The Cap-O-Matic Fisher Space Pen series

The Cap-O-Matic line utilizes cap activation to extend and retract the point, and each carries a pressurized PR style ink refill cartridge, which means that they offer all of the unique capabilities that are synonymous with Fisher products: they will write upside down - at any angle, under water, through grease, extreme temperatures (-30 to +250 degrees F), on almost any surface, three times longer than the average pen, and of course in the gravity free vacuum of space.