Resources needed for colonization would save more lives deployed terrestrially

(Zahaan works for Google and is a recipient of Nasa’s Exceptional Public Achievement Medal for YouTube Space Lab. )

The most polarising issue in the Mars debate is arguably the tension between those dreaming of a second home and those prioritising the one we have now. Before his death, Stephen Hawking made the bleak prediction that humanity only had 100 years left on Earth. Faced with a growing list of threats – climate change, overpopulation, nuclear war – Hawking believed that we had reached "the point of no return" and had no choice as a species but to become multi-planetary – starting with the colonisation of Mars. Elon Musk has also said on numerous occasions that we need a “backup planet” should something apocalyptic – like an asteroid collision – destroy Earth. However, not everyone agrees. In the Pew survey mentioned earlier, a majority of US adults believed that Nasa’s number one priority should be fixing problems on Earth. The billions – if not trillions – of dollars needed to colonise Mars could, for example, be better spent investing in renewable forms of energy to address climate change or strengthening our planetary defences against asteroid collisions. And of course, if we have not figured out how to deal with problems of our own making here on Earth, there is no guarantee that the same fate would not befall Mars colonists. Furthermore, if something truly horrible were to happen on Earth, it’s not clear Mars would actually be an effective salvation. Giant underground bunkers on Earth, for example, could protect more people, more easily than a colony on Mars. And in the event of apocalyptic scenario, it is possible that the conditions on Earth – however horrific – may still be more hospitable than the Martian wasteland. Let's not forget that Mars has next to no atmosphere, only one third gravity and is exposed to surface radiation approximately 100 times greater than on Earth.