Evidence That the `Dark Comet’ 1998 KY26 Might Be the Failed Soviet Spacecraft Phobos 1

A model of Phobos 1 looks very different from a comet, yet it accounts for the orbit, non-gravitational acceleration and light curve of the space object 1998 KY26, which was labeled a "dark comet" by comet experts. The first recognized interstellar object 1I/`Oumuamua showed non-gravitational acceleration away from the Sun, which scaled inversely with heliocentric distance squared, and had a disk-like shape. This led to the proposal that it might be a technologically-produced object. The discovery of 2020-SO, later identified as the upper stage of the Surveyor 2 mission, supported this interpretation. Comet experts argue that 1I/`Oumuamua is a dark comet, but no gas or dust was detected, contradicting their explanation.

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