Somewhere on the ridge of Cerro Pachón in northern Chile, a telescope with an 8.4-metre mirror is in the final stages of preparation for the most comprehensive survey of the solar system ever attempted. The NSF–DOE Vera C. Rubin Observatory completed its construction phase in October 2025 and is currently in an early operations period. According to a 1 May 2026 update posted by Rubin director Bob Blum to the LSST Community forum, the team has “moved significantly closer to the start of the LSST” and Data Preview 2, based on science-grade commissioning data, is on schedule for July through September 2026. The full ten-year Legacy Survey of Space and Time has not yet formally started. When it does, the inventory of known solar system objects will change substantially.
How substantially is the subject of a preprint submitted to arXiv in June 2025 by an international team led by researchers at Queen’s University Belfast. The paper, “Predictions of the LSST Solar System Yield” published in The Astronomical Journal uses a simulation framework to estimate how many near-Earth objects, main-belt asteroids, Jupiter Trojans, and trans-Neptunian objects Rubin will detect over the course of the survey. The numbers are large enough that they warrant reading carefully.
What Rubin is and what makes it different
The Rubin Observatory’s primary instrument is the Simonyi Survey Telescope, paired with the LSST Camera: a 3.2-gigapixel array that covers a 9.6-square-degree field of view in a single exposure. That field of view is roughly 45 times the area of the full moon. The telescope is designed to image the entire visible southern sky every few nights, in six filters spanning the visible and near-infrared. The result, accumulated over a decade, will be a continuously updated time-lapse record of a large fraction of the sky.
What this means in practice for solar system science is that small, dim, fast-moving objects that have been missed or undersampled by every previous survey come into reach. Existing surveys have covered most of the sky, but at cadences and sensitivities that leave large populations undetected. Rubin goes deeper, covers sky faster, and returns to the same patches of sky repeatedly, which is how you find objects that are moving against the background of stars. Its six-filter design also means that every detected object gets colour information, something most prior asteroid surveys have not provided at scale.
In the roughly ten hours of observations released at the First Look event in June 2025, before the full survey had even started, Rubin identified 2,104 previously unknown asteroids, including seven near-Earth asteroids. That rate of discovery — in a single night’s science validation data — indicates what the systematic ten-year survey will produce once it begins in earnest.
The scale of what remains unseen
As of now, the Minor Planet Center catalogue contains roughly 1.3 million known minor planets. The Kurlander et al. simulation predicts that Rubin will expand known small-body populations by factors of four to nine, depending on the population. The specific estimates in the preprint are approximately 5 million newly detected main-belt asteroids, around 40,000 trans-Neptunian objects, and more than 10,000 comets. The near-Earth asteroid tally, which has particular relevance for planetary defence, is expected to more than triple.
These are simulation results, not confirmed discoveries. The paper uses Sorcha, an open-source software package developed alongside the study for modelling the expected LSST solar system yield. Simulations of this kind depend on assumptions about the underlying population distributions, the survey’s actual cadence and efficiency, and detection pipeline performance, all of which introduce uncertainty. The estimates should be understood as the team’s best current modelling of the expected yield, not as guarantees of specific numbers.
The broader point — that there are many millions of solar system objects we have not yet catalogued — is not in doubt. The question is one of completeness at different size thresholds and orbital families, and Rubin is designed to push those thresholds substantially further than any prior survey.
Where the timeline actually stands
It is worth being precise about what has and has not happened, because the timeline has shifted several times. The Rubin Observatory was for years anticipated to begin survey operations in 2023 or 2024; those schedules slipped. In June 2025, the observatory released its first images from the full LSST Camera at a public event in Washington, DC. In October 2025, the construction phase was formally declared complete and the observatory transitioned to operations. The Rubin team began what they are calling the “early operations system optimisation period,” which involves nightly on-sky observations alongside continued engineering work to improve image quality and survey efficiency.
As of week 29 of that period, in mid-May 2026, the system is performing progressively better. The May 2026 operations update describes image quality approaching target survey performance, with steady improvement in uniformity across the field. Data Preview 1, based on commissioning camera data, has already been released to the scientific community. Data Preview 2, drawing on the full-scale LSST Camera, is scheduled for the July to September 2026 window.
No specific date for the formal start of the LSST survey has been announced as of this writing. The Rubin programme page says only that the survey start date will determine when Data Release 1, the first annual data release, is produced. In the May 2026 update, Blum describes a “strategic action plan” for continued improvement, and commits to communicating to the community what to expect in DR1 and beyond. That language is the framing of a team managing the final approach, not a team still years away.
What the survey will and will not resolve
The most straightforward benefit of the LSST solar system programme is improved planetary defence coverage. Near-Earth asteroids in the 100-metre to 1-kilometre range, which are large enough to cause significant regional damage but have not been fully catalogued, are exactly the population Rubin is well placed to find. The US Congress tasked NASA with cataloguing 90 per cent of near-Earth objects larger than 140 metres across; current completeness estimates at that size threshold are well below that target. Rubin will contribute substantially to closing that gap, though it will not complete the survey on its own and its southern-sky focus means some northern-sky populations will remain undersampled.
The trans-Neptunian object population is scientifically interesting for different reasons. Objects in that region carry information about the early solar system’s dynamical history: where the giant planets formed, how they migrated, what the disc of material that surrounded the early Sun actually looked like. Current trans-Neptunian catalogues contain only a few thousand objects. Rubin’s projected yield of 40,000 would make statistical analysis of orbital families and size distributions far more meaningful than what is currently possible.
The interstellar object question is also relevant. The observatory contributed to observations of 3I/ATLAS, the third known interstellar object, shortly after that object’s discovery by the ATLAS survey in July 2025. Rubin’s survey cadence and depth should make it better than any prior facility at detecting such objects early in their solar system transit, when follow-up observations are still possible.
What the survey will not do is replace the targeted follow-up work, spectroscopic characterisation, and radar observations that tell you what a detected object is actually made of, whether it has a moon, or how it might behave if it needed to be deflected. Detection at scale is the first step. The science that follows is a separate, slower programme.
What to watch next
The immediate milestone to track is the formal start of the LSST survey and the subsequent Data Preview 2 release, currently scheduled for July to September 2026. That release will be the first look at what the full LSST Camera produces in a science-grade observing mode, and it will give the community its first real-data test of the simulation predictions in the Kurlander et al. paper.
The Kurlander et al. preprint’s prediction that Rubin will discover more solar system objects in its first year than have been found in all of human history is the kind of claim that is easy to state and hard to fully absorb. It is worth sitting with: the solar system we think we know is, in inventory terms, probably a fraction of the solar system that exists. The survey designed to change that is, at the time of writing, a few months from beginning in earnest.
