging from a hasp on the cover for the controls. Somebody had sawed it open.
     “They were printing these out here,” Strode said.
     “For what? To hand them out to who?”
     “To the crew. Somebody wanted them to know about all this.”
     Cohn nodded at the printer. “Okay. And this guy …” He gestured at the bloodstains. “Got shot doing it.”
     “Looks like it.” “It’s called podsolnechnik (подсолнух)—Sunflower,” Morris called out. “Operation Sunflower. That’s the name.”
     Cruz was looking over his shoulder. “Well at least they got a sense of humor about it …”

     A fusillade of shots rang out from the corridor. The men outside starting shouting and then returned fire. Strode heard the roar of shotguns as he headed for the door, struggling to grip his pistol with the oversized suit gloves.
     They were still firing when he reached the door, two shotguns and one light MG. A suited man was pinwheeling slowly down the corridor in the direction they had come from.

---

     “We’ve taken a casualty, sir. Keiran is KIA. This ship is definitely under control by hostiles.” Strode squeezed his eyes shut. In the USAF, you didn’t call boomers ‘ships.’ They were ‘spacecraft.’
     But the colonel had missed it. “Lieutenant Keiran? That poor boy. How did it … ? Well, that will wait. Ahh … I think you’d better return to the LeMay, Major. We need to confer on our next move …”
     Strode made a disgusted face. He couldn’t say he was surprised. Klaus had started out flying EB-47 electronics warfare aircraft out of Japan during the sixties. He’d later been transferred to tankers. A decade as a 135 pilot had given him a truck driver’s mentality: stolid, cautious, and slow moving. “I disagree, sir.”
     “Ah … what’s that, Major?”
     Strode gave him a quick rundown on what Morris had discovered.
     “They’re not individual propulsion units?”
     “No, sir, they’re not …” Strode bit off his words before he could say “pills,” another term Klaus didn’t care for. “The yield is in the megaton range.”
     “I see. So the Rokossovsky was in fact some kind of backup for the Moscow plotters.”
     “So it seems.” It was as they’d suspected in the first place. It was simply too much of a coincidence that a nuclear-armed boomer had broken its assigned orbit and started heading for Earth at the same time that Boris Pugo and the KGB moved against the Soviet government. The Committee of National Renewal under arrest, Yeltsin shot for treason, people being executed in the streets …
     But they’d missed Gorbachev, who reached a friendly Army base and rallied the people to resist the coup plotters. At which point the Rokossovsky, halfway between Earth and Luna, had lit off an entire string of pills and headed off in what seemed a perfectly random direction. It had taken the LeMay a week and half to catch up, at nearly unbroken acceleration, in the process using up most of its pill supply. They’d have to be refueled one way or another before they headed for home.
     “… we’ll need to locate and secure that warhead cache.” Or destroy it, if it came down to that.
     “Agreed. You understand that we’ll have to arm a warhead, Major.”
     “I wouldn’t have it any other way, sir. I’d also advise that the LeMay move away twenty or thirty kilometers. Their electronics seem to be degraded, but whether they can fire a weapon, I have no idea.”
     “And your next move, Major?”
     “I’m gonna track ’em down and clean ’em out.” A moment passed before he remembered to add, “Sir.”
     “Ah, all right, Major. Best of luck. And keep us in the loop.” Strode signed off. That last was going to be quite a trick. The hull of this bird was too thick for a headset radio to penetrate, so they’d been dragging along a relay box with a cable connected to the EV. Unfortunately, they’d about reached the end of the cable.
     He turned things over in his mind for a moment, well aware of the team’s eyes on him. Boarding tactics for spacecraft were still largely theoretical. In point of fact, this was the first time they’d ever actually been carried out. So this operation was going to be one for the books—either how it was supposed to be done, or how you never ever do it unless you’re some kind of brain-damaged halfwit like Frankie Strode. “Awright—so we’re not fighting the entire crew.”
     Gogol shook his head. “Nahhh—if there was a couple hundred of them, they’d be up our asses.”
     The others nodded and grunted agreement. “I think we can take it for granted that they’re KGB. Not combat troops.”
     “Used to beating up widows and orphans.”
     “More or less. So that’s good. Now, they’re going to be defending critical points …”
     “CIC.”
     “Right. So we’ve gotta hit ’em there, and they know we’re coming.” He ran his eyes over their faces, shadowed and distorted in the helmet lights. “Here’s what we’re gonna do …”

