Ingenuity (helicopter)

Ingenuity, nicknamed Ginny, is an autonomous NASA helicopter that operated on Mars from 2021 to 2024 as part of the Mars 2020 mission. Ingenuity made its first flight on April 19, 2021, demonstrating that flight is possible in the extremely thin atmosphere of Mars, and becoming the first aircraft to conduct a powered and controlled extra-terrestrial flight. It was designed by NASA's Jet Propulsion Laboratory (JPL) in collaboration with AeroVironment, NASA's Ames Research Center and Langley Research Center with some components supplied by Lockheed Martin Space, Qualcomm, and SolAero.

Ingenuity was delivered to Mars on February 18, 2021, attached to the underside of the Perseverance rover, which landed at Octavia E. Butler Landing near the western rim of the 28 mi Jezero crater. Because radio signals take between five and 20 minutes to travel between Earth and Mars, depending on the planets' positions, it could not be controlled directly in real time but flew autonomously to execute flight plans designed and sent to it by JPL.

Originally intended to make only five flights, Ingenuity completed 72 flights in nearly three years. The five planned flights were part of a 30-sol technology demonstration intended to prove its airworthiness with flights of up to 90 seconds at altitudes ranging from 3 - 5 m. Following this demonstration, JPL designed a series of operational flights to explore how aerial scouts could help explore Mars and other worlds. In this operational role, Ingenuity scouted areas of interest for the Perseverance rover, improved navigational techniques, and explored the limits of its flight envelope. Ingenuity's performance and resilience in the harsh Martian environment greatly exceeded expectations, allowing it to perform far more flights than were initially planned. On January 18, 2024, Ingenuity's rotor blades were damaged while landing on its 72nd flight, permanently grounding the helicopter. NASA announced the end of its mission one week later. Ingenuity had flown for a total of two hours, eight minutes and 48 seconds over days, covering more than 17 km.

Concept


The development of the project that would eventually become Ingenuity started in 2012 when JPL director Charles Elachi visited the lab's Autonomous Systems Division, which had done relevant concept work. By January 2015, NASA agreed to fund the development of a full-size model, which came to be known as the "risk reduction" vehicle. NASA's JPL and AeroVironment published the conceptual design in 2014 for a scout helicopter to accompany a rover. By mid-2016, $15 million was being requested to continue development of the helicopter.

By December 2017, engineering models of the vehicle had been tested in a simulated Martian atmosphere. Models were undergoing testing in the Arctic, but its inclusion in the mission had not yet been approved or funded.

Mission integration
When the Mars 2020 program was approved in July 2014, a helicopter flight demonstration was neither included nor budgeted.

The United States federal budget, announced in March 2018, provided $23 million for the helicopter for one year, and it was announced on May 11, 2018, that the helicopter could be developed and tested in time to be included in the Mars 2020 mission. The helicopter underwent extensive flight-dynamics and environment testing, and was mounted on the underside of the Perseverance rover in August 2019. NASA spent about $80 million to build Ingenuity and about $5 million to operate the helicopter.

In 2019, preliminary designs of Ingenuity were tested on Earth in simulated Mars atmospheric and gravity conditions. For flight testing, a large vacuum chamber was used to simulate the very low pressure of the atmosphere of Mars – filled with carbon dioxide to about 0.60% (about $1/undefined$) of standard atmospheric pressure at sea level on Earth – which is roughly equivalent to a helicopter flying at 34000 m altitude in the atmosphere of Earth. In order to simulate the much-reduced gravity field of Mars (38% of Earth's), 62% of Earth's gravity was offset by a line pulling upwards during flight tests. A "wind-wall" consisting of almost 900 computer fans was used to provide wind in the chamber.

In April 2020, the vehicle was named Ingenuity by Vaneeza Rupani, a girl in the 11th grade at Tuscaloosa County High School in Northport, Alabama, who submitted an essay into NASA's "Name the Rover" contest. Known in planning stages as the Mars Helicopter Scout, or simply the Mars Helicopter, the nickname Ginny later entered use in parallel to the parent rover Perseverance being affectionately referred to as Percy. Its full-scale engineering model for testing on Earth was named Earth Copter and, unofficially, Terry.

