Alien probes in the solar system? Four types of objects baffle scientists

The idea that alien civilizations might have sent robotic probes into our solar system, a concept once explored by mathematician John von Neumann, is being re-examined by scientists. A new study assesses the feasibility of detecting such probes with current technology, with results that are reportedly "quite disappointing."

Researchers have categorized potential artificial objects into four types based on their location and operational status: passive probes (non-functional objects passing through the solar system), active probes (operational spacecraft), passive surface artifacts (non-operational equipment on a planet or moon), and active surface artifacts (still-functioning machines).

A primary challenge for passive probes is distinguishing them from the millions of natural asteroids and comets. The object 2020 SO, initially classified as an asteroid, was later identified as a 1966 NASA rocket stage due to its spectral signature. For surface artifacts, the vastness of the solar system and the limited resolution of current imaging make detection difficult, with only massive objects being noticeable. Even on the Moon, detailed imaging covers only a small fraction of the surface.

Active probes, theoretically easier to detect due to heat emission, have shown anomalies in some surveys. However, these anomalies cannot yet be reliably assessed or definitively separated from natural bodies. While next-generation observatories are expected to provide millions of detailed images and spectra, confirming an object's artificial origin will likely necessitate sending a probe for close examination, a task complicated by the immense search area.