Dragonfly Preparation for Powered Flight: Lander Separation State Control to Ensure Successful Landing

NASA’s Dragonfly mission, led by The Johns Hopkins University Applied Physics Laboratory, is a relocatable octocopter lander to study Saturn’s largest moon Titan. The scientific goals of the mission include studying Titan’s prebiotic chemistry, geology, and atmosphere. Upon Titan arrival, the lander will enter the atmosphere, descend on a parachute to a ground-relative altitude of about 1000 m before being released, and then fly on internal power down to the surface. To guarantee desirable initial conditions for the lander release, the lander must meet certain angular rate conditions. These conditions include reducing the spin rate about the vertical axis to 4.9 deg/sec, using the rotors as actuators; and releasing with a negative pitch rate (rotating nose down) to ensure a successful transition to powered flight. This is achieved using a release trigger. Achieving these desired rates for lander release is part of the mission phase known as ‘preparation for powered flight’ (PPF). This paper proposes controls and logic to achieve the desired conditions for releasing the lander from the parachute.