Ingenuity was designed to be a technology demonstrator by JPL to assess whether such a vehicle could fly safely. Before it was built, launched and landed, scientists and managers expressed hope that helicopters could provide better mapping and guidance that would give future mission controllers more information to help with travel routes, planning, and hazard avoidance. Based on the performance of previous rovers through Curiosity, it was assumed that such aerial scouting might enable future rovers to safely drive up to three times as far per sol. However, the new AutoNav capability of Perseverance significantly reduced this advantage, allowing the rover to cover more than 100 meters per sol.

Development team


The Ingenuity team was comparatively small, with never more than 65 full-time-equivalent employees from JPL. Program workers from AeroVironment, NASA AMES and Langley research centers brought the total to 150. Key personnel include:
 * MiMi Aung – Ingenuity Mars Helicopter Project Manager at NASA's Jet Propulsion Laboratory,
 * Bob Balaram – Chief Engineer (prior to Nov 2021)
 * Timothy Canham – Flight Software Lead and Operations Lead (prior to June 2021)
 * Håvard Fjær Grip – GNC Lead and Chief Pilot
 * Matt Keennon – AeroVironment Technical Lead
 * Ben Pipenberg – AeroVironment Design Lead
 * Josh Ravich – Mechanical Engineering Lead
 * Teddy Tzanetos – Operations Lead
 * Nacer Chahat – Antenna Engineer and Telecom System Engineering

On June 15, 2021, the team behind Ingenuity was named the 2021 winner of the John L. "Jack" Swigert Jr. Award for Space Exploration from the Space Foundation. On April 5, 2022, the National Aeronautic Association awarded Ingenuity and its group in JPL the 2021 Collier Trophy.

Opposition
The idea to include a helicopter in the Mars 2020 mission was opposed by several people. Up until the end of the 2010s, several NASA leaders, scientists and JPL employees argued against integrating a helicopter into the mission. For three years, the future Ingenuity was developed outside the Mars 2020 project and its budget. And although NASA management accepted assurances in the spring of 2018 that the addition of a helicopter would not harm the goals of the expedition, Mars 2020 chief scientist, Kenneth Farley, stated "I have personally been opposed to it because we are working very hard for efficiencies and spending 30 days working on a technology demonstration does not further those goals directly from the science point of view". Farley was convinced that the helicopter was a distraction from the priority scientific tasks, unacceptable even for a short time.



The skepticism on the part of NASA leadership was not unfounded. Scientists, engineers and managers proceeded from a pragmatic comparison of the benefits of additional aerial reconnaissance with the costs that inevitably fall on the schedule for the rover to complete all the tasks assigned to it. During a live-stream from NASA, MiMi Aung, the Ingenuity Project Manager, and Jennifer Trosper discussed the value of Ingenuity. Trosper argued that the rover would outpace the helicopter due to its auto-navigation capability, thus negating one of central arguments for the value to the mission of the helicopter. During the operations on Mars, Trosper was shown to be correct when, in the spring of 2022, at the beginning of Sol 400 the helicopter fell behind the rover.

At the end of the "test window", NASA extended support for Ingenuity for another 30 sols, limiting the frequency of departures to one flight every few weeks.

On 14 June 2021, the Director of the Mars Exploration program, E. Janson, and the Principal Mars Explorer, M. Meyer, directly addressed all the staff of the Mars 2020 project. During this address they cautioned the staff to keep their Ingenuity enthusiasm in check, and concentrate on collecting samples. On the same date, in their report to the Planetary Advisory Committee (PAC), the helicopter was mentioned only in the past tense, e.g. "...placed Ingenuity and completed the technology demonstration phase...". Despite this early pessimism, Ingenuity has since proved to be more than capable of keeping up with Perseverance, actually staying ahead of the rover for the majority of the traverse up the Jezero delta.

Insufficient solar energy during the Martian winter was the main driver of poor operational performance in the latter half of 2022.

Mechanical design


Ingenuity consists of a rectangular fuselage measuring 136 x suspended below a pair of coaxial counter-rotating rotors measuring 1.21 m in diameter. This assembly is supported by four landing legs of 384 mm each. It also carries a solar array mounted above the rotors to recharge its batteries. The entire vehicle is 0.49 m tall.

