On the early morning of the 7th of January, 1948, the skies above the Ankoli flats were suddenly lit up by a flash of bright white light - so incredibly brilliant in its intensity that had there been anyone standing within several dozen kilometers of the event, they would have instantly been blinded.
Project Nikkō, started almost a full decade ago, had over the course of its life suffered enormous setbacks, failures, cost overruns, and on more than one occasion diverted funding from other, more directly important projects with near-disastrous results. And yet, on that cold winter day, in less than a thousandth of a second it repaid every single one of the 2 billion dollars spent on it a hundred times over.
For the first time since large uranium-infused asteroids stopped raining down on Atlas over 3 billion years ago, an atomic detonation had blossomed over the planet’s surface. It would not be the last.
It was an aeronautical engineer, attached to the team of people working on weapon delivery concepts, who came up with the idea of using this new, incredible source of power as a propulsion system first. The engineer in question, upon doing some back-of-a-napkin math, wrote up an article on his idea that was then published in 1949 in an internal technical journal used by the people working on the program. Needless to say, this quickly garnered a lot of attention. Over the next few months, as a sort of side project while working on more pressing concerns, the nuclear engineers and physicists on the program slowly came up with, researched, and even tested various different ideas for how to propel a spacecraft using atomic power. It wouldn’t be until a full two years later however, when they finally made a breakthrough.
While originally focusing on riding the shockwaves from successively detonating atomic devices behind the ship, one scientist working on the project came up with a different idea, known as a fizzler. In this concept, fissile material would be mixed with some sort of binding agent and formed into a massive stick. The bottom end of this so-called ‘atomic firecracker’ would be set off with a nuclear trigger, and the entire thing would subsequently burn much like a solid rocket booster. However, this concept had a very notable problem, in that it was completely uncontrollable. That did not, though, stop it from serving as an invaluable source of inspiration.
Not long after the invention of the fizzler, another scientist came up with an even more radical idea - the nuclear salt water rocket (NSWR). The basic concept was simple; take some salt water, and mix in to it so much enriched uranium that it would spontaneously become supercritical and explode when allowed to pool in one place. Store this water in a bunch of tubes made from a neutron-absorbing material like boron, and when you want to accelerate, feed them into a combustion chamber alongside a bunch of regular, pure, water, to cool it down and prevent the chamber from melting, and also act as more reaction mass.
This propulsion system proved to be unimaginably powerful and efficient, to the point that the entire solar system could become unlocked to humanity should they choose to pursue it. And so, obviously, they did.
In 1954, hidden away in the more mountainous regions of the Akitsukunian islands, the US government set up the headquarters for project Taimatsu [torch]. Their goal was to develop and build a series of vehicles that could launch satellites, carry humans into space, and enable the construction of offworld research stations and facilities.
Once full-scale research and development started it wasn’t long before the NSWR concept underwent one final iteration. By salting the water with lithium-6-deuteride instead of uranium, and wrapping a neutron source like, say, a high neutron-flux atomic reactor around the combustion chamber, you could achieve the same very high thrust and efficiency, but with no radioactive products in the exhaust plume.
The researchers at project Taimatsu got to work right away, and by 1959 they had managed to rig up a prototype engine on a static test stand. It didn’t go super well at first, with the initial such engines usually disintegrating due to the massive thermal and mechanical stresses involved, but after around 3 years of non-stop, painstaking development work, the kinks were ironed out.
The XLR-1 was, by modern standards, barely worthy of being called a rocketship at all. By the standards of the day, however, it may as well have been an interstellar starship. Standing almost exactly 25 meters tall, she was equipped with the very first flight-ready NSWR in existence, the Type 1A3. Ordered in late 1961, construction work took around 6 months to finish, but the engines wouldn’t be ready for almost another year. Finally, in 1962, the XLR-1 blasted off from the test facility into the morning sky, rising to over 300 kilometers before falling back to the ground and being recovered via parachute.
By the end of 1962 the World War was officially over, and with national security no longer at risk the program was gradually declassified and shifted operations. No longer a simple black project, the entire program was handed over to a newly created public organization, the National Aeronautics and Space Administration (NASA).
