Early bombardment of the moon: Connecting the lunar crater record to the terrestrial planet formation

Chemical conditions on Hycean worlds

“…113 While the estimates for the total mass delivered to Earth in this Late Heavy Bombardment/Late Veneer scenario vary (as does the precise timing of these events, although this is not relevant to us), our value is on the lower end of usual estimates. 53,114…”

“…113 While the estimates for the total mass delivered to Earth in this Late Heavy Bombardment/Late Veneer scenario vary (as does the precise timing of these events, although this is not relevant to us), our value is on the lower end of usual estimates. 53,114 Table 2 Estimates of element masses required to provide the necessary concentrations in our canonical Hycean ocean. C PO is the estimated concentration of a given element in Earth's primeval ocean, 101 shown in log(moles/litre), and M req is the median estimate of the element mass (in kg) required, assuming a median ocean depth of 200 km.…”

A race against the clock: Constraining the timing of cometary bombardment relative to Earth’s growth

“…In this study and in Joiret et al (2023), we mainly focus on bigger objects and emphasize the importance of the stochastic component of the cometary bombardment. Nesvorný et al (2023) found that leftover planetesimals (called locally-sourced planetesimals in our study) dominated the impacts on Earth after the Moon-forming impact. They showed that ≃ 6 × 10 4 >10 km leftover planetesimals, ≃ 500 >10 km comets and ≃ 100 >10 km asteroids impacted the Earth before the Moon-forming impact, and ≃ 4 × 10 4 >10 km leftover planetesimals, ≃ 200 >10 km comets and ≃ 100 >10 km asteroids after the Moon-forming impact (see Fig.…”

“…They showed that ≃ 6 × 10 4 >10 km leftover planetesimals, ≃ 500 >10 km comets and ≃ 100 >10 km asteroids impacted the Earth before the Moon-forming impact, and ≃ 4 × 10 4 >10 km leftover planetesimals, ≃ 200 >10 km comets and ≃ 100 >10 km asteroids after the Moon-forming impact (see Fig. 13 in Nesvorný et al (2023)). According to their results, the cumulative collision rate of comets relative to asteroids or leftover planetesimals decreases after the Moon-forming impact.…”

Impact-induced initiation of Snowball Earth: A model study

“…We can estimate, to first order, the probability of impact-induced Snowball episodes. We assume that an object of greater than 5-km diameter is sufficient to induce Snowball conditions given a suitable background climate and impact site; an object of this size or larger strikes the Earth every ∼40 Ma ( 52 – 54 ). A recent study has suggested that 13% of the Earth’s surface is covered by hydrocarbon-rich materials that would lead to marked global cooling upon large impact ( 48 ).…”