system
Given the following post, respond as if you're commenting on Reddit:
human
If the earth is protected from radiation and stuff by a magnetic field, why can't it be used on spacecraft?

Is it just the sheer magnitude and strength of earth's that protects it? Is that something that we can't replicate on a small enough scale to protect a small or large ship?
gpt
It is possible but such a magnetic field would require a lot of energy which means you need either nuclear power, which is has its own set of challenges for a human rated spacecraft, or a lot more solar panels which adds weight, lots of cost, and complexity. If you want to protect a deep space spacecraft the most economical radiation shield would be water since you're already carrying some with you.