There is no fundamental reason we could not send people to Mars, but it is a very difficult engineering problem. It only takes 3 days to get to the Moon and back, but a trip to Mars would probably take about 3 years. You would have to be able to provide water, food, heat, sanitation, and any medical supplies for at least 3 years. We can't currently build a spacecraft large enough to hold all this equipment. We would probably have to launch many cargo rockets and build the actual Mars spacecraft in orbit. There are also a lot of difficult problems that are raised when you can't buy new materials. For example, people tried living in a sealed environment for 2 years in the Biosphere II experiment, but from time to time, they would find things that had to be brought in from outside. And that's something you could not do if you're all the way on Mars. They had other problems, too, like their food plants dying. Going to Mars is a very interesting and hopeful possibility, but it may also be the most expensive thing humans have ever done. It can be hard to justify the cost of sending people when they cost a million times more than sending wonderful robots like the Mars rovers. Finally, you have to find astronauts who could live together peacefully in a very small space for 3 years. Imagine the fights you'd have in a car trip where you couldn't even stop for gas for 3 years!

Hopefully, someday astronauts will be able to land on Mars.It is not beyond our technology, since we were able to send astronauts to the moon, and the Mars Lander to mars. However, it is a very expensive project as well as a very long one, since Mars isn't very close to Earth for much of its orbit around the sun. I think when they launched the Mars Lander, it was the closest that Mars would get for almost a hundred years; and when Mars is too far away, it becomes very difficult to provide the astronauts with enough supplies and materials to make it that far. As it is, it already takes a few months to travel to mars when it is as close as it can get.