First in Flight: NASA Just Proved Flying on Mars Is PossibleNext Up Is the Solar System – Scientific American

Picture the scene: A small drone the size of a suitcase descends into a dark Martian crevasseperhaps a lava tube that was formed billions of years ago by volcanic activity on the Red Planet. The drone illuminates its surroundings, recording views never seen before by human eyes as its suite of instruments seeks out signs of past or present alien biology. Finally, its reconnaissance complete, the drone flies back to a landing zone on the surface to transmit invaluable data back to Earth. After soaking up the Martian sunlight to recharge its batteries, it continues its explorations of terrain inaccessible to any other machine.

Far from being some starry-eyed flight of fancy, such a mission could soon become a reality thanks to the resounding success of NASAs Ingenuity rotorcraft, sometimes referred to as a helicopter or dronea technology demonstration that has taken place on Mars over the past few weeks. Carried to the planet by NASAs Perseverance rover, which touched down on February 18, this small machine, weighing a paltry 1.8 kilograms, was the first attempt at controlled aerial flight on another worldmore than a century after that same feat was mastered on Earth by the Wright brothers. We can now say that human beings have flown a rover craft on another planet, said MiMi Aung, project manager of Ingenuity at NASAs Jet Propulsion Laboratory (JPL), in a speech to her team from mission control following the successful first flight on April 19. We together now have our Wright brothers moment.

With Ingenuitys success, space scientists are contemplating the roles that aerial vehicles might play in our exploration of the solar system. Few worlds possess the necessary conditions for powered aerodynamic flight, namely an atmosphere and rocky surface like that of Mars or Earth, but there are two others of note. The general technique of aerial flight is applicable to places like [Saturns moon] Titan and Venus, said Bob Balaram, chief engineer of the Ingenuity team, in a press briefing following the first flight. The latters exceedingly high temperatures and pressures pose some unique challenges: Near the surface its closer to swimming, says Paul Byrne, a planetary scientist at North Carolina State University. Yet flight there is not impossible, which was proved by the Soviet Unions Vega balloons in 1985. With a rotorcraft called Dragonfly already being developed to visit Titan in the next decade and work continuing on a conceptual successor to Ingenuity, the future looks bright for aerial exploration of alien worlds. This could be the start of a new era, Byrne says.

Ingenuitys first flight, from a strip of land on Marss Jezero Crater that is now dubbed Wright Brothers Field, was modest but impressive: the planets atmosphere is incredibly thin, just 1 percent that of Earth, so generating lift is exceedingly difficult. Its similar to Earth at about 100,000 feet above the ground, says Ben Pipenberg, an engineer at defense contractor AeroVironment, who helped build Ingenuity. With Perseverance watching from a safe distance, Ingenuity spun its blades at 2,500 revolutions per minute (rpm) to rise to an altitude of three meters, where it hovered for 30 seconds and performed a 96-degree rotation. Then it descended back to the ground, landing on its four legs, with a total flight time of 39.1 seconds.

From there, things got more complex. The second flight lasted 51.9 seconds, reaching a height of five meters. And it included a lateral movement of about two meterssomething not attempted in the confines of the test chamber on Earth where Ingenuity first flew in simulated Mars conditions. Flight three saw Ingenuity travel half the length of a football field, some 50 meters, reaching a top speed of just more than two meters per second. The fourth flight on April 30 pushed the envelope once again, with Ingenuity remaining airborne for nearly two minutes117 secondsand reaching an impressive speed of 3.5 meters per second as it scouted a potential future landing zone over a round trip of more than 260 meters. Ingenuitys fifth flightcompleted on May 7 and initially planned to be its lastsent it on a one-way trip to the new landing zone to await the arrival of Perseverance, its mother ship.

Nowthis wildly successful technology demonstration drone is entering a new phase of its missiona second month-long set of more ambitious operational tests. These tests are meant to show how airborne drones could play an active role in a future rover science mission, says Dave Lavery, program executive for Ingenuity at NASA headquarters in Washington, D.C. Although Ingenuity will not directly support the science objectives of Perseverancenamely looking for signs of past life on Marsit will help scout out the rovers potential route ahead as the team plans the optimal path through Jezero Craters riches.And the craft mayphotograph nearby locations that are not in the Perseverances planned path. There is even a slim chance that Ingenuity could support the rovers later mission, tooif the craft survives. We might see about potentially looking over the rim of the crater, Lavery says.

Much has been made of how these vehicles might one day support human missions, acting as reconnaissance drones for humans to scout out regions of interest near a landing site or carrying tools between locations. In the near-term, prospects of more exciting robotic science are on the horizonperhaps in the same way that the Sojourner rover in 1997, itself a prototype of wheeled exploration and part of NASAs Pathfinder mission, paved the way for its successors Spirit, Opportunity, Curiosity and now Perseverance. I do think were going to see some flying vehicles in the future, says Michael Meyer, lead scientist of NASAs Mars Exploration Program at the agencys headquarters. It will now be part of our portfolio of methods that we use for exploration. There are things you can do with a helicopter that you cant do with other platforms.