---

     Strode studied the blank circle of the CIC entrance up ahead. The lights were still off, so he was using the lowlight slide-down goggles built into the suit helmets. They could lower over the wearer’s eyes even with the faceplate in the up position.
     It had puzzled him for a moment that there wasn’t a hatch they could close, but after a little thought had realized that the ship’s KGB unit would want open access to the CIC at all times.
     He hoisted the pistol. It was a piece of sh*t called a Gyrojet, basically a handheld rocket launcher. It had the heft of a water pistol and he didn’t trust it at all. But a recoilless pistol was still in the works, unlike the shotguns and grenade launchers the other troops were armed with.
     He still had his visor up and was listening closely. He’d sent Heske into one of the air ducts. He had a spare conformal oxy tank and was supposed to toss it up the duct after ten minutes had passed. He was about thirty seconds late now.
     On the opposite side of the ship, Kruger and Page were headed up a secondary access tube. They ought to be …
     He heard a rattle that seemed to be coming from somewhere to his right. Immediately, there were muffled sounds from the CIC. He nudged Cruz, who has gripping the cover from the computer room printer. Cruz let it sail toward the entrance, assorted parts and objects attached with bungee cords banging against the metal bulkhead as it went.
     Shouts rang out, followed by gunfire as the cover sailed into the CIC. Strode squeezed his eyes shut and lowered his head as the team fired four high-intensity flares into the space. The shouts got louder, the gunfire intensified.
     “Let’s go …”
     Cruz and Gogol were already at the entrance. They slipped inside, shotguns blazing, just before Strode reached them. Strode swung over the edge and down to get out of the way of the rest of the team. He collided with a wall console with a thud and glanced around the space.
     Four of his team—he couldn’t tell one from the other—were blasting away at a several dark figures silhouetted by the glare of the tumbling flares. They seemed to be well at home in mike, using the cover of the consoles as they fired back. As Strode watched, one of them was hit and slammed into the far bulkhead. He raised his pistol but couldn’t find a clear shot.

---

     He bent closer. “Can he talk?”
     “Chto sluchilos? ("What happened?")”
     The man’s eyes remained closed. “Gebisti.”
     “KGB did this,” Morris said.
     “Plekhov. U cheloveka d’yavol.”
     “Plekhov. A human devil.” “He’s the chief political officer,” Morris went on. “CO of the KGB unit on this bird … Part of a camarilla … that’s a conspiracy … To destroy the perestroika infection, wipe out the main enemy … and create a new Russian imperium … a new Rome.”
     “Nice,” Strode said. “What happened to the crew?”
     “Mostly dead … Plekhov killed them. Some tried to escape in the EVs—he dropped a pill and vaporized them.”
     “Oh my God …” That was Cohn. He shook his head as well as he could in the suit and turned away.
     “There was a gun battle … KGB having most of the guns … They captured the rest of the crew …”
     “Good—one minute. What about … Krilov?”
     “Krilov …” the man’s eyes opened wide. “Velikiy chelovek, Krilov.”
     “A great man, Krilov … he defied Plekhov, brought the ship out here, he …” The Russian groaned and his head fell back.

(ed note: I will note in passing that the end of this story is in the great tradition of Robert Heinlein's The Long Watch)

• 

DOOMSDAY ORION
Length overall	89.25 m
Pusher Plate diameter	26.21 m
Nuclear Device	1,650 tons
Estimated Yield	8.25 gigatons

     One notional 1959 concept for a large military Orion was the “doomsday weapon" idea. Instead of one Orion carrying a large number or weapons, able to rain down devastation on many separate targets, the idea was to equip one Orion with one single weapon, a hydrogen bomb of immense size and capability. While data is sketchy. the payload would be a single nuclear device with a mass of 1,650 tons. Yield is not readily available. but is estimatable. Numbers vary from source to source, but maximum yield-per-bomb-mass seems to be around five megatons per metric ton of bomb based on current technology; this could increase to well above 100 megatons per ton of bomb for a highly efficient nearly pure-fusion lithium deuteride device. But assuming 5 megatons per ton, 1,650 tons of bomb yields 8,250 megatons, or 8.25 gigatons. This falls far short of the 100 million megaton “yield” of the dinosaur-killing asteroid or comet from the end of the Cretaceous era, but would still wreak vast havoc upon the Earth. A 1,650 metric ton bomb composed chiefly of lithium deuteride would have a volume of about 2,115 cubic meters, although a large hydrogen bomb probably cannot be made as simple as a block of lithium deuteride with a fission trigger in it. In reality, it would very likely be a structurally complex device.

     Such a massive weapon would of course be a last ditch weapon, one to be used only when the United States was threatened with extermination. The idea was that the mere existence of such a weapon would deter the Soviets from doing anything foolish. The bomb would be detonated well over the Soviet Union, several hundred miles out; it would not be blast but radiation which would do the job. However, weapons of this size were so far beyond contemporary understanding that nobody really knew exactly what would happen if the bomb was touched off. Would the high energy radiation simply sleet through the atmosphere, only being absorbed in the ground or structures? Would it be largely absorbed in the upper atmosphere, which would as a consequence be heated well past incandescence… essentially setting the sky on fire? Whatever the effects were, they would be spread over most of a hemisphere.

• 

     It’s not certain if the Doomsday Orion was meant to be an orbital version, perhaps launched piecemeal… or a ground based version, only launched when The Time Has Come. It seems most likely to have been the latter. At the very least, the primary complaint about ground launching Orion — fallout — would fade into staggering insignificance with the Doomsday Orion. Thus there would have had to have been a giant silo somewhere, 86 or more feet in diameter, filled with one very large vehicle kept in a constant state of readiness by a large crew of experts. The security surrounding the facility would have had to have been quite impressive… not only would the Soviets have been interested in disabling it, but so would activists of all stripes. And there would almost assuredly be those who would want to break in and launch the vehicle in order to bring about their own version of Ragnarök.

---

Scott Lowther: A whole lot of the weight of even a big, efficient fusion bomb is stuff that doesn't exactly contribute to the actual yield, but is required to make it work… structure, radiation reflectors, that sort of thing. Exactly how it would break down in a bomb massing over a thousand tons is anyones guess. Design and analysis of fusion bombs in the gigaton range is somewhat above my pay grade, so my estimate was based on simply scaling the mass/yield of the best American H-bombs. Presumably a 1,600 ton bomb would be extremely efficient… but who knows.

8 gigatons is the yield determined from scaling. It could well be more. But let's face it… the difference between 8 gigatons and 50 is the difference between getting vaporized and getting vaporized a little harder.

• 

• 

      The feasibility of extraterrestrial industrialization depends totally on adequate and cost-effective transportation. The first step toward the development of a geolunar transportation system is obviously the Shuttle. Without discussing its extension into geosynchronous orbit and to the Moon, a brief appraisal is presented of low-cost mass transportation as needed for cost-effective distribution of industrial goods and raw materials.

     The most universally usable mode for industrial transportation is advanced nuclear propulsion. For the transportation from Moon or planets to be economically viable, the energy must be very inexpensive and the space freighters must travel in relatively slow paths. To be inexpensive, the energy must be extremely concentrated and the materials (expellant) expended in propelling the transporters must be small in mass and low in cost. Only propulsion using nuclear explosives meets these conditions (e.g. [25, 26]). Because of the large payloads, the transporter requires high thrust values. Fusion pulse drives, operating through pulsed fusion energy release, can most readily attain high thrust values while keeping propellant consumption low.

     The energy releasing device is a nuclear fusion charge of adequate strength. The energy transmitting device is an expellant that could be either a metallic or non-metallic element, or combination of elements, depending on design specifics of the engine.