The lower gravity of Mars (about a third of Earth's) only partially offsets the thinness of the 95% carbon dioxide atmosphere of Mars, making it much harder for an aircraft to generate adequate lift. The planet's atmospheric density is about $1/100$ that of Earth's at sea level, or about the same as at 87000 ft, an altitude never reached by existing helicopters. This density reduces even more in Martian winters. To keep Ingenuity aloft, its specially shaped blades of enlarged size must rotate between 2400 and 2900 rpm, or about 10 times faster than what is needed on Earth. Each of the helicopter's contra-rotating coaxial rotors is controlled by a separate swashplate that can affect both collective and cyclic pitch. Ingenuity was also constructed to spacecraft specifications to withstand the acceleration and vibrations during launch and Mars landing without damage.

Avionics
Ingenuity relies on different sensor packages grouped in two assemblies. All sensors are commercial off-the-shelf units.

The Upper Sensor Assembly, with associated vibration isolation elements, is mounted on the mast close to the vehicle's center-of-mass to minimize the effects of angular rates and accelerations. It consists of a cellphone-grade Bosch BMI-160 Inertial measurement unit (IMU) and an inclinometer (Murata SCA100T-D02); the inclinometer is used to calibrate the IMU while on the ground prior to flight. The Lower Sensor Assembly consists of an altimeter (Garmin LIDAR Lite v3), cameras, and a secondary IMU, all mounted directly on the Electronics Core Module (not on the mast).

Ingenuity uses a 425×165 mm solar panel to recharge its batteries, which are six Sony Li-ion cells with 35 - 40 Wh of energy capacity (nameplate capacity of 2 Ah). Flight duration is not constrained by available battery power, but by thermals – during flight, the drive motors heat up by 1 °C every second, and the thin Martian atmosphere makes for poor heat dissipation. The helicopter uses a Qualcomm Snapdragon 801 processor running a Linux operating system. Among other functions, it controls the visual navigation algorithm via a velocity estimate derived from terrain features tracked with the navigation camera. The Qualcomm processor is connected to two radiation-resistant flight-control microcontrollers (MCUs) to perform necessary control functions.

The telecommunication system consists of two identical radios with monopole antennae for data exchange between the helicopter and rover. The radio link utilizes the low-power Zigbee communication protocols, implemented via 914 MHz SiFlex 02 chipsets mounted in both vehicles. The communication system is designed to relay data at 250 kbit/s over distances of up to 1000 m. The omnidirectional antenna is part of the helicopter's solar panel assembly and weighs 4 grams.

Cameras and photography


Ingenuity is equipped with two commercial-off-the-shelf (COTS) cameras: a high-resolution Return to Earth (RTE) camera and a lower resolution navigation (NAV) camera. The RTE camera consists of the Sony IMX214, a rolling shutter, 4208 × 3120-pixel resolution color sensor with a built-in Bayer color filter array and fitted to an O-film optics module. The NAV camera consists of an Omnivision OV7251, a 640 × 480 black and white global shutter sensor, mounted to a Sunny optics module.

Unlike Perseverance, Ingenuity does not have a special stereo camera for taking twin photos for 3D pictures simultaneously. However, the helicopter can make such images by taking duplicate color photos of the same terrain while hovering in slightly offset positions, as in flight 11, or by taking an offset picture on the return leg of a roundtrip flight, as in flight 12.



While the RTE color camera is not necessary for flights (as in flights 7 and 8), the NAV camera operates continuously throughout each flight, with the captured images used for visual odometry to determine the aircraft's position and motion during flight. Due to limitations on the transmission rate between the aircraft, the rover, and Earth, only a limited number of images can be saved from each flight. Images to save for transmission are defined by the flight plan prior to each flight, and the remaining images from the NAV camera are discarded after use.

As of December 16, 2021, 2,091 black-and-white images from the navigation camera and 104 color images from the terrain camera (RTE) have been published.

Flight software


The helicopter uses autonomous control during its flights, which are telerobotically planned and scripted by operators at Jet Propulsion Laboratory (JPL). It communicates with the Perseverance rover directly before and after each landing.

The flight control and navigation software on the Ingenuity can be updated remotely, which has been used to correct software bugs and add new capabilities between flights. Prior to flight 34, the software was updated to avoid hazards during landing and to correct a navigation error when traveling over uneven terrain. This update became necessary as the helicopter traveled away from the relatively flat terrain of the original landing site, and towards more varied and hazardous terrain.

