Sure, here is the completed text using the -ing form or the infinitive of the verbs in brackets:

Next stop Mars...

(1) **Traveling** to Mars might (2) **become** a reality sooner than you think. Scientists are planning (3) **to send** astronauts (4) **to explore** Mars in the future. The surprising thing is that they are not planning (5) **to send** animals first, but insist on (6) **sending** people, even though it may (7) **be** risky. That's because scientists believe that it's the only way (8) **to find out** if there is or ever has been life on the planet and if there could ever (9) **be**. "We are in favour of (10) **exploring** the possibility of (11) **being** able to live there. There's no point in (12) **beginning** this expedition with animals, is there?" says Professor Huxley. Other experts in the field object to (13) **sending** people up there so soon in the experiment. "We need (14) **to study** the planet as much as we can before we start (15) **risking** astronauts' lives and (16) **doing** anything. It's no good (17) **spending** millions of dollars until we are absolutely sure."