• 

     Subsequently, an example is presented that is indicative of the high, geo-competitive transportation economy attainable with nuclear-pulse freighters (NPF). These NPF are large, with payload capacities in the multi-thousand ton range. Assume a relatively small NPF, capable of delivering a discretionary payload of 3000 tons from a lunar-type environment to Earth. Its dry weight is about 1000 tons. It will be propelled by nuclear pulse units (NPU) of 0.3 to about 0.6 kiloton (kt) yield, depending somewhat on its mission. The cost of an NPU decreases with its size, in contrast to that of a chemical high-explosive, which is about 2.4×10_-14$/erg, or $1,000,000 (1972 dollars) per kt (= 4.236×10¹⁹ erg). By extrapolation of publicly [24] given data, it was assumed that 20 years from now the cost of a 1 kt NPU could be reduced by a factor of 2 to 4 to a value of 2.10¹⁵$/erg and the cost of an 0.1 kt NPU to 10^-14$/erg. Therewith, the cost of the NPUs driving the above specified NPF would lie above 2.10^-15 and below 10^-14$/erg. In this example, however, we have assumed 10^-14$/erg. Thus, if 10 NPUs@0.3 kt are expended, the resulting cost is higher, namely, the equivalent of 30 NPUs@ 0.1 kt. This amounts to 1.271×10²⁰erg at 10^-14$/erg or $1.271×10⁶ per 3 kt, i.e. $424,000 per kt. A nuclear pulse engine design [27] was assumed that permits the use of an expellant combination (e.g. lithium, steel and ammonia) whose production costs are negligible compared to the cost of the nuclear fuel (the NPUs) and to the transportation costs from manufacturing place of the expellants (probably Earth in the case of the above expellant composition). In the transportation sector, the biggest allowance was made for future advances by assuming a transportation cost of NPUs and expellant to the NPF of $20,000 per ton ($9 per pound). With the Space Shuttle presently under development by NASA at North American Rockwell, the transportation costs, though greatly reduced compared to expendable boosters, would still be slightly below $400,000 per ton (based on delivery of 50,000 lb to about 130 n.mi. orbit@ $180 per lb). The above low cost is based on a large reusable Earth-to-orbit shuttle of 3000 ton payload capability as part of a macro-space-transportation system that could be available 30 years from go-ahead of an extraterrestrial industrialization program [1].

     The assumed mission profile of the NPF provides departure from and return into a geosynchronous elliptic orbit with perigee at 450 km (250 n.mi.) and apogee at 12 Earth radii. This makes it possible for the NPF to execute an apogee capture maneuver outside the Earth's radiation belt, while at the same time minimizing the transportation costs for its resupply (there are several alternatives available for unloading, including direct drop to pre-designated sites). The return-maneuver at the apogee of the ellipse requires more energy than if executed at the perigee. But at the specific impulses of the NPF (see below), the penalty in terms of propellant consumption is insignificant. The NPF leaves the circumterrestrial orbit, carrying as its outbound payload the NPU and expellant load needed for the return flight. It may well be possible that suitable expellant materials will be found on other celestial bodies (especially on Mars), which would result in significant further reductions of transportation costs, this possibility has not been priced into the present example, The magnitude of the outbound payload—hence of the NPU and expellant consumption on the outbound leg of the mission—varies with the destination, causing the range of NPU-yield to be somewhat mission dependent, as indicated before. The return flight payload is 3000 tons of extracted metal or products for all missions considered. Although in planetary round-trip missions (in contrast to lunar missions) the overall maneuver velocity change required tends to be different for outbound and return, the subsequent example is based on calculations for equal velocity changes both ways, for the sake of comparing various round-trip mission energy levels.

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     Figure 19 surveys the propellant (NPU and expellant) costs per mission under the assumptions stipulated above. The result is shown for three levels of transportation energy, corresponding to: (a) 10 kilometers per second; (b) 20 kilometers per second; (c) 40 kilometers per second each way. Lunar missions are well under the level of curve (a). Mars missions would fall near to or somewhat above curve (a) etc. Each curve shows the propellant cost per kilogram of the 3000-ton payload versus the nuclear energy expended on the roundtrip at the defined level of transportation energy.

