Jump to content

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


Recommended Posts

 Reposting here for posterity (as to why I'm using nuclear thermal propulsion instead of electric, which would make more sense considering Japan's usage of it in the Hayabusa missions)

On 7/30/2022 at 11:34 AM, Beccab said:

Now I'm curious, has NASDA/JAXA ever published a design of a crewed mars lander/base? I've tried searching a bit for it on google to no avail, the furthest I got was finding a few lunar landers (and even then, it's one crew lander and one cargo lander)

On 7/30/2022 at 1:47 PM, SunlitZelkova said:

A search of “日本の有人火星着陸” (Japanese crewed Mars landing) yields nothing.


They would probably use an opposition class profile, to avoid a prolonged stay on the surface. If the Fukushima disaster still happens in any world you decide to use this in, nuclear power is likely out of the question. Lack of a reactor would probably not permit a prolonged surface stay.

If somehow Japan doesn’t develop a “nuclear power allergy”, nuclear electric propulsion would also be a possible choice. But NTRs are unlikely to be adopted, simply because Japan has more experience with ion propulsion.

5 hours ago, Pipcard said:

I was thinking of the same thing, too. But Japan has started to come back to nuclear power in spite of the Fukushima disaster.

I know that in reality, Japan would be more likely to use (low-thrust) electric propulsion over nuclear thermal, and was considering it for my Ceres mission, but from what I've read elsewhere, the Persistent Thrust mod isn't always reliable.

Edited by Pipcard
Link to comment
Share on other sites

  • 7 months later...

After sending humans to the Moon, Mars, Venus, and asteroids, JAXA+ was now ready to venture into the outer solar system. The Raijin mission, named after the Japanese god of lightning and thunder, would transport 3 astronauts to two of Jupiter's major moons (discovered by Galileo) in the 2050s. They would stay a few months at a pre-deployed base on Callisto, then briefly land on Ganymede. The other two Galilean moons,  Europa and Io, were not an option as they were deep inside Jupiter's radiation belts. The longer duration of the mission in interplanetary space required heavier radiation shielding and more propellant, resulting in the initial mass of the piloted vehicle approaching 6000 tonnes.

A new launch vehicle, the H-ZA, was developed to carry payloads up to 1070 tonnes (fact sheet), about twice the lift capacity of the Sea Dragon. The core stage diameter was widened to 21 meters, and the fairing to 26 meters. It had 19 LE-Z engines on the first stage with up to 8 SRB-Z boosters (a total of 11 times the Saturn V's launch thrust), and 4 LE-Z vacuum engines on the second stage.

(I made a custom patch to add gold foil textures to the ROTanks mod.)


Tanegashima model by Tyler Raiz. Instead of using the Kerbal Konstructs mod like in their video (which causes the custom island model to disappear at a certain distance), I had to:

- resize the island to a more reasonable (but not exact) size
- edit the Earth heightmap .dds, replacing the default terrain with water (so it doesn't intersect with the new island model)
- move the space center in LaunchSites.cfg
- create a patch to use the PQS City2 function of the Kopernicus mod to have the island visible at longer distances (like in Katniss's Cape Canaveral mod)

A test launch lifting a 1000 t liquid hydrogen tank into low Earth orbit







Edited by Pipcard
Link to comment
Share on other sites

2049-09-30 - Three DRTS-X relay satellites (DRTS-X16, 17, and 18) were launched by an H-Z 102 rocket to Callisto. These satellites were powered by RTGs as sunlight was less powerful at Jupiter's distance. They would reach Jupiter by the end of 2052, and arrive at Callisto in early 2053.

Advances in materials allowed for the construction of lighter hydrogen fuel tanks that could carry more propellant in the same volume. A propulsion bus similar to the one used for the Ceres comsat network could thus be used to take the trio of satellites all the way to Callisto orbit.
(meta note: the new version of Realism Overhaul for KSP 1.12 changed tank masses when LH2 is loaded)





2050-10-01 - One year after the comsats were launched, the first module of the Raijin Jupiter Cargo Vehicle (JCV) was launched by an H-ZA 208 rocket. It weighed over 1000 tonnes at launch and consisted of the Earth Departure Stage (21 m diameter, 2 LE-N engines) and Jupiter Orbit Stage (13.9 m, 1 LE-N engine).

