I thought it was about time for a little update about my book ‘Catching Stardust’. I’ve been writing for a good few months now and I’m happy to report that it’s going well, and I’m really enjoying the process too. I now have about eight chapters, with about three left to go. Not that this means the book will be finished very soon because once I have everything written then I’m going to need to go back and check what I’ve got as I can barely remember what I wrote back in January now so I assume I might’ve repeated myself a bit…or maybe even missed something out completely…so, I’ll need to have a careful check. It’d be awful to get to the end and find that I’d completely forgotten to explain what a comet is, for example! But don’t worry, I know I haven’t forgotten anything that obvious.

So what have I covered so far and how did I go about approaching writing this book? Having never undertaken such a big writing task before – even my PhD thesis was only 35,000 words and this book will end up around 90,000 words – I decided to start at the very beginning; discussing the beginning of the Solar System. Although I have to admit that this isn’t actually quite the beginning of the book as it will, instead, form Chapter 2. I plan to provide a more general introductory chapter as Chapter 1 which I’ll write at the very end, once I have a much clearer idea of what I’ve actually ended covering throughout the rest of the book. The beginning of the Solar System is a big topic on its own, and I’ve had to summarise some topics within this, for example, the physics as 1) this isn’t my speciality and other scientists are much better placed to describe this in detail (I’ve been reading Carl Sagan’s books and they are just perfect so I’ll refer you there instead) and 2) the focus of this book is more on the birth of the comets and asteroids so the aim here is to put them into the context of the early Solar System, where these objects came from and how they formed.

Of course, before I started putting ‘pen to paper’ (or rather, ‘fingertips to keys’) I began this process with what I thought was a well thought through plan for the book. This seemed like a good idea to wrangle my ideas into a reasonable format, and it gave me confidence that I had enough content in order to make a whole book when I was worried about meeting the daunting word count. However, I’ve surprised myself how much I’ve changed this plan around as I’ve been writing as I discovered that things didn’t end up fitting in exactly where I thought they would. In some cases it didn’t take as many words to describe what I wanted to get across, but in other cases it took much longer as I’d overlooked how important something was, or just that to do it justice for a non-specialist really took some more careful thought.

One of those examples is the subject of meteorites. I was planning to slot them into a chapter with asteroids, but once I got writing about them I had so many words that I found they needed to have their own standalone chapter. In hindsight, it’s such a big topic that it seems obvious that they needed this now but I think I’d just taken for granted what I know about these cool space rocks and forgot that I would need a fair amount of space to get across this excitement. However, as much as I’ll admit that I like plans, I also enjoyed seeing how my book plan changed once I began writing, adapting to new things I wanted to add in or expand upon, and I’m now much happy with the flow of the book from chapter to chapter. I hope that non-specialists can follow my thinking too and if the book is read from start to finish then it should gradually take the reader through the topics, with each chapter building on knowledge learnt from previous chapters, so that they will understand everything I discuss and, more importantly, be as excited about comets and asteroids as I am. However, I was also keen to make each chapter standalone a little bit, sort of like an essay in itself, in case people want to dip in and out of the book (which I wouldn’t recommend because I’d prefer for the whole thing to be read but I like this being an option too) so I think it might also be possible to do this.

Catching Stardust really does cover a lot of ground (or space, perhaps), including life in the Solar System, space missions and space mining to name a few, alongside the basics of what comets and asteroids are, how they formed, and how we analyse them to find out more about the early Solar System. I’m currently working on the space mining chapter, the first of the ‘futuristic’ chapters, as I’ll describe them, simply because the science hasn’t exactly happened yet, but it’s getting close. This chapter has probably taken me the longest so far, involving a lot more research than the others but I’ve learnt so much about this exciting new area of space exploration, and the more I write about it the less like science fiction it seems. There are entire books out there dedicated to the topic of space mining and, of course, I would refer you to these if you want to have a really detailed look in to the subject, but I think that my chapter will provide a good overview of the various space mining plans, putting into context how we might be able to use comets and asteroids in our future. These space rocks don’t just allow us to see into our past, but they might hold the answers for our future to. I’ll leave you with that thought for now.

 

Part 2 of the StarTalk Live! show I was involved in at New York’s Beacon Theatre on Broadway last September is out now and available here or you can listen directly on the SoundCloud link above. Part 1 is already online here as it came out Friday 3^rd June. In Part 2 you should hear all about the New Horizons mission, Pluto and the Kuiper Belt. However, rather hilariously, Neil and I also had a ‘debate’ on whether Pluto should be classified as a planet or not. I took on the argument that Pluto IS still a planet and Neil the opposite…you’ll have to listen to see who wins…or who persuaded the audience of their argument the best anyway. There’s also a hilarious song about Pluto which you’ll have to listen out for.

Here’s a direct link on SoundCloud to my StarTalk Live! ‘Chasing Comets’ podcast from last week. The 2nd part is out tomorrow so I’ll provide a link to it soon. You can also download the show on iTunes. Hope you enjoy listening 🙂

I’m re-posting this article from The Conversation website written my good friend Dr Jessica Barnes about her own new research that has recently been published in the journal Nature Communications. She’s looked at whether comets or asteroids delivered water to the Moon and this work has some obvious implications for water on Earth too. To save you having to sift through the more complicated journal paper I think this article summarises the research really nicely. Good job Jess!

