Here’s a really neat article by Prof Monica Grady that I’m sharing from The Conversation website. It’s primarily about the bright spots on the asteroid/dwarf planet Ceres but it also discusses the fact that perhaps Ceres is a Kuiper Belt object instead. I love how every time we go to see some space objects up close that we learn they are so much more complex than we first thought. The fact that there seems to be a blurred distinction between comets and asteroids is no surprise to someone like me but it does surprise me that Ceres is looking a little bit comet-like now!

 

Ceres reveals its salty secrets – and blurs the line between comets and asteroids

Monica Grady, The Open University

When Guiseppe Piazzi reported his observations of a minor planet in 1801, he originally thought it might be a comet. But follow-up observations by fellow astronomers suggested that Ceres was actually an asteroid. So it’s somewhat ironic that the latest results from NASA’s Dawn mission suggest this asteroid is confusingly similar to a comet.

Dawn has found a number of mysterious features on Ceres so far, including bright white spots on its surface. Its latest results suggest that these are salts left behind as ice vaporised from the surface by sublimation – a process often seen in comets. They also suggest Ceres may have formed far away from its current location in orbit between Mars and Jupiter. This would be surprising as many astronomers believe that a key difference between comets and asteroids is that asteroids form closer to the sun.

Mysterious spots

Ceres is the largest asteroid we know of – it is also classified as a dwarf planet. Its bright spots were first discovered when Dawn started orbiting Ceres in 2014, the largest at a latitude of around 25°N. There was intense speculation about what these features were, as they had the characteristics of ice. The Herschel Space Observatory later found that water vapour was being produced at specific locations on Ceres.

It therefore seemed that Ceres was acting like a comet, with ice-rich regions releasing dust and vapour during daylight hours. If that were the case, then ice might be a major component of the asteroid, buried below a surface of dust and rubble.

But the two new studies (see here and here), using information from different instruments on the Dawn spacecraft, did not record any ice on the surface. However, one article speculates that ice may still be buried just below the surface while the other suggests that water bound in minerals is abundant.

The researchers also investigated the bright feature at the bottom of Occator Crater, the brightest of the white spots, and concluded that they may be hydrated magnesium salts. The salts are deposits left behind from recent sublimation of water ice that have not yet been covered by soil. Other bright spots, although not as prominent, may also be salt deposits, but that material is likely to be older.

A Kuiper Belt Object?

The researchers also identified a mixture of minerals on the surface of Ceres, which they think are ammonia-bearing clay minerals and magnesium carbonate. The clay minerals could have been produced by silicates reacting with ammonia ice. However, if Ceres had formed where it is now, it would not have been able to pick up any ammonia ice to enable such a reaction, because the ice would not be stable.

This means that Ceres may have originally formed in the Kuiper Belt on the outskirts of the solar system and then scattered inwards as the giant planets migrated outwards. Alternatively, Ceres could have formed more or less where it is, and incorporated nitrogen-containing organic molecules, which, like the water ice, were transported inwards from beyond Neptune.

Did Ceres form in the main belt and incorporate ammonia from the outer solar system or did Ceres itself form there?
L.Giacomini

While this might not sound all that significant, it does have quite profound ramifications for our understanding of how material has been mixed to form planets, minor planets, comets and Kuiper Belt Objects.

This year has been an amazing one for small icy bodies. Images from the New Horizons mission to Pluto have shown us the variety of landscapes that can be sculpted on an icy surface. Similarly, pictures of the surface of comet 67P Churyumov Gerasimenko taken by Rosetta have revealed canyons and pits probably caused by fracturing and ice sublimation.

Now we can add a third small body where a combination of ice, water and salts have left behind an environment in which there is the potential for an active, sub-surface chemistry that might, eventually, result in formation of complex molecules. It is also becoming more clear than ever that strict division between comets and asteroids is no longer realistic, and that they represent a spectrum of objects of varying activity and orbit.

Just one last word about the surface of Ceres. I might not be much of a farmer – but I’m fairly certain that magnesium salts and nitrogen-bearing clays are important ingredients in a good, rich soil for raising crops. So naming Ceres after a harvest deity was more appropriate than Piazzi could have imagined!

