Position and Time Determination without Prior State Knowledge via Onboard Optical Observations of Delta Scuti Variable Stars

We present a navigation concept for solving the lost in space and time problem using optical observations of $\delta$ Scuti variable stars. Only a small number of techniques exist that allow a spacecraft to recover from being lost in both space and time, which can be caused by a failure of the onboard clock and navigation systems. Optical observations of $\delta$ Scuti stars, which can be collected onboard from star trackers or navigation cameras, may enable faster and/or more accurate position and time solutions compared to existing techniques without requiring additional equipment. Our results indicate that one day of observation by the OSIRIS-APEX MapCam may enable position and time determination accuracy within 0.05 au (3$\sigma$) and 15 s (3$\sigma$).