How about writing on the moon while it's dark? Reflect enough sunlight onto the dark side to make it about as bright as the light side. That would give a good contrast.
You would need an array of mirrors about the size of France in orbit about the earth. Thin film mirrors would be a lot lighter than asphalt. Precisely aiming the mirrors would be the challenge.
Comments
How about writing on the moon while it's dark? Reflect enough sunlight onto the dark side to make it about as bright as the light side. That would give a good contrast.
You would need an array of mirrors about the size of France in orbit about the earth. Thin film mirrors would be a lot lighter than asphalt. Precisely aiming the mirrors would be the challenge.