JAXA+ | What if Japan had an unlimited space budget? | 2060-02-18 - Massive crewed missions to Jupiter, Venus, Mars, and more! [VIDEO]

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The Japanese economy, which had been the second largest in the world, crashed in late 1991. The popping of the bubble would lead to a rapid decline in the Japanese economy, and would lead to the 90s being referred to as “the lost decade” in Japan. As a result of harsh economic realities, to save money, the Japanese space program's budget would be slashed. Part of this involved shelving the manned spacecraft, and delaying Hayabusa [a cargo vessel in this timeline]. NASDA would be put through the ringer, jumping through hoops to keep the program afloat.

The economic impacts of the Japanese bubble in the 1980s have taken decades to shake out IOTL, and would generally do the same here. In short, even with an earlier station capability, we the authors have serious doubts that NASDA/JAXA will do anything substantively different than they did OTL.

...after almost a decade of dreams shattered by the unexpected financial upset which had broken the Japanese economy, JAXA was becoming more comfortable making its plans based on following where the US was willing to lead.

In response to the Japanese economy and space program losing its ambitions in almost every modern timeline, an alien space bat decided to give the Japan Aerospace Exploration Agency (JAXA) an unlimited budget and resources for space development. The agency thus became known as JAXA+. The early 2020s saw the debut of the H-Z, a super-heavy launch vehicle capable of carrying 285-485 tonnes to low Earth orbit or 75-150 tonnes to the Moon or an escape trajectory, surpassing rockets such as SLS or Starship. This rocket would enable single-launch space stations and lunar bases, as well as the construction of massive crewed interplanetary missions. It was designated "Z" as it was the ultimate letter. H-Z is an upscaled version of their previous H3 and H-IIA/B rockets, following the pattern of a core stage + upper stage fueled by liquid hydrogen/oxygen, which is surrounded by 2 or 4 monolithic solid rocket boosters. This time, JAXA+ borrowed decades-old plans by Aerojet for the M-1 and AJ-260, the largest liquid and solid rocket engines ever tested. The H-Z first stage uses nine M-1s (redubbed "LE-Z") on the first stage and zero to four AJ-260 boosters ("SRB-Z"), with one vacuum-optimized LE-Z on the second stage.

Launch of VEP-Z (Vehicle Evaluation Payload) from Tanegashima Space Center
(screenshot from Kerbal Space Program - Real Solar System mod)

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Solid rocket booster separation

1st/2nd stage separation

 

[Balkanized U.S.A]

This goes over to Alien Space Bats, I think.

 

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This goes over to Alien Space Bats, I think.

(this is more of a graphical thing with KSP screenshots, though)

 

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A successor to the "Kibo" module on the International Space Station, the Kibo-2 space station was launched by a single-stage (with boosters) version of the H-Z (H-Z 102), which could carry 160 tonnes to low Earth orbit (not including the first stage). However, this station was designed as a "wet workshop," meaning that the first stage propellant tanks could potentially be converted into a vast living space; therefore, the total initial mass in orbit was almost 470 tonnes. The first stage was coated with a white sealant to preserve the orange insulation foam in orbit and prevent it from popping in the vacuum of space. At the top of the rocket during launch was a crewed version of the HTV-X cargo resupply spacecraft, which performed a transposition and docking maneuver with the station. The first stage engines shut down over the course of the launch to reduce g-forces and prevent the trajectory from overshooting its target altitude.

(note: might retcon this later)

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2026-03-05 - A H-Z 304 rocket launched the Tsukuyomi lunar lander, which was named after the moon god in Japanese mythology. The crew consisted of Mutta Nanba, Hibito Nanba, and Takio Azuma, and the destination was the Moon's south pole. This H-Z configuration had third stage powered by three LE-7 engines, boosting lunar payload capacity from 150 to 200 tonnes. Tsukuyomi acted as a self-contained lunar base (175 tonnes at launch) with about one year of life support supplies, and a direct ascent module which the crew would ride on the outbound journey and the return to Earth. Landing occurred on March 9, near Shackleton Crater. The descent propulsion stage of Tsukuyomi used five LE-5B-3 engines (using cryogenic hydrolox), while the ascent stage used five LMAE engines (using storable hypergolic propellants). Crew transfer between the capsule and the base itself involved an elevator mechanism (Infernal Robotics) to reduce ladder climb distance. A folding ramp also gave crew access to the surface. The long lunar night required the use of two Kilopower reactors and large radiators to dissipate the heat.

