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Rubin Observatory to detect millions of new solar system objects in vivid detail, simulations suggest

A group of astronomers from across the globe, including a team from the University of Washington and led by Queen's University Belfast, have revealed new research showing that millions of new solar system objects will be detected by a brand-new facility, which is expected to come online later in 2025.

The NSF–DOE Vera C. Rubin Observatory is set to revolutionize our knowledge of the solar system's "small bodies"—asteroids, comets and other minor planets.

The Rubin Observatory, under construction on the Cerro Pachón ridge in northern Chile, features the 8.4-meter Simonyi Survey Telescope with a unique three-mirror design capable of surveying the entire visible sky every few nights.

At its heart is the world's largest digital camera—the 3.2-gigapixel Legacy Survey of Space and Time (LSST) Camera—covering a 9.6 square-degree field of view with six filters, roughly 45 times the area of the full moon. Together, this "wide-fast-deep" system will generate 20 terabytes of data every night—creating an unprecedented time-lapse "movie" of the cosmos over the next 10 years, and an incredibly powerful dataset with which to map the solar system.

The team of astronomers, led by Queen's University's Meg Schwamb, created , an innovative new open-source software used to predict what discoveries are likely to be made.

Sorcha is the first end-to-end simulator that ingests Rubin's planned observing schedule. It applies assumptions on how Rubin Observatory sees and detects astronomical sources in its images with the best model of what the solar system and its small body reservoirs look like today.

"Accurate simulation software like Sorcha is critical," said Schwamb, a reader in the School of Mathematics and Â鶹ÒùÔºics at Queen's University. "It tells us what Rubin will discover and lets us know how to interpret it. Our knowledge of what objects fill Earth's solar system is about to expand exponentially and rapidly."

In addition to the eight major planets, the solar system is home to a vast population of small bodies that formed alongside the planets more than 4.5 billion years ago. Many of these smaller bodies remain essentially unchanged since the solar system's birth, acting as a fossil record of its earliest days. By studying their orbits, sizes and compositions, astronomers can reconstruct how planets formed, migrated and evolved.

These objects—numbering in the tens of millions—provide a powerful window into processes such as the delivery of water and organic material to Earth, the reshaping of planetary orbits by giant planets and the ongoing risk posed by those whose paths bring them near our planet.

In addition to Queen's University and the UW, the international team includes researchers from the Center for Astrophysics | Harvard & Smithsonian and the University of Illinois Urbana-Champaign.

A series of papers describing the software and the predictions have been accepted for publication by the Astronomical Journal and are available now on the preprint server arXiv.

Beyond just finding these new small bodies, Rubin Observatory will observe them multiple times using different optical filters, revealing their surface colors. Past solar system surveys were typically observed with a single filter.

"With the LSST catalog of solar system objects, our work shows that it will be like going from black-and-white television to brilliant color," said Joe Murtagh, a doctoral student at Queen's University. "It's very exciting—we expect that millions of new solar system objects will be detected and most of these will be picked up in the first few years of sky survey."

The team's simulations show that Rubin will map:

• 127,000 near-Earth objects—asteroids and comets whose orbits cross or approach Earth. That's more than tripling today's known objects, about 38,000, and detecting more than 70% of potentially hazardous bodies larger than 140 meters. This will cut the risk of undetected asteroid impact of catastrophic proportions by at least two times, making a tremendous contribution to planetary defense.
• More than 5 million main-belt asteroids, up from about 1.4 million, with precise color and rotation data on roughly one in three asteroids within the survey's first years. This will give scientists unprecedented insight into the characteristics and history of the solar system's building blocks.
• 109,000 Jupiter Trojans, bodies sharing Jupiter's orbit at stable "Lagrange" points—more than seven times the number cataloged today. These bodies represent some of the most pristine material, dating all the way back to the formation of the planets.
• 37,000 trans-Neptunian objects, residents of the distant Kuiper Belt—nearly 10 times the current census—shedding light on Neptune's past migration and the outer solar system's history.
• Approximately 1,500–2,000 Centaurs, bodies on short-lived giant planet-crossing orbits in the middle solar system. Most Centaurs will eventually be ejected from the solar system, but a few lucky ones will survive to become short-period comets. The LSST will provide the first detailed view of the Centaurs and the important transition stage from Centaur to comet.

Rubin Observatory's LSST is a once-in-a-generation opportunity to fill in the missing pieces of our solar system, said Mario Juric, a member of the Sorcha team and a UW professor of Astronomy. Juric is also a team lead of Rubin's Solar System Processing Pipelines and a director of UW's DiRAC Institute.

"Our simulations predict that Rubin will expand known small-body populations by factors of 4–9x, delivering an unprecedented trove of orbits, colors and light curves," Juric said. "With this data, we'll be able to update the textbooks of solar system formation and vastly improve our ability to spot—and potentially deflect—the asteroids that could threaten Earth."

It took 225 years of astronomical observations to detect the first 1.5 million asteroids, and researchers found that Rubin will double that number in less than a year, said Jake Kurlander, a doctoral student at the UW.

"Rubin's unparalleled combination of breadth and depth make it a uniquely effective discovery machine," Kurlander said.

Siegfried Eggl, an assistant professor of Aerospace Engineering at the University of Illinois Urbana-Champaign added, "Only by debiasing LSST's complex observing pattern can we turn raw detections into a true reflection of the solar system's history—where the planets formed, and how they migrated over billions of years. Sorcha is a game-changer in that respect."

The Sorcha code is open-source and with the simulated catalogs and animations. By making these resources available, the Sorcha team has enabled researchers worldwide to refine their tools and be ready for the flood of LSST data that Rubin will generate, advancing the understanding of the small bodies that illuminate the solar system like never before.

Rubin Observatory is scheduled to unveil its first spectacular imagery at its "First Look" event on June 23, offering the world an early glimpse of the survey's power. Full science operations are slated to begin later this year.