How Japan might have done a manned lunar mission [RSS/RO mini-series - Complete]

[Pipcard]

I have an interest in the "what-ifs" of the Japanese space program, which were only denied because of problems with the country's economy : ( .

In the mid-2000s, JAXA announced that they would be sending astronauts to the Moon in 2020. In 2008, this was the plan according to Mitsubishi Heavy Industries: 6 launches of a next-generation rocket known as "H-X" (the preliminary version of what is now known as the H3 rocket) would launch a lunar lander, a manned cislunar transfer vehicle, and several Earth Departure Stages (found via a NASAspaceflight forum thread). I also found another paper done by JAXA. The launch vehicle shown here uses a custom version of the LE-7 engine from Forgotten Real Engines, with the thrust and Isp of the future LE-9 engine.

This will be a recreation of the mission profile using Real Solar System and Realism Overhaul.

EDIT: I re-did the mission because of a few things: I needed a slightly bigger rocket for the Earth Departure Stages, I wanted to launch to the lunar orbital plane during the daytime so I waited about 200 days, and I changed my mind regarding the use of RTGs over solar panels. The original version of this post can be found here. Just remember to get an ambient light mod like this or this if you're taking screenshots at night.

The first launch from Tanegashima Space Center would put the lunar lander module in a low Earth parking orbit.

Liquid rocket booster separation (and fairing jettison)

Second stage ignition (and orbital circularization)

Payload jettison

The lander, waiting in low Earth orbit.

Edited March 23, 2023 by Pipcard

[UnusualAttitude]

Awesome.  It's always interesting to see alternative solutions to the problem of a crewed lunar landing in RSS. Looking forward to the rest of the mission! 

[Pipcard]

Thanks!

Just a notice, I re-did the first launch.

Edited July 22, 2016 by Pipcard

[Geschosskopf]

On 7/20/2016 at 0:50 PM, Pipcard said:

The lander, waiting in low Earth orbit.

Pretty nifty.  I know next to nothing about the Japanese space program so look forward to learning something.  I've already learned you can use the Mk1 passenger fuselage as a lander can

 

[Pipcard]

The second H-X launches an Earth Departure Stage (designated EDS2-L as it is going to act as the second stage for trans-lunar injection and lunar orbit insertion). The EDS is supposed to look like an H-IIA upper stage but I would need a ring-shaped docking port with a 5-m diameter.

To reduce boil-off of the liquid hydrogen, I had to put some radiators.

It makes maneuvers to rendezvous and dock with the lunar lander module.

Edited July 22, 2016 by Pipcard

[Pipcard]

Having technical difficulties right now - yesterday (when I did the last mission), the radiators were working to mitigate the hydrogen boiloff (not completely, of course, but just enough so that it could sit in orbit for a few days without losing a significant amount of fuel). But now they aren't and I'm not sure why.

Edited July 22, 2016 by Pipcard

[Geschosskopf]

2 hours ago, Pipcard said:

But now they aren't and I'm not sure why.

Space lampreys?  I hear they infest LEO in RSS   Good luck smacking them.

 

[Bev7787]

2 hours ago, Pipcard said:

Having technical difficulties right now - yesterday (when I did the last mission), the radiators were working to mitigate the hydrogen boiloff (not completely, of course, but just enough so that it could sit in orbit for a few days without losing a significant amount of fuel). But now they aren't and I'm not sure why.

Are the tanks cryogenic? They help mitigate boil-off.

[Pipcard]

21 minutes ago, Bev7787 said:

Are the tanks cryogenic? They help mitigate boil-off.

I checked, and they were cryogenic.

Over the two days it took to catch up and rendezvous, it only lost about 100 L of liquid hydrogen (out of ~50000), even at high time accelerations. But now the radiators are ineffective, and it's losing thousands of liters over a few days.

And I did right click and activate the radiators.

Edited July 23, 2016 by Pipcard

[Bev7787]

Could be an issue with RF then.

