Theoretical Situation.

[manoeuver]

As some of you may have heard, the US is planning to go back to the Moon in five years or so.
Russia is also planning a manned Moon program.

I am arranging a US vs Russia arm-wrestling tournament on the Moon.
Winner selects the next US president.

YOU are the scorekeeper for the tourney.
Due to strict weight restrictions, you are only allowed to bring one pen with which to fulfill your duty.
The tournament lasts 30 days.

Due to the fictional nature of this situation, any of your fountain pens will function as though they were at home.

Space train leaves in 5 minutes. You have to fill a pen and get going.

Also, the floor is lava. You'd better go.

Which pen do you grab, and what do you fill it with?