What’s going on on Europa?

The bizarre surface of Europa

Europa is an intriguing little place. It’s the second innermost of the 4 Galilean satellites (there are actually more than 60 moons around Jupiter but these are all much, much smaller than the 4 big, Galilean, ones) and it has a very interesting and bizarre surface.

When we look at most moons in the Solar System we find that there are an awful lot of craters on them. Some of these are very small whilst others are very big. What’s useful about this is that through looking at the craters we can tell how old the surface is. When we look at the cratering record on the Moon we find that it is about 4 billion years old. Europa is a different story altogether. In the image above you can see very few craters, if any at all. What this means is that the surface of Europa is very, very young. After careful analysis it appears that the surface of Europa is, on average, only 65 million years old (that’s considered very young in geologic terms). Therefore there must be a process on Europa that is working to erase the evidence of these craters. What could it be?

The secret to Europa’s resurfacing lies in Jupiter’s massive gravitational field and interactions with 3 of the other big Galilean satellites. Through this process (tidal heating) the interior of the inner two moons are kept warm. This leads to the spectacular volcanoes of Jupiter’s innermost moon, Io. Io looks kind of like a pizza and is the most volcanically active body anywhere in the Solar System. Europa is under these same processes but to a lesser extent.

The Galileo mission to Jupiter, launched in 1989, found that Europa had a magnetic field about it. This inferred that Europa either has a salty ocean beneath the ice or that there is motion in its core. It is now accepted that this is probably due to the presence of an ocean. Further evidence for the existence of this ocean comes from one of Europa’s few impact craters, Pwyll. The crater is unusual in that its base isn’t any lower than the surrounding terrain and shows the hallmarks of the impact having been into thin ice (about 20km thick). It would be useful here to note that lots of different models come up with different thicknesses for the ice shell, some as little as 3km and some up to 100km. This is where the problems starts. Some features on Europa are explained by there being a thin ice shell and others only by a thick ice shell.

A new theory, published in the journal Nature, sets out to put aside some of these problems and explain how what’s called chaos terrain can form. It was previously suspected that you need a very thin layer of ice for them to form, but this theory explains how shallow sub-surface lakes may be responsible.

Thera Macula (false color) is a region of likely active chaos production above a large liquid water lake in the icy shell of Europa. Color indicates topographic heights relative to background terrain. Purples and reds indicate the highest terrain. Credit: Paul Schenk/NASA

The new theory states that phenomena similar to mantle plumes here on Earth heat the base of the ice. Convection occurs and ice lower in impurities slowly rises and melts forming a lens of water a few kilometers below the surface. This would cause the surface to subside and lead to cracks forming from the top of the lens and surface. Eventually these cracks would end up creating rafts, water would then freeze in between and the lens would slowly refreeze and then causing a dome to form at the surface. This process would take millions of years.

It has been speculated that these lakes would be ideal habitats for life. I’m not so sure though. As these lakes would eventually freeze over the only life they could sustain would be some kind of extremophile. In my opinion it would seem that life would be better off living in the ocean beneath the ice. I don’t know enough on this area of astrobiology though to make a truly sound argument.

Europa is a bizarre, intriguing and beautiful place but the only way we’re going to learn more about it is sending a mission there. A review said a mission to Europa should be NASA’s second highest priority (I guess succumbing only to a Mars sample return mission?). Previous missions have been cancelled, like the Jupiter Icy Moons Orbiter (JIMO). Work going on in Antarctica at Lake Ellsworth and Lake Vostok will help us with a possible lander mission to Europa. These lakes in Antarctica are hidden beneath deep layers of ice, drilling technology being used will help us when we come to drill and venture beneath Europa’s icy shell.

Four step process for building “chaos terrains” on Europa

If I haven’t explained any of this adequately (and I probably haven’t, I’ve been up since 5am) or purely just if you’re interested I’ve put some links below this and also the video from the initial conference explaining the theory.