Asteroids most likely delivered water to the moon – here’s how we cracked it

Jessica Barnes, The Open University

One of the moon’s greatest mysteries has long been whether it has any water. During the Apollo era in 1960s and 70s, scientists were convinced it was dry and dusty – estimating there was less than one part in a billion water. However, over the last decade, analyses of lunar samples have revealed that there is a considerable amount of water inside the moon – up to several hundred parts per million – and that it’s been there since the satellite was very young.

But exactly where this internal water came from has remained an enigma. There have been many suggestions, such as comets or asteroids bringing it there. Another is that some of the water could have been there since the moon formed, from material that originally came from the Earth. Now our new study suggests that most of the water inside the moon must have been delivered by asteroids some 4.5 to 4.3 billion years ago.

The moon formed some 4.5 billion years ago – shortly after Earth. But whereas Earth has been constantly renovated through the effects of plate tectonics, the moon has been relatively quiet. The Earth’s ever-changing face means that we know very little of its earliest history. The moon, however, has acted like a time capsule, helping us better understand its history – and the Earth’s.

Digging for water

To probe how water got to the moon’s interior, we performed calculations using published data for water in lunar samples and bulk estimates of water inside the moon. We also used data available for the water content and composition of meteorites and comets. The model also accounted for different types of water, (such as “heavy water” which is made up of relatively more deuterium than hydrogen). This is very useful because because water in different objects in the solar system has different signatures – most comets, for example, have heavy water.

By calculating different mixtures of water from different sources and comparing the results to what we observe for the moon, we discovered that water-rich carbonaceous asteroids are the most likely candidates for bringing the majority of “volatile elements” (elements and compounds with low boiling points) to the moon – such as water, nitrogen and carbon. We also found that comets most likely delivered a maximum of 20% of such elements to the lunar interior.

Based on the data and models currently available, we think that these impacts happened over a couple of hundred million years after the moon formed, just before its huge magma ocean solidified. The asteroids and comets crashed into this magma ocean and were likely retained (rather than boiled off) due to a thermal lid which formed at the surface of the huge pool of magma.

The results are important because they tell us about the kinds of objects that struck both the moon and the Earth more than four billion years ago. Potentially it could also help us understand the origin of water in the Earth. In fact, water inside the Earth is so similar in composition to the water in the moon that, along with other geochemical evidence, it seems likely that our water also came from asteroids.

Of course, this is not an open and shut case, there is still a lot that we do not know about water and other volatiles in the moon and how they relate to each other. For example, we still need to fully understand the processes that operated inside the moon over geological time and work out what happened to the volatiles when lavas were erupted to the lunar surface. We can gain a huge amount of information from further study of samples returned from the Apollo and Luna missions. There are some 382kg of such samples, but only 2% have been investigated for analyses of volatiles.

But ultimately, we need to explore the entire moon to properly understand it. Our work is timely especially in light of the plans to send robotic and human prospecting missions to previously unexplored regions of the moon. In fact, the Apollo astronauts covered a distance on the lunar surface equivalent to a return journey from Edinburgh to Glasgow, so there is every possibility that rocks from the far side and polar regions of the moon may tell a different story.

In addition to the water trapped in glasses and minerals, there is also water-ice and other volatiles on the surface of the moon. As national space agencies gear up for the next era of lunar missions they are primarily focused on investigating how much water is on the surface, where it is and in what form. This will be crucial to determine whether water can be used as a resource for sustaining a moon base or enabling further exploration of the solar system. My feeling is that our nearest neighbour still has a lot to show and tell, and that the next 10 to 20 years are going to be eye-opening.

Jessica Barnes, PhD student, The Open University

This article was originally published on The Conversation. Read the original article.

Tomorrow (June 3^rd) you can listen to Part 1 of the StarTalk Live! show I was involved in at New York’s Beacon Theatre on Broadway last September. It’s a really fun show, mostly because the other guests on stage were hilarious and made the whole experience such a giggle. On stage with me were the amazing Neil deGrasse Tyson as host, joined by Ilana Glazer, Eugene Mirman and Paul Adsit. The audience were also fantastic, as seems usual for StarTalk Live!

I guess the show could be described as a rather ‘icy’ though because we discuss various cold space objects; the Rosetta mission and comets, then the New Horizons mission, Pluto and the Kuiper Belt. As it was a long live show the podcast has been split into two so this week you’ll hear the first cometary half. Part 2, I believe, should be available on Friday 10^th June which covers Pluto and New Horizons, so watch this space for an update. And enjoy!

The show (StarTalk Live! at the Beacon (Part 1): Chasing Comets) is available June 3rd 7pm (EDT) on the StarTalk Radio website, as well as on iTunes Podcasts, Stitcher, TuneIn, SoundCloud and now, on Google Play Music.