How do archaeologists locate, conserve and recover historical treasures from old shipwrecks? What is erosion revealing on the foreshores of the River Thames? And how do you weld up an oil or gas pipeline one kilometre underwater? This week we're looking at the "appliance of science" beneath the waves as well as hearing how the ageing Voyager space probes have discovered the births of new stars in the Milky Way, how a gene therapy technique can block HIV infection and how a computer programme can spot to what extent a photo's been doctored. Plus, does heading a football cause brain damage?