Primary mission
Perseverance dropped the debris shield protecting Ingenuity on March 21, 2021, and the helicopter deployed from the underside of the rover to the Martian surface on April 3, 2021. That day both cameras of the helicopter were tested taking their first black-and-white and color photographs of the floor of Jezero Crater in the shadow of the rover. After deployment, the rover drove about 100 m away from the drone to allow a safe flying zone.

Ingenuity rotor blades were unlocked on April 8, 2021, (mission sol 48), and the helicopter performed a low-speed rotor spin test at 50 rpm.

A high-speed spin test was attempted on April 9, but failed due to the expiration of a watchdog timer, a software measure to protect the helicopter from incorrect operation in unforeseen conditions. On April 12, JPL said it identified a software fix to correct the problem. To save time, however, JPL decided to use a workaround procedure, which managers said had an 85% chance of succeeding and would be "the least disruptive" to the helicopter.

On April 16, 2021, Ingenuity passed the full-speed 2400 rpm rotor spin test while remaining on the surface. Three days later, April 19, JPL flew the helicopter for the first time. The watchdog timer problem occurred again when the fourth flight was attempted. Rescheduled for April 30, the fourth flight captured numerous color photos and explored the surface with its black-and-white navigation camera.

On June 25, JPL said it had uploaded a software update the previous week to permanently fix the watchdog problem, and that a rotor spin test and the eighth flight confirmed that the update worked.

Each flight was planned for altitudes ranging 3 - 5 m above the ground, though Ingenuity soon exceeded that planned height. The first flight was a hover at an altitude of 3 m, lasting about 40 seconds and including taking a picture of the rover. The first flight succeeded, and subsequent flights were increasingly ambitious as allotted time for operating the helicopter dwindled. JPL said the mission might even stop before the 30-day period ended, in the likely event that the helicopter crashed, an outcome which did not occur. In up to 90 seconds per flight, Ingenuity could travel as far as 50 m downrange and then back to the starting area, though that goal was also soon exceeded with the fourth flight.

The commissioning sequence was as follows:



After the successful first three flights, the objective was changed from technology demonstration to operational demonstration. Ingenuity flew through a transitional phase of two flights, 4 and 5, before beginning its operations demonstration phase. By November 2023, the principal mission priorities had become:
 * Avoid significant interference with, or delay of, rover operations
 * Maintain vehicle health and safety
 * Perform scouting for tactical planning and science assessment
 * Perform experiments to inform mission and vehicle design for future Mars rotorcraft, or collect data for discretionary science

Operations Demo Phase


Just before the final demonstration flight on April 30, 2021, NASA approved the continued operation of Ingenuity in an "operational demonstration phase" to explore using a helicopter as supplementary reconnaissance for ground assets like Perseverance. Funding for Ingenuity was renewed monthly.

With flight 6, the mission goal shifted towards supporting the rover science mission by mapping and scouting the terrain. While Ingenuity would do more to help Perseverance, the rover would pay less attention to the helicopter and stop taking pictures of it in flight. JPL managers said the photo procedure took an "enormous" amount of time, slowing the project's main mission of looking for signs of ancient life.

On May 7, Ingenuity flew to a new landing site.

After 12 flights by September 2021, the mission was extended indefinitely. After 21 flights by March 2022, NASA said it would continue flying Ingenuity every two to three weeks until at least the coming September. The area of the helicopter's next goal was more rugged than the relatively flat terrain it flew over in its first year of operation. The ancient fan-shaped river delta has jagged cliffs, angled surfaces, and projecting boulders. Ingenuity helped the mission team decide which route Perseverance should take to the top of the delta and aided it in analyzing potential science targets. Software updates eliminated the helicopter's 50-foot altitude limit, allowed it to change speed in flight, and improved its understanding of terrain texture below it. NASA associate administrator Thomas Zurbuchen noted that less than a year previously, "we didn't even know if powered, controlled flight of an aircraft at Mars was possible." He said that the advancement in understanding what the aircraft can do is "one of the most historic in the annals of air and space exploration."

The helicopter's longer-than-expected flying career lasted into a seasonal change on Mars. This lowered the atmospheric density, which required higher rotor speed for flight: probably 2700 rpm, according to the flight team's calculations. JPL said this might cause dangerous vibration, power consumption, and aerodynamic drag if the blade tips approach the speed of sound. So the flight team commanded Ingenuity to test the rotor at 2800 rpm while remaining on the ground.

