Simultaneous observations by Webb and Earth-based telescopes would allow a precise distance measurement for interstellar objects passing within the Earth-sun separation. The Webb telescope is located 1 million miles away from Earth. The most significant instrumentation advance since `Oumuamua’s discovery is the launch of the Webb Space Telescope in 2021. Nevertheless, in another recent paper, coauthored with my student Carson Ezell, we calculated that LSST could find interstellar objects that are a few times smaller than `Oumuamua every couple of years. However, their detection is more challenging because they reflect less sunlight and can therefore be noticed only at smaller distances - where they move faster across our sky. It is, therefore, likely that smaller technological relics are far more abundant. ![]() Incidentally, NASA never launched a spacecraft as big as `Oumuamua – the size of a football field. This second object, named 2020 SO, was definitely artificial because NASA produced it. It was later identified as a rocket booster launched by NASA in 1966 with thin walls made of stainless steel. In September 2020, the Pan-STARRS telescope in Hawaii that discovered `Oumuamua, identified another object pushed away by reflecting sunlight with no cometary tail. In a recent paper, I suggested that a membrane of this type might be space trash, possibly a piece of a broken Dyson sphere that was originally composed of thin tiles of light sails. While we know of no natural astrophysical process that produces disk-shaped membranes, a technological civilization could have manufactured it. In order for radiation pressure to be effective, `Oumuamua had to be a thin membrane. In 2018, it occurred to me that this non-gravitational force could result from the reflection of sunlight. Moreover, `Oumuamua did not show any hint for a cometary tail while being pushed away from the sun by a mysterious non-gravitational force that declined smoothly in inverse proportion to the square of the distance from the sun. This suggested an extreme geometric shape, and a detailed model by astrophysicist Sergey Mashchenko implied that `Oumuamua was disk-like at 91 percent confidence. ![]() ![]() As `Oumuamua was tumbling every eight hours, the flux of sunlight reflected from it changed by a factor of 10, whereas for solar system asteroids the variation level is at most a factor of three. The data collected on `Oumuamua in late 2017 was not sufficient to conclusively test whether it was a technological artifact, but it was sufficient to indicate that `Oumuamua did not resemble familiar asteroids or comets in the solar system. Through most of the survey, we will “swipe to the left” when noticing an ordinary comet or asteroid, but on occasion we might discover another interstellar object worthy of attention because its anomalies might reflect an extraterrestrial technological origin. Together with my postdoc, Richard Cloete, we are currently developing software that will allow us to identify and characterize interstellar objects from the data stream of the Legacy Survey of Space and Time (LSST) planned with this camera. Its 3.2-billion-pixel camera will survey the southern sky every four days and is forecasted to find new interstellar objects every few months. Rubin Observatory in Chile will be our “dating app” for finding the next anomalous interstellar object after `Oumuamua.
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