The steady state population of Earth’s minimoons of lunar provenance
Bibliographic record
Abstract
This work examines the plausibility of a lunar origin of natural objects that have a negative total energy with respect to the geocenter, i.e. E T = potential＋ kinetic energy < 0 , while they are within 3 Earth Hill radii ( R H ), a population that we will refer to as ‘bound’. They are a super-set of the informally named population of ‘minimoons’ which require that the object make at least one orbit around Earth in a synodic frame rotating with Earth and that its geocentric distance be < R H at some point while E T < 0 . Bounded objects are also a dynamical subset of the population of Earth’s co-orbital population, objects in a 1:1 mean motion resonance with Earth or, less specifically, on Earth-like orbits. Only two minimoons have been discovered to date, 2006 RH 120 and 2020 CD 3 , while 2024 PT 5 and 2022 NX 1 meet our condition for ’bound’. The likely source region of co-orbital objects is either the MB of asteroids, lunar ejecta, or a combination of both. Earlier works found that dynamical evolution of asteroids from the MB could explain the observed minimoon population, but spectra of 2020 CD 3 and 2024 PT 5 and Earth co-orbital (469219) Kamo‘oalewa are more consistent with lunar basalts than any MB asteroid spectra, suggesting that the ejection and subsequent evolution of material from the Moon’s surface contributes to the minimoon and, more generally, Earth’s co-orbital population. This work numerically calculates the steady-state size-frequency distribution of the bound population given our current understanding of the lunar impact rate, the energy of the impactors, crater-scaling relations, and the relationship between the ejecta mass and speed. We numerically integrate the trajectory of lunar ejecta and calculate the statistics of ‘prompt’ bounding that take place immediately after ejection, and ‘delayed’ bounding that occurs after the objects have spent time on heliocentric orbits. A sub-set of the delayed bound population composes the minimoon population. We find that lunar ejecta can account for the observed population of bound objects but uncertainties in the crater formation and lunar ejecta properties induce a many orders of magnitude range on the predicted population. If the bound objects can be distinguished as lunar or asteroidal in origin based on their spectra it may be possible to constrain crater formation processes and the dynamical and physical evolution of objects from the MB into near-Earth space. • Some natural objects can be temporarily bound (TBO) to the Earth. • About 1 in 5 TBOs are ‘minimoons’. • ‘Minimoons’ make ≥ 1 revolution around Earth while approaching within 1 Hill radii. • TBOs may be lunar ejecta but with orders-of-magnitude uncertainty in their number. • TBO spectra and number counts may constrain the cratering and ejection processes.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".