Image credit: NASA/JPL-Caltech/Cornell University

The piece of metal with the American flag on it in this image of a NASA rover on Mars is made of aluminum recovered from the site of the World Trade Center towers in the weeks after their destruction. The piece serves as a cable guard for the rock abrasion tool on NASA’s Mars Exploration Rover Spirit as well as a memorial to the victims of the September 11, 2001, attacks. An identical piece is on the twin rover, Opportunity.

The rock abrasion tools were built by Honeybee Robotics in lower Manhattan, less than a mile from the site.