Many American spacecraft have reached Mars. All were unmanned, however.
As of yet, there have been no manned Mars spacecraft at all.
Not yet, only probes have. In the future, NASA are hoping to reach Mars.
No humans have visited Mars yet. Only robotic spacecraft, like the Mars rovers, have been sent to explore the planet.
No, not yet. So far, we've only managed to send machines there.
No, humans have not traveled to Mars yet. Only robotic spacecraft have been sent to explore Mars, such as the Mars rovers and orbiters. The first crewed mission to Mars is currently planned for the mid-2030s by NASA.
No spacecraft has been built yet that's capable of transporting human beingsto Mars, particularly if they're the kind of people who'd be expecting to breatheduring the trip, and to wrap it up some day by returning to earth alive.
No person has yet walked on mars.
No human has visited Mars yet. However, there are plans by space agencies like NASA to send astronauts to Mars in the future using advanced spacecraft and technology.
Not yet.
No, as of yet there is no evidence of any life existing on Mars but they are still looking.
An astronaut landing on Mars would require a spacecraft to enter the Martian atmosphere, slow down through a combination of aerodynamic drag and parachutes, and use retro-rockets for a controlled descent to the surface. The spacecraft would need to deploy landing gear to touch down safely on the Martian terrain.
As of July 2014, no animal has been sent to Mars yet. In 2008 it was announced that Russia planned to send monkeys to Mars, but this hasn't happened yet.