Solar System objects collide violently due to their motion leading to high relative speeds. These are often at greater than a few km/s. Impacts at such speeds are termed hypervelocity and cause unusual degrees of damage. One odd feature of such impacts is that the projectile not only fragments, but partially melts and even starts to vaporise.
Fortunately most impactors in space are small, micron sized is typical, mm size less so, and cm size very rare. But large impacts have occurred in the past (witness our Moon and the large craters thereon) and still occur at irregular intervals.
At Kent laboratory studies of hypervelocity impact processes use a two stage light gas gun (see Burchell et al. Measurement Science Technology vol. 10, pages 41-50, 1999 for a description of our gun) to fire projectiles (35 microns to 3 mm) at between 1 to 7.5 km/s. Targets have included: rocks, metals and ices.
For details of our gun click on the link to the right.
Our in-house facilities such as Raman spectroscopy and SEM-EDX allow us to examine targets after impact. We also carry out hydrocode modelling of impact processes, led by Dr. Mark Price.
Research topics include:
Solar system dust includes natural dust and that arising from human activities in space. Kent has a long history of studying both. Since 2000, we have worked heavily on the NASA Stardust mission, assisting with analysis of tracks in aerogel, residues in crater on aluminium foils, and the interstellar dust grain analysis. (https://research.kent.ac.uk/astrophysics-and-planetary-science/research-themes/stardust/).
Real time measurements of dust flux in space
More recently we have been working on designs for new dust collectors to be placed in Earth Orbit or near the Moon. Kent has been working for over a decade on a series of NASA led programmes to develop new impact sensors. These require new sensors which can be placed on bodies in space and give real time readout of the impact flux.
Impact work has already started at a variety of labs in the US and at Kent. We are collaborating with NASA, the US Naval Research Laboratory, US Naval Academy, and Virginia Tech. on a series of projects. Using the Kent two stage light gas gun we have conducted a series of tests already with more planned.
There are 3 projects in collaboration with NASA:
- DRAGONS (USNA – PI) which is to develop a new impact sensor technology of deployment on satellites (test detector placed on the ISS in January 2018), see https://www.nasa.gov/mission_pages/station/research/experiments/2145.html
- OCE-MMSE (NASA Orbital Debris Programme Office – PI) to develop an impact sensor with acoustic capabilities which can characterise the micrometeoroid environment and which could be embedded in inhabited structures for example.
- FOMIS (NASA Orbital Debris Programme Office – PI) to develop a large area impact sensor based on a drum like surface which vibrates after impact, to characterise the micrometeoroid environment on say the lunar surface.
Collection of cosmic dust and debris
Dr. Penelope Wozniakiewicz has been leading several studies for a new generation of passive dust collectors which could be flown in space. These would be retrieved at the end of their life and brought back to Earth for analysis of their contents.
Dr. Wozniakiewicz is also looking at cosmic dust collected on the Earth’s surface in clean environments like Antarctica.
The role of ice in the Solar System is of interest to members of the group. At present research has focussed on hypervelocity impact processes in ice, including studies of:
- Survival of projectiles during impacts on ices (https://core.ac.uk/download/pdf/82497743.pdf)
- Cratering on ice surfaces over different substrates (https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.12913)
- and catastrophic disruption of icy bodies with interior oceans.
Kent has a variety of research interests in Astrobiology. In the hypervelocity filed, Kent was the first to show that microorganisms could survive in hypervelocity impacts (Experimental Tests of the Impact related Aspects of Panspermia, M.J.Burchell et al., in Impacts on the Early Earth pp. 1-26, eds. I. Gilmour & C. Koeberl, pub. Springer 2000). Later we showed survival rates vs. peak shock pressure (e.g. Survival of Bacteria and Spores Under Extreme Pressures. M.J. Burchell, J.R. Mann and A.W. Bunch. Monthly Notices of the Royal Astronomical Society 352, 1273 – 1278, 2004, or or Price M.C., et al., Survival of yeast spores in hypervelocity impact events up to velocities of 7.4 km s-1. Icarus 222, 263-272, 2013).
We also showed that ejecta from impacts could carry viable microbes (Survivability of Bacteria Ejected from Icy Surfaces after Hypervelocity Impact, M.J. Burchell, et al., Origin of Life and Evolution of the Biosphere, 33, 53 – 74, 2003).
We have even looked at what happens to seeds in hypervelocity impacts (Survival of Seeds in Hypervelocity Impacts. Jerling A., Burchell M.J., Tepfer D. Int. J. Astrobiology 7, 217 – 222, 2008).
More recently, Dr. Mark Price led a team which found a new way to synthesis amino acids. This was in impacts on ice mixtures. See Martins et al., Shock synthesis of amino acids from impacting cometary and icy planet surface analogues. Nature Geoscience 6, 1045 – 1049, 2013.
Currently we are continuing the shock synthesis of materials relevant to life processes. We are also looking at what happens to organic biomarkers in impacts. And the niche question of how to collect material of astrobiological interest when flying at high speed through a water plume such as those emitted by icy worlds like Enceladus or Europa.
Contact Prof. Mark Burchell for further details of hypervelocity impact work at Kent, or contact the other named staff direct.