About the International Asteroid Warning Network (IAWN) and the Space Mission Planning Advisory Group (SMPAG).

Atmospheric entry of asteroids or comets can cause significant damage to Earth. Two international bodies, the International Asteroid Warning Network (IAWN), and the Space Mission Planning Advisory Group (SMPAG) are working on dealing with potential threats.

Heterogeneous chemistry in the atmosphere of Mars.

Hydrogen radicals are produced in the martian atmosphere by the photolysis of water vapour and subsequently initiate catalytic cycles that recycle carbon dioxide from its photolysis product carbon monoxide. These processes provide a qualitative explanation for the stability of the atmosphere of Mars, which contains 95 per cent carbon dioxide. Balancing carbon dioxide production and loss based on our current understanding of the gas-phase chemistry in the martian atmosphere has, however, proven to be difficult.