     The curves have a rather pronounced minimum. The minimum cost increases, of course, with the energy level. It is seen that, by doubling the velocity from 10 to 20 km/s per transfer, the lowest cost value—hence the associated propellant consumption—is tripled instead of being quadrupled, as suggested by the fact that doubling the velocity means quadrupling the energy requirement. Propellant consumption is proportional to the mission energy level. But propellant consumption is quadrupled only for constant mass outbound and return; whereas for the actual minima shown in Fig. 19 the outbound ship mass is smaller than the return mass.

     To the right of each minimum lies a region of increasing nuclear fuel consumption and decreasing expellant consumption. The more nuclear fuel is consumed, the lighter becomes the vehicle's expellant load, i.e. the specific impulse increases. But, aside from posing increasingly severe technological problems, the transportation economy also deteriorates, because of the comparatively higher cost of the nuclear fuel.

     To the left of each minimum lies a region of decreasing nuclear fuel consumption and increasing expellant consumption; in other words, of decreasing specific impulse. The amount of nuclear material needed per flight declines. This reduces the cost per flight. But the quantity of expellant increases so rapidly, that the cost of transporting it into orbit dominates the cost picture (even at the relatively low value assumed here), resulting again in a rise in transportation cost. In the case of energy level (b) and (c), the curve actually bends "backwards" (to the right) as it goes up, indicating an increase in propulsive energy just to push the large expellant mass, needed for the return flight, to the target.

     To each point on the curve, hence to each minimum, belongs a particular mixture ratio of nuclear fuel and expellant, resulting in a particular specific impulse. The results suggest that the really important specific impulse for industrial space transportation ranges from 5,000 to 10,000 sec. Only the nuclear pulse engine offers a realistic promise of generating such specific impulses, while at the same time producing a thrust powerful enough to push the desired large payload mass. The development of the nuclear pulse engine is of the utmost long-range importance. Its development could be completed within 20 to 25 years.

     Of course, the figures in Fig. 19 are not the total cost—not even the total transportation cost. The latter includes the cost of ship maintenance, loading and unloading and crew maintenance during layover times in Earth orbit and at the target. These additional transportation costs can presently be detailed only on a highly speculative basis. But they will hardly as much as double the indicated minima. Possible reductions in nuclear fuel cost or reductions in Earth-to-orbit transportation cost would have a far greater effect.

     The point to be made here is that contrary to a generally held assumption, interorbital transportation costs can be decreased to a competitive level. Transportation costs need not be a principal constraint for extraterrestrial industrialization.

---

References

1. Ehricke, K. A. and Miller, E. A., The Extraterrestrial Imperative (New York: Doubleday, 1973).
24. Engineering with Nuclear Explosives, Proc. 3rd Plowshare Symp. April 1964, U. of California, TID-7695, 1964.
25. Eerkens, J. W., Thrust from Nuclear Explosions, Nucleonics 19, No. 4, 100 (1961).
26. Nance, J. C., Nuclear Pulse Propulsion, Trans. Inst. Electrical and Electronics Engineers, Vol. NS. 12, No. 1, 1965.
27. Ehricke, K. A., Morphological Analysis and Comparison of Nuclear Pulse Drive Mechanization Concepts, Presented at the AIAA 5th Propulsion Joint Specialist Conference, Colorado Springs, Colo., June 1969.

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      Finally, another unrealized, but practically developed at the time, project for the use of nuclear explosives is a nuclear explosion, the idea of ​​which was expressed by Andrei Dmitrievich Sakharov in 1962 at the Federal Nuclear Center (Sarov).

     The idea of ​​A.D. Sakharov consisted in using NII for the launch into space of a huge useful weight. The propulsion system was supposed to use the energy of successive explosions of nuclear weapons. A payload of 1,000 or more was supposed to provide the crew with a long-term stay in space.

     The task of developing such an explosion was very difficult. Nevertheless, as a result of design work, it was still concluded that it was possible to create a propulsion system using nuclear energy.

     The schematic diagram of the explosion in the form as originally proposed by A.D. Sakharov is shown in Fig. 3 a. In Fig. 3, b, a structural diagram of one of the variants of the PK-5000 explosion is reproduced (5000 - total weight in tons).

