Why cant you write in space?

Answer 1

You CAN write in space.

With a chalkboard and eraser or with pencil and paper. The problem is that in the vacuum of space, the liquid ink of a pen evaporates too quickly and dries out the pen.

Additionally, within the pressurized crew compartment of a spacecraft, there is no gravity that is needed to cause the ink to "fall down" onto the ball of a ballpoint pen. To solve this problem, NASA solicited the design of a special ballpoint pen that could write in zero-G or upside down. The result was a pen with an ink cartridge pressurized with nitrogen, which would force the ink to the ballpoint even when inverted.