Let's lighten the mood a bit.

Astrophysicist Dr. Iosif Samuilovich Shklovsky calculated the orbital motion of Martian satellite Phobos and came to the jaw-dropping conclusion that the moon is artificial, hollow, and basically a titanic spaceship.

Phobos is spaceship says famous scientist Dr. Iosif Samuilovich Shklovsky
The scientist is world-renown for penning the classic science book, “Intelligent Life in the Universe” with famous Cornell University professor, the late Carl Sagan of PBS and Voyager space probe fame.
An intriguing possibility, whether true or not.

And not without some support:

Yet, no less than the United States Naval Observatory weighed in on the Russian astrophysicist’s amazing revelation, stating: Dr. Shklovsky quite correctly calculated that if the acceleration of Phobos is true, the Martian moon must be hollow, since it cannot have the weight of a natural body and behave in the prescribed manner.
Thus, even that august American institution conceded that mysterious alien ships might be orbiting Mars…the objects’ strange origins and ultimate purposes completely unknown.