system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why NASA is building a new rocket instead of re-using the Saturn V design.

The new rocket (Space Launch System) can carry just over 8% more cargo than the old Saturn V. I understand that the old Apollo capsule and lunar lander are unsafe and have less modern technology, but not much has changed in rocket design. Why are we spending money making a new rocket?
gpt
They are no longer capable of making a Saturn V. It required millions of components, many very unique. These are no longer being made. It's much easier to just develop a new modern and safer vehicle which we will be able to build for a long time.