How do we get robots to take self-portraits on Mars? – Perseverance-Ingenuity and Curiosity selfies

The Perseverance rover landed in Jezero crater,Mars, on 18 February 2021. It carried with it a technologydemonstration, the Ingenuity helicopter, which hasdemonstrated the first controlled, powered flight on anotherplanet. This paper describes how an iconic, April 2021 imageof the Perseverance rover with the Ingenuity helicopter wasdesigned and executed as the rover was getting ready todeploy the helicopter. WATSON is a camera mounted at theend of the rover’s robotic arm and was used to acquire theself-portrait. WATSON is designed to take close up picturesof rocks and regolith on Mars but can also provide views ofthe terrain. A single image covers a small portion of thescene. In order to a create a mosaic covering the full roverand helicopter, 62 WATSON images were acquired. To allowthe images to be mosaicked together, the camera needs to bekept in the same spot. The robotic arm has five degrees offreedom for motion; small changes in orientation can requiresignificant repositioning of the robotic arm joints. Todocument this, a movie of the arm motion was acquired bythe rover’s mast-mounted left navigation camera pointed atthe WATSON and robotic arm while it was simultaneouslymoving to acquire the selfie. For the first time, we alsocaptured the sound of the arm motion as it was acquiring theselfie. In the case of the Perseverance selfie with the Ingenuity helicopter, we also had to think about how toposition the rover with respect to the helicopter and fit theselfie acquisition into the helicopter prime mission timeline.This paper also describes the history of NASA Mars roverselfies.