EPSC 2013: Simple High School experiment aids understanding of asteroids
A simple experiment – dropping a meteorite sample into a container of liquid nitrogen and measuring the mass of nitrogen that boils away – is helping astronomers understand better the composition of asteroids and how they behave in orbit.
Scientists working at the Vatican Observatory, the University of Central Florida, Louisiana State University and the Arecibo Observatory in Puerto Rico have developed the experiment as a fast, cheap and non-destructive system for calculating the heat capacities of meteorites, an essential parameter for understanding the asteroids that these meteorites come from. Most techniques for making this measurement use expensive equipment and require that the sample be cut into small pieces.
“Our goal in this work has been to devise a simple, inexpensive system that could be appropriate even for a student lab,” says Guy Consolmagno, curator of the Vatican’s meteorite collection, who will present results at the European Planetary Science Congress 2013 at University College London on Monday 9 September.
“The only expenses, beyond a source of liquid nitrogen, are for the small vacuum flask – we use a stainless steel coffee travel mug – plus a digital scale and data-collection system, items that most labs may already have. And even the data collection system can be replaced by a patient student with a notebook!” he adds.
The experiment measures the total heat content removed from the sample as it cools from room temperature to that of liquid nitrogen, -195.8 degrees Celsius, which is similar to temperatures found in the asteroid belt. Dividing the total heat content by the sample mass and the change in temperature yields average heat capacity of the sample over this range of temperatures.
Knowing a meteorite’s heat capacity allows astronomers to work out various properties of its parent asteroid, besides its basic composition. For example, the heat capacity is needed to calculate how the thermal re-emission of absorbed sunlight alters the orbits and spin rates of asteroids. To date, however, only a handful of meteorite heat capacities have been published, virtually all at temperatures much higher than those found in the asteroid belt between Mars and Jupiter.
The data the team has collected via the experiment have already revealed significant trends of heat capacity with meteorite composition. In particular, they confirm that the average heat capacity of meteorites at temperatures appropriate to the asteroid belt is about two-thirds that of materials measured at room temperature. They show that metal rich meteorites are significantly lower in heat capacity than stony meteorites, while meteorites (and asteroids) rich in volatiles like carbon or water will have a higher heat capacity than other samples.
“At this stage, our data are still preliminary, but these results illustrate the nature of the questions that might be addressed in future work,” says Consolmagno.
The other team members have been key in working out how to understand and correct for systematic errors that creep into the procedure, such as frost forming on the cold flask holding the nitrogen.
A paper describing the technique has been accepted for publication at the journal Planetary and Space Sciences. http://www.sciencedirect.com/science/article/pii/S0032063313001888
Movie showing the experiment in progress. Credit: G Consolmagno https://dl.dropboxusercontent.com/u/66538944/LN2%20movie.mov
Sequence of stills from the movie. Credit: G Consolmagno
Equipment required for the experiment. Credit: G Consolmagno
Brother Guy Consolmagno SJ Specola Vaticana V-00120 Vatican City State
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NOTES FOR EDITORS
About the European Planetary Science Congress (EPSC)
EPSC is the major European meeting on planetary science. EPSC 2013 is taking place at University College London (UCL) from Sunday 8 September to Friday 13 September 2013. It is the first time that the Congress has been held in the UK. The 2013 programme includes around 75 sessions and workshops. Details of the Congress and a full schedule of EPSC 2013 scientific sessions and events can be found at the official website: http://www.epsc2013.eu/
EPSC 2013 is organised by Europlanet, UCL and Copernicus Meetings and the event is sponsored by the UK Space Agency, UCL, Astrium and the Science and Technology Facilities Council.
To celebrate EPSC coming to London, a ‘Festival of the Planets’ has been organised across the Capital in collaboration with partners including the Baker Street Irregular Astronomers, the Bloomsbury Theatre, the British Astronomical Association, the British Interplanetary Society, the Natural History Museum, the Open University, Queen Mary University of London, the Royal Astronomical Society, Royal Museums Greenwich and University College London. More information about the events can be found at: http://www.europlanet-eu.org/epsc2013/outreach-activities
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About Europlanet Europlanet is a network of planetary scientists, whose aim is to bring together the disparate European community so that Europe can play a leading role in space exploration. Europlanet’s activities complement the mission activities of the European Space Agency through field work at planetary-analogue terrains on Earth, laboratory measurements, computer modelling and observations from ground-based telescopes. Founded in 2002 and funded by the European Commission from 2005-2012, Europlanet has evolved into a community-based organisation that will carry on this work and plan for future missions and mission support.
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