20-EPN2-068: Primitive Space Materials (PriSMa)

Visit by Chrysa Avdellidou of the Observatoire de la Cote d’Azur (France) to TA2.7 Light Gas Gun Laboratory, University of Kent (UK)
Dates of visit: 17-21 April 2023

Report summary: Simulants of surface materials for various small bodies were sourced, characterised and formed into blocks. These blocks were sent to the University of Kent and used as targets in their two-stage light gas gun. An extensive programme of 20 shots was carried out at speeds from 0.39 to 4.9 km/s. This covers a range from low speed impacts up to the mean speed of impacts in the asteroid belt (5 km/s). All targets were weighed and imaged before each shot. Post-shot, the resulting impact craters were all been imaged, and crater size and shape have been measured. Crater ejecta was also collected. More detailed analysis is underway. With the results so far, it is now possible to predict crater shape in the strength regime over a wide speed range for such bodies and estimate the volume of ejected material. This experimental campaign included novel impact experiments to study the contamination of primitive bodies surfaces by foreign material.

This programme was successful and is being used to interpret remote sensing data from previous and upcoming space missions, such as OSIRIS-REx and MMX.

22-EPN3-083: SHOCKchar: Charring of Wood Induced by a Shock Wave during a Hypervelocity Impact

Visit by Anna Losiak, Institute of Geological Sciences Polish Academy of Sciences (Poland) to TA2.7 Light Gas Gun Laboratory, University of Kent (UK)
Dates of visit: 23 November – 01 December 2023

Report summary: Proximal ejecta blankets of very small (<200 m in diameter) impact craters contain fragments of charcoal (Losiak et al. 2022). They were found in Campo del Cielo, Whitecourt, Kaali Main, Kaali 2/8, and Morasko, as well as in two suspected craters: Sobolev and Ilumetsa. Those charcoals can be used to: precisely and accurately date impact structures, determine environmental effects of impact of small asteroids and, potentially in the future, better understand the energy distribution during formation of very small impact craters or identify impact origin of yet unknown structures. The formation mechanism of impact charcoals is unknown. The first hypothesis, based on field observations, assumes impact charcoals were formed by burial of branches in locally warm ejecta, resembling charcoals buried within pyroclastic flows. An alternative explanation, based on numerical modelling (Svetsov and Shuvalov 2020), is that charcoals are formed by shock-wave propagation through trees. THE AIM of this project is to test if impact charcoals can be formed by a shock wave passage, and to characterize the properties of resulting charcoals. The Light Gas Gun laboratory at the University of Kent was selected to conduct the experiment because it is one of very few in the world that allows to reach >5km/s velocities as well as perform experiments at atmospheric pressure.

During the Europlanet TA visit we have performed 8 experiments. We have varied the following parameters: 1) velocity: 5 / 3 / 2 km/s, 2) wood dryness: fresh / dried, 3) atmospheric pressure: 1 bar / ~0 bar.

The initial evaluation of the results suggests that wood hit at 5 km/s results in production of a very small amount of thermally processed material. It is not clear if this material has similar properties to impact charcoals. The full analysis is ongoing

20-EPN-064: Impact induced polypeptide synthesis on low-temperature astrochemical ices containing amino acids

Visit by Ragav Ramanchandran and Jaya Krishna Mekaof the Physical Research Laboratory, Ahmedabad, (India), to TA2.7 Light Gas Gun Laboratory, University of Kent (UK)
Dates of visit: 25 June – 10 July 2023

Report summary: Impacts are the most common events across the solar system, shaping the evolution of planetary bodies,including icy satellites, such as Jupiter’s moon Europa, which are prime targets for future space missions finding signatures of life. Impacting bodies are known to deliver important organics, such as amino acids, to the planetary surface and sub-surface. Apart from this, high pressure and temperature created during impacts can provide pathways for chemical reactions leading to the formation of more complex molecules from simple precursors. Thus impacts have significant consequences for the potential habitability and synthesis of organic compounds.

We performed a series of experiments at the light gas gun facility of the University of Kent, simulating the impact on targets containing amino acids embedded in water ice. A stainless steel bolide of size 1.5 mm was used as a projectile and fired at a velocity of ~ 5 km s^-1. After impact, the ejecta ice materials were collected in a specially designed chamber, and materials were also collected from crates and theirsurroundings that were formed after impact. The collected materials will be analyzed using different techniques for the identification of synthesized products after impact. Previous studies suggested that building blocks of life, such as amino acids, can be synthesized by impact-induced processes. However, it is unknown how the formation of macromolecular architectures from the combination of simple building blocks would have happened. Our objective with these experiments will be to explore the formation of such macromolecules through impact events and explore potential pathways toward life.  

20-EPN2-116: HIDISCC (Hypervelocity Impacts for DISC Calibration)

Visit by Vincenzo Della Corte, Osservatorio Astronomico Capodimonte Napoli, INAF (Italy), to TA2.7 Light Gas Gun Laboratory, University of Kent (UK)
Dates of visit: 27-29 March 2023

Report summary: The Comet Interceptor space mission is to launch in 2029 to study a dynamically new comet. Two of the three spacecraft involved will host copies of the Dust Impact Sensor and Counter (DISC), which will measure the physical properties of cometary dust. The spacecraft’s velocity (7-70 km/s) will result in hypervelocity dust impacts on DISC. Combined with the range of dust particle sizes, this will create a wide range of impact momentum (10-11–10-3 kg/m/s). To cover the upper part of the momentum range, DISC calibration will be performed with hypervelocity simulated impacts induced by lasers. To perform DISC characterization and calibration in the lower momentum range, we carried out experiments at the Light Gas Gun Impact Facility at the University of Kent (UK).

To calibrate DISC and check the sensing element formed by the aluminum plate and the piezoelectric transducers:

• We performed 9 shots at the Light Gas Gun Impact Facility at the University of Kent. We used different particle sizes and materials and different speeds, utilising different approaches, i.e. single particles with diameters down to 400 nm and buck-shots of a mixture of minerals and very light hollow spheres.
• The signals from the piezoelectrics will be used to verify DISC estimated performance and enable a generally-valid impact sensor calibration procedure.

All 9 shots provided signals, this was for both single impacts and multiple buck- shot impacts. The results of the experiment confirmed the capability of the instrument to measure the momentum of particles impacting in the hypervelocity range.