After reviewing the split second ignition of the 3 Starship SN 9 Raptor engines on their successful liftoff and ascent on video, thoughts began to focus on their relight issues during the "seven seconds of terror" Hoverslam landing technique.
Specifically, during a launch, the engines are static and upright. Gaseous methane, lighter than air, will accumulate near the top of the combustion chamber.
However, during the landing maneuver, the Raptor nozzle is in the equivalent of a Category 5 hurricane airstream. This would seem to potentially cause a great deal of unstable, turbulent airflow around the nozzle, and act as a vacuum aspirator, pulling the fuel air mixture out before sustained ignition can be achieved.
Jets solve this issue by protecting the flame with a "can". Could it help the Raptor to "keep a pilot light on" using can(s) to ensure reliable ignition for their powered landings?