Showing Tractrix (Seeds of Civilization) by R. J. Archer

When aerospace engineer and recent widower Frank Morton wins an $86 million lottery jackpot, he decides to retire and devote his time to a lifelong interest in ancient mysteries. Coincidently, an old Viet Nam buddy shows up with a mysterious black sphere inscribed with what appear to be Maya glyphs. Intrigued, Frank convinces his buddy and two other friends, an anthropologist and a newspaper researcher, to help him investigate the origin and purpose of the sphere.

Their search takes Frank and friends on a journey from Seattle to the secret military installations of Nevada and on to Mexico's Yucatan Peninsula. Along the way, they attract the unwanted attention of government agents, Mexican Federales and an ancient Maya priest. They also stumble across a three thousand year old secret that suggests a possible link between the shamans of Mesoamerica and a race of alien explorers.