A few years ago, a team of researchers dedicated to finding killer asteroids before they kill us came up with an interesting trick.
Instead of scanning the sky with telescopes for asteroids, scientists wrote an algorithm that sifts through old images of the night sky and discovers about 100 asteroids which had been neglected in these images.
On Tuesday, these scientists, working with the Asteroid Institute and the University of Washington, revealed an even bigger reward: 27,500 newly identified solar system bodies.
That’s more than was discovered by all the world’s telescopes last year.
“It’s a sea change” in the way astronomical research will be conducted, said Ed Lu, executive director of the institute, which is part of the B612 Foundation, a nonprofit group that Dr. Lu contributed to to found.
The discoveries include about 100 near-Earth asteroids, space rocks that pass through Earth’s orbit. None of the 100 appear to be on a collision course with Earth in the near future. But the algorithm could prove a key tool for spotting potentially dangerous asteroids, and the research helps the “planetary defense” efforts undertaken by NASA and other organizations around the world.
Most of the space rocks identified by the institute are found in the main asteroid belt, between the orbits of Mars and Jupiter. Others, known as Trojans, are trapped in Jupiter’s orbit. The research also discovered much more distant small worlds, known as Kuiper Belt Objects, beyond the orbit of Neptune.
“There’s a lot of great science here,” said Dr. Lu, a former NASA astronaut who noted that in the future the key to astronomical discoveries may not be more observing time on telescopes, but rather more powerful computers to already process vast quantities of observations. gathered.
Historically, astronomers spotted new planets, asteroids, comets and Kuiper Belt objects by photographing the same strip of sky several times during the same night. The configuration of distant stars and galaxies remains unchanged. But much closer objects, within the solar system, move noticeably within a few hours.
Multiple observations of a moving object, called a “tracklet,” trace its trajectory, providing enough information to give astronomers a good idea of where to look another night and determine its orbit.
Other astronomical observations inevitably include asteroids, but only at a single time and place, not the multiple observations needed to assemble a tracklet.
The 412,000 images in the digital archive of the National Optical-Infrared Astronomy Research Laboratory, or NOIRLab, contain some 1.7 billion points of light that appear in a single image.
The algorithm used in the current research, known as Tracklet-less Heliocentric Orbit Recovery, or THOR, is capable of connecting a point of light seen in one image with a different point of light in a different image taken on a different night – sometimes through a different telescope – and discover that these two points are actually the same object, usually an asteroid that has changed position as it orbits the sun.
THOR’s identification of candidate asteroids across disparate images is a daunting computational task, one that would have been impossible not so long ago. But Google Cloud, a distributed computing system, was able to complete the calculations in about five weeks.
“This is an example of what’s possible,” said Massimo Mascaro, CTO of Google Cloud’s Office of the Chief Technology Officer. “I can’t even quantify the scale of the opportunities that exist in terms of the data already collected and which, if analyzed with the appropriate calculations, could lead to even more results.”
Dr Lu said improved software tools have made it easier to harness computing power. When scientists no longer need a giant software engineering team to research their data, “that’s when really interesting things can happen,” he said.
The THOR algorithm could also transform the operations of the new Vera C. Rubin Observatory in Chile, which is expected to begin operations next year. The 8.4-meter telescope, funded by the National Science Foundation and the Department of Energy, will repeatedly scan most of the night sky to track changes over time.
Currently, the Rubin telescope must scan the same part of the sky twice a night, a cadence designed to spot asteroids. With THOR, the telescope might not need the second pass, which could allow it to cover twice as much area.
“Most science programs would be happy to move from a basic cadence with two observations to just one observation per night,” said Zeljko Ivezic, an astronomy professor at the University of Washington and Rubin’s construction director.
The algorithm could increase the number of asteroids Rubin can find, perhaps enough to meet a mandate passed by Congress in 2005 to locate 90 percent of near-Earth asteroids measuring 460 feet in diameter or larger.
“Our latest estimates speak of around 80 percent,” Dr. Ivezic said. “With THOR, maybe we can push it to 90 percent.”