By 1965, the program had progressed to the point that the first crewed, orbital flight test could take place. Lifting off from the test facility during the dead of the night an XLR-2, carrying the somewhat infamous test pilot Samantha Pearson, soared into orbit, staying up there for a full day before deorbiting. To protect itself from the effects of reentry, the rocketship fired its motor retrograde the entire time during descent, both slowing it and forming a protective layer of gas in front of it, diverting the oncoming airstream. The XLR-2, having practiced this many, many times on previous uncrewed flights, pulled off a pinpoint landing just under 2 kilometers from the designated bullseye out on the massive Soldova salt flats.
As impressive as that was though, to progress from there a new vehicle was needed. The XLR-2, while a competent spacecraft, was not designed for regular flights or carrying any significant amount of payload. Its tiny crew cabin in fact was actually added later on, in the equipment bay originally used for carrying various scientific experiments. Clearly, something better would be necessary going forwards.
That something would take the form of the XLR-3. First drawn up as a set of rough design sketches in 1963, this rocketship was intended to conduct long-term experiments in Earth orbit and cislunar space, and to be able to carry both a fairly large crew of five cosmonauts, plus a sizable amount of cargo. However, budget cuts on the program in the aftermath of the end of the World War caused her to also be pressed into another role, one that was originally intended to be serviced by a dedicated clean sheet design; that of a Lunar lander.
In order to make this possible a number of changes to the design would take place, though large structural alterations were out of the question. The avionics and control systems were overhauled, additional long-range communication systems were added, an astrogation dome was installed on the flight deck, and most notably, a crane assembly and a Lunar Roving Vehicle (LRV) - colloquially known as the Moon tank - was mounted in the payload bay, along with a small collapsible gondola for lowering cosmonauts to the Lunar surface. This did not come without compromise however; the XLR-3, never designed for such an expansive role, only had a small single-person airlock, and the massive LRV took up so much space that it would have to be lowered out of the rocketship to the ground first, before the cosmonauts could walk over to the other side of the bay to set up the gondola and follow it down. Luckily the entire rocket’s crew cabin was designed to be pressurized with pure oxygen at 22% atmospheric pressure, which meant that the crew didn’t need to spend a lot of time adjusting themselves to the lower pressure of their suits before a spacewalk, allowing them to cycle through the airlock in only about 5 minutes.
Five XLR-3s were constructed between 1965 and 1967; USS
Senden (SN 5), USS
Bōken-ka (SN 6), USS
Igen (SN 7), USS
Yūkan (SN 8), and USS
Taikyū (SN 9). Over the next few years they would all take turns flying into orbit and, starting in 1968, conducting uncrewed Lunar landings to prove the avionics systems.
Igen would tragically be lost during one of these missions, her main computer suffering a software malfunction and causing her to lose attitude control, sending her crashing into the Lunar surface at several thousand kilometers an hour. Nevertheless, slowly but surely the problems were found and addressed, and in June of 1969 the time finally came for a crewed landing to be attempted.
For this daunting mission USS
Senden would be selected. She blasted off from the Soldova cosmodome on the 9th of June, 1969, rising into the skies atop a column of atomic flames. Aboard her, sitting in foldable crash couches on the flight deck were five cosmonauts, all of whom were about to make history.
Lieutenant Laurelia Saunders, the mission’s commander, had been in the US Army Air Force before transferring to NASA. Born in 1931, she became obsessed with flight from a very early age and was by all accounts an excellent pilot, scoring 11 kills in the World War before becoming a test pilot and flying all manner of experimental aircraft.
Next down the ranks was Masami Katayama, the executive officer, who was a physicist with an extensive knowledge of orbital mechanics, cosmonavigation, and rocket flight dynamics. After her was Satoshi Kuno, an aeronautical engineer with degrees in both mechanical and electrical engineering, who was very good at troubleshooting and fixing problems on the fly, sometimes literally. Finally there was Samson Tokuda and Sylvie Forest, who were both geologists, and Tokuda also had a degree in astronomy.
