Shielding the Moon: How NASA Models Micrometeoroid Threats to Future Artemis Bases
Daniel A. Yahalomi and colleagues used NASA’s Meteoroid Engineering Model to predict how often micrometeoroids strike a lunar base. They found that an unshielded base would face up to 23,000 impacts yearly, but modern Whipple shields block 99.9997% of them. A shielded base might experience a penetrating impact only once every few decades, with the lunar south pole emerging as the safest site for long-term Artemis missions.
How the Asteroid Belt Shapes Earth’s Impact History
Julio Fernández’s paper explores how the asteroid belt steadily loses mass through both fragments and dust, with about 80% of the loss occurring as dust. This depletion directly shapes Earth’s impact history, linking asteroid belt dynamics to the decline in bombardment over billions of years. Geological evidence suggests past fluctuations, with higher impact rates tied to catastrophic collisions and early gravitational stirring.
Building Earth Through Cosmic Collisions: How Giant Impacts Shaped Rocky Planets
The study by Maeda and Sasaki shows that Earth-like planets form through repeated giant impacts and chemical reactions between atmospheres, magma oceans, and cores. Early impacts load protoplanets with too much hydrogen, while later collisions, after the gas disk fades, strip and rebalance this excess. This sequence produces planets with core compositions and densities similar to Earth’s, highlighting the importance of timing in planet formation.
A New Dance Partner for Uranus: Discovering a Minor Planet in Outer Resonance
Daniel Bamberger and colleagues discovered that minor planet 2015 OU194 is in a rare, stable 3:4 outer mean motion resonance with Uranus, the first known example. Using extended observations and simulations, they showed its orbit remains resonant for over a million years. Two other candidates were examined, but none matched 2015 OU194’s stability and near-circular orbit.
A New Kind of Trojan: JWST Reveals Unusual Asteroids Near Jupiter
Using JWST, Brown and colleagues studied four small, unusually bright Jupiter Trojans and found they share unique spectral features unlike any known Trojan class. These objects resemble the Trojan Polymele, suggesting the existence of a third, previously unrecognized surface type. The upcoming Lucy spacecraft flyby of Polymele may help reveal their origins.
The Invisible Danger: Could Undiscovered Asteroids Near Venus Threaten Earth?
A new study led by Carruba suggests that many low-eccentricity asteroids sharing Venus’s orbit may exist undetected due to observational bias. Simulations show some could come dangerously close to Earth. While ground-based telescopes struggle to detect them, space missions near Venus could reveal this hidden, potentially hazardous population.
Asteroid 2023 NT1: A Close Call and Lessons in Planetary Defense
Asteroid 2023 NT1 narrowly missed Earth in July 2023, exposing gaps in detection systems for small asteroids. If it had impacted, it could have caused significant local damage. The "Pulverize It" strategy proposes fragmenting asteroids with hypervelocity penetrators to minimize ground effects. Simulations show this method effectively mitigates threats, even with short warning times, emphasizing the need for better detection and advanced planetary defense technologies.
Exploring the Orbital Properties of Decameter-Sized Earth Impactors
The paper examines decameter-sized asteroids that impact Earth, comparing their observed frequency with predictions from telescopic data, which differ significantly. Using new data from U.S. satellite sensors, the study analyzes 14 impact events, finding no strong evidence for recent tidal disruptions as a cause for the discrepancy. Both impactor and asteroid populations likely originate from similar main asteroid belt regions, with most objects delivered through key orbital resonances.