In this two part series, Squadron Leader Michael Spencer details the significance of NASA’s remote piloted aircraft, the Ingenuity helicopter. In this first installment, Spencer outlines NASA’s mission concept and system designed to integrate the air domain into space exploration. This disruptive technology showcases the innovation of NASA engineers and how accessible off-the shelf technologies can be all that’s needed to challenge traditional methods and missions. The Ingenuity helicopter’s importance goes beyond space exploration, with the mission providing understanding of design risks for remote piloted aircraft systems missions and mission systems on Earth.
NASA is preparing to test fly its "Ingenuity" helicopter deployed on Mars in mid- April 2021 in an experimental technology demonstration of humankind's first powered and controlled flight on another planet. The test flight and mission systems' designs have followed fundamental principles that can be important considerations to make effective designs for remotely piloted air power on Earth.
Figure 1. NASA illustration depicting the Ingenuity Mars helicopter standing on Mars next to the Perseverance rover (NASA image).
Ingenuity & Perseverance – NASA Effort to Integrate Air and Space Power
Air power theorists and practitioners should be keenly monitoring the Mars 2020 Perseverance mission. NASA configured the Perseverance rover to carry the "Ingenuity" helicopter to demonstrate the first remotely piloted air vehicle operated by humankind on another planet as a potential disruptive technology to include in future space missions.
NASA specifically designed the vertical lift air vehicle for autonomous, powered, and controlled flight in thin Martian air. NASA's mission objective for Ingenuity is not part of the primary science mission for the Perseverance rover but a separate and discrete engineering target to "demonstrate the viability of rotorcraft flight in the extremely thin atmosphere of Mars." NASA hopes the Ingenuity flight test will demonstrate a disruptive technology that may expand options available for future NASA interplanetary exploration missions to planets with an atmosphere.
Mission complexity has increased with each successful NASA mission to Mars. In early missions, NASA landed sensors on the Martian surface that directly observed the landing site area and periodically exchanged data when Earth appeared in view. The latest NASA exploratory program relies on increasing the rover's size with each mission to mobilise increasingly larger sensor payloads to cover a greater surface area.
Most recently, NASA successfully landed its Mars 2020 Perseverance mission on Mars with the largest-sized rover ever launched from Earth. Perseverance can carry more sensors with a greater capacity for mission roles and functions. The Perseverance rover will autonomously follow its daily uplinked mission plans to gather scientific data for NASA to study different types of Martian terrain. It also collects rock and dust samples where a future NASA recovery mission will return them to Earth and seek out microbial signs of ancient life on Mars. However, ground features on the Martian surface can pose risks and constraints to the rover missions' daily plans. Rough terrain, steep slopes and soft soil can adversely affect the stability, manoeuvrability, routing options, and maximum daily endurance and operating range.
Figure 2. The Mars Helicopter Delivery System (centre) holds Ingenuity aboard the Perseverance rover (NASA image).
Ingenuity, a solar-powered, electric motor driven and autonomously controlled helicopter was stowed on board the Perseverance rover. NASA is using Ingenuity to explore the feasibility and advantages of exploiting the Martian air domain to aerodynamically stabilise, manoeuvre, and mobilise an airborne sensor with greater freedom of manoeuvre than is possible with a ground vehicle. Ingenuity is a test asset and is not carrying sensors to support the Perseverance rover's science mission. NASA designed Ingenuity to demonstrate autonomous operations, follow remotely planned missions, and exchange data and command signals with its base station configured in the Perseverance rover to communicate with Earth.
An air vehicle can more easily and readily reach new vantage points over and beyond ground features that might generally limit or deny routes for the rover, constraining the reach of groundborne sensors. Accessing and exploiting the Martian air domain will improve future NASA exploration missions to deploy sensors with increased speed, reach, flexibility, and responsiveness and with improved sensor coverage over the ground. More importantly, the air power advantage provides a perspective that will enable the airborne deployed sensor to see further in range, see more within the same field-of-view, and cover greater ground area more quickly.
Vertical lift negates the constraints and additional design burdens needed to enable fixed-wing aircraft flight. The ability to reach an altitude above the ground will improve the search capabilities by elevating a sensor to extend the surface range and expand the coverage area using the same sensor field-of-view. Additionally, the hover capability will enable the airborne placement and steering of a sensor to look at surface phenomena from above and make observations where the ground terrain denies access to the rover.
