Over 30,000 asteroids approach Earth, ranging from potential threats to harmless minimoons. Beyond their immediate threat assessment, scientists are intrigued by the prospect of these minimoons playing a pivotal role in advancing human exploration, particularly contemplating their potential in facilitating humanity's ambition of becoming an interplanetary species.
Artist's conception of Earth with two moons, generated in Celestia with addon from Eugene Stauffer (GPLv3)
Earth's Minimoons and Their Potential for Future Cosmic Exploration
The minimoon 2006 RH120, identified in 2006 by astronomers from the NASA-backed Catalina Sky Survey in Arizona, was an unusual object that emerged within Earth's artificial satellite cluster. The small natural satellite temporarily ensnared in Earth's orbit resembling the moon.
This several-meter-diameter minimoon orbited the planet for a year before being expelled from its orbital path. Recently, another minimoon, 2020 CD3, roughly the size of a small car, was unearthed by the Catalina Sky Survey. It traveled through Earth's orbit before breaking free from the Earth-moon system's influence in March 2020.
Minimoons captivate scientists due to their potential as targets for robotic spacecraft missions that could bring entire asteroids back to Earth. This presents unique scientific opportunities, offering pristine rocks unaffected by atmospheric entry, weathering, or erosion.
While astronomers possess numerous rocks from space, those collected on Earth are altered by atmospheric passage, and even lunar rocks are comparable to terrestrial ones. The mass of lunar rocks returned is also insufficient compared to a single 1-meter diameter minimoon.
Aside from potential sample return missions, minimoons offer observational opportunities. Even without spacecraft missions, ground-based telescopes can provide detailed insights into their characteristics. Spectrographs can reveal rotational speeds and surface composition details, allowing scientists to understand the journey of asteroids from the main belt to Earth's vicinity.
While detecting minimoons is challenging due to their faintness and uncertain locations, the ATLAS survey telescope is positioned to make significant contributions by scanning the entire sky nightly. ATLAS's capabilities offer the prospect of identifying and studying minimoons, potentially paving the way for future spacecraft missions.
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Minimoons: A New Frontier for Space Exploration Strategies Post OSIRIS-REx
NASA's OSIRIS-REx mission, launched in 2016 to collect a sample from the potentially hazardous asteroid Bennu, has ignited a reevaluation of strategic approaches to near-Earth exploration.
Scientists are now considering the use of nearby asteroids, particularly minimoons, as stepping stones for future Mars missions. Unlike more distant targets like Bennu, minimoons offer accessibility due to their proximity and low gravitational influence, requiring less fuel for spacecraft propulsion.
Minimoons, with their low delta-V indicating minimal required changes in velocity, prove conducive to testing space technologies. This makes them easily reachable with minimal propulsion, streamlining spacecraft transportation from low Earth orbit to rendezvous with the asteroid. Envisioned minimoon missions could potentially complete a round trip in approximately 100 days, consuming less fuel than journeys to other celestial bodies.
Despite their advantageous attributes, the transient nature of minimoons introduces challenges in mission planning and execution. Nevertheless, scientists recognize their value as ideal subjects for experimenting with deep space technologies, encompassing life support systems, engines, and propulsion systems.
Minimoons, though not a definitive solution for spacecraft refueling due to their size and potentially dry surfaces, provide valuable opportunities for refining spacecraft maneuvers near asteroids. The upcoming Vera C. Rubin Observatory and NASA's NEO Surveyor, designed for asteroid detection from space, are crucial for discovering and studying minimoons, potentially unveiling solar system mysteries and enhancing our understanding of life's chemical origins on Earth.
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