In the last of his reports from the United States, the Today programme's Justin Webb visits Nasa's base in central Florida for a look at the future of the country's space exploration programme.

"Space could hold the key... to better protein structures" for treatment of diseases such as cancer, hopes Bobby Block, who works for the Center for the Advancement of Science in Space, a non-profit company that this year sent the world's first non-government rocket to the International Space Station.

But not everyone agrees. "I think there is no place for commercial space flight," believes Chris Milner, a former Nasa employee, one of many Americans concerned about the country's national security.

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