Visits to other planets in the Solar System may be possible in the following decades, according to the head of Nasa.
The announcement came as a Nasa space probe hurtles towards the Red Planet. The unmanned 2002 Mars Odyssey spacecraft will attempt to scan the surface for underground water.
The voyage is just one of a number of steps designed to clear the way for piloted missions to Mars.
'Landing spots'
A probe called Mars Reconnaissance Orbiter will soon be able to obtain high-resolution pictures of the planet, Mr Goldin told an audience at George Washington University, Washington DC.
"It will find the landing spots, not just for the robots but for the astronauts," he said.
Nasa plans to touch down a precision landing craft on the Red Planet in 2007, while samples of the Martian surface will be brought to Earth between 2009 and 2011.
The Nasa chief said experiments aboard the International Space Station would prove crucial in working out ways for humans to safely leave the Earth's orbit.
"Let's burn it into our brains that, in our lifetimes, we will extend the reach of this human species on to other planets and to other bodies in our Solar System, and build the robots that will leave our Solar System to go to other stars, then ultimately to be followed by people," he said.
Recent setbacks
The upbeat prediction came despite the two recent serious setbacks for the US Mars exploration programme. The Mars Climate Orbiter space probe was lost in 1999.
Shortly afterwards, the Mars Polar Lander went silent after its scheduled touch down on the Martian surface.
Meanwhile, a spacecraft built by European scientists is due to land on the surface of Mars in 2003.
Beagle 2 is flying as part of the Mars Express mission, which includes an orbiting spacecraft that will investigate the planet's atmosphere and geology.