     By the way, at the suggestion of A.D. Sakharov, while developing the design, considered the issue of placing plantations with chlorella in his living compartment for 10-20 people.

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Blast Sakharov

     In the USSR, the idea of ​​using nuclear charges in space technology was put forward more than 30 years ago. The discussion was initiated by academician Andrei Sakharov.

     In July 1961, all leading Soviet nuclear specialists received an urgent invitation to the Kremlin. There they were received by Nikita Khrushchev and informed about the government’s decision to conduct an “autumn-winter session” of nuclear tests, during which all types of warheads that were in the arsenals of the Soviet Army would be tested. At the same time, the Soviet leader was interested in the latest work of specialists in the field of nuclear weapons. Sakharov, who was present at the meeting, told Khrushchev about the possibility of creating a 100-megaton thermonuclear charge. Khrushchev liked the idea, and he authorized the work on preparing the charge for the test. The explosion of the Tsar Bombs (sometimes called her Kuzkina’s mother, recalling Khrushchev’s intention to show her to America) was made in the fall of that year. True, they did not dare to explode the charge of full power, but also 58 megatons

     At the same meeting, Sakharov outlined to the head of state the idea of ​​a nuclear explosion, similar in meaning to the Orion project.

     Structurally, Sakharov’s explosion would consist of a control compartment, a crew compartment, a compartment for accommodating nuclear charges, a main propulsion system and liquid rocket engines. The ship also had to have a nuclear charge supply system and a damping system to level the rocket after a nuclear explosion. And, of course, tanks of sufficient capacity for fuel and oxidizer. A screen with a diameter of 15-25 m was to be mounted in the lower part of the ship, in the focus of which nuclear explosions were supposed to “boom”.

     Start from the Earth was carried out using liquid rocket engines located on the lower supports. The fuel and oxidizer were supposed to be supplied from external mounted fuel tanks, which could be dumped after emptying. On liquid engines, the apparatus rose to a height of several kilometers (or tens of kilometers), after which the main propulsion system of the ship was turned on, which used the energy of successive explosions of nuclear charges of small power.

     In the process of working on the explosion, several design options of various dimensions were considered and calculated. Accordingly, the starting mass and the mass of the payload that could be put into orbit changed. But it should be noted that, despite the significant mass of the structure, it did not differ in large sizes. For example, PK-3000 (Manned Complex with a launch weight of 3000 tons) had a height of about 60 m, and PK-5000 (Manned Complex with a launch weight of 5000 tons) was less than 75 m. Payload output into orbit, in these variants it was 800 and 1300 tons, respectively.

     An elementary calculation shows that the ratio of the mass of the payload to the starting mass exceeded 25%! But a modern chemical fuel rocket will take into space no more than 7-8% of the starting mass.

     One of the regions in the north of the Soviet Union was chosen as the launching pad for the "explosion" — the designers believed that a special spaceport would have to be built to launch a new spacecraft. A place for him was chosen on the basis of two considerations. Firstly, the northern latitudes made it possible to lay a missile flight route over hard-to-reach sparsely populated areas, and in the event of an accident this avoided unnecessary casualties. Secondly, the "start" of a nuclear engine far from the equatorial plane outside the zone of the so-called geomagnetic trap made it possible to avoid the appearance of artificial radiation belts.

The ideology prevented the further development of the idea of ​​Sakharov’s explosion. On this occasion, in the Soviet scientific journals expressed the following:

     “... Often the attractiveness of explosive thermonuclear engines is often explained by the possibility of using up with their help the stockpiles of thermonuclear (hydrogen) bombs accumulated in a number of countries when the peoples of the world come to an agreement on world disarmament. It seems to us that neither from a political nor from a technical point of view this argument does not stand up to criticism. The accumulated thermonuclear weapons can be disposed of if it will be necessary to achieve a more complete discharge, much more efficiently and in a shorter time, without spending many years waiting for the creation of the most unique and complex new engineering space structure.
     “Apparently, the appearance of the first examples of thermonuclear energy in the industrial arena should be expected by the end of our century. This will open unusual horizons for mankind, will allow us to restore the resources of our planet ...” — this idea was expressed by the outstanding Soviet physicist, President of the USSR Academy of Sciences, Academician A P. Alexandrov, as well as possible confirms the above considerations. Firstly, the advent of space thermonuclear engines is still a long way off, whereas the discharge and peaceful disposal of thermonuclear warheads are a requirement of our time. Secondly, the importance of scientific research on the practical application of thermonuclear energy, including in space exploration, is already obvious ... "

