Numerical Modelling of Impact Cratering on Asteroids
Lead Research Organisation:
Imperial College London
Department Name: Earth Science and Engineering
Abstract
Near-Earth Asteroids represent a low-probability, high-consequence natural hazard to Earth. Momentum transfer from a kinetic impactor, such as a large spacecraft, is one of the most straightforward methods of deflecting a small asteroid from an impacting trajectory, if the body is detected well in advance. The NASA Double Asteroid Redirection Test (DART) would be the first mission to test a controlled deflection of a near-Earth asteroid, by impacting the moon of Didymos. My project consists in numerical studies of impacts onto asteroids using a range of initial conditions in order to determine the reaction of different types of asteroids to a possible impact, and subsequently to determine the momentum transferred from the impactor for deflection.
Organisations
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| ST/N504312/1 | 01/10/2015 | 30/09/2021 | |||
| 1839044 | Studentship | ST/N504312/1 | 01/10/2016 | 31/05/2020 | Sabina Raducan |
| Description | Asteroids in the Solar System are numerous and have varied composition. Analysis of impact crater sizes and morphologies on asteroids can provide a direct diagnosis of the surface material properties and near-surface structures. This work describes numerical simulations of impacts into low-gravity asteroid surfaces using the iSALE shock physics code to inform this diagnosis. Asteroids may pose a future catastrophic threat to Earth and to avoid it, the incoming asteroid can be deflected by a spacecraft impact. However, the efficiency of the deflection is determined by target properties. This work considered different target scenarios to determine the sensitivity of crater morphology, ejecta mass-velocity distribution and momentum transferred, to asteroid surface properties and shallow structures. For homogeneous targets, the surface cohesion, initial porosity, and internal friction were found to greatly influence ejecta mass/velocity distributions and the amount an asteroid can be deflected. In a two-layer target scenario, the presence of a less porous, stronger lower layer can cause both amplification and reduction of ejected mass and momentum relative to the homogeneous case. Impacts into targets with decreasing porosity with depth only produced an enhancement in the ejected momentum for sharp exponential decreases in porosity. Using reasonable estimates for the material properties of the Double Asteroid Redirection Test (DART) asteroid target, the simulations show that the ejecta produced from the impact can enhance the deflection 2 to 4 times. Simulations of impacts into possible target structures on Psyche show large diversity in possible crater morphologies that the 'Psyche' mission could encounter. If Psyche's interior is homogeneous, then the mission will find simple bowl-shaped craters, with a depth-diameter ratio diagnostic of rock or iron. If Psyche has a layered structure, the spacecraft could find craters with more complex morphologies, e.g. concentric or flat-floored craters. Based on 3-4 proposed large craters on Psyche's surface, model size-frequency distributions suggest that Psyche could be at least 3 billion years old if rocky and more than 4 billion years old if metal-rich. |
| Exploitation Route | This research is important for planning of future space missions to small bodies, such as NASA's DART and Psyche or ESA's Hera. The outcome of this research is also of importance when analyse and understand the data returned by these missions. |
| Sectors | Other |
| Description | Earth is continuously impacted by space debris and small asteroids, and, while large asteroid impacts are very rare, they have the potential to cause severe damage. An asteroid could therefore one day threaten the Earth. The most major meteoroid airbust recorded in the last century (in 1908), Tunguska, in Russia, produced extensive extensive damage, flattening approximately 2000 square km of forest. The impactor catastrophically disrupted above an area with a very low population density. As a result, few casualties were reported, however, the energy produced would have been capable of causing extensive damage and fatalities in a large metropolitan area, such as London or New York. The other large event in recent history happened in Chelyabinsk, in February 2013, when a ~20 m meteoroid entered Earth's atmosphere and exploded in the vicinity of Chelyabinsk, Russia. This event raised public awareness of the risks and frequency of such events. This subject is very much of interest to the general public and it is important to educate people about such threats. Efforts to detect and to asses the dangers of asteroid impacts are led by both Europe and the US and if an asteroid of a few hundred meters is detected in advance to be on an Earth-colliding trajectory, an appropriate action can be taken to deflect its orbit. This project will help the science as well as government and private-sector initiatives to study asteroids, and particularly help in developing greater deflection techniques and interpret the results. |
| First Year Of Impact | 2020 |
| Sector | Aerospace, Defence and Marine,Communities and Social Services/Policy,Education,Government, Democracy and Justice,Other |
| Impact Types | Societal,Policy & public services |
| Title | Data from the model simulations used in Raducan et al, 2020 (PSS) |
| Description | Additional supporting information. Data from the model simulations used in Raducan, S. D., Davison, T. M., Collins, G. S. (2020) The effects of asteroid layering on ejecta mass-velocity distribution and implications for impact momentum transfer. Planetary and Space Science. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2019 |
| Provided To Others? | Yes |
| Impact | Additional supporting information. Data from the model simulations used in Raducan, S. D., Davison, T. M., Collins, G. S. (2020) The effects of asteroid layering on ejecta mass-velocity distribution and implications for impact momentum transfer. Planetary and Space Science. |
| URL | http://doi.org/10.5281/zenodo.3458252 |
| Title | Ejecta data in support to Raducan et al. 2019. Icarus. |
| Description | Additional supporting information. Ejecta data from the model simulations used in Raducan, S. D., Davison, T. M., Luther, R., Collins, G. S. (2019) The Role of Asteroid Strength, Porosity and Internal Friction in Impact Momentum Transfer. Icarus. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2019 |
| Provided To Others? | Yes |
| Impact | In this study we numerically simulate impacts into low-gravity, strength dominated asteroid surfaces using the iSALE shock physics code, and the results are important especially in the context of the Double Asteroid Redirection Test (DART) mission. |
| Title | sr516/Psyche_craters_diversity: Psyche_craters_diversity |
| Description | Additional supporting information. Input files and results data from S. D. Raducan; T. M. Davison; G. S. Collins; (2020) Morphological diversity of impact craters on asteroid (16) Psyche: insight from numerical models. JGR: Planets |
| Type Of Material | Database/Collection of data |
| Year Produced | 2020 |
| Provided To Others? | Yes |
| Impact | Additional supporting information. Input files and results data from S. D. Raducan; T. M. Davison; G. S. Collins; (2020) Morphological diversity of impact craters on asteroid (16) Psyche: insight from numerical models. JGR: Planets |
| URL | https://zenodo.org/record/3939073 |
| Title | iSALE shock physics code |
| Description | iSALE (impact-SALE) is a multi-material, multi-rheology shock physics code for simulating high speed impacts and other violent geophysical phenomena. iSALE includes constitutive and porous-compaction models specifically developed for impact simulations. The code is being continually developed, improved and maintained by research groups at the Museum für Naturkunde, Berlin and Imperial College London. |
| Type Of Technology | Software |
| Year Produced | 2006 |
| Open Source License? | Yes |
| Impact | iSALE has been used in pioneering studies of the formation of large impact craters on the Earth and the influence of target property variations on crater formation, the influence of a water layer on crater formation, as well as investigating the mobility of large rock avalanches.The software has been extensively validated against laboratory experiments and used to show, for the first time in numerical simulations, the important effect of friction and porosity on crater growth in granular materials. |
| URL | http://www.isale-code.github.io |