In mid-September, the flight team began preparing for the Martian winter and solar conjunction, when Mars moves behind the Sun, blocking communications with Earth and forcing the rover and helicopter to halt operations. When the shutdown began in mid-October 2021 the helicopter remained stationary 575 ft from Perseverance and communicated its status weekly to the rover for health checks. JPL intended to continue flying Ingenuity since it survived solar conjunction. NASA leaders said that extending the mission would increase the project's expenses, but that they believed the cost to be worthwhile for the information learned.

The launch time of each flight was influenced by the temperature of the batteries, which needed to warm up after the night. During Martian summer lower air density imposed a higher load on the motors, so flights were shifted from noon (LMST 12:30) to morning (LMST 9:30) and limited to 130 seconds to not overheat the motors.

On May 3 and 4, 2022, for the first time in the mission, the helicopter unexpectedly failed to communicate with the rover, following the 28th flight on April 29. JPL determined that Ingenuity's rechargeable batteries suffered a power drop or insufficient battery state-of-charge while going into the night, most likely because of a seasonal increase in atmospheric dust reducing sunshine on its solar panel and due to lower temperatures as winter approached. When the battery pack's state of charge dropped below a lower limit, the helicopter's field-programmable gate array (FPGA) powered down, resetting the mission clock, which lost sync with the base station on the rover. Contact was re-established on May 5. Controllers decided to turn off the helicopter's heaters at night to conserve power, accepting the risk of exposing components to nighttime's extreme cold. This daily state-of-charge deficit is likely to persist for the duration of Martian winter (at least until September/October).

In a June 6, 2022, update, JPL reported Ingenuity's inclination sensor had stopped working. Its purpose was to determine the helicopter's orientation at the start of each flight. Mission controllers developed a workaround using the craft's inertial measurement unit (IMU) to provide equivalent data to the onboard navigation computer.

In January 2023, the helicopter began to have enough solar power to avoid overnight brownouts and FPGA resets due to the start of Martian spring. This meant the helicopter was able to fly more frequently and over longer distances.

In March 2023, the helicopter made frequent flights to deal with limited radio range in the rough terrain of the Jezero delta. In the narrow canyons of the river delta, the helicopter needed to stay ahead of the rover, rather than entering a "keep out" zone and passing it, which JPL considered potentially hazardous.

Three times, mission controllers lost contact with Ingenuity after a flight, when the helicopter was not in the line of sight with Perseverance, preventing radio communication with the rover, which relays flight data between the helicopter and Earth. After the 49th flight on April 2, 2023, JPL lost contact with Ingenuity for six days, until Perseverance drove to a spot where communication was re-established. JPL had no contact with the helicopter for 63 days after flight 52 on April 26, 2023. Mission controllers had intentionally flown Ingenuity out of radio range, expecting to regain communication in a few days. Perseverance controllers, however, changed their exploration plans and drove further out of range, and then had difficulty collecting rock samples, adding another delay before finally driving toward the helicopter and re-establishing contact on June 28. Communication with Ingenuity was lost again at the end of flight 72 on January 18, 2024. Communication was re-established on January 20 but during the subsequent post-flight assessment, images of Ingenuity's shadow, taken by its navigation and horizon cameras after the flight, showed damage to its rotor blade tips. This ended the Operations Demo Phase and the mission.

End of mission
Ingenuity was permanently grounded after flight 72 on January 18, 2024, when a rotor blade broke off and other blade tips were damaged during the landing. The mishap is believed to have resulted from an autonomous navigation error in a mostly featureless area of sand dunes, which offered few points of reference. JPL said such problems may be avoided in the future with an established GPS system on Mars.

On January 25, 2024, NASA Administrator, Bill Nelson, announced the end of the mission. Ingenuity's final location is at Airfield Chi (χ) within the area since nicknamed by the project team, Valinor Hills, a reference to the final residence of the immortals in the J.R.R. Tolkien trilogy, The Lord of the Rings.

In the days after its accident, Ingenuity remained responsive to signals from JPL, which commanded a low-speed rotation of the rotors. The helicopter photographed the rotor shadows, which revealed that one of the blades was entirely missing.