     That is, it was understood that disarmament with the elimination of nuclear arsenals would occur much earlier than the ship was built. Time has shown the absurdity of such expectations. It turned out that disarmament and the elimination of nuclear arsenals were in no way connected with each other, and there was no, and no, Sakharov explosion.

     The ideas of our outstanding compatriot turned modern engineers. They indicate that the apparatus proposed by Sakharov does not withstand criticism from the point of view of today's ideas about ecology and safety. The reason for returning to this project is that there is a demand for technologies that can protect the Earth from collisions with a comet or asteroid. So far, the only way to eliminate this danger is a huge nuclear charge, which must somehow be delivered to the target. For this, it is proposed to use Sakharov's explosion as a charge carrier.

     Unlike the previous project, which was supposed to launch from the Earth’s surface, which is unpromising from the point of view of ecology and safety, the start of a new “Explosion” is supposed from the orbital trajectory. Due to this, the design will become lighter and simpler.

     The principle of operation of the "Explosion" is to create a mechanical impulse on the screen ("sail") due to the energy of the explosion of the charge. The construction of the motor system can be carried out in two different versions. In one case, the basis is laid on a simple exchange of kinetic energy between the screen and the expanding working substance located directly on the charge, and in the other, the pressure pulse on the screen is transformed by heating a special substance supplied on the surface of the screen directly at the time of the next explosion, - option with Sweating screen. The design of such an “Explosion” assumes a payload of 1000 tons.

      A nuclear pulse spaceship is a space vehicle equipped with a pulsed thruster. The lower part of the spaceship contains a thermally-insulated solid metallic disk known as a pusher. Nuclear explosions periodically go off under the pusher, which give the rocket motor impulse. This technology is quite interesting and makes it possible to reach an enormous speed. For example, the US Orion spaceship project envisaged the vehicle’s maximum speed as equal to one-thirtieth of light speed. The Orion would have taken 130 years to reach the nearest star in the Centauri Constellation. The Daedalus interstellar unmanned spacecraft designed by the British Interplanetary Society was supposed to travel three times faster.

     In the USSR, the Vzryvolyot, or nuclear pulse spaceship, was conceived by the inventor of the nuclear bomb, Academician Andrey Sakharov. He first presented his design of a spaceship powered by the energy of nuclear explosion in 1961.

     What was the fate of these projects? Both in the USSR and the US they were shut down, even though the potential for manned flight by such a spacecraft had been demonstrated using a common chemical explosive. But, as usual, material problems arose: what should the pusher be made of, to avoid its evaporation? Even today, the pulsed thrusters are still beyond consideration even in motor engine development. Their time, as well as that of interstellar flight, is yet to come.

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(ed note: this is fictional, but amusing)

(Turns out the first ship I want to do isn’t one of the ones anyone asked for. Oh, well.)

SILVERFALL-CLASS LUNAR EXPLORER – BLOCK II

Operated by: Spaceflight Initiative
Type: Early exploration vessel.
Construction: Spaceflight Initiative.

Everyone’s heard of the Silverfall-class explorer, the starship that first carried eldrae from Eliéra to its moons. (A surprisingly large number of them have visited the museum out on Seléne where Silverfall Four — Moondancer — rests in state out on the regolith, where she was flown to her resting place by her original crew, and is kept in flight-ready condition by her many admirers.)

The design discussed here is of the Block II variant of the Silverfall-class, which incorporates the modifications made to improve performance and livability after studies performed on Silverfall Zero and Silverfall One, and whose two examples can be considered representative of the class, including as they do the actual craft, Moondancer, which made the first landing on Seléne; later design revisions included a number of specialized variants, but made no further changes to the basic design.

