Tracking meteorites with Desert Fireball
Finding meteorites - little balls of rock from outer space - is key to understanding what's beyond our beloved planet Pluto. Meteor strikes are relatively common - 2009 Leonid Meteorthey happen five to ten times a year - but the difficulty isn't necessarily in finding them here on Earth, it's actually trying to figure out where they came from, as Philip Bland from Curtin University has discovered. He set up Desert Fireball to tackle this problem and told Georgia Mills how it worked...
Philip - It's a project where we've put out lots of little kind of observatories across Australia and they look at the whole sky and image everything that comes through the atmosphere. What we do then is we're able to triangulate the orientation of anything coming through, track it back to where it comes from in the Solar System and forward, if it lands to where it lands. We get its orbit and we get a full position.
Georgia - And are you also trying to use the great power of the masses to help in this project?
Philip - Yes, we are. So, if you see a fireball, you can pull out your phone and hold it up to the sky, click to where it started, where it ended, the colour. You can log all of these stuff and then blip us that information and that also helps us triangulate it. If we get enough data and we can tell you your fireball came from out beyond Mars and hit the top of the atmosphere at 20 kilometres a second.
Georgia - I guess it's people's first instinct anyway when they see something incredible in the skies, "Get your phone out!"
Philip - Exactly. So, this actually gives you a scientific purpose to get your phone up.
Georgia - Anyone taking meteorite selfies?
Philip - Well, we've not actually had that yet.
Georgia - When you get this data from all your observatories and maybe from people as well, what do you do? How do you go and find the asteroid?
Philip - That's the hard part. So, we build this wind model and then you head out in the middle of nowhere with a team of 6, 7 people and you've just got to be very optimistic and perky for a week, and try and keep them going while you don't find it, until in the end hopefully, you do. And then you will have a bottle of wine or several.
Georgia - I believe you've got something you have found with you here.
Philip - This is a meteorite. This was the first one we found. This kind of proves that it works.
Georgia - It looks and feels a bit like a sort of shiny lump of coal. You mentioned that this little guy - does he have a name?
Philip - Yes, this Bunburra Rockhole. The meteorites normally get named for the nearest post office, needless to say, the nearest post office is I think about a thousand kilometres away from where this was found. So, it isn't really narrowing down. Then you get named for the nearest topographic feature. Now again, I'd encourage people to take a look at the Nullarbor. There's no topography. So, from that point of view as well, it's a complete disaster.
Georgia - You'll just end up naming them all desert.
Philip - Yeah. I mean, the nearest thing on the map with any name was 40 kilometres away which was like kind of a little sinkhole in the limestone, and that's the only thing with any name which is kind of bonkers.
Georgia - Once you have this rock and you've used your tracking to work out where it's come from, what do you do with it once you find it?
Philip - We'll look at the isotopic composition, the chemistry, we'll use microscopy, we'll do CT scans over the thing. So, there's a ton of analyses that we can do to kind of build up a picture of its whole history. So, the exciting thing about - I guess, there's a few things. So, we've got an orbit for this and the orbit was very, very weird. The orbit is actually almost the same as Earth's orbit. So pretty much, the whole orbit for this one is interior of the Earth's orbit. It doesn't go anywhere near the asteroid belt and that's bizarre. The composition of the thing is also really weird.
So, the best we can tell is that this might be, it's not like a dead ringer for the precursor material that went in to make the Earth. But this sort of rock is part of that story. So, we're trying to work out what the precursor was that got the Earth got built from. This helped us get a little bit closer to that. So, having the orbit and the rock, were really, really useful for that.
Georgia - What's the furthest you've ever got anything from?
Philip - The furthest thing, I've never held it in my hand, but it was material from the Stardust mission. So, I was looking enough to be part of the preliminary analysis team for the Stardust mission and the goal in that mission which was very successful was to bring back dust from comet Wild-2 and the spacecraft flew through the tail of the comet, got pretty close actually and got pretty battered, and then put that in a capsule, reentered the Earth's atmosphere and then a whole bunch of researchers from around the world kind of joined together to analyse it. It was fantastic. This was when I was back in the UK and I was waiting for my samples and I was expecting some very official NASA kind of delivery man, kind of Men in Black-type situation with the briefcase locked to his wrist. It came in a DHL padded envelope.
Georgia - No expense spared.
Philip - No! but still very, very cool to get samples of a comet and a student of mine, Penny Wozniakiewicz did an amazing job analysing that material and people at Natural History Museum as well, colleagues of mine did a wonderful job analysing it and being part of that whole process with other researchers, an incredible amount of information has come out. It's been a really successful mission.
Georgia - And this was out from as far as the Kuiper belt. Would any specimens from the Kuiper belt actually fall to Earth? Is that something you're looking for?
Philip - We go through streams of comet debris on a regular cycle which are meteor streams. Most of that stuff is dust which means that it'll almost all burn up in the atmosphere really high up. But some of it is chunkier and there's one stream in particular, the germinids, it's a comet that's been cooked up a lot by many close approaches to the sun. So, it's certainly not in as good shape as it was originally, but what that's done is the material is denser now and it looks like some of that should be able to make it to the Earth's surface.
So, my kind of holy grail if we're ever going to find anything would be that we'd see something come in, we'd put those images together, we'd calculate its orbit. It's orbit would match one of these germinid meteors and we work out it had landed, and we'd going to pick it up, and that would be absolutely incredible. It wouldn't be nearly as pristine as some of the others, but technically, that's possible.
Georgia - Best case scenario, what could you learn from a meteorite that have come all that way?
Philip - That's a really good question. Best case scenario, I got into planetary science and studied meteorites because as a geologist, it felt like a lot of the things in geology, we'd worked out pretty well. We know the kind of grand unifying theory for geology, plate tectonics and it's been kind of a case of putting the finishing touches to that really.
But in terms of what happened before planets got made, or how we made planets, or why the Earth has the composition that it does, we really have very little idea. So, if you ask someone, "How do you make terrestrial planets? How do you get a planet that's got a very nice mix of rock and ice and water, and organic material?" Well, no one knows. There's dozens of different options. I find that really, really exciting as kind of a young researcher so that's why I got into it.
So, in the best possible case, we'd work out why we have terrestrial planets in the inner Solar System, why that process of depleting the inner solar system in what we call volatile elements, why that happened, and that's a big part of the key to... if that's a normal part of planet formation, then it means that rocky planets are common in the universe and that would be quite exciting to know that.