With Japan’s Hayabusa2 currently investigating asteroid Ryugu and Nasa’s OSIRIS-REx currently en route to Bennu, the future of asteroid exploration looks bright. However, one thing is missing: a map that can track where these icy rocks are moving within our busy solar system.
“For all aspects of planetary defense or planetary exploration, we need a map,” says Danica Remy, president of the B612 Foundation, a nonprofit organisation dedicated to the discovery and deflection of near-Earth asteroids. “If you want to protect the planet from a possible asteroid impact, you would need to know where it is and where it's going."
Alessondra Springmann, planetary scientist at the University of Arizona, agrees, saying that “it’s important to understand where these asteroids are and what they're made of.” An asteroid impact near what is now the Yucca Peninsula in Mexico is widely thought to have contributed to the extinction of the dinosaurs. Unlike dinosaurs, however, humans have the technology to prevent a similar catastrophe, she argues.
B612 is working to create a dynamic map of all near-Earth objects. “The goal of the Asteroid Decision Analysis and Mapping (ADAM) project is to provide open source cloud-based infrastructure for large-scale orbital dynamics and computation related to identifying, tracking, and analysing asteroids,” says Remy. Asteroids are constantly moving, so a static map isn’t as useful, she argues. That’s why ADAM seeks to render not just locations but also velocities of celestial objects, creating a predictive map.
Right now, B612 is focused on building the technology that can support a dynamic asteroid map.
“Because we understand the laws of celestial mechanics under which these trajectories of bodies and space move under the influence of gravity, we can actually predict where an asteroid is and where it was,” says Remy. “The work that we're doing right now is building the infrastructure to hold that predictive map.” While simple in concept, the actual implementation of precisely calculating an asteroid’s trajectory is complicated. Tiny effects like the curvature of spacetime, irregular thermal re-radiation as an asteroid rotates, and even how minute deviations in the Sun’s spherical shape influences an asteroid’s orbit, need to be incorporated into the calculations.
But getting data to feed into the map is also a challenge. “The really good news that is NASA has found the civilisation-ending asteroids,” says Remy, explaining that the American space agency completed a comprehensive inventory of roughly a thousand large, potentially hazardous asteroids several years ago. But the search for smaller near-Earth objects continues.
Even an asteroid just a few tens of meters in diameter can create an city-damaging air burst capable of injuring thousands of people. Researchers have identified the orbits of roughly 18,000 smaller asteroids akin to the meteors that disintegrated over Chelyabinsk, Russia in 2013 or flattened the forest near Tunguska, Siberia in 1908, but predict five million are yet to be found. With 1,500 to 2,000 new asteroids of this size found every year, it’ll take millennia to find them all at this rate.
Along with finding the asteroids, it’s also important to understand what they’re made of, says Springmann. While researchers can use meteorites found on Earth to theorise about the composition of asteroids in space, astronomers sometimes find mismatches. This difference may be due to space weathering, explains Springmann, as bombardment of small particles alters surface materials.
“You can think of it as a potato in that on the surface it looks one way — it might be brown, it might have some darker patches — but when you cut it open, the subsurface that looks different,” explains Springmann. The difference between surface and interior of these lumpy space spuds may not be as dramatic as in an actual potato, but it takes sample return missions like Japan’s Hayabusa2 and NASA’s OSIRIS-REx to confirm the composition of an asteroid below its weathered shell.
“Our biggest challenges is that we need to accelerate the rate of asteroid discovery using technology that we already have today,” says Remy. She’s hopeful that the Large Synoptic Survey Telescope (LSST) in Chile will increase the pace of discovery to fifty to a hundred thousand new asteroids per year. But LSST is still under construction and astronomy research is not anticipated to start until 2022. Once it comes online, it’ll produce enormous datasets that will need to be filtered to search for new asteroids.
“One of the challenges is finding asteroids that are behind the Sun because you can't really look for asteroids during the day when the Sun is up,” says Springmann, explaining the limitations of relying solely on ground-based telescopes like LSST. Several researchers have proposed space-based telescopes to help fill this gap in asteroid surveys.
Remy is optimistic that even as she wishes asteroid surveys had more funding, public support is growing. Along with creating their dynamic asteroid map, B612 also works on building public awareness for the threat of asteroid impact. They do this in large part through an annual worldwide Asteroid Day held on June 30, the anniversary of the Tunguska event. This summer, a Pew Institute survey found Americans overwhelmingly supported monitoring asteroids as a top priority for NASA, just behind monitoring the Earth’s climate. “Collectively, humanity realises that this is a problem and that we could also solve it,” says Remy.
“We’re building a platform and an engine right now to put that data into, but what humanity really needs is to accelerate the rate of discovery.” says Remy. “The really exciting thing is that it's completely solvable using science and all the great new technology that is coming online.”
This article is part of our WIRED on Space series. From the global fight over how we handle first contact with aliens to the endless search for dark matter and the inside story of China's top-secret space ambitions, we're taking an in-depth look at humanity's future amongst the stars.
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This article was originally published by WIRED UK