Monica Grady, Professor of Planetary and Space Sciences, The Open University

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

I was lucky enough to be invited to write a special book chapter about the Rosetta mission in ‘Patrick Moore’s Yearbook of Astronomy 2016‘. Luckily this book series has been lovingly continued by Jon Mason despite the death of Sir Patrick Moore in 2012. I already have a copy and there’s some other really great articles in there too so make sure to pick up your copy in time for 2016!

What an absolutely amazing experience, I honestly had the most fun doing StarTalk Live at the Beacon Theatre on Broadway, New York. Here’s some photos of the event, I’ll post more details about the show when it’s out, probably November time.

Well, I am very excited to finally announce that I have been invited to appear on StarTalk Live in New York (New York, so good they named it twice). It’s being recorded tonight (Monday September 21^st) but what’s even more exciting is that the show will be at the Beacon Theater on Broadway in front of a 2500 strong audience. For those not in ‘the know’, the show is hosted by Neil deGrasse Tyson who is an astrophysicist based at the American Museum of Natural History and Director of the Hayden Planetarium. Neil is also a very popular broadcaster and science communicator in the USA. I’ll update more on here on my return because I’ve been sworn to secrecy until the event, I can’t wait to meet Neil and the other guests on the show. I’ll be covering topics related to my research so you can expect comets, asteroids, Rosetta, outer Solar System, Kuiper Belt, and there’ll also be some Pluto chat.

Luckily, everyone can listen to these shows, even if you aren’t based in the USA because they’re all available for FREE on iTunes!! Although it may take a few months for the show I’m in to be edited as a podcast.

Because it is sort of a long way to go, I’m also giving a research seminar at the American Museum of Natural History on Tuesday 22^nd September. Here I’ll be talking about my primary research: ‘An insight into the early Solar System from the analysis of cometary dust’. Then it’s straight back home to reality…

I’m very excited that a new BBC series called ‘World’s Weirdest Events’ is due to start this month (Thursday Sept 3rd) and the trailer for the show is pretty cool (see below). It’ll be presented by Chris Packham and is made by the team that produced ‘Nature’s Weirdest Events’. The new series looks at unlocking the secrets behind some of the world’s most unusual occurrences. I’m mostly excited because I was involved with a couple of the episodes where I’ve been interviewed to help explain some of the ‘weird’ events; one in Indonesia involving a volcano that appears to be spewing out blue lava and one in Siberia where some mysterious holes have appeared in the ground, you’ll have to watch to find out more. I’ll try to find out when exactly my episodes will be on but it looks like it’ll be on Thursdays (BBC2) at 8pm repeated on Sundays (BBC2) at 6pm.

I love this beautiful animation of Comet 67P/C-G as it approached perihelion (closest approach to the Sun – 186 million km distance). Perihelion occurred on August 13th 2015 when activity on the comet will have reached peak intensity but it will continue to be active for weeks to follow. In the animation below you can see jets and outbursts of activity as the frozen ices and gases are heated up by the Sun and burst from the comet. Thank goodness 67P didn’t get any closer to the Sun otherwise it might have broken into pieces!

I couldn’t be much more excited about this movie coming out because it was one of the best books I’ve read in recent years. The Martian is one of those books that you’re reading and suddenly start laughing out loud, which can get you funny looks if you’re reading it in public, but the author Andy Weir has done such a fabulous job with it. However, I tend to prefer the books to the movie re-makes but as this has Matt Damon (and Jessica Chastain!) in then hopefully it’ll be good, and hopefully the humour from the book will survive too.

Wow! I can’t believe I haven’t had time to write about this yet. We’ve been totally spoilt in the last year or so with images from space haven’t we? However, I have to say that when the very first pixelated Pluto images appeared on the web that I was a little underwhelmed….but I had no idea how good they were due to get (see above). Within weeks the most breathtaking pictures of Pluto and its moons Charon, Hydra and Nix were appearing daily and what beautiful world’s these were turning out to be (OK, so for Hydra and Nix the images are still a little blurry (see below) but I’m not complaining now).

More surprising for most of us was the relatively geologically young surface displayed by Pluto – we weren’t expecting this but we weren’t really sure what to expect of this mysterious little world. We’re not re-writing the science books but we’re just simply writing them now – we knew so little about Pluto before these pictures came in. And they say a picture is worth 1000 words, I think in the case of Pluto that a picture is worth many millions of words. But I’ll leave that to the specialists – I’m sure there’s plenty of papers to come from this mission. In the meantime, check out The Planetary Society blogs by Emily Lakdawalla here, here and here etc, she’s covered things really well (as usual). Plus, it’s not all over, there’s data set to be beamed back to Earth for months to come still.

