Mark Megahan
Mother Terra has a friend that nobody knew about before, a companion “Trojan” asteroid has been discovered in the same orbit as Earth. Named 2020 XL5, this freshly confirmed asteroid is “much bigger” than the only other previously discovered Earth Trojan, 2010 TK7. That makes it better suited as a base for “advanced exploration of the solar system.” At the very least, it can be mined for resources.
A Trojan Earth Companion
Rather than an enemy of the ancient Greeks, when astronomers use the word “Trojan” they’re referring to an object which efficiently shares the same orbit as another object. Because of the way gravity works, the orbit of the companion can only remain stable when it’s near one of the main body’s “Lagrange” points.
Starting with two massive bodies, say the Earth and Sun, L1, L2, and L3 all lie along a line connecting the center of mass for each main body. L4 and L5 are points exactly 60 degrees ahead and behind the smaller object. The nifty new James Webb Space Telescope will be parked at our L2 point.
In 2020, astronomers working with the Pan-STARRS 1 survey telescope in Hawaii “thought they’d found something incredible: the second so-called Earth Trojan asteroid ever seen.” Amateur astronomer Tony Dunn “went on to calculate the object’s trajectory using NASA’s publicly-available JPL-Horizon’s software and found that it orbits L4.” Two years later, “a new team of researchers has confirmed that it’s real.”
Our newly discovered companion space rock “confirms that 2010 TK7 is not a rare exception and that there are probably more.” That’s good news. TK7 is also located at the L4 point.
According to Toni Santana-Ros, a researcher at the University of Alicante and the Institute of Cosmos Sciences at the University of Barcelona, the discovery of this new companion asteroid “encourages us to keep enhancing our survey strategies to find, if exists, the first primordial Earth Trojan.”
Literally anything could be hiding directly across the sun from us.
Not passing through
Just because the rock happened to be spotted in the right place didn’t automatically qualify it as a legitimate companion for Mother Earth. It could just be “a nearby space rock crossing Earth’s orbit.” To find out for sure, the object had to be carefully tracked for a while.
A “team led by Santana-Ros observed the object with the SOAR Telescope in Chile along with the Lowell Discovery Telescope in Arizona and the European Space Agency’s Optical Ground Station in Tenerife in the Canary Islands.”
“These were very challenging observations,” co-author Cesar Briceño explains, “requiring the telescope to track correctly at its lowest elevation limit, as the object was very low on the western horizon at dawn.” It “is a pain for astronomers to point to the L4 and L5 points of the sun-Earth system while being on our planet!” Briceño complains.
Despite the difficulty, he got enough data to confirm the object as a true companion. “If we are able to discover more Earth Trojans, and if some of them can have orbits with lower inclinations, they might become cheaper to reach than our Moon,” Briceño notes. “So they might become ideal bases for an advanced exploration of the solar system, or they could even be a source of resources.”
To back up their fresh observations, “the team also factored in archival data from SOAR to try and fully understand the object and its orbit.” They fed the computer “about a decade’s worth of observations and data.” Then, they sat back and spun they’re prayer wheels while they waited for the numbers to crunch.
They were thrilled when the computer confirmed the asteroid is a companion Trojan object. “They also found that the object is also likely a C-type asteroid, the most common asteroid type in the solar system that is high in carbon and dark.” It won’t stick around forever but the computer says it should be handy for the next 4,000 years or so.