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2026-04-02 - The Lunar Cruiser XL rover, an upgraded version of a Toyota concept, was launched by an H-Z 200S rocket. It was essentially a mobile pill-shaped base on six wheels, powered by a dozen RTGs, that could support a small crew for several months. The front of the vehicle had an observation cupola, while the rear had the airlock and access ladder. Lunar orbit insertion and landing used four expendable tanks with RL10 engines (CECE low throttle variant). As soon as the rover arrived, the crew of Tsukuyomi boarded and drove to the rim of Shackleton Crater and back.

(also note that the Tsukuyomi lander slid down a 2 kilometer slope before coming to a stop)

(one more thing: I should have put more RTGs, apparently crew habitats in Kerbalism consume extra power for "climatization" at night)

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2027-03-09 - After spending a year on the lunar surface, it was time for the crew of Tsukuyomi to head back to Earth. They boarded the ascent stage, which lifted off using 5 Lunar Module Ascent Engines (the center of which could gimbal) to a polar orbit, passing by Shackleton Crater one more time. The small ascent stage was capable of directly returning to Earth, and was powered by solar arrays. After Trans-Earth injection, the crew re-entered and splashed down in the Atlantic Ocean almost five days later.

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Trans-Earth injection

 

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2028-05-15 - An H-Z 204S launched the "Momotarou" asteroid rendezvous mission with Kenji Makabe, Reiji Nitta, and Serika Itou. It was named after the hero of a folktale, a boy who was born from a peach and journeyed to an island to fight demons (or ogres) and retrieve the treasure they were hoarding. The near-Earth asteroid that the spacecraft would be visiting was named "Onigashima" after the island. This continued the theme of "retrieiving treasure from an asteroid" that motivated the naming of Ryugu, the destination of the Hayabusa2 asteroid sample return probe.

The design was a slight modification from Tsukuyomi - the heavy direct ascent stage was replaced by the lighter crewed HTV-X, the landing legs and ramps were removed, and since the spacecraft would be in almost-constant sunlight, four solar arrays were used instead of Kilopower fission reactors. The smaller heat radiators only needed to prevent liquid hydrogen boil-off [which it does as long as time warp is not over x10,000]. Thus, the spacecraft was 145 tonnes (30 t lighter than Tsukuyomi) and therefore did not need a third stage. However, Momotarou had the addition of an inflatable centrifuge ring, spinning to generate 0.1 G of artificial gravity. Launch proceeded with a transfer burn to the asteroid after parking orbit insertion, and a subsequent transposition and docking maneuver. It also had more advanced water recyclers, so less water needed to be carried onboard. A mid-course correction burn was performed at the end of July.

On 2028-11-12 (six months later), Momotarou arrived at the asteroid, decelerating relative to the target. Then the spacecraft was carefully maneuvered using RCS thrusters to make a soft "landing" on the asteroid, which was about 1 km wide. The mission further tested technology for future crewed deep-space missions.

(Note that the advanced grabbing unit didn't seem to work. This is a Class D asteroid in RSS; Class E asteroids and larger are also too large for the physics render distance (>2 km), and Physics Range Extender doesn't work for this. In fact, I had to swap another asteroid with this one in the save file)

Right to left: Kenji Makabe, Reiji Nitta, Serika Itou

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Asteroid transfer burn

Transposition and docking

Mid-course correction

Arrival at asteroid

(screenshot below used CameraTools to rotate the camera)

Size comparison

 

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2028-11-25 - After staying at the asteroid Onigashima for almost two weeks, the Momotarou spacecraft performed a burn pointing radially outwards from the Sun to return to Earth. Arriving six months later, Momotarou made a distant flyby of the Moon on 2029-06-03 before the crewed HTV-X undocked from the rest of the interplanetary vessel, which would pass 200 km from Earth. The HTV-X lowered its perigee to 60-70 km before jettisoning the service module. The capsule containing Kenji, Reiji, and Serika, as well as some asteroid samples, performed a slight skip re-entry to splash down south of the Ryukyu Islands.

