Monday, 29 July 2013

How Mars died....

Today the red planet looks like this:

Basically it's a red desert. As you probably guessed from the phrase 'red planet'. 

Unless you thought I meant it had soviets on it.

Calm down Sam, there are no Martian Soviets, we promise......

But anyway: It's got a certain desolate beauty, but the key word there is 'desolate'. The whole planet is dead (or near enough): Liquid water can barely exist there*, there are worldwide 200mph dust storms, the winter temperatures routinely make the air freeze and fall as snow....

....and yet our space craft have found billion year old river valleys, our rovers have found ancient stream beds, and we've identified minerals that form in liquid water.

What the hell happened?

1: Mars got hit by an asteroid the size of Pluto.....

This isn't exactly accurate, but it's pretty close. It's actually an animation of a Moon sized asteroid hitting a Mercury sized planet, in another solar system. But it gives you an idea of just how badly a day like that can bugger your planet.

The blast levelled the entire northern hemisphere. Nearly everything north of Mars's equator is part of a ten thousand kilometre wide crater....

2: The magnetic field died:

A planet's magnetic field is created by molten metal churning about in its core. The mega-impact shattered the Martian core, killing the protective magnetic field. 

Which meant the solar wind - a gale of protons from the Sun - started blasting the air away into space, like this:

3: The volcanoes went off, big time:

....The martian volcano Olympus Mons is the biggest in the solar system. Its 22 km tall and 600 km across its base. That's bigger than Great Britain.....

 Above: Olympus Mons next to Everest and a hawian island (which are also big volcanoes). Imagine being around when that thing went bang. It's a pretty short imagining, yes?

...and Mars is covered in giga-sized volcanic features like this, which all formed at roughly the same time.

Does that sound like it did (what little was left of) the environment any favours?

Olympus Mons, seen from an orbiting space probe. Looks like  great big spot, doesn't it?

Not unless you consider piling volcanic devastation onto asteroid devastation a favour. Which would make you some kind of planetary sadist**. 

Is it possible any trace of ancient life could have survived all that?

Maybe. Nature is always springing surprises on us.....

**So I won't be inviting over for tea, in case you decide to torture my pet meteorite.

* If you're about to go: 'My high school textbook said water was impossible on Mars', then I direct you to this paper, or the zillion like it on the internet. Your text book was wrong.