Length: 42.2 m, of which:

• Mission module: 12.2 m.
• Engineering frame: 18 m (overlaps with propulsion module)
• Propulsion module: 12 m
• Shock absorbers and pusher/ground plate: 12 m

Beam: 12 m (mission and propulsion module); 22m (widest point)
Mass (fueled): 616,200 kg

Gravity-well capable: Yes.
Atmosphere-capable: No.

Personnel: 2 required, as follows:

Flight Commander
Flight Director/Engineer

Accommodates 6 further mission specialists.

Drive: Silverfall-specific fission pulse drive with laser trigger; cold-gas attitude control and landing system.
Fuel: Plutonium coated fuel pellets.
Cruising (sustainable) thrust: 2.4 standard gravities
Delta-v reserve: 16,800 m/s

Drones: Simple automation only.

Sensors:

Star tracker
Inertial tracking platform
Passive EM array
Short-range collision-avoidance and docking radar
Mk. 1 Eyeball

Weapons: None, unless you count the drive.

Other systems:

Thorium pebble-bed power reactor
Omnidirectional radio transceiver
Communications laser
Whipple shield (habitable area only)
Canned (non-regenerative) life support; CO2 scrubbers
Redundant flight control systems
NaK pumped-loop high-power radiators and maneuvering heat-sinks
NH3 low-power radiators

Small craft: None.

DESCRIPTION

The original Phoenix-class orbiter was once described as an explosion in a girder factory, and its smaller cousin, the Silverfall, maintains much of that look, despite at least some improvements in elegance between the designs. That, and that unlike the Phoenix, the Silverfall was designed as a pure space vessel, intended to be built at and operate from Oculus Station in Eliéra orbit, and to land only on airless Seléne and Elárion.

The layout of the Silverfall-class can be divided into four sections: the upper mission module, the engineering frame which sits atop and wraps around the propulsion module, and the shock absorber/pusher plate section at the bottom.

At the top, the mission module is divided into three tail-lander decks with plenum space in between. The uppermost deck, topped by a blunt cupola and surrounded by the various navigational and communications antennae, contains semicircular bridge and mission management sections, surrounded by the ship’s avionics. From it, an axial passage descends through the next two decks, terminating in a small engineering space (housed in an aft projection) where the mission module connects to the primary thrust truss of the engineering frame. A secondary access tube, normally depressurized, runs down from this passage through the engineering frame.

The second deck houses three pie-segment areas; the ship’s laboratory, workshop, and main stowage area. Opposite the stowage area, between the laboratory and workshop, a secondary airlock provides maintenance access while in flight to the exterior of the ship (with a ladder down to the upper levels of the engineering frame), and is the main access point when the starship is docked.

(Opposite this airlock, centered on the mission module’s vertical axis, is the gold plaque bearing the Imperial Star and the stylized rocket-and-crescent-moon of the Spaceflight Initiative, with beneath them the various names and logos of the various contributors making the Silverfall mission possible.)

The third, lowermost deck contains the crew quarters, divided into a number of modular pods, along with the galley, central mess, ‘fresher, and a small medical bay.

Six meters below the mission module is the propulsion module, a heavy steel capsule containing the guts of the nuclear-pulse drive that powers the Silverfall. For the most part, however, it is hidden by the engineering frame which wraps around and atop it, a mesh of trusses containing, most notably, the six pellet silos, evenly spaced around the ship, containing the plutonium fuel pellets, and the spherical tanks of cold-gas propellant and life-support supplies.

The lower surface of the engineering frame (along with that of the propulsion module) is the solid sheet of the protective shadow shield, protecting the upper sections of the craft from radiation produced by the pulse drive. The secondary access tube descending from the base of the mission module connects to the primary airlock, located directly above the edge of the shadow shield vertically beneath the secondary airlock, and from which a descent ladder can be lowered once the drive shroud is in place.

At its edges, laser modules extend past the edge of the shield to trigger the explosive coatings of the fuel pellets; just within those edges, sealed slots permit the segmented drive shroud to be lowered after landing, surrounding the mechanics of the shock absorbers and pusher plate, to protect disembarked astronauts from residual drive radiation.