Departing Onigashima on 2028-11-25

Approaching Earth on 2029-06-05

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Lunar flyby on 2029-06-03

 

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The Zeta rocket is an upscaled version of the Epsilon rocket, using an SRB-Z (AJ-260) as the first stage. The second stage uses two LE-7-R engines, which have been modified (from the CH4 mod, changed .cfg) to be restartable. The capacity is 53.5 tonnes to low Earth orbit and 17.5 tonnes to geostationary transfer orbit.

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2030-01-18 - A Zeta rocket launched from Uchinoura Space Center carrying a new generation Data Relay and Tracking Satellites (DRTS-X), nicknamed Kodama-X. It could launch three geostationary satellites at once. Each satellite performed a sequence of burns to insert themselves in a synchronous orbit spaced eight hours apart.

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Geostationary transfer burn

 

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In the late 2020s and early 2030s, the H-Z Heavy was introduced. This variant of the H-Z used one or two liquid rocket boosters in conjunction with two SRB-Zs, increasing the payload capacity to 685 (H-Z 212, 1 LRB) or 900 (H-Z 222, 2 LRBs) tonnes to low Earth orbit, surpassing and almost doubling the capacity of the Sea Dragon. The core stage of the H-Z 222 had five engines instead of nine to save propellant until booster separation. The unusual configuration of the H-Z 212 used seven engines on the core stage (arranged with most of the engines on the side opposite from the booster to balance thrust as much as possible), and required special control software [a kOS script] to prevent the rocket from drifting sideways during the first few seconds of launch

H-Z Heavy 222L

H-Z Heavy 212L

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The Kagutsuchi Mars Mission, named after the Japanese god of fire (Mars being known as the "fire star" in East Asia), aimed to send three astronauts to the Red Planet. It would utilize the asymmetrical H-Z 212L. In 2030, the Mars Habitat Module would be sent before the crew, attached to a propulsive capture stage and entering the Martian atmosphere with an inflatable heat shield. The MHM also had a rover called the Mars Cruiser. In 2033, a Mars Transport Vehicle would be assembled in four launches, serving as living space for the crew between Mars and Earth, and carrying the Mars Ascent Vehicle that would take the astronauts to the surface and back to orbit.

2030-12-21 - A week before the launch of the MHM, a Zeta rocket (with a third stage for extra performance) launched three DRTS-X communications relay satellites to Mars, which were almost identical to their counterparts in geostationary orbit.

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Trans-Mars injection

Course correction on 2031-01-22

2030-12-28 - The H-Z 212L launched the Mars Habitation Module. The transfer/capture stage used 1 LE-7-R engine [from the CH4 mod, .cfg modified to have multiple restarts] and 2 LE-5 engines for course corrections. Both the MHM and the relay sats would arrive at Mars in October 2031.

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Trans-Mars injection

Course correction on 2031-01-28

 

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2031-09-29 - Nine months later, DRTS-X4, X5, and X6 arrived at Mars (spaced a few hours apart), inserting into an elliptical Mars orbit, performing a plane change maneuver to align with the Martian equator, and inserting into an areostationary orbit. The network was completed by 2031-10-05.

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After orbit insertion

Network complete

2031-10-08 - About a week afterward, the Kagutsuchi MHM performed its Mars orbit insertion burn, first inserting into an elliptical orbit before a plane change aligned it with the orbit of Phobos, then entering a ~250 km low Martian orbit. On 2031-10-11, the solar arrays and radiators were retracted as the transfer stage de-orbited and separated from the MHM using a pair of retrorockets. The Hypersonic Inflatable Aerodynamic Decelerator (HIAD) expanded to a 25 m diameter, providing ample surface area for the 48-tonne payload to slow down in the Martian atmosphere. The large 70 m parachute deployed 15 km above the surface, then the HIAD detached with another pair of retrorockets. The MHM cut off its parachute before making its final propulsive descent with 4 RL10 engines (CECE methalox version), landing in Kasei Valles, named after the Japanese word for Mars. The solar arrays were redeployed to power four drills, which would extract regolith to convert to radiation shielding.

Second Mars Orbit Insertion

Landed at Kasei Valles

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First Mars Orbit Insertion

Trajectory plan

Plane alignment with Phobos using LE-5 engines

De-orbit

Entry with HIAD

Parachute deployed

Propulsive descent and landing

 

[Teiresias]

What if an alien space bat decided to give the Japan Aerospace Exploration Agency (JAXA) an unlimited budget and resources for space development? This

Well, the government probably institutes a 99% tax rate on JAXA.