Following a few final transmissions and a farewell message by the rotorcraft on April 16, 2024, the JPL team uploaded new software commands that direct the helicopter to continue collecting data well after communications with the rover have ceased. Ingenuity will serve as a stationary platform, testing the performance of its solar panel, batteries, and electronic equipment. In addition, the helicopter will take a picture of the surface with its color camera and collect temperature data from sensors placed throughout the rotorcraft and store it onboard, such that in-case of future retrieval, the results will provide long-term perspective on Martian weather patterns and dust movement, aiding the design of future rotorcraft. Engineers expect Ingenuity to store up to 20 years of daily data, if the craft is unhampered by the local conditions. Perseverance will continue exploration of Jezero crater autonomously, out of Ingenuity's radio range.





Follow-on missions and future work and conceptions
There are currently no plans to send Curiosity/Perseverance-class scientific laboratories to Mars, and funding for Martian projects is frozen to the level necessary to complete the Mars sample-return campaign.

Sample Return Helicopter


The idea of future Martian helicopters has been proposed. In March 2022, AeroVironment engineers, who previously created Ingenuity, presented the concept of a new helicopter with a payload of 280 g. A 90 g small manipulator arm with a two-fingered gripper and a self-propelled landing gear make it possible to use vehicles of this type instead of a fetch rover to select sample tubes cases with samples collected by Perseverance. At a briefing on September 15, 2022, NASA Planetary Science Division Director Laurie Gleizes confirmed her intention to use two of these helicopters.

The choice of Ingenuity as the prototype for the intended pair of assembler helicopters was based on the impressive safety margin built into it by AeroVironment designers. In principle, even the limit of 100 landings for the high-wear shock absorbers of the chassis is sufficient to transfer all 43 sleeves. Multiple small payloads can be carried by these types of helicopters, deployed and re-deployed to various locations, to perform a variety of distributed and networked operations.

Inertial navigation was one of the main challenges on Mars for the Ingenuity. The helicopter needs to show the ability to accurately follow the track it has already "mapped" on previously collected NAV frame sets and land at the takeoff point. In a future sample return mission, each cartridge case would require a pair of flights ending at the point of departure. Landing accuracy was an assigned task of Ingenuity's 31st flight. The very thin atmosphere of Mars does not allow repeating the maneuvers and landing techniques of terrestrial helicopters.

Mars Science Helicopter


Data collected by Ingenuity are intended to support the development of future helicopters capable of carrying larger payloads. The Mars Science Helicopter task is the next evolutionary step for Martian rotorcraft at JPL. The key focus is to develop the technology needed to deploy science payloads (0.5 kg – 2 kg) on rotorcraft platforms at the surface of Mars. MSH will inherit many of the technologies created by the Mars Helicopter Technology Demonstrator (MHTD) baselined for Mars 2020, and extend capabilities in order to enable a new class of mesoscale planetary access across Mars.

Designing and proving how science payloads can be deployed, recovered, integrated, and operated on a dynamically and computationally representative rotorcraft will be critical in expanding a new frontier for Martian scientific exploration.

The focus will include:
 * Rotorcraft configurations capable of carrying and deploying science payloads
 * Forecasting technological advancements in avionics, batteries, power systems, and navigation algorithms.
 * Earthbound demonstration testbed for evaluating avionics and payload integrations along with MHTD inherited FSW, C&DH, and eventual autonomous science mission execution.

MAGGIE
Mars Aerial and Ground Global Intelligent Explorer (MAGGIE) is a compact fixed wing aircraft proposed during 2024 NIAC selections.

Tributes to the Wright brothers
NASA and JPL officials described the first Mars Ingenuity helicopter flight as their "Wright Brothers moment", by analogy to the first successful powered airplane flight on Earth. A small piece of the wing cloth from the Wright brothers' 1903 Wright Flyer is attached to a cable underneath Ingenuity's solar panel. In 1969, Apollo 11's Neil Armstrong carried a similar Wright Flyer artifact to the Moon in the Lunar Module Eagle.

NASA named Ingenuity first take-off and landing airstrip Wright Brothers Field, which the UN agency ICAO gave an airport code of JZRO for Jezero Crater, and the drone itself a type designator of IGY, call-sign INGENUITY.