Measuring human impact on earth, Awards for engineers, Sounds of space junk.

Quantifying the impact of humanity on the earth's natural systems. Why human activity now has a larger effect on our planet than the forces of nature. We look at how mathematical equations can now be used to compare historical natural processes with contemporary man made changes. And we ask where current developments will take us in years to come.

The Queen Elizabeth Prize for Engineering has been awarded to the inventors of digital imaging sensors. First invented in the 1970's, many of us use this technology everyday. These sensor can be found inside every digital camera ever made, from the devices used on space probes to collect distant images from the far reaches of the universe to the ubiquitous pocket cameras in our mobile phones.

The earth is surrounded by junk - space junk. Many thousand of pieces of junk orbit the planet, left over from the history of everything we've ever sent into space. A new project has given a voice to this junk, and created a machine which plays simulated sounds of the junk as it passes overhead.

Producer: Julian Siddle

Presenter: Gareth Mitchell