Of course, all of the cosmonauts also had a very wide general knowledge base as well, and were trained extensively before the mission on every aspect of it that might be relevant. In addition, this wasn’t the first time any of them had flown into space. Sauders, Kuno, Forest, and Tokuda had all done orbital flights before on the XLR-3 (and in the case of Sauders, the XLR-2), and Tokuda had actually been on the USS
Taikyū when she performed the first crewed circumlunar flight back in December of 1968, looping around the Moon on a free-return trajectory. But this was the first time that any of them - and indeed, that any humans at all - would attempt to actually touch down on the Lunar surface.
The ascent was nominal and
Senden settled into low orbit, and after spending several hours in orbit checking their systems, she lit up her drive for a second time and performed her translunar injection burn, putting her on a course to the Moon. The outbound trip took around 3 days to complete, and she performed her breaking burn into Lunar orbit perfectly on June 12th. She had originally been placed on a free-return trajectory, so that if her atomic engine failed to ignite she would not crash into the Lunar surface, but instead return into near-Atlas space so that another XLR-3 could rendezvous with her and rescue her crew. That proved unnecessary however and her motor fired perfectly once again, placing her into low Lunar orbit.
About 14 hours later Sauders stood up in the so-called descent cockpit, a control station mounted in front of a massive glass astrogation dome, while the rest of the crew stood at the semi-circular bank of control consoles behind her. The collapsible crash couches used for ascent and descent on Atlas were folded away, not needed due to how low the Lunar gravity is. The breaking burn to the Lunar surface would top out at just 0.8g.
The descent was, in the end, a rather hair-raising affair. As it turned out the guidance computer program had been set up incorrectly, causing the system to run into memory overflow issues and crash. Sauders, thinking fast, was able to switch to the manual control mode and elected to continue the landing attempt. A misreading of the propellant loading earlier on caused them to go long, that is to say, fly further downrange than they should have, and they ended up outside their pre-designated landing zone, in an area covered with boulder fields. Saunders spotted a flat area several kilometers in front of her, even further outside the area they had trained on, but elected to go for it. The decision proved to be the right one in the end; after flying at low altitude looking for a safe site for several minutes, USS
Senden softly touched down on the Lunar surface at 15:31 AST, on the 13th of June, 1969.
Sylvie Forest, being the lowest-ranked member of the crew, was undoubtedly quite surprised when the rest of them all insisted that she be the first to step onto the surface - traditionally, captains and other high-ranking officers liked to reserve the glory of being the first to step foot on some new piece of land for themselves. Nevertheless, she was more than happy to abide by their request. Kuno, being their designated engineer (though to be fair, all of them were more than qualified to do it as well), suited up first, entering the unpressurised cargo bay and using the crane mounted there to offload the Moon Tank. Forest suited up next, followed by Sauders, and they assembled the collapsible gondola and attached it to the crane. Sauders and Forest stepped into the gondola and were lowered down to the surface, whereupon Forest stepped off its mesh floor and onto the Lunar regolith for the first time.
Following them a short while later, Kuno, Katayama, and Tokuda were all lowered down the side of the rocketship as well. Their first order of business was to get the LRV working, and then Sauders drove around 500 meters away to plant the United States of Akitsukuni flag, so that the exhaust plume from their ascent later wouldn’t cause it to blow over.
Over the course of the next two weeks, the 5 cosmonauts unpacked the various pieces of scientific equipment they had brought with them, a lot of it packed inside the LRV’s cabin due to how little space there was available on the XLR-3, and set it up at various points around the nearby Lunar landscape. The LRV did have a somewhat spacious interior, for a given definition - two people could survive in it for about a day and a half before they started (figuratively) going mad - so the crew were able to use it to travel quite a fair distance. All in all they drove about 530 kilometers (not all in a straight line of course), and collected samples from places as far as 120 kilometers from the landing site.