2050-10-27 - An H-Z 102 launched the Jovian Moons Landing Module (JMLM) and Callisto Habitation Module (CaHM) to rendezvous and dock with the JCV using a auxiliary propulsion stage. After arriving in Callisto orbit, the CaHM would proceed to land on the surface while the JMLM would remain in orbit until the crew arrived. A propellant cache would refuel the lander after the stay on Callisto, so it could land and take off from Ganymede after being pushed there by another vehicle.

On October 30, the Trans-Jovian Injection was performed, to arrive in early 2054. It was split into three burns (1400 + 1500 + 3700 = 6600 m/s) due to the relatively low thrust of the LE-N engines.


Third trans-Jovian burn (after stage separation)







1st burn (apogee)


2nd burn (apogee)



Edited by Pipcard
Link to comment
Share on other sites

2052-12-27 - The Data Relay satellites were the first to arrive in the Jupiter system. Just over a month later (2053-02-06), the three satellites settled into 8-hour equatorial orbits 2900 km above Callisto.





2054-01-19 - The Jupiter Cargo Vehicle performed orbital insertion and reached Callisto in late February 2054. After entering a 500 km parking orbit, the Callisto Habitation Module and Jovian Moons Landing Module separated from the transfer stage. On Feburary 26, the CaHM used its 4 RL10 engines to descend to 100 km before landing in a flat equatorial area where Jupiter could be visible just above the horizon. Like the Tsukuyomi Moon base, which had to be powered for several days without sunlight, it used a Kilopower nuclear reactor and needed large radiators to dissipate heat.

Callisto had been selected for its safe distance from Jupiter’s radiation belts. Ganymede is at the innermost limit, while Europa and Io are constantly bombarded by radiation.









Edited by Pipcard
Link to comment
Share on other sites

2054-09-26 - The first module of the Raijin Jupiter Piloted Vehicle, consisting of the Earth Return Stage and Jupiter Orbit Stage, was launched into a 400 km orbit by an H-ZA 208 rocket. Over the next six months, six more H-ZA 208s would launch the three parts of the Earth Departure Stage, as well as three refueling tankers. On March 9, 2055, the crew of the Raijin mission launched: mission commander Hachirota Hoshino (whose girlfriend worked in orbital debris cleanup), engineer Ken’ichi Obikawa, and scientist Juri Araki. The crew vehicle and orbital habitat brought the total mass of the JPV to 5700 tonnes in low Earth orbit. The JPV began its departure in two parts from March 12 to 14, changing its velocity by a total of 6500 m/s (2900 + 3600) for a 2 year journey to the Jupiter system.




2054-09-12 - Launch of Earth Return Stage and Jupiter Orbit Stage



2054-10-08 - Launch of Earth Departure Stage


2054-11-02 - Launch of Earth Departure Stage B1


2054-11-27 - Launch of Earth Departure Stage B2


2054-12-23 - Launch of Refueling Tanker 1


2054-01-17 - Launch of Refueling Tanker 2


2055-02-11 - Launch of Refueling Tanker 3


2055-03-09 - Launch of Raijin crew and orbital habitat




Edited by Pipcard
Link to comment
Share on other sites

2057-06-22 - The Raijin Piloted Vehicle entered an elliptical orbit around Jupiter, using the last of the propellant in the Earth Departure Stage before activating the JPV's Jupiter Orbit Stage. 1 month later, the Jupiter Orbital Vehicle, a relatively small craft intended for transportation within the Jupiter system, undocked from the rest of the massive JPV. The JOV would enter Callisto orbit on July 23 while the JPV would continue to fly past on other side of Callisto, a gravity assist to lower its orbit around Jupiter. On July 25, the JOV docked with the Jovian Moons Landing Module (and propellant cache), which had been waiting in a 500 km orbit. After the crew transferred into the lander, they left the JOV and propellant cache behind as they made their descent and landed near the Callisto habitat. Hachirota Hoshino, Ken’ichi Obikawa, and Juri Araki climbed down, planted the flag, and walked to the habitat where they would stay until December.