Links
Video: Jupiter Moon’s Subsurface Ocean of Water

NASA Probe Data Show Evidence of Liquid Water on Icy Europa

Active formation of ‘chaos terrain’ over shallow subsurface water on Europa

References
Greenberg et al (1999)
Schmidt et al (2011)
An Introduction to Astrobiology – C4 Europa – Dr David Rothery (OU study book)

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What does God do in his spare time?

As I’ve just started reading The God Delusion, I’ve found myself pondering more about religion than usual. Just how stupid it is basically.

I have some friends who are religious, not extremely religious, but religious nonetheless. They all accept the scientific method, believe in evolution, the Big Bang and so on (if so why they believe in God I don’t know). Thinking about this I came to a startling conclusion. God must have a heck of a lot of free time.

God initiated the Big Bang and set forth the clock of cosmic evolution. He would have been exceedingly bored for about 13.5 billion years until we came along and he could give us rules to live by, and so we could kneel down and worship him. What did he do with all that time? I usually got bored when I haven’t done anything for 15 minutes.

I almost think that, after pondering about this, if you believe in God, creationism makes a bit more sense – God created the Universe a few thousand years ago, made people and there wasn’t really much free time.

Ofcourse, creationism is a load of bollocks.

Thoughts?

The Great Dinosaur Migration

Did Dinosaurs Migrate?

We’re familiar with some pretty big animal migrations. The Wildebeest, various birds, and hundreds of other animals. But did dinosaurs migrate? It has long been thought that yes, they did, but there has been no evidence for it…until now.

After studying the teeth from a small species of sauropod, Camarasaurus, that lived in the Wyoming and Utah area during the late Jurassic it appears that these dinosaurs almost certainly did migrate.

During the late Jurassic the area where these dinosaurs have been found would have been a floodplain, a great place for food. It would have periodically dried out during the dry seasons though, it would make sense for the dinosaurs to leave for pastures new.

We need evidence though, and evidence is now what we have. Scientists analysed the oxygen isotopes in the teeth. Certain ratios of these isotopes determine by what water they drank. It was discovered that the ratio in the teeth was different to that of the ratio in the floodplain, suggesting that the dinosaurs migrated and drank water from a completely different area.

Further analysis showed that the isotopes changed over a period of 5 months, inferring a seasonal change.

Did predators also migrate? Probably

Can you imagine? Giant sauropods, hundreds of them, on a great migration in search of food and water. Another interesting fact to add though is that it wouldn’t just be sauropods migrating. When modern herbivores migrate predators follow them. It’s thought the same probably happened in the late Jurassic but by the extremely successful predator Allosaurus.

Book Review: My Life on Mars

My Life on Mars: The Beagle 2 Diaries - Click image to be redirected to Amazon

My Life on Mars: The Beagle 2 Diaries by Prof Colin Pillinger.

First of all, please bear in mind that it has taken me quite a while to read this book – I’ve been rather busy over the last few months with OU studies and so on.

I was 13 on Christmas Day 2003, when Beagle 2 was due to land on Mars. I had got up extra early to pop and the news and see what had happened. It wasn’t good news.

Since then though I have always been astonished that we actually sent a mission to land on Mars, we the British people had made a lander to look for the signs of life on another world. I needed to know how it was done – finally Colin’s book came out.

It’s quite an intense book, there’s a lot of information, a lot of names to follow. I found at times that this made it slightly difficult to read, having to head back a few pages to figure out which person was being discussed now. I understand that in a project as grand as this a lot of people are involved, and at the end of the day the story needs to be told.

In this book we learn about Colin’s family history, his youth, how he became interested in science and eventually how he sent a lander to Mars. I had no idea how difficult it could be. The meetings, the letters, the phone calls, the arguments. I was very surprised about the European Space Agency, this book has changed my opinion of them, and not in a good way. Infact near the end I quite liked this quote regarding ESA ‘The way things are going the Universe will end before ESA arrives on Mars’, this referring to their Aurora programme.

If you’re interested in space exploration and want to understand how a space mission works and is put together this is a must read. It had me laughing and gasping in shock, you’ll enjoy it.

It’s 4 out of 5 from me!

Next book – The God Delusion by Prof Richard Dawkins (finally!)