During the stay on the Lunar surface, the crew spent about half of their time on the surface, driving around, collecting samples, and performing observations of the surrounding terrain, and the other half inside the rocketship relaxing. In order to enter and exit the ship the cosmonauts used a regular airlock, which presented a problem, in the form of Lunar dust. Previous uncrewed XLR-3 missions had returned samples of the Lunar regolith, which had revealed that it was composed of a very fine powdery material that got absolutely everywhere, and tore up eyes and lungs over even short periods. In order to counter this, the airlock included electrostatic scrubbers which would run over the pressure suit to remove the dust from it, which was then collected in a container for future study. In addition special high-power air circulation and filtering systems were installed in the cabin, to pull dust particles out of the air.
Inside the rocketship, the cosmonauts had access to quite a fair amount of space to rest in. The main flight deck had foldable crash couches that were now stored away, allowing a regular couch and a television to be set up, and on the deck below there was a large table around which they could all sit. And on the top deck were three crew cabins, two of which had bunk beds, and the third of which had a single bed for commander Saunders - though in practice, Katayama tended to sleep in there with her.
On the 27th of June, 1969, after a final photoshoot the entire crew all climbed back aboard the rocketship from the Moon’s surface for the last time - at least for now - and blasted off, this time directly onto a trajectory that would take them back to Atlas (though the periapsis of their new orbit was above the atmosphere, so again if her atomic engine failed another XLR-3 could rendezvous with her). Three days later, after a course correction maneuver to make sure she hit her intended landing site, her crew climbed into their foldable crash couches and braced themselves as her rocket motor ignited for the final time. Retroburning the entire way through reentry, and hitting as many as 7 gees in the process,
Senden gracefully fell out of the sky atop a white-hot pillar of nuclear fire, touching down with pinpoint accuracy just a mere 500 meters from her landing target.
The entire Soldova salt flats, for safety reasons, did not have anyone present in them when this happened, which was rather ironic in the end, as it made them quite literally one of the only places on Atlas where the cheering at their success could not be heard.
After more than 300,000 years, homo sapiens had truly slipped the bonds of their planet for the first time. It would not be the last.
XLR-3 class, USS
Senden (SN 5)
Ordered - November 1963
Laid down - February 1965
Commissioned - April 1966
First flight - August 1966
Last flight - May 1979
Fate - On display at the National History Museum
Height - 45.35 meters
Diameter - 6.02 meters
Wingspan - 13.78 meters
Dry mass - 780 tonnes
Propellent mass - 280 tonnes of pure water, 5 tonnes of water salted with Lithium-6-Deuteride, 50 tonnes of RCS propellent
Payload mass - 20 tonnes, including crew and provisions
Wet mass - 1115 tonnes
Primary propulsion system - Type 4A1 Neutron-boosted Nuclear Salt Water Rocket
Fuel sources - Water salted with Lithium-6-Deuteride, high-flux reactor running HEU for neutron production
Propellants - Water salted with Lithium-6-Deuteride, pure water
Mass flow rate - 132 kilograms per second at max thrust, 6.6 kilograms per second at min thrust
Thrust - 20,000 kilonewtons maximum, 1,000 kilonewtons minimum
Burn time - 36 minutes at max thrust, 12 hours at min thrust
Exhaust velocity - 165,000 meters per second
Delta-V - 44,776 meters per second
Attitude control system - 12 bipropellant high-impulse RCS thrusters, 9 monopropellant RCS thrusters
Crew - 5 maximum, 0 minimum
Payload - 50 cubic meters non-pressurized cargo space
Endurance - 3 weeks with typical loadout
Cross-sectional overview:
Starting at the top of the rocketship, we find the forward attitude fine-control thrusters. The XLR-3 has two types of RCS thruster; high-impulse bipropellant thrusters, which are typically used for keeping her stable during take-off and landing and for minor course corrections, and fine-control monopropellant thrusters, which are used for the minute attitude adjustments needed to stationkeep and keep her pointed in a desired direction. The forward thrusters, due to how far they are from the rest, have their own set of propellent tanks just behind the nosecone.
Moving downwards, next we come across the forward pure water tank, nestled inside the top of which are a set of 3 helium pressure tanks. As the water is drained from the tank the pressure in it naturally wants to drop, and so to ensure it stays constant these tanks are connected with a sensor, and gradually release helium to balance out the pressure drop as the tanks are emptied.
