....Why do you think it would take a manned spaceship longer to get to Mars than an unmanned one? I'm sure they would do everything possible to make it as quick as possible. This way they wouldn't have to worry about having extra food and resources.
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Because the orbits of the two planets have to line up in a way that makes it a short trip. A short trip "coming AND going" isn't going to happen.
Face it, round trip to Mars is four years or longer.
4 years sounds reasonable. It's a lot more reasonable than the 2-3 years each way that was mentioned here before. I didn't really think about the fact that you'd have to wait for Mars to be close to Earth again to go back. That is a good point. I looked it up and it actually seems to happen every 2-3 years. (
https://mars.nasa.gov/allaboutmars/nightsky/mars-close-approach/). More specifically approximately every 26 months. If you could get to Mars in half a year, you could have 14 months on Mars and make it back the next time it gets closer to Earth. I'm not sure when you'd have to launch. I guess it would actually have to be 6 months before Mars is close. That would actually give you 20 months on Mars, assuming you could do the trip in 6 months. This would be a total of 32 months, or 2 years and 8 months. This seems reasonable for a first trip.