So. Last night was The Big Announcement from the MER team, attending a big science bash in San Francisco, about just why “Homestake” had got them all as giddy as schoolgirls spotting their favourite popstar. I’m not sure how many people ‘tuned in’ to the announcement at the AGU Conference by watching the press presentation on a live streaming vidow link, but I was one of them, and all credit has to go to the people behind the live stream, because it was very well done, with a nice clear picture (though maybe the panelists did look rather small as the camera was so far away from them!), and the illustrations were shown bang on time too as the panel members gave their presentations (unlike some of the JPL media briefings, where slides sometimes don’t appear, or are in the wrong order, but I won’t criticise that too much as I know how easy it is to mess up a Powerpoint presentation, and I can’t really begin to imagine what a high pressure job it must be to provide the pix for a big event at JPL!)
So, the panel was assembled, the media were gathered in front of them, and the world was watching… What had Oppy found at, and in, Homestake?
I’m not going to even try to give a point by point scientific breakdown of what Oppy found, I’ll leave that to the heavy science websites which will be able to cover it in a lot more detail and more accurately than I could ever dream of doing (as always, your first call should be at The Planetary Society’s site, where AJS Rayl has updated her monthly Update with full details of the Homestake story… http://www.planetary.org/explore/topics/mars_exploration_rovers ) but the simple, back of an envelope story is this: Oppy’s measurements showed that Homestake is made out of a mineral, or minerals, that really could only have been deposited there, and in that way, by water. So, the discovery of Homestake is effectively the best piece of proof yet that water existed on the surface of Mars.
Now I know what some of you are thinking: oh great, big deal, they’ve discovered water on Mars AGAIN. But it’s not like that. This is a big discovery in its own right (and if it had been made back at the start of the mission it would have been hailed as a truly HUGE discovery, a real jaw-dropping achievement, but both Oppy and Spirit had found evidence for water on Mars before Homestake came into view, so I like to think that this discovery slots one more corner piece of the Big Jigsaw of Martian History at Meridiani neatly into place.), proof that this part of Mars, at least, was once warmer, and wetter, maybe with hot springs. maybe not. Add all those elements together and you might have an environment – even if only a short-lived one – that martian life might have found quite acceptable, cosy even.
Which isn’t the same as saying “There was once life on Cape York and at Endeavour Crater! It’s nothing like saying that! But it does suggest that this particular part of Mars might once have been a not-too-horrible place for primitive martian life to hang out…
But going back to basics, what has Oppy actually found? Well, she’s found out that Homestake is – or was, before they trashed it! – very likely made of this stuff, gypsum…
That’s a piece of gypsum from the brilliant mineral collection on display at Kendal Museum, here in Kendal. Here it is under a different illumination…
Here on Earth, gypsum is often found in the form of very familiar-looking veins, like these at Chugwater in Wyoming, USA…
And what’s so special about gypsum? Well, it’s basically formed when water, moving through cracks in rocks, deposits minerals into those cracks and fills them up, creating a ‘vein’ of gypsum. If you compare those pictures above to the MI images of Homestake (see below) you’ll see they look very similar, and that Homestake’s surface does appear to have layers too. And why is the discovery of gypsum here at Meridiani so important? Simply because it means that this part of Meridiani was warmer, and wetter, than it is now, and that water was moving through cracks in the rock here long, long ago.
Now, as I already said, I’m not going to try to disect and analyse the science of this discovery here. I don’t know enough about it, I don’t know enough about geology in general, so it would be a waste of time. Please, just check out AJS Rayl’s updated Update at the link given back near the top of this post. What I’m going to do instead is just post all my favourite images of Homestake here for you all to look at, in the hope they give you all a hint of the importance of this story.
The Road To Endeavour 