Rubin Observatory will undertake a thorough exploration of our Solar System with two goals in mind: learning how it originally formed, and protecting Earth from hazardous, near-flying asteroids.
Discovering the origin of the Solar System requires a thorough census, but identifying objects in the outer solar system is challenging. Despite the difficulty, the effort is worth it; gaining a detailed understanding of that region of rocks and dust beyond Neptune could not only clarify the formation history of our solar system, but could point the way to how other systems may form and how star formation in general proceeds.
Protecting the Earth from a possible asteroid impact is not strictly a scientific question but it bears extraordinary importance for life on Earth. While the frequency of near-Earth object (NEO) impacts is exceptionally low, the damage they can cause is immense. A 100-meter diameter asteroid impact would be equivalent to 1600 megatons of TNT—in an ocean basin, the resulting tsunami could devastate coastal margins.
Frequency of occurrence may be low but our ability to predict such events using available technology is higher than for any other form of natural disaster. A recent national Research Council report titled "Defending Planet Earth: Near-Earth Object Surveys and Hazard Mitigation Strategies" found that Rubin Observatory is the most cost-effective way of surveying the most likely and potentially most damaging Earth-threatening objects.
In addition to dark energy and matter, the Milky Way mapping and transient Universe, mapping the Solar System is one of the four key scientific design drivers, with emphasis on efficiently detecting potentially hazardous asteroids (PHAs). Rubin Observatory will make uniquely powerful contributions to the study of small bodies throughout the Solar System, identifying and characterizing 10 to 100 times more objects than are currently known. With these exquisite orbital, color and photometric variability measurements, we will be able to improve models of how our Solar System formed and how it has evolved over time. The latest publication about Rubin Observatory capabilities for enabling Solar System science is Jones et al. (2015)
For up-to-date news about the most threatening objects currently known, see JPL's NEO page.