<p><strong>Introduction. </strong>Post-accretionary impact bombardment is part of planet formation and leads to localized, regional [e.g., 1-3], or even wholesale global melting of silicate crust [e.g., 4]; less intense bombardment can also create hydrothermal oases favorable for life [e.g, 5]. Here, we generalize the effects of late accretion bombardments to extrasolar planets of different masses (0.1-10M<sub>&#8853;</sub>). One example is Proxima Centauri b, estimated at ~2&#215; M<sub>&#8853;</sub> [6]. We model a 0.1M<sub>&#8853; </sub>&#8220;mini-Earth&#8221;<sub></sub>and &#8220;super-Earth&#8221; at 10M<sub>&#8853;</sub>, the approximate upper limit for a &#8220;mini-Neptune&#8221; [7]. Output predicts lithospheric melting and subsurface habitable volumes.</p><p><strong>Methods. </strong>The model [1,2] consists of (i) stochastic cratering; (ii) analytical thermal expressions for each crater [e.g., 8,9]; and (iii) a 3-D thermal model of the lithosphere, where craters cool by conduction and radiation.</p><p>We analyze impact bombardments using our solar system&#8217;s mass production functions for the first 500 Myr [10]. Surface temperatures and geothermal gradients are set to 20 &#176;C and 70 &#176;C/km [2]. Total delivered mass for Earth is 7.8 &#215; 10<sup>21</sup> kg, and scaled to other planets based on cross-sectional areas, with 1.7 &#215; 10<sup>21</sup> kg for mini-Earth, 1.2 &#215; 10<sup>22</sup> kg for Proxima Centauri b, and 3.6 &#215; 10<sup>22</sup> kg for super-Earth. The impactors' SFD is based on our main asteroid belt [11]. Impactor and target densities are set to 3000 kg m<sup>-3</sup> and planetary bulk densities are assumed to be 5510 kg m<sup>-3</sup>, omitting gravitational compression [7]. Impactor velocity was estimated at 1.5 &#215; v<sub>esc</sub> for each planet, with 7.8 km s<sup>-1</sup> for mini-Earth, &#160;16.8 km s<sup>-1</sup> for the Earth, 21.1 km s<sup>-1</sup> for Proxima Centauri b, and 36.1 km s<sup>-1</sup> for super-Earth.</p><p><strong>Results. </strong>We assume fully formed crusts, so melt volume immediately increases due to impacts. Super-Earth reaches a maximum of ~45% of the lithosphere in molten state, whereas mini-Earth reaches a maximum of only ~5%. &#160;This is due to much higher impact velocities and cratering densities on the super-Earth compared to mini-Earth. We also show the geophysical habitable volumes within the upper 4 km of a planet&#8217;s crust as the bombardment progresses. Impacts sterilize the majority of the habitable volume on super-Earth; however, due to its large total volume, the total habitable volume is still higher than on other planets despite the more intense bombardment in terms of energy delivered per unit area.</p><p><strong>References:</strong> [1] Abramov, O., and S.J. Mojzsis (2009) Nature, 459, 419-422. [2] Abramov et al. (2013) Chemie der Erde, 73, 227-248. [3] Abramov, O., and S. J. Mojzsis (2016) Earth Planet Sci. Lett., 442, 108-120. [4] Canup, R. M. (2004) Icarus, 168, 433-456. [5] Abramov, O., and D. A. Kring (2004) J. Geophys. Res., 109(E10). [6] Tasker, E. J. et al. (2020). Astronom. J., 159(2), 41. [7] Marcy, G. W. et al. (2014). PNAS, 111(35), 12655-12660. [8] Kieffer S. W. and Simonds C. H. (1980) Rev. Geophys. Space Phys., 18, 143-181. [9] Pierazzo E., and H.J. Melosh (2000). Icarus, 145, 252-261. [10] Mojzsis, S. J. et al. (2019). Astrophys. J., 881(1), 44. [11] Bottke, W. F. et al. (2010) Science, 330, 1527-1530.</p>