The intervening weeks will be spent in a manoeuvre called aerobraking, which involves using the air-resistance of the thin Martian atmosphere to change the elliptical initial orbit into a circular one from which the planet's surface can be examined in detail.

ECONOMIST: Mars Odyssey

Using a powerful supercomputer, weather forecasters divide the atmosphere up into an elaborate three-dimensional grid, assign initial values of pressure, wind-speed, humidity and so on, and then apply the laws of physics to see what happens next.

ECONOMIST: Next, the fire forecast

If a typical electric car is driven 50, 000 miles over its lifetime, the huge initial emissions from its manufacture means the car will actually have put more carbon-dioxide in the atmosphere than a similar-size gasoline-powered car driven the same number of miles.

WSJ: Bjorn Lomborg: Green Cars Have a Dirty Little Secret