#weekendusers Reproducing the origins of planets with a gas gun

09-12-2016

Impact is thought to have had a fundamental role in the creation of asteroids and planets from the dust of the early solar system. Scientists from Imperial College London (UK) are performing some of the first gas gun experiments at the ESRF to recreate these dynamic conditions.

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In order to reconstruct the conditions that led to the creation of the planets, a team of six scientists from Imperial College London, had to load up a van full of scientific instrumentation, cross the Channel and a big chunk of France to find themselves at the ESRF fourteen hours later. It may sound a bit convoluted, but there is no other way around it. “The highly transient nature of our sample loading, coupled with the intrinsic heterogeneity of our specimens has presented a real measurement challenge for the dynamics community”, explains Daniel Eakins, Deputy Director of the Institute of Shock Physics at Imperial College. “High energy X-ray beamlines, such as the ID19 tomography and imaging beamline at the ESRF, are therefore becoming instrumental to build-up a hierarchical picture of dynamically compressed matter.”, he adds. The crown jewel in their equipment is the gas gun, which is used to mimic the extreme conditions present during the primordial universe.

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David Chapman (left) and Daniel Eakins (right) installing the gas gun on ID19. Credits: C. Argoud/ESRF.

The goal is to understand how early dust in space agglomerated to provide insight into how planetary systems were formed. “We work closely with Drs. Gareth Collins, also of Imperial College, and Phil Bland at Curtin University, whose recent simulations of astrophysical impact events have prompted re-examination of the nature of impact-driven consolidation in the early solar system. Our experiments seek to provide the first experimental validation of these models, by studying the local mesoscopic compaction response of bi-modal silica powder mixtures.”, explains Eakins.

A common way of dating meteorites consists in correlating their phase composition to their respective formation pressures. It is widely believed that at the beginning of the solar system, the impacts of dust were more violent than later on. Thanks to the gas gun set-up, the scientists can apply high-velocity impact onto the powder samples in the same way as it was done in the origins of planets and record it at the same time. This will hopefully increase understanding of meteorite formation, as well as help refine models of planetary impact and formation.

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In the control hutch of ID19. Credits: E. Escauriza.

This weekend’s experiment takes place in the framework of a Long Term Proposal. In three years, the scientists will develop a gas gun that will be made available to other users in the future.  It is now on ID19 but researchers can use it on other beamlines where impact of events are required. “A gas gun available for the general users programme of the ESRF will allows us to welcome a new community: shock physicists,” outlines ID19 beamline responsible Alexander Rack. “Especially with ESRF EBS, where we can progress to unprecedented ultra-high speed imaging, we will be able to depict dynamics which have never been seen before.”

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The Imperial College team with the collaborators from ID19. Credits: C.Argoud/ESRF.

The team from Imperial is joined by Amitay Cohen, a scientist from the Nuclear Research Centre in Israel. In parallel to the gas gun, he will develop a so-called Hopkinson pressure bar to study the dynamic behaviour of materials at lower compression rates.

The potential use of the gas gun goes beyond academia. “The mining industry could benefit from this instrument, as they try to understand the optimal way to extract minerals from rock”, explains David Chapman, scientist of Imperial College.

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The scientists setting up the gas gun (right) and the cameras (left) for the experiment. Credits: E. Escauriza. 

Text by Montserrat Capellas Espuny

Top image: Scientists from Imperial College (UK) study the origin of planets on ID19 with a gas gun. Copyright: NASA.