Mars Robotic Aircraft Design and Testing: providing aerial platforms for autonomous and human-centered reconnaissance, exploration, and transportation.

Benefit
This technology could apply to early, purely robotic missions dedicated to exploring and characterizing potential human landing sites and demonstrating one approach to precision landing and hazard avoidance. It could also apply to planetary mobility systems during the phase of active astronaut exploration by providing teleoperated and autonomous reconnaissance and aerial transportation.

Research Overview
The main technical challenges of flying on Mars are 1) understanding and modeling the low Reynolds number, high subsonic Mach Number aerodynamics, 2) building appropriate, often unconventional airframe designs and aerostructures, 3) mastering the dynamics of deployment from a descending entry vehicle aeroshell, and 4) integrating a non-air breathing propulsion subsystem into the system. The Ames/NRL team has conducted research activities and made progress on all these fronts since 1996, mainly by designing and test-flying small UAVs that demonstrate one or more of the critical features required.

Right: Astronaut suit test in analog environment with companion surface rover and aircraft.

The first full mission and system design conducted by the Ames/NRL team was the Airplane for Mars Exploration, or AME mission, in 1996. This would have been a relatively complex airframe, with 7 wing and body folds, but would have resulted in a high aspect ratio wing and thus relatively long range. It was targeted for flight over the Gusev Crater followed by an autonomous deep stall landing onto the surface. A 20% scale model of the airframe was built and drop-tested, showing that it was possible to unfold all wing and body hinges. The second mission and system design, in 1998 was the Mars Aircraft for Geophysical Exploration or MAGE--a much simpler design intended to simply over fly the Valles Marineris and crash at the end of its mission. A small, powered scale-model of MAGE was test flown at low altitudes to gather L/D data to predict range and speed performance of the full-scale vehicle. In 1999, two designs were produced at the informal request of the NASA Administrator to serve as candidates to fly on Mars in 2003 on the centennial of the Wright Brothers historic first flight in 1903. Although the flight opportunity for the centennial mission was eventually cancelled, one of the Ames/NRL designs was constructed at full scale in glider form in order to be flown on Earth at sufficiently high altitudes to mimic the aerodynamic flight conditions of Mars. This occurred in August of 2001, when NASA aircraft tail number 731 was lifted to 31.4 km by a balloon at Tillamook OR, and dropped into stable gliding flight. The aerodynamic lift on the wings first exceeded the weight of the aircraft at an altitude of 29.9 km, thereby proving that flight at Mars-like conditions is both aerodynamically possible and predictable. So far as is known, this flight remains a world altitude record.

In September 2002, an attempt was made to refly the NASA 731 design with a high speed propeller propulsion system. This resulted in disintegration of the aircraft at an altitude above 32.9 km and a speed above Mach 0.8 for reasons most likely related to gyroscopically induced forces due to the oversized propeller that was required.

Left: AME Mission Deployment Sequence.

Currently, the team is building and planning to test a new rocket powered, reaction-control stabilized design known as Mars Advanced Technology Airplane for Deployment, Operations and Recovery (MATADOR) capable of demonstrating stable flight above 32.0 km and controllable deep-stall landings onto the Martian surface. First flight is scheduled for summer of 2005.

Background
The Advanced Projects Branch of the Space Projects Division began investing internal R & D in Mars Airplane robotic exploration in 1996, drawing upon its capabilities and interests in aerodynamics to develop, faster, better, cheaper planetary exploration mission design, and Mars atmospheric modeling. This included development of exploration mission concepts--both purely robotic and with humans in the loop--as well as the underlying critical technologies. A crucial partnership was formed between NASA-Ames and the Naval Research Laboratory, which had been developing folding- and deployable-wing UAV designs for national security applications for more than 10 years. This is a technology that is critically important for delivering completely autonomous aircraft to the Martian atmosphere for early robotic exploration missions.

After astronauts arrive at Mars, the function of aerial platforms will change, as will their design. It is possible to envision a range of aircraft functions and sizes, including small, reconnaissance units to accompany field excursion explorers with a range of a few km, medium size regional explorer sensor platforms teleoperated from a central base, and large vertical take-off and landing platforms capable of transporting high value cargo over medium ranges in much the same way as bush pilot aircraft operate terrestrially, today. In all cases, such designs must incorporate high reliability, low logistics costs, and use of in-situ produced propellants, where possible.

This IR&D activity led to 3 complete mission proposals of the Discovery or Scout class, and won 3 separate Mars Technology development awards from NASA HQ, Code S.

Right: MATADOR model.