Clint Cowen, age 14, of Newport News, Virginia, for his question:

Are the astronauts' backpacks as heavy on the moon?

True, the astronauts did seem to struggle around the lunar landscape under heavy burdens. But they did not labor under those enormous backpacks. These weighed only one sixth of what they weigh on the earth. So do bodies and all other objects transported from the earth to the moon. There were several reasons the earthmen appeared slow and clumsy. They were on a strange world where any risk was unthinkable. A torn space suit would be fatal and the purpose of the mission depended on preserving a lot of delicate scientific equipment.

Another problem was muscles    muscles trained to cope with the mighty gravity of the earth. On the moon it is possible to jump six times higher and carry loads six times heavier. However, earth trained muscles need time and practice to adjust to such delightful possibilities. The visit was too short and practice too risky. This may explain why our well trained astronauts moved with such carefully controlled caution.