What is the lowest mass to the Moon and back craft?

[Gene]

As the title says im trying to find the smallest craft(in terms of weight) to the moon and back to earth(for 1.5)

Im trying to get this craft below 25 tons and wanted to sere what the current record is

r

 

[Altaïr]

Ah, that's an interesting challenge

Your design is well thought, but I managed to improve it a little:


The main trick is that the upper tank is not full:


Even with only half its capacity, the ion engines are so efficient that it's enough to perform the mission. It's also less weight so I can reduce the number of engines.

Changing the Valiant by 2 Kolibris allowed to save one more ton.

Then, the mission:


LEO reached! Then the Moon part:


Now lift-off and back to Earth:


Sadly, the ion engines broke when landing. I should have fired the ion engines to help it to slow down.

I did it with 22.52 tons, but it's probably possible to improve it again. In particular, keeping the Valiant and removing a bit of fuel from the tank may be a better move to save mass. And a single Valiant still gives a better kick than 2 Kolibris.

But below 25 tons is definitely possible

 

[Space pilot]

Ah, that's an interesting challenge

Your design is well thought, but I managed to improve it a little:
View attachment 74355

The main trick is that the upper tank is not full:
View attachment 74356

Even with only half its capacity, the ion engines are so efficient that it's enough to perform the mission. It's also less weight so I can reduce the number of engines.

Changing the Valiant by 2 Kolibris allowed to save one more ton.

Then, the mission:
View attachment 74357 View attachment 74358 View attachment 74359 View attachment 74360

LEO reached! Then the Moon part:
View attachment 74361 View attachment 74362 View attachment 74363 View attachment 74364 View attachment 74365 View attachment 74366

Now lift-off and back to Earth:
View attachment 74367 View attachment 74368 View attachment 74369 View attachment 74370

Sadly, the ion engines broke when landing. I should have fired the ion engines to help it to slow down.

I did it with 22.52 tons, but it's probably possible to improve it again. In particular, keeping the Valiant and removing a bit of fuel from the tank may be a better move to save mass. And a single Valiant still gives a better kick than 2 Kolibris.

But below 25 tons is definitely possible

Oh now!, Now that's a challenge

 

[Gene]

Yep, I was experimenting with lowering the fuel in the top tank, as well as seeing if breaking 2 ion engines on the moon would give more delta V