Examples could include exploring the aforementioned lava tubes or perhaps approaching crater wallstoo high and steep for a rover to scalewhere a helicopter could take images and perform some up-close analysis as well. Another example could be studying recurring slope lineae, dark flows on Mars that have arguably been linked to liquid water flowing on the surface. Perversely, it is this possibility of waterand the accompanying risk of contamination with bacteria imported from Earththat essentially prohibits anyone or anything from setting foot (or wheel) there to seek out signs of native Martian life. But a hovering drone could look without touching, offering a novel route of exploration. A rotorcraft would give us the ability to go and look up close at something that we would otherwise deem not suitable for a rover, Byrne says, either because of planetary protection issues or because its too dangerous.

One concept for a possible aerial vehicle beyond Ingenuity is already being investigated. Known as the Mars Science Helicopter, this six-bladed hexacopter would weigh nearly 30 kilograms. And it would be equipped with several kilograms worth of instruments to analyze different regions of the Martian surface and would have the ability to fly for minutes at a time over several kilometers. Were trying to learn from Ingenuity and ask ourselves, What could we accomplish if we push it further? says Theodore Tzanetos of JPL, who is part of the Mars Science Helicopter concept team. The science such traits would afford would be tremendous, bringing large swathes of the Martian surface suddenly within reach. The current distance record on Mars is held by NASAs Opportunity rover, which traveled more than 42 kilometers in a little more than 11 years. A helicopter could achieve the same feat in weeks.

Other ideas involve using rotorcraft to perform surveys of exposed water ice on regions of the Martian surface inaccessible to rovers. Drones could dive into Martian valleys such as the two-kilometer-deep Mawrth Vallis, looking for evidence of clays linked to astrobiology, or perhaps use instruments to probe the lower reaches of the Martian atmosphere, says Shannah Withrow-Maser, Mars Science Helicopter vehicle systems lead at NASAs Ames Research Center. And this could all be done either alongside a bigger rover mission or as more cost-effective and much lighter standalone missions, enabling more widespread exploration of a variety of Martian locales. I personally would love that, Withrow-Maser says.

Elsewhere in the solar system, flight options are more limited. One could imagine a rotorcraft in the atmosphere of one of the gas giants such as Jupiter or Saturn, where theoretically flight would be possible. But actually getting there would be an issue. The problem, of course, is slowing down and the amount of energy that would take on arrival at the planet, Byrne says. But Titan, Saturns intriguing moon with an incredibly thick atmosphere and lakes of hydrocarbons on its surface, is a very tantalizing prospect. In 2019 NASA selected a mission that would attempt to deploy the rotorcraft Dragonfly on the moon. Dragonfly is intended to launch as early as 2026 and arrive in 2034, and its team has been watching Ingenuitys successes very closely.

Weve been following with great interest, says Elizabeth Turtle, lead of the Dragonfly mission at the Johns Hopkins University Applied Physics Laboratory. Were very anxious to see what lessons we can take forward to Dragonfly. Like Ingenuity, Dragonfly will be flying autonomously, so it will make use of similar onboard image processing capabilities to decide where to land on the Titanian surface. (Ingenuity performs terrain mapping by taking 30 images of the ground per second.) But Dragonfly is a mammoth compared to Ingenuity, weighing nearly half a metric ton and powered by plutonium. And it is a standalone mission rather than a ride along like Ingenuity. Its like Perseverance [in scale], except we fly instead of drive across the surface, Turtle says.

Despite Titan being a much more distant alien world than Marswith a light travel time from Earth of about an hour, compared with up to about 20 minutes for the Red Planetflight is relatively easier there. Titans gravity is only 14 percent that of Earth and much less than that of Mars, while the moons much thicker atmosphere makes generating lift a comparative breeze. A person could put wings on and soar over Titans surface, Turtle says. Winds on Titan are also much slower, barely more than a kilometer an hour versus tens of kilometers an hour on Mars. And whereas Ingenuitys blades require 2,500 rpm to lift its fragile 1.8-kg body off the surface, Dragonflys half-metric-ton bulk can be lofted just by its rotors spinning at 800 rpm. Titans major challenge is its temperature, which averages only about 180 degrees Celsiushence the need for a long-lived, heat-generating plutonium power source. Its certainly cold, Turtle says. Its a nontrivial challenge.

With Dragonfly on the horizon, and perhaps future missions such as the Mars Science Helicopter in the works, there is plenty to be excited about beyond Ingenuity. This little machine has, for the first time, proved flight on alien worlds is possiblefrom both a physical and logistical point of view. Now this exciting new era of discovery awaits, and while only a handful of worlds afford the right conditions for this method of exploration, the sky is very much the limit for the science that could be performed by aerial vehicles in these alien skies. There are things to be sorted out, Meyer says. Then I think were going to start seeing some new and improved helicopter platforms that can actually carry tempting payloads.

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First in Flight: NASA Just Proved Flying on Mars Is PossibleNext Up Is the Solar System - Scientific American