The LAGEOS Satellites Map Earth for Future Earthlings

From: Tom H.

Sent: October 7, 2012

To: undisclosed recipients

Subject: Fw: The LAGEOS Satellites Map Earth for Future Earthlings

I found out today that there are two satellites named LAGEOS 1 and 2 that are orbiting Earth, they are expected to come back down in 8.4 million years, they carry maps of what earth looks like today for future residents of Earth.
Both satellites are spherical bodies with an aluminum shell wrapped around a brass core. The design was a compromise between numerous factors including the need to be as heavy as possible to minimize the effects of non-gravitational forces vs. being light enough to be placed in a high orbit and the need to accommodate as many retroreflectors as possible vs. the need to minimize surface area to minimize the effects of solar pressure. The materials were chosen to reduce the effects of the Earth's magnetic field on the satellite's orbit. 426 cube-corner retroreflectors are imbedded in the satellites' surface. 422 of these are made of fused silica glass while the other 4 are made of germanium. The vehicles have no onboard sensors or electronics, and are not attitude controlled. NASA