The vertical lift capability enables Ingenuity to take-off and land without needing a prepared runway to transition between zero and flight speed, unlike fixed-wing aircraft. Ingenuity's vertical-lift capability allows it to descend vertically over the edge of steep terrain or into a naturally formed cavernous hole (e.g. fissure, crater, lava tube, etc.) and recover, using a vertical trajectory to reach a point in time and space more efficiently than is possible for a rover navigating through the varying conditions on the ground.
Perseverance will travel to a previously surveyed area assessed by NASA as suitable for supporting the flight trials. The first mission outcome is to validate that the Perseverance mission successfully delivered a functioning helicopter to Mars.
Ingenuity needs a test area that is level with stable solid ground and with low risks of foreign object damage from the dust and debris blown up from its rotor-wash. For similar safety reasons, plus compliance with planetary protection protocols, Perseverance will depart to maintain a safe standoff distance from the flight test area for the flight trial duration. NASA did not intend for Ingenuity to operate organically with Perseverance. Still, it will maintain line-of-sight communications with the Perseverance base station to receive downlinked mission plans from the remote pilots on Earth and uplink flight test results back to Earth.
Figure 3. The flight test programmed planned by NASA for Ingenuity (NASA image).
Ingenuity will be programmed to ascend only to a height of three-metres for its first test flight. The test flight program will incrementally increase the flight duration, operating altitude, and travel distance over each of five test flights planned on separate days over a month. After the end of the month-long flight trial, Perseverance will depart to continue on its intended science mission without Ingenuity.
NASA JPL engineers challenged themselves to develop a design for the air vehicle, preferably using off-the-shelf software, system components, and manufacturing techniques where possible. The final design needed to be lightweight, radiation-resistant, ruggedised to survive a space lift, transit, and descent to Mars, and then perform powered controlled flight in the thin Mars air. The result is the 1.8 kg Ingenuity helicopter appearing similar in physical size to a box of tissues configured with an electrically powered motor to drive two contra-rotating composite carbon-fibre rotor blades. The made-for-Mars helicopter design uses two stacked contra-rotating blades spinning at 2,400 revolutions per minute, creating a spinning disc measuring about 1.2 metres in diameter.
The Ingenuity power subsystem is configured with a battery in the payload and solar panels optimised to harvest the reduced solar flux arriving at Mars and mounted above the rotors. The battery can be recharged within one Mars day. Approximately one-third of the power budget is needed to heat the onboard systems to survive the freezing temperatures at night; the electronic payload uses one-third of its power for navigation (feature imaging camera, point-to-point mission guidance software, laser altimeter, inertial measurement system), flight management, and communications (to the Perseverance base station); and one-third of the power drives the rotor blades on each daily mission.
The remote operation of both the Mars rovers and the Ingenuity helicopter incurs a significant time delay needed for the control and data signals, travelling at the speed of light to transit between Earth and Mars. On average, the one-way transmission time is about 20 minutes, depending on the planets' relative positions. The average 40-minute delay in receiving feedback signals means that the mission cannot rely on remote pilots to control the helicopter manually. Ingenuity needs to rely on a flight management system to autonomously follow a downlinked mission plan with a digitised representation of the flight trajectory prepared during the previous Martian day by the remote pilots on Earth.
Operating during Martian daylight hours, Ingenuity will use its laser-altimeter, inertial measurement unit, and a downwards looking feature camera. The camera captures distinctive ground features that can be autonomously identified to track relative position, speed and direction from sequential images to navigate Ingenuity around the flight test area.
The designs for the mission and mission system have critically relied on years of scientific observations of Mars, the Martian air and land operating environments, and the Sun-Earth-Mars integrated operating environment that will be described in Part 2 of this article.
Squadron Leader Michael Spencer is a Maritime Patrol & Response Officer in the Air Force Reserve. He started his Air Force career as a Navigator in P-3C Orions, conducting long-range maritime patrols. During an extensive and diverse Air Force career, he completed postgraduate studies in space science at the Royal Military College of Canada for duties back in Australia in the Defence Space Coordination Office and Defence acquisitions of ground-based space surveillance systems. Currently, he is employed in the Defence COVID-19 Task Force and the Air Force Remotely Piloted Aircraft Systems(RPAS) Team. He also promotes space interests and opportunities through volunteering with the Space Law Council –Australia & New Zealand and the American Institute for Aeronautics & Astronautics.
Open-source intelligence available online from NASA for Mars, Perseverance, and Ingenuity.
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