What's it like being an astronomer?

An interview with meteorite expert Dr Katie Joy from Birkbeck College London

In Issue 4 of the Starlight Newsletter (which is now available to download - just follow the links from the top of the page) - we interview Dr Katie Joy, a meteorite specialist from Birkbeck College London who studies the geological history of the Moon by looking at meteorites that were blasted off its surface in impact events, travelled through space, and landed here on Earth. She is also involved in the Chandrayaan-1 mission which is currently in orbit around the Moon.

Why is it important to study lunar meteorites?
Lunar meteorites are important as they provide us with samples of the Moon from locations that were not visited by the Apollo missions or the Soviet Luna sample return missions. By studying real bits of the Moon in the form of meteorites, we can learn what sort of volcanic processes happened on the Moon at different times.

How do you go about studying meteorites?
I use a very powerful microscope, called a scanning electron microscope, to look at individual mineral grains that are as small as 0.01 millimetres. I measure the chemistry of these minerals to see how similar they are to other Moon minerals from rocks returned by the Apollo missions, and then work out what this tells us about the geological history of the Moon. I also blast the meteorite with a narrow laser beam to get even more chemistry and geology information from them (the laser blasts leave quite large holes so I have to be careful not to blast the whole sample away!). For one meteorite sample, I looked at the chemistry of minerals and worked out that it is about 3950 million years old (3.95 billion years old). It is very old in comparison to most rocks on Earth, however, it is young by Moon standards – some rocks on the Moon are 4560 million years old – nearly as old as the Solar System itself!

What’s the most interesting thing you’ve found out in your research?
I recently have found a meteorite within a meteorite. I discovered a tiny (less than 1 millimetre) fragment of rock in one of my lunar meteorite samples that wasn’t actually from the Moon (we know that it is not lunar as it has a different chemistry). It must have landed on the Moon billions of years ago, was trapped in the lunar soil, and then blasted off the Moon with a whole other bunch of Moon rock and then fell on Earth as a meteorite. It is a pretty amazing story, and I am just trying to work out where this bit of rock might have come from – could it be a bit of the early Earth or from an asteroid?

One of Katie’s Moon rocks (called NWA 4472) that likely originated from the nearside of the Moon. It is made of lots of different fragments of Moon rock. Image: K. Joy.

What qualifications do you have?
I did a whole mixture of GSCEs and A-levels as I couldn’t make up my mind what I wanted to study at university, although I have always been very keen on anything to do with space exploration, and I have wanted to be an astronaut for as long as I can remember. To keep my options open I studied English Language, Biology and Geography. I then did a BSc degree in Geology at Royal Holloway, University of London. One of the courses was in planetary science, where we looked at geological processes on other planets (such as volcanoes on Mars and earthquakes on the Moon). I loved every minute of it and decided that I wanted to know more about our place in the Solar System. After my degree I completed a PhD at University College London where I studied lunar meteorites and lunar chemistry data from the European Space Agency’s SMART-1 satellite.

What advice would you give to someone who wants to follow in your footsteps as a meteorite specialist?
I would recommend studying chemistry and maths at school – both subjects would have been very helpful to me and I wish that I had studied them! At University I would suggest studying Earth or Natural Sciences or Chemistry.

Let us know what you thought of this interview, or who else you think we should interview, by emailing us at yoursay@starlight-news.co.uk. We'll even post your suggestions on the 'Have Your Say' part of this website!