Mysterious chalkings have been reported throughout NASA Langley Research Center.
The puzzling messages appeared overnight and urge employees to take bizarre actions, such as smile, dance through crosswalks and skip to work.
Safety officials tested the chalk and have confirmed that it presents no problem to employees.
Langley spokesperson Marny Skora says management encourages employees to take risks, noting that as one chalking indicates, "Every noble work is at first impossible."
Credit: NASA/Sean Smith