… This immense reflector-antenna is heading into space, to “weigh” Earth’s forests. It’s a key component on the European Space Agency’s Biomass mission, now under construction in the UK at aerospace manufacturer Airbus. When unfurled, the space brolly’s 12m by 15m wire-mesh membrane will be part of a very special P-band radar system. It’s special because of its long wavelength. At 70cm, it can look past the leaf canopy of forests to map the woody parts below – all those trunks and branches. Using an approach akin to tomography, like that used in a CT scan, the 1.2-tonne satellite will analyse slices through the trees on repeat passes to build up a picture of how much woody material is present. Global maps should be produced every six months. The plan is for Biomass to gather at least five years’ worth of data, to be able to spot trends.