Killer asteroid hunters spot 27,500 discarded space rocks

Two years ago, a team of researchers dedicated to finding killer asteroids before they kill us came up with a neat trick.

Instead of scanning the sky with telescopes for asteroids, scientists wrote an algorithm that sifts through old images of the night sky, discovering about 100 asteroids that had been overlooked in those images.

On Tuesday, these scientists, in collaboration with the Asteroid Institute and the University of Washington, unveiled an even bigger reward: 27,500 newly identified objects in the solar system.

This is more than was discovered by all telescopes in the world last year.

“This is a radical change” in how astronomical research is conducted, said Ed Lu, executive director of the institute, which is part of the B612 Foundation, a non-profit group Dr. Lu helped found.

The discoveries include about 100 near-Earth asteroids, which are space rocks that pass within Earth's orbit. None of these 100 planets appear to be on a collision course with Earth any time soon. But the algorithm could be a key tool in detecting potentially dangerous asteroids, and the research is helping “planetary defense” efforts by NASA and other organizations around the world.

Most of the space rocks identified by the institute are located 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 found some very distant small worlds known as Kuiper Belt objects, beyond the orbit of Neptune.

“There is Lots of great science here.” Collected.

Historically, astronomers have discovered new planets, asteroids, comets, and Kuiper Belt objects by imaging the same area of ​​the sky multiple times during a single night. The pattern of stars and distant 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 “track,” chart its path, providing enough information to give astronomers a good idea of ​​where they should look on another night and determine its orbit.

Other astronomical observations inevitably include asteroids, but only at one time and place, not the multiple observations needed to piece together a track.

The 412,000 images in the digital archive of the National Infrared Optical Astronomy Research Laboratory, or NOIRLab, contain about 1.7 billion points of light that appear in just one image.

The algorithm used in the current research, known as Tracklet-less Heliocentric Orbit Recovery, or THOR, is able to correlate a point of light appearing in one image with a different point of light in a different image taken on a different night — sometimes with a different telescope — and discover that these two… The two points are actually the same object, usually an asteroid that has changed position as it orbits the Sun.

Determining the THOR of asteroid candidates across disparate images is a daunting computational task, one that would have been impossible not long ago. But Google Cloud, a distributed computing system, was able to do the calculations in about five weeks.

“This is an example of what is possible,” said Massimo Mascaro, technical director in the Office of the Chief Technology Officer at Google Cloud. “I can't even begin to quantify the opportunity in terms of the data that has already been collected, and if analyzed with the proper calculation, it could lead to even more results.”

Dr. Lu said improved software tools made it easier to harness computing power. When scientists no longer need a giant software engineering team to dig through their data, “that's when some kind of really interesting things can happen,” he said.

The THOR algorithm could also transform 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 scan most of the night sky repeatedly to track changes over time.

Currently, the Rubin telescope will scan the same part of the sky twice a night, a rhythm designed to detect asteroids. With THOR, the telescope may not need a second pass, which could allow it to cover twice the area.

“Most science programs would be happy to go from a baseline rhythm of two observations to just one observation per night,” said Željko Ivezic, a professor of astronomy at the University of Washington who serves as 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 that are 460 feet in diameter or larger.

“Our latest estimates are about 80 percent,” Dr. Ivecic said. “With THOR, we can probably raise it to 90 percent.”