 

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2033-01-10 - The first module of the Kagutsuchi Mars Transport Vehicle, which would take people to Mars and back, was launched by a H-Z 204L. It consisted of the Mars Orbit Stage (3x LE-7-R engines and 3x LE-5B-3 engines) and Earth Return Stage (1x LE-7-R and 2x LE-5B-3). The LE-5B-3 engines were used for insertion into an orbit 400 km above Earth.

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2033-02-08 - The first of two Earth Departure Stages (6x LE-7-R) were launched by an H-Z 212L, and would dock linearly at the aft end of the MTV.

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2033-03-08 - The second EDS was launched by another H-Z 212L.

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2033-04-07 - The final assembly flight consisted of the Mars Ascent Vehicle, which would take crews to and from the surface of Mars (with the help of an inflatable deceleration shield, slightly smaller than the one used for the MHM), and the Mars Transport Vehicle Habitat, which the crew would live in on the trip to Mars orbit and back. They were launched by an H-Z 102S with the astronauts Takeyoshi Homura, Makoto Watanuki, and Akane Furukawa on board. The MAV performed a transposition, docking, and extraction with the MTV Hab once in orbit, and used a tug with a single methalox RL10 engine to rendezvous with the rest of the MTV. Once docked, the centrifuge ring inflated and began operating in 3 hours, generating 0.25 Gs of artificial gravity. A few days later, the first Japanese crewed mission to Mars would leave Earth.

Total mass in orbit: 1725 tonnes

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Transposition and docking

 

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2033-04-13 - The Kagutsuchi MTV began its journey to Mars as the six LE-7-R engines of the first Earth Departure Stage ignited for over five minutes, putting the vehicle in an elliptical orbit with an apogee of 11,000 km. The EDS was then jettisoned using solid separation motors. Almost four hours later, the second identical EDS fired its engines for about three minutes to put the MTV on course for Mars, then detached. The transfer to Mars would take 6.5 months, with a small course correction using the three LE-5B-3 engines of the Mars Orbit Stage just a few days after leaving Earth.

First Earth Departure Stage

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Separation of first EDS

Apogee before coming down for the second burn

Second EDS ignition

Leaving Earth

Course correction

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2033-10-26 - The Kagutsuchi MTV arrived at the Red Planet, performing the same maneuvers demonstrated by the Mars Habitation Module. It first inserted into an elliptical orbit with a high point of almost 57000 km, where the vehicle performed a plane change to align itself with the orbit of Phobos on October 27 (using less propellant compared to a plane change near Mars). The day after that, the MTV entered its final orbit of 260 x 240 km as the crew prepared to head down to the surface.

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Mars orbit insertion part 1

Plane change to align with Phobos' orbit

Mars orbit insertion part 2

 

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2033-10-29 - The crewed Kagutsuchi Mars Ascent Vehicle undocked from the interplanetary Transport Vehicle, just over an hour before executing the de-orbit burn with the tug stage (1x methalox RL10 engine). This burn was mostly conducted perpendicular to the prograde direction to align the MAV's path to land near the Mars Habitation Module. The tug stage was then separated, and the Hypersonic Inflatable Aerodynamic Decelerator shield inflated. It was slightly smaller than the decelerator used for the MHM (20 instead of 25 m), but was sufficient at reducing velocity such that when the parachutes deployed at 15 km above the surface, a brief force of only 5-6 Gs was experienced by the crew. The shield fell, leaving the landing legs to extend. Four methalox RL10 s ignited for the final descent and landing, softly touching down on the Martian surface.

The MAV landed about 10 km south of the MHM in Kasei Valles. The crew of the MAV put on their suits before the cabin was depressurized. Takeyoshi Homura was the first to climb out of the hatch and down the ladder, becoming the first Japanese person on Mars. Followed by Makoto Watanuki and Akane Furukawa, he planted the red sun flag of Japan on the Red Planet. They waited for their ride to the MHM: the Mars Cruiser rover, which drove autonomously to the MAV's landing site, a trip lasting about 10-15 minutes. The three astronauts boarded the Mars Cruiser, driving it back to the MHM, the base where they would live for the next 1.4 years.

