Asteroid mining labs are circling Earth
Researchers discover natural minimoons orbiting our planet Metal Tech News – Nov. 25, 2020
Last updated 12/1/2020 at 6:56pm
Natural "minimoons" that temporarily orbit Earth may be interesting targets for both scientific study and to practice asteroid mining techniques.
While Earth is orbited by thousands of artificial satellites and one large natural one, the Moon, it has only been recently that scientists have confirmed that small natural objects are also circling our planet.
About eight years ago, researchers at the University of Hawaiʻi Institute for Astronomy predicted that there must be a population of small, natural minimoons that temporarily orbit Earth.
On November 22, a team of 23 researchers from 14 academic institutions announced a study on 2020 CD3, the second minimoon ever discovered.
Kacper Wierzchos and Teddy Pruyne, research specialists at the University of Arizona's Lunar and Planetary Laboratory in Tucson, discovered the minimoon using the 1.5-meter Mt. Lemmon telescope, operated by the Catalina Sky Survey.
Picking out an object like CD3, which is between the size of a small dishwasher and a refrigerator, amongst the artificial "space junk" orbiting Earth is no easy feat.
An object that was thought to be a minimoon discovered earlier this year with University of Hawaiʻi Institute for Astronomy's Pan-STARRS1 survey telescope on Haleakalā, Maui turned out to be just artificial space debris.
The new research paper, however, conclusively shows that 2020 CD3 is a natural object that is likely a fragment of a larger asteroid that orbits the Sun somewhere between Mars and Jupiter. Extensive follow-up observations were needed to accurately determine the object's orbit.
"The high-precision astrometry we obtained from the University of Hawaiʻi 2.2-meter telescope and the Canada-France-Hawaiʻi Telescope on Maunakea was absolutely essential to confirm that 2020 CD3 is a captured asteroid, and not something artificial," said Dora Föhring, a researcher at the University of Hawaiʻi Institute for Astronomy and paper co-author.
The team's calculations indicate that 2020 CD3 had been orbiting Earth for more than two and a half years, but was only discovered as it made a very close approach to Earth, before being flung back out into an orbit around the Sun.
"It is incredible that modern astronomical telescopes can detect minimoons the size of big boulders as far away as the Moon," said University of Hawaiʻi Astronomer Robert Jedicke, a co-author on the 2020 CD3 research paper.
Jedicke's work showed that, even though it was bright enough to be detected at least half a dozen times in the past few years, there were only one or two opportunities when it was bright enough and moving slowly enough to be discovered.
The University of Hawaiʻi researchers say minimoons pose no danger to Earth, even though about 1 out of every 1,000 meteors that strike our planet are actually tiny minimoons before they enter Earth's atmosphere.
A dishwasher-sized minimoon, which would weigh more than a ton, would yield critical clues about the formation of our solar system and also provide a near-Earth place to test space mining techniques.
"[Minimoons are] outstanding targets for space missions," said Grigori Fedorets, lead author of the paper and a postdoctoral research fellow at the Astrophysics Research Center at Queen's University in Belfast. "Minimoons effectively bring the asteroid belt close to the Earth so that, in astronomical terms, we can reach out and touch them, and potentially collect samples."
"It is difficult to monitor and control spacecraft around distant asteroids where it can take many minutes to verify that a single command has been properly executed," explained Jedicke, who is excited about the opportunity to use minimoons to test asteroid mining technology. "Minimoons are so close to Earth that we can imagine using a joystick at ground control to perform mining operations."
Though 2020 CD3 is now taking its own trajectory through the solar system, University of Hawaiʻi researchers say it is possible that this asteroid will once again be drawn in by Earth's gravitational pull.
In the meantime, Fedorets expects there will be many more minimoons discovered by the Vera C. Rubin Observatory – an 8-meter-class telescope coupled to a 3.2-gigapixel camera – which is under construction in Chile and expected to begin operations in 2022.
The minimoons expected to be discovered by this massive observatory will provide researchers a near-Earth asteroid laboratory and space miners a prospect to practice techniques before applying them to the wider expanse of our solar system.