[Pipcard]

Maybe the RTGs are one of the culprits (due to their heat release): I undocked the Earth Departure Stage from the lander, quicksaved, then reloaded. The liquid hydrogen wasn't quickly boiling off anymore.

But that doesn't explain what happened here with a newly-launched EDS.

At 1x time acceleration, the "radiation flux" is positive (as it should be, because when the internal flux is more negative, that's when the liquid hydrogen boils off faster), but steadily decreasing. The LqdHydrogen is being consumed at a rate of 0.01 L per second, it should be 0.00.

(yes, there's a hyperedit icon, but I honestly only use it for testing purposes, not actual missions. And I do use the MechJeb autopilots, but only during launch. I also can't stand doing a manual rocket launch when playing Orbiter)

At 10x time acceleration, the radiation flux made a drastic jump to -144.72 kW.

At 100x time acceleration, the radiation flux becomes somewhat less negative but the cooling effectiveness is much lower.

Over a day at 10000x time acceleration, it has lost >1000 L of liquid hydrogen. This wasn't happening yesterday.

Edited July 23, 2016 by Pipcard

[Kerbart]

When comparing "2001" to contemporary "Godzilla" movies it becomes clear why Japan couldn't do a "moon mission."

[Geschosskopf]

17 minutes ago, Pipcard said:

Maybe the RTGs are one of the culprits (due to their heat release): I undocked the Earth Departure Stage from the lander, quicksaved, then reloaded. The liquid hydrogen wasn't quickly boiling off anymore.

But that doesn't explain what happened here with a newly-launched EDS.

Hmm, I have no idea.  Only thing I can suggest is maybe pointing one end at the sun so the radiators are all edge-on to the incoming heat?

18 minutes ago, Pipcard said:

(yes, there's a hyperedit icon, but I honestly only use it for testing purposes, not actual missions. And I do use the MechJeb autopilots, but only during launch. I also can't stand doing a manual rocket launch when playing Orbiter)

It's not cheating if it's fixing or working around a bug.  Your ship should be working.  It isn't.  The game started the fight, so don't be bashful about finishing it

 

[UnusualAttitude]

I believe heat is calculated differently at high timewarp, hence the discrepancies your experiencing. Avoid x10000 or simply timewarp from the tracking station.

The only way I know of reliably reducing or eliminating boiloff is with Starwaster's Heat Pumps mod, and even with this you may get surprises at high warp. 

[Pipcard]

I did test out the Heat Pumps mod, and it works, even with heat-releasing RTGs. I just rotated the radiators for aesthetic purposes. The internal/radiation flux doesn't matter. And I can accelerate time to high speeds without problems.

As you can see, hydrogen consumption when idle is at 0. Not 0.00, just 0. It feels somewhat like a cheat, but this needs to last for a week.

Edited July 25, 2016 by Pipcard

[UnusualAttitude]

If you're really losing sleep over this,  you could use hyperedit to remove 5-10% of your fuel after timewarp to simulate a week of boiloff from a decent cryogenic tank. Zero Boiloff is actually a thing (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110004377.pdf) by the way, but so far only in laboratory conditions. 

Don't let the inadequacies of the physics model cheat you out of an interesting mission ! 

[Pipcard]

re-do of the second part

Edited July 27, 2016 by Pipcard

[Pipcard]

Another Earth Departure Stage (designated EDS1-L) was launched.

It was used for the first phase in the trans-lunar injection burn, then separated.

At the next perigee (about 3 hours later), the first EDS was used to complete the rest of the burn.

A course correction was made as the spacecraft was on its way to the Moon.

Earth was getting farther away.

and the Moon was getting closer.

Lunar Orbit Insertion

The lander was left in low lunar orbit.

Edited July 27, 2016 by Pipcard

[mcdouble]

Wow this is really interesting, I'd never heard about this mission. Looking forward to seeing more.

[lodger]

On 20.7.2016 at 7:50 PM, Pipcard said:

That's great stuff. What parts MODs are you using?

Edited July 27, 2016 by lodger

[Pipcard]

stock + Procedural Parts

edit: there are parts that come with Realism Overhaul that use the stock part models.

