Catalyst

Cities are one of our greatest inventions, they bring us together and drive wealth, but as more of us flock to live and work in them, we need to find ways to make them greener, more sustainable and efficient places to live. Physicist Dr Niraj Lal explores some of the engineering solutions driving change. To see how we’ll keep our growing population moving he visits the construction site of the largest public transport system ever undertaken in Australia and discovers how engineers are finding ways to replace concrete - one of the biggest CO2 emitters in the world - with greener alternatives.

Astrophysicist Professor Tamara Davis explores the impact asteroids have had on our planet and discovers that they may hold the key to one of the greatest scientific mysteries of all - how life began. In the Northern Territory, Tamara sees firsthand the destructive power of an asteroid - the gaping 25km wide Tnorala crater. Keeping an eye on current threats are teams at the Siding Spring Observatory, where Tamara observes one of the thousands of potentially hazardous asteroids rocketing through space. Tamara uncovers the story of Victoria's Murchison meteorite, which contains complex organic compounds that scientists are experimenting with in New Zealand, to determine if a meteorite could have kickstarted life on earth.

This program sets up a pop-up dental clinic in Western Sydney to investigate Australia's most common dental complaints, uncovering the tips to keep your mouth healthy and revealing surprising secrets behind a beautiful smile.