There are some astronomers who believe that the converse is also true - Jupiter also flings in Kuiper-Belt Objects into Earth-Crossing Orbits. The results are c

There are some astronomers who believe that the converse is also true - Jupiter also flings in Kuiper-Belt Objects into Earth-Crossing Orbits. The results are complicated, https://academic.oup.com/astrogeo/article/49/1/1.22/306978 https://academic.oup.com/astrogeo/article/49/1/1.22/306978 Relevant quote, > The flip side of the coin is also true, however — for an object to threaten the Earth, it first has to have an Earth-crossing orbit. Were Jupiter absent, there would be far fewer short-period comets, and it is likely that the asteroid belt would be far less heavily stirred, though it is also true that, without Jupiter, the asteroid belt would no doubt look very different! Every encounter between a small body and Jupiter is random — it throws objects inwards as well as outwards, and can just as easily place objects onto an Earth-crossing orbit as it can remove them from these orbits. Therefore, it is clear that at least some of the objects that hit the Earth would not have done so, had Jupiter not played a role. > Whether Jupiter acts as a friend or a foe comes down to the balance between the two effects discussed above — does Jupiter provide more of a shielding effect, or is the contribution to the terrestrial impact flux so enhanced by the objects it throws our way that this outweighs its defensive work? In order to examine this balance, we are in the process of a series of detailed integrations, following the behaviour of hundreds of thousands of potential impactors in a range of theoretical solar systems. Given that there are three reservoirs of potentially hazardous objects (the Oort Cloud, the Edgeworth-Kuiper belt, and the asteroid belt), our study will be looking at each of these reservoirs in turn. It is currently unclear whether the net effect is harmful or beneficial. But what we do know is that the fact that we are dyadic system (i.e. our moon is arguably the size of a planet - and we exist in a pair with it) has protected us during Sol's younger and more active days. More specifically it protected us from ending up like Mars with a stripped away atmosphere. This hypothesis is fairly well studied and is held to be very likely to be true. Our moon, along with Jupiter, may also act as interference for the Earth w.r.t. Earth-crossing asteroids. There are arguments against this because of the smaller size of the Moon, but there are also some analyses for this - given that the asteroids are affected by the Moon's gravity, and even though the Earth-Moon Barycentre lies within the Earth, the combined system may afford some protection. (i.e. asteroids are more likely to have more near misses given the displacement of the barycentre from the centre of the Earth). But this is a guess, and more study is needed. Papers, When the Moon had a magnetosphere - https://www.science.org/doi/10.1126/sciadv.abc0865 https://www.science.org/doi/10.1126/sciadv.abc0865 The timeline of the Lunar bombardment - revisited. - https://arxiv.org/pdf/1801.03756.pdf https://arxiv.org/pdf/1801.03756.pdf The Late Heavy Bombardment in The Inner Solar System: Is there Any Connection To Kuiper Belt Objects? - https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.615.8510&rep=rep1&type=pdf https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.61... Bashing holes in the tale of Earth’s troubled youth - https://www.nature.com/articles/d41586-018-01074-6 https://www.nature.com/articles/d41586-018-01074-6