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MAV undocking from MTV

De-orbit/plane change burn

Separation of tug stage

HIAD entry

Large parachutes

Final descent

Takeyoshi Homura climbs down the ladder

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The Mars Cruiser is deployed from the MHM

 

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2033-11-01 - The Mars Cruiser rover was designed for long range ground expeditions, having about three weeks worth of supplies. On this day, it was driven 75 km west of the Habitation Module to explore Kasei Valles, the longest outflow channel on Mars. It was thought to have been formed by massive floods of liquid water that occurred billions of years ago, carving through the planet's surface over hundreds of kilometers. As this region was once covered in water, the crew of the Kagutsuchi mission studied and analyzed the ground for any fossilized remains of ancient lifeforms. Over time, the solar wind stripped away the Martian atmosphere (Mars being too small for a magnetic field), and the low temperatures and pressures caused liquid water to either freeze or evaporate. The crew returned to the base several hours later, and would continue their exploration for 1 year and 5 months.

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Driving away

One of many sols

2035-04-02 - The crew got ready to leave the Habitation Module, entering the Mars Cruiser for one last time and driving back 10 km to the Mars Ascent Vehicle. They climbed back into the MAV, and almost six hours later, the ladders and solar arrays were retracted for launch (to be redeployed once in orbit). The four methalox RL10 engines ignited while the landing legs were tucked in, as the single-stage vehicle ascended to a 200 km orbit. A day later, it caught up and docked with the Mars Transport Vehicle once again. The tapering section of the MTV contained a tank with almost 30 tonnes of liquid methane and oxygen to refuel the MAV, which would be used again to visit the moons of Mars. The MAV was also resupplied with food, water, and other necessities.

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2035-04-10 - After refueling and a week of rest at the Mars Transport Vehicle, the Kagutsuchi crew undocked once again to travel to the two moons of Mars, Phobos and Deimos. The MAV performed a series of Hohmann transfer burns to intercept and match velocities with the targets. Landing on Phobos occurred about 8 hours later. The Martian moons were very small compared to their parent planet, being similar to carbonaceous asteroids. Due to its low density, Phobos was also considered to be a collection of rocks loosely held together by gravity. Their escape velocities were about 10 m/s or less, requiring careful and gentle engine burns. The RL10 CECE methalox variant could throttle down to 25% of full thrust, and with half of the engines disabled, the effective throttling could be as low as 12.5%. On the surface, walking felt more like floating, and taking a single step could take an astronaut dozens of meters away. The crew only stayed on Phobos for two days due to the solar arrays not getting enough exposure to the Sun, as it was often occluded by Phobos and Mars. They lifted off straight from the surface, escaping from the moon's tiny gravitational pull very easily, and headed for Deimos (half the size of Phobos), where they landed on April 13 and stayed for only one day. The MAV returned to low Mars orbit and docked with the MTV on April 15.

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Video of the Kagutsuchi mission:

2035-05-01 - After 1.5 years of exploring Mars and its moons (a "conjunction class" or long-stay mission), it was finally time for the crew of Kagutsuchi to return to Earth. The Mars Transfer Vehicle jettisoned its Mars Orbit Stage, leaving the Earth Return Stage (which was identical to the transfer stage of the Mars Habitation Module, with its 1 LE-7-R and 2 LE-5B-3 engines). The MTV's orbit being aligned with Phobos, but it was misaligned for a return to Earth. To correct this, it would perform the Trans-Earth Injection in several phases, essentially a reverse of the maneuvers completed at Mars arrival (first burn, inclination change, then second burn). The orbital inclination was shifted by over 40 degrees at the apoapsis [the required inclination for transfer calculated with the help of KSPTOT]. 6 and a half months later, the MTV arrived home. The MAV undocked to redirect itself, leaving the rest of the MTV to fly past Earth as close as 250 km. The MAV's capsule separated, re-entered and splashed down in the middle of the Pacific Ocean.

2035-05-03 - Second phase of the Trans-Earth Injection burn

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Blue: Initial Mars orbit

Orange: TEI Phase 1

Purple: Inclination change

Green: TEI Phase 2

Separation of the Mars Orbit Stage

TEI Phase 1

Inclination change

Leaving Mars

2035-11-19 - Return to Earth

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