Meanwhile, sat at the bottom of the forward water tank are four spherical oxygen tanks. These contain all of the oxygen the rocketship uses for her life support system, stored at a very high pressure of around 400 psi. Since the atmospheric pressure inside the rocketship is only 22% of sea level these small tanks, each around 500 liters, actually contain enough oxygen for 4 weeks of operations with 5 cosmonauts, though in practice flights rarely last this long.
Situated below the forward pure water tank is the crew compartment. This section is divided into three main decks; the habitation deck, the flight deck, and the equipment deck. In addition, on the top and bottom of the crew compartment there are small spaces, about a fourth of a deck high, which are used to store batteries and various pieces of life support equipment such as CO2 scrubbers.
The habitation deck, located at the top of the crew compartment, is home to 3 small crew cabins each around 8.5 cubic meters. Of these, two are equipped with bunk beds, while the third has a single bed for the mission commander. It also has a head, equipped with a special waste disposal system designed to work in microgravity, and a storage closet for various consumables and pieces of equipment.
The flight deck, directly below, is home to a large semi-circular bank of consoles from which every aspect of the rocketship’s systems can be monitored and controlled. It also features the landing cockpit, a control console and set of joysticks positioned in front of a large astrogation dome, such that an cosmonaut standing there can see the Lunar surface and effectively pilot the rocketship down to a safe landing site. The flight deck also has a large space where the foldable crash couches can be set up during take-off and landing on Atlas, or where a regular couch and other pieces of furniture can be set up to provide the crew with a relaxation area, and a hatchway built into the wall of the pressure compartment. Because it’s just a hatch, and not a full airlock, this is only used to enter and exit the rocketship from her launch gantry when she’s on Atlas’s surface.
Finally, at the bottom of the crew compartment is the equipment deck. This is home to the entry hatch to the ship’s airlock, and the storage racks for the 5 spacesuits. It also has a supply closet, for storing all of the food used on the trip, and various other small pieces of equipment. This deck also has a table and chairs mounted to the floor, for the crew to eat meals at.
Next, below the crew compartment we find the payload bay. Originally designed for the launching of small satellites, the reconfiguration of the ship for a Lunar landing mission has left it fairly cramped, with the Lunar Roving Vehicle (LRV, colloquially known as the Moon Tank) and its crane taking up so much room that it has to be lowered down to the Lunar surface before the crew can actually leave the vehicle themselves. This section also houses the ship’s only airlock, sized for a single cosmonaut at a time. Luckily, due to the low atmospheric pressure used in the entire ship, it only takes around 5 minutes to cycle. And finally, installed in bays inset into the walls of this section are a directional high gain and two omnidirectional low gain antennas, for use in communicating when out in cislunar space.
Underneath the payload bay is the main RCS propellent tankage. This consists of four propellant tanks for the bipropellant RCS thrusters, along with a central helium tank to keep the pressure inside them constant. The section that houses these also has two star-trackers and two descent radar system assemblies built into its walls, which provide the rocketship with information about her orientation and altitude. Underneath that is the aft pure water tank, again with helium pressure tanks mounted at the top, and nestled within it is the main motor assembly.
At the top of the motor assembly is a cylindrical tank used to store water salted with Lithium-6-Deuteride, which is the main fuel and propellent used by the nuclear engine located just below. Said engine has two main sections, the turbopumps and electrical turbine generators located at the top, and the main combustion chamber assembly below, around which is wrapped a high-neutron flux nuclear reactor used to initiate the fusion reactions in the engine. And beneath even that, located at the very bottom of the rocketship are 6 bipropellant RCS thrusters, 3 used for attitude control, and 3 aft-facing ones used for minor course correction maneuvers.
Lastly, around the side of the ship there are three large swept-back wings, affixed to the ends of which are the landing pods. Each pod contains 2 bipropellant and 2 monopropellant thrusters, and the propellant tanks to feed them (though fuel transfer lines are in place linking them with the tanks in the core of the ship). And, located at the back of the pods, are the truly massive shock absorber assemblies used to cushion her landing.