It seems at work that people decided to have a little fun with my comet model that I had made for the Royal Society Summer Exhibition of 2014 (see above). Although I never intended the model to accurately represent 67P – because when we made the model we had no idea what it looked like – instead it was meant to be a generic comet (whatever that is?!)). Anyway, turns out my comet looks more like Pluto now. Oh well, it’s all outer Solar System stuff right?!

 

I have been extra naughty having not written about Rosetta recently. Time is flying by and the lander results came out in a special issue of the journal Science when I was away at MetSoc in California (July 31st) so I was totally inundated with conference and jetlag. So, what do we have? Well, the little lander may have taken its last gasp of comet air since it re-awoke on the comet surface in June, of which we will have to await results. However, it managed to get us a huge amount of data during its rather short but productive few days directly after landing in November 2014 – and these are the results that have just come out in a new selection of papers. It may seem like a long wait since November but I’m afraid that this is the scientific process in action – it takes time to assess data and present it for peer-review before it can be released. We’ve already learnt a lot about the comet from the initial orbiter results that were published earlier in the year so it wasn’t a huge surprise that the lander has also detected organics on the comet. The important thing about these organics is that they are complex molecules that can represent the key building blocks of life…reigniting the big question of whether comets delivered life to Earth (even if the water on 67P apparently appears to be quite different to the water on Earth). We’ve also learned more about the rise and fall of the temperature of the comet and more detail about the surface and internal properties. This mission is far from over though and there’s plenty more detail to come but what we’re learning is helping us shape our picture of how comets formed and how important they might have been in the history of the Earth.

Naughty me, I haven’t been keeping up to date with my updates here at all well. This might just signal that I’ve been busy with lots of exciting projects, which is true. However, conferences and holiday also got in the way.

The conference I went to was The Meteoritical Society meeting at the end of July in Berkeley CA. A great location, especially as I had a day free on arrival to explore the surrounding area (and the amazing sports facilities at the University). We also got a day off mid-week to attend a baseball game. I was there with a bunch of mostly clueless Brits from the conference (in the nicest way possible – clueless only in terms of baseball that is – very much not clueless in terms of meteorites) but luckily an American was sat next to me so I had my personal commentator to explain what was going on. And thank goodness, baseball has some important differences to rounders! What I learned here is that the ball is not hit very often but that the whole experience is such a spectacle so its all thoroughly enjoyable anyway – particularly as the game was played at the most gorgeous of locations, the AT&T park in San Francisco. If you get the chance then go! The atmosphere is amazing; a crowd of 46,000 people and it was something like their 138^th consecutive sell-out game…it was on a Wednesday afternoon too so I’m not sure how all these people had the day off. Anyway, enough of ball games, the meeting itself was great too.

UC Berkeley is a stunning location for a conference (as you’ll see by the picture above) and with around 400 planetary scientists in attendance, but with only 2 parallel sessions, it made for a more intimate and networking-type meeting than I’m used to at LPSC in Houston. I was chairing the Microsample Analysis session on Friday morning which I also spoke in (and presented a poster for on the Tuesday night). We kicked off with a very interesting talk suggesting that there might not be a continuum of compositions between comets and asteroids. This talk was given by Don Brownlee (of Stardust and IDP fame) and it really made me think about my own samples and the paper I’m currently working on. I actually think I will review my data in light of this. My talk went fairly well – although it’s always hard to tell when you’re speaking because 12 minutes feels like 2 minutes so it’s really hard to assess, but I got some good questions and discussions afterwards. I presented some data on an exciting IDP that I’m working on that has some really strong similarities to very organic rich particles collected as micrometoerites from the ice in Antarctica (and which are thought to be cometary in origin also). I still find it amazing that I get to play with comet dust that’s come all the way from the outer Solar System, and is 4.6 billion years old. It’s well known that we have organic matter in space (just see the Rosetta results, summarised quite nicely in this The Conversation article) but organic matter is often not preserved very well in meteorites because they’ve been through secondary processing in space. Organic matter also doesn’t tend to survive atmospheric entry very well either as it gets heated up and altered there too. So, when we get special comet particles collected from the ice in Antarctica and from the stratospheric dust collections then it makes them very special and I think they are currently a little under-appreciated. I’ll try to change that!