There's water on Mars so how about food?

Mars has been in the news quite a bit recently, last week it was revealed scientists had discovered an underground lake on the planet.

So what are the possibilities here, could food be grown there, and if so, how? Meanwhile, the bright red dot in the sky is going to be unusually bright this week, and there's an interesting reason why. 

Dr Ian Griffin is an astronomer and the director of the Otago Museum, he answers all our Mars-related questions.