Recreating the instantaneous destruction of asteroid surfaces via sunlight
Authors: Schirner Leonard , Tsirvoulis Georgios , Granvik Mikael 
Published: July 2024

Using our Space and High-Irradiance Near-Sun Simulator (SHINeS) [Tsirvoulis 2022] and high-fidelity CI asteroid simulant [Britt 2019] we recreate the vacuum, insolation and material conditions on asteroid surfaces close to the Sun (0.06 - 0.25 au). We observe instantaneous explosive events triggered solely by solar-like irradiation. Depending on the level of irradiation the process results in centimeter-sized samples to be destroyed in minutes or hours. The observed phenomenon could explain what causes active asteroids similar to (3200) Phaeton to emit particles at their closest passage to the Sun.It may also partially explain why there is an observed lack of asteroids with small perihelion distances compared to predictions from dynamical models [Granvik 2016]. Here we present destruction time scales at different heliocentric distances, allowing us to estimate first order survival lifetime depending on distance.&#160;Furthermore we report on experiments to assess the influence of material parameters such as porosity and grain size on the destruction process. For this we created porous samples using a vacuum drying process, which over time inflates the samples. This enables us to control the porosity levels within our simulant samples. We then experiment with these samples of varying porosity at the same simulated heliocentric distance. This approach lets us systematically examine how variations in porosity affect the destruction timescales of the porous samples when subjected to solar-like irradiation.We also investigated the exact mechanism of the destruction process. Initial insights suggest a correlation between the destruction process and sulfur outgassing, alongside potential chemical reactions [MacLennan 2023] occurring within the simulant material. Additionally, we observed that grain size may also influence this process. These preliminary findings hint at complex interactions between these parameters. Further research is necessary to understand the interplay of these processes in detail.Looking ahead, the deployment of the DESTINY Dust Analyzer aboard the JAXA mission DESTINY+ presents an exciting opportunity to corroborate our experimental results in situ. By analyzing the chemical and physical properties of the dust emitted by Phaeton, the DESTINY Dust Analyzer could provide invaluable data for comparison with the materials generated in our laboratory experiments.&#160;References: [1] Tsirvoulis, G., Granvik, M., Toliou, A.: Shines: Space and high-irradiance near-sun simulator. Planetary and Space Science 217, 105490 (2022) https://doi.org/10.1016/j.pss.2022.105490[2] Britt, D.T., Cannon, K.M., Donaldson Hanna, K., Hogancamp, J., Poch, O., Beck,P., Martin, D., Escrig, J., Bonal, L., Metzger, P.T.: Simulated asteroid materialsbased on carbonaceous chondrite mineralogies. Meteoritics amp; Planetary Science54(9), 2067&#8211;2082 (2019) https://doi.org/10.1111/maps.13345[3] Granvik, M., Morbidelli, A., Jedicke, R., Bolin, B., Bottke, W.F., Beshore, E.,Vokrouhlick &#769;y, D., Delb`o, M., Michel, P.: Super-catastrophic disruption of asteroidsat small perihelion distances. Nature 530(7590), 303&#8211;306 (2016) https://doi.org/10.1038/nature16934[4] MacLennan, E., Granvik, M.: Thermal decomposition as the activity driver ofnear-earth asteroid (3200) phaethon. Nature Astronomy 8(1), 60&#8211;68 (2023) https://doi.org/10.1038/s41550-023-02091-w