Any manned mission to Mars - where Nasa successfully landed a probe - is at least 10 years away yet.
Nasa would have to develop loads of new technology to get to Mars and back, and it's hoped some of that technology can be used in other areas too.
Brand new space missions are often very popular in the US, and some people are wondering if President Bush is talking about the new plans because they're well liked.
If he wants to be president for another four years he has to win a Presidential Election in November, and the more popular he is the better his chance of winning.
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