You unknowingly proved my thesis. When you said, "...it would take fifty years...," you stated it was possible to exceed the limits of of the solar system. The question was "Could We Get Out of the Solar System?" not "Could We Get Out of the Solar System in 1-49 Years?" Once again thank you for proving my thesis.
Astronauts would not be able to stay on a spacship going out of the solar system i 1-50 years. The pressure of the space would kill them if they stayed in space too long. The pressure would push their bones out of place, breaking their bones. this would keep happening until all of their bones are broken and they would eventually die from loss of air beacause the spaceship could only have so much air.