“Mars ain’t the kind of place to raise your kids – in fact it’s cold as hell,” sings Elton John in Rocket Man. And it’s true: the present atmosphere and surface of Mars are certainly inhospitable for any aspiring rocket man. Since Mars lost its magnetic field 3.8 billion years ago, the pressure of its once Earth-like atmosphere has gradually reduced to just 1% of Earth’s, letting through damaging UV light and cosmic radiation that make the surface a lot less habitable.
We don’t really know how or why this happened. But new results from NASA’s MAVEN mission, published in Science, have shed some light on the mystery – it’s to do with solar storms and shocks from the Sun billions of years ago. There’s a bright side to the new results as well: an aurora over most of the planet’s night-time hemisphere has been discovered.
