An in-situ seismic investigation of asteroid Apophis

• DOI: 10.5194/epsc2024-495
• Publication Date: 2024-07-03T11:09:04Z
• Authors: Naomi Murdoch; Raphael F. Garcia; Anthony Sournac; Alexandre Cadu; Arnaud Wilhelm; Melanie Drilleau; Alexander Stott; Joseph DeMartini; Taichi Kawamura; Philippe Lognonné; Patrick Michel; Pierre Bousquet; David Mimoun

Introduction:  The tidal encounter of asteroid Apophis with the Earth in 2029 offers ideal scenario for first in-situ seismic investigation an asteroid. A seismometer can be used to monitor seismicity due forces [1], and other natural sources such as micro-meteoroid impacts or thermal cracks; [2-4]. In addition, a image Apophis’ sub-surface internal structure [2] providing information about asteroid’s physical properties that is critical planetary defense, understanding evolutionary history asteroids. As consequence, there strong international support experiment on asteroid.We have developed Compact Seismometer designed specifically fit inside small surface package function challenging environment surface. instrument team has extensive experience developing, testing, operating [5,6] acoustic [7] instrumentation.Scientific Objectives: main science technological goal perform ever study asteroid.  specific compact objectives are follows:Threshold objectives:(O1) Constrain mechanical during landing(O2) Measure background noise ApophisBaseline objectives:(O3) Quantify response forces(O4) Probe subsurface ApophisBonus objective:(O5) Perform active using OSIRIS-APEX spacecraft – interactionsCompact Seismometer: consists three commercial geophones will each measure ground motion along one axis, dedicated electronics (Figs 1-2). passive, contain no withstand extreme environments (e.g., terrestrial boreholes).  analog been carefully high sensitivity low intrinsic noise. currently at TRL level 4/5 (4 electronics, 5 sensors), development schedule compatible RAMSES schedule. current best estimates mass, volume power budgets ~1 kg, 0.8 L ~ 2W, respectively.Figure 1. (left) Schematic diagram Seismometer. (right) containing geophones.Operational scenario: should deployed prior closest Earth. lead up perigee, periodic measurements made commissioning measurements. Then, from 3 hours before 6 after perigee - when tidal-induced activity expected occur [1] continuous monitoring performed. Following close further evolution diurnal variations seismicity. If survive long enough, excavation thrusters [8] would provide unique opportunity Seismometer.Figure 2. Possible concept operations Seismometer.Surface coupling levelling: must land contact However, operate any orientation does not require levelling.  proposed solution attempt couple surface; only upper layer regolith, which itself may coupled sub-surface. lofting occurs, these events characterize subsequent touchdown. Performance testing: