Read some articles about the issue and watch some news:
Hawking backs interstellar travel project (BBC news) >>> Watch it on CBS news
14 April 1961: Yuri Gagarin comes back down to earth (The Guardian)
However, if we ever take this decision to send a spaceship into space, scientists will have to bear this in mind:
Space debris collisions expected to rise (BBC news)
1957: Sputnik satellite blasts into space (BBC news)

So we will have to start 'cleaning up the space' (listening exercise, 6 Minute English, BBC)
LINGOHACK: