The second day of Astrofest starts with a talk by Alan Fitzsimmons of Queens University Belfast on the Chelyabinsk Incident. On 15 February 2013 an asteroid entered Earth’s atmosphere and fell over Southern Russia and produced the largest known impact in over 100 years. The fireball was brighter than the Sun and injured over 1,000 people.
A key reason scientists were able to learn so much about this asteroid was the fact that Russians all have cameras mounted on their cars and there was therefore a lot of footage of the incident from all angles. The main points to come from a years work are:
- the object was 19 metres across and weighed 10,000 tons so was a fairly small asteroid.
- nobody had seen it coming because it was small and very dim.
- the rock formed approximately 4.5 billion years ago but was only exposed to space 1.2 million years ago. So it was part of a larger object which broke up possibly as a result of a close approach to Earth or Venus at that time.
- it entered the Earth’s atmosphere at a speed of 19 kms/sec and broke up at 29.7 kms above the surface.
- it was brighter than the Sun and exploded with a force equivalent to 500 thousand tons of TNT.
What has been learnt from the Chelyasbinsk incident has led to a re-think of how often these things happen. Prior to Chelyabinsk it was thought that an event of this magnitude would occur once every 300 years. That has now been revised down to once every 30 years!
The second talk of the morning session came from Carole Mundell from Liverpool John Moores University. Carole talked about Gamma Ray Bursts and how they have changed the way astronomy has to be done. Where, in the past, astronomers have looked at the Universe as being essentially static with changes occurring on timescales of millions or billions of years GRB’s happen on timescales of seconds to minutes and therefore a whole new way of working has had to be developed to ensure instant response to the discovery of GRB’s can be achieved.
Carole spoke of the role of the Liverpool Telescope and NASA’s Swift space telescope in revolutionising how this work is undertaken. She also touched on the importance of this work including the hope that better understanding GRB’s “the biggest bang since the Big Bang” might help in trying to reconcile General Relativity with Quantum mechanics.
The third talk came from Sanjeev Gupta of Imperial College London who has the job of playing with the ultimate big boy’s toy – he drives the Mars Curiosity rover – jealousy all round the room! In reality he doesn’t drive it but he does help to decide where it should go and what it should do because he is the lead geologist on the team.
Sanjeev had some fascinating photos from Curiosity to show including detail of sandstones, mudstones and cross stratified rocks all of which are clear signs that there once was water in Gale crater and in some cases that water was flowing as in a river. There is now, he says, no question that there was once water on Mars.
Curiosity is now on its way to the central mountain in Gale crater where they believe they will find layered rock which will help in starting to map out the history of Mars.
That’s it for session 3. I will post a final report on session 4 this evening.