Edited July 27, 2016 by Pipcard

[Pipcard]

Fourth launch:

Fifth launch

[Pipcard]

Meet the crew: Hibito, Mutta, and Kenji

(TextureReplacer + Extended Sylith's Kerbal heads pack with some modifications)

Liftoff!

Booster jettison

Fairing jettison

Launch escape system jettison

Deploying solar paddles

\

This is based on a concept for a manned version of the H-II Transfer Vehicle (HTV). In the actual concept, the re-entry and service modules would not detach to re-dock with the orbital habitation module, but would be reconfigured using a "rail-and-wheel system" (probably to reduce risk). I might be able to replicate that with Infernal Robotics but it would just add too much mass.

Rendezvous and docking with the Earth Departure Stages

Edited July 30, 2016 by Pipcard

[Geschosskopf]

 

9 hours ago, Pipcard said:

Fourth launch:

Fifth launch

OK, please tell me if I understand this correctly....

The whole mission requires 6 launches to assemble 2 ships in Earth orbit.  Each ship consists of a payload (crew or lander) and 2 transfer stages.  Then these 2 ships will go to the Moon independently and rendezvous there.  The crew would then get in the lander, go down to the surface, then rendezvous again in Moon orbit.  Then the crew vehicle comes home leaving the lander behind.  Is that correct?

 

5 hours ago, Pipcard said:

This is based on a concept for a manned version of the H-II Transfer Vehicle (HTV). In the actual concept, the re-entry and service modules would not detach to re-dock with the orbital habitation module, but would be reconfigured using a "rail-and-wheel system" (probably to reduce risk). I might be able to replicate that with Infernal Robotics but it would just add too much mass.

That's an interesting concept, switching ends with the re-entry vehicle mechanically instead detaching and docking.  You'd think such a system would have to be pretty heavy, so it could withstand the forces of launching from Earth.  Given that the whole mission seems to require at least 6 normal docking evolutions to begin with (4 to assemble the ships and 2 at the Moon), why not do one more?  I guess you're probably right about the safety issue, given that all the life support is in the hab, not the re-entry capsule.  But OTOH, the crew has to leave the hab behind when they're in the lander, so what's the difference?

I'm assuming the re-entry plan is to land straight from the transfer back from the Moon without circularizing at Earth.  Otherwise, there seems no point in lugging the re-entry capsule all the way to the Moon and back.  Is that correct?

[Pipcard]

6 hours ago, Geschosskopf said:

OK, please tell me if I understand this correctly....

The whole mission requires 6 launches to assemble 2 ships in Earth orbit.  Each ship consists of a payload (crew or lander) and 2 transfer stages.  Then these 2 ships will go to the Moon independently and rendezvous there.  The crew would then get in the lander, go down to the surface, then rendezvous again in Moon orbit.  Then the crew vehicle comes home leaving the lander behind.  Is that correct?

Yes, that's how it works.

6 hours ago, Geschosskopf said:

That's an interesting concept, switching ends with the re-entry vehicle mechanically instead detaching and docking.  You'd think such a system would have to be pretty heavy, so it could withstand the forces of launching from Earth.  Given that the whole mission seems to require at least 6 normal docking evolutions to begin with (4 to assemble the ships and 2 at the Moon), why not do one more?  I guess you're probably right about the safety issue, given that all the life support is in the hab, not the re-entry capsule.  But OTOH, the crew has to leave the hab behind when they're in the lander, so what's the difference?

I'm assuming the re-entry plan is to land straight from the transfer back from the Moon without circularizing at Earth.  Otherwise, there seems no point in lugging the re-entry capsule all the way to the Moon and back.  Is that correct?

There is one person who stays behind in lunar orbit while the other two land, according to the diagram on page 3 here (it also shows H-IIBs, but those won't have enough lifting capacity). They also need the hab for the transfer between the Earth and the Moon. Re-entry is probably direct like Apollo.

Edited July 30, 2016 by Pipcard