The Jupiter Piloted Vehicle one day before orbital insertion

(zoomed in with low field of view)


The Jupiter Orbital Vehicle docked to the Jovian Moons Landing Module


Right to left: Hachirota Hoshino, Ken’ichi Obikawa, and Juri Araki landed on Callisto




Orbital insertion around Jupiter



The Jupiter Orbital Vehicle undocks


Arrival at Callisto


Callisto orbital insertion and rendezvous was performed in three phases (and one plane change)


Rendezvous with the lander


The Jovian Moons Lander descending onto the surface of Callisto


The Callisto habitat, now occupied


Edited by Pipcard
Link to comment
Share on other sites

2057-08-10 - After the main interplanetary ship performed its gravity assist and entered a circular orbit between Ganymede and Callisto on August 3, the Raijin crew (Hachirota Hoshino, Ken’ichi Obikawa, and Juri Araki) deployed the Callisto Cruiser rover to explore the surroundings of Jupiter's outermost Galilean moon. Callisto was known to have a rocky and icy surface covered in impact craters that are about as old as the Solar System itself. The lowlands tend to be darker while hills or pinnacles may be coated in a bright white frost. Callisto is also thought to have a subsurface liquid water ocean over 100 kilometers below the surface. After over four months living in the surface habitat, the crew lifted off in the Jovian Moons Landing Module on December 3 to re-dock with the Jupiter Orbital Vehicle 500 km above, where it was refueled by the spare tank/depot to prepare for a landing on Ganymede.

Disclaimer: I forgot that the Radial Attachment Point in the landing module does not allow fuel crossfeed. An External Fuel Duct can enable propellant transfer, but I forgot to put one in (I made the same mistake when doing an RSS Moon mission in 2016). Since it is too late to redo the mission starting from 2050, I had to manually edit the save file to refuel the lander (by carefully subtracting numbers from one propellant tank and adding them to the other).

Surface exploration on August 10


Returning to orbit on December 3


Docking with the Jupiter Orbital Vehicle



The Jupiter Piloted Vehicle (currently unpiloted) inserting into a circular orbit 1.4 million km above Jupiter (between Ganymede and Callisto)


Hachirota, Ken'ichi, and Juri boarding the rover



Ascent on December 3



Edited by Pipcard
Link to comment
Share on other sites

2057-12-06 - Leaving the refueling tank behind, the Raijin Jupiter Orbital Vehicle departed Callisto on a Hohmann transfer to Ganymede, the largest moon of Jupiter and the Solar System as a whole, and the only moon with a significant magnetic field. The transfer took less than a week as the JOV inserted into a 500 km orbit on December 12. The Jovian Moons Lander undocked and performed the same descent and landing procedure as on Callisto, touching down in a location where Jupiter could be seen on the horizon. This was only meant to be a short "flags and footprints" operation that briefly studied the surface, composed of silicates and ice and dotted with various craters and grooves. Ganymede's surface may also hide an ocean underneath. Only 16 hours later (on December 13), they launched back into orbit and docked with the JOV.





Undocking the refueling tank


Callisto departure (Hohmann transfer)


Approaching Ganymede


Ganymede orbit insertion


The lander undocks and lowers its orbit from 500 to 100 km






Returning to orbit




Edited by Pipcard
Link to comment
Share on other sites

14 minutes ago, Pipcard said:

More like New Year's.

I did just remember that KSP has fireworks. But to be honest, rockets are more exciting than fireworks. But to be slightly more honest, rockets are just big fireworks. So to be really and truly honest, or just a little annoying, KSP has had fireworks from the beginning.

Link to comment
Share on other sites

2057-12-13 - Leaving the lander behind, the Raijin Jupiter Orbital Vehicle raised its orbit from 500 to 1100 km to reduce exposure to radiation redirected by Ganymede's magnetic field. On December 15, the JOV departed Ganymede to return and dock with the main Jupiter Piloted Vehicle (which was currently orbiting Jupiter between the orbits of Ganymede and Callisto) on December 20. After going around Jupiter for one more time, the JPV performed its departure burn on January 1, 2058, making a distant flyby of Callisto over a day later.

The return to Earth took another 2 years. The JOV undocked to decelerate by 5000 m/s before releasing the crew return capsule, which splashed down in the middle of the Pacific Ocean on February 18, 2060.

Leaving Ganymede


Jupiter Departure


Return to Earth




JOV rendezvous burn before docking with JPV



JPV Earth Return Stage



Passing by Callisto


Decelerating at Earth






Edited by Pipcard
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...