  Mid-Air Helicopter Delivery (MAHD) is a new Entry, Descent and Landing (EDL)
architecture to enable in situ mobility for Mars science at lower cost than
previous missions. It uses a jetpack to slow down a Mars Science Helicopter
(MSH) after separation from the backshell, and reach aerodynamic conditions
suitable for helicopter take-off in mid air. For given aeroshell dimensions,
only MAHD's lander-free approach leaves enough room in the aeroshell to
accommodate the largest rotor option for MSH. This drastically improves flight
performance, notably allowing +150\% increased science payload mass. Compared
to heritage EDL approaches, the simpler MAHD architecture is also likely to
reduce cost, and enables access to more hazardous and higher-elevation terrains
on Mars. This paper introduces a design for the MAHD system architecture and
operations. We present a mechanical configuration that fits both MSH and the
jetpack within the 2.65-m Mars heritage aeroshell, and a jetpack control
architecture which fully leverages the available helicopter avionics. We
discuss preliminary numerical models of the flow dynamics resulting from the
interaction between the jets, the rotors and the side winds. We define a
force-torque sensing architecture capable of handling the wind and trimming the
rotors to prepare for safe take-off. Finally, we analyze the dynamic
environment and closed-loop control simulation results to demonstrate the
preliminary feasibility of MAHD.
