Key Takeaways

Sample Definition And Size

The study simulated tens of thousands of meteoroid ejecta particles from Earth and Mars using n‑body simulations. Specifically, approximately 43,500 particles were ejected from Earth and 40,500 from Mars in the 10 Myr simulations; a subset (9,000 from Earth and 6,000 from Mars) were extended to 30 Myr simulations ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC3870607/?utm_source=openai)).

Study Type

This is a computational study using n‑body simulations (hybrid symplectic integrator MERCURY) to model the trajectories of ejecta from Earth and Mars over time, assessing transfer probabilities to other Solar System bodies ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC3870607/?utm_source=openai)).

Conflicts Of Interest

No conflicts of interest are declared in the accessible metadata or full text ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC3870607/?utm_source=openai)).

Results Summary

Key findings include: from Earth ejecta, probabilities over 3.5 Gyr of transfer were ~0.041% to Jupiter (≈83,000 fragments; ~2.8×10^10 kg) and ~0.0069% to Saturn (≈14,000 fragments; ~4.7×10^9 kg); from Mars ejecta, ~0.04% to Jupiter (≈320,000 fragments; ~1.1×10^11 kg) and <0.0025% to Saturn (<20,000 fragments; <6.8×10^9 kg) ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC3870607/?utm_source=openai)). Simulations of moon impacts yielded expectation values of one to a few objects reaching Io, Europa, Ganymede, Callisto, Enceladus, and Titan from Earth since the Late Heavy Bombardment, with slightly higher numbers from Mars; Mars‑to‑Saturn moon transfers were less likely but not entirely ruled out ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC3870607/?utm_source=openai)).

Abstract

Material from the surface of a planet can be ejected into space by a large impact and could carry primitive life-forms with it. We performed n-body simulations of such ejecta to determine where in the Solar System rock from Earth and Mars may end up. We found that, in addition to frequent transfer of material among the terrestrial planets, transfer of material from Earth and Mars to the moons of Jupiter and Saturn is also possible, but rare. We expect that such transfers were most likely to occur during the Late Heavy Bombardment or during the ensuing 1-2 billion years. At this time, the icy moons were warmer and likely had little or no ice shell to prevent meteorites from reaching their liquid interiors. We also note significant rates of re-impact in the first million years after ejection. This could re-seed life on a planet after partial or complete sterilization by a large impact, which would aid the survival of early life during the Late Heavy Bombardment.

Referenced In

StarTalk Show Notes

a month ago

StarTalk

Season 17, Episode 22: Asteroid Bennu and the Origin of Life in the Solar System

Hey StarTalkians! Neil and Chuck sat down with Professor Harold Connolly Jr. for season 17, episode 22, talking about his work on the OSIRIS-Rex mission and the asteroid Bennu. After covering the basics of the mission, they briefly discussed what it could mean for the origin of life in the solar system:

Secrets of Asteroid Bennu with Harold Connolly Jr. - StarTalk Radio

(From 53:55)

The discussion touches on the “panspermia” hypothesis. The overall idea is unlikely, to say the least, but a limited form of it could be more promising.

What They Found on Bennu

As Professor Connolly explains in the podcast, the asteroid Bennu contained a lot of organic materials.

One paper he co-authored describes what they found on the carbon-rich asteroid. Most importantly, this included 14 out of 20 terrestrial amino acids, the building blocks of life. Interestingly, these may have been formed in low-temperature reactions involving ammonia ice, unlike previous cases that depended on mild temperatures and liquid water.

Another paper added a 15th terrestrial amino acid, noting that such prebiotic molecules could have been deposited onto the young Earth by asteroid impacts.

The Panspermia Hypothesis

This leads into Chuck’s question about “lithopanspermia,” a variant of the panspermia hypothesis. This is the idea that the earliest forms of life may have developed away from the Earth, eventually being delivered to our planet by asteroid impact events (hence “litho”) and evolving terrestrially.

This hypothesis isn’t super likely, though. After all, could life really survive the journey through space and the impact itself? And the whole thing requires extra-terrestrial life to exist in the first place.

Pseudo-lithopanspermia – A Viable Alternative?

Instead of living microbes making the unlikely journey through space, the more likely “pseudo-panspermia” hypothesis posits that prebiotic organic molecules arrived on Earth that way. If this came from an asteroid like Bennu, we might call this “pseudo-lithopanspermia.”

Professor Connolly’s research shows that such molecules certainly exist. Additionally, modelling suggests that plenty of material from other bodies ends up on Earth – including 21 million landing from Mars alone over 3.5 billion years.

This removes a lot of problems with panspermia, and it’s definitely an interesting possibility. However, Neil’s point in the podcast pours cold ~~water~~ ammonia over this: why would we need extra-terrestrial amino acids if they seem to form everywhere anyway?

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Created: Apr 16, 2026