I wrote not long ago about how the Mars mission of the just-landed Perseverance rover included the testing of a little helicopter, if all went well, dubbed “Ingenuity”. Nothing like that had ever been attempted before, and it was by no means certain that the thing would work. Though it weighs only four pounds, the little chopper faced an uphill battle because the atmosphere on Mars is extremely thin, only about 1% of the density here at sea level on our planet, and more like the conditions you’d find at an altitude of 90,000 feet or so. That’s a little sparse for flying. Here on Earth, a few aircraft have “zoom climbed” to altitudes like that, propelling themselves upward and then coming back down, almost like artillery shells, but the altitude record for sustained level flight is about 85,000 feet, set by an SR-71, the amazing (now retired) US reconnaissance jet that travelled considerably faster than a high velocity rifle bullet. That plane had engines that produced about 30,000 lbs. of thrust each. Little Ingenuity has only the few pounds of upward thrust provided by it’s small, solar-powered rotors.
To provide sufficient lifting surface, they equipped the Mars ‘copter with two rotor assemblies, one on top of the other, which turn in opposite directions (they “contra-rotate”, which has the additional benefit of rendering the usual tail rotor unnecessary). Replicating the Martian atmospheric conditions in special hypobaric facilities, NASA engineers worked out that those little rotors, roughly four feet in span, would have to spin at a rate of 2,400 RPM, about five to ten times as fast as the blades on terrestrial helicopters (it depends on the size of the helicopter and the length and width of the blades), which in tests created the lift necessary to pull the small machine into the air. It clawed itself aloft in the trial runs down here. That was promising. It didn’t mean it would fly up there.
It did though. Indeed they’ve now executed three flawless flights, and while a fourth was cancelled today owing to some sort of software glitch, they’ll be trying again as soon as tomorrow.** So far it’s hit an altitude of 16 feet while flying about 280 feet down range, not exactly the flight of the Spirit of St. Louis, but hey, it flies. Let me rephrase that: the frigging thing actually flies!! ON MARS! They put a functioning flying machine on Mars!
Ingenuity is just a technology demonstrator, meaning it has no role in the mission other than to see if it could work at all. A really useful aviation capability would obviously require the aircraft to carry a more sizeable load of instruments a lot higher and farther than anything Ingenuity will be able to demonstrate, sure, but c’mon – the first flight of the Wright Brothers was pretty underwhelming too, their rickety contraption travelling only 120 feet at a barely-off-the-ground altitude of less than twice the height of Wilbur’s hat (later in the same day, they coaxed their wood and canvas machine to another flight of over 850 feet). The point is, just as it was then, that the vehicle actually flies. That’s a magnificent thing to have achieved, in a way just as momentous as that initial success at Kitty Hawk: the first powered flight of a machine on another planet. Things have a strange way of snowballing after breakthroughs like that. Orville and Wilbur could scarcely have imagined, that December day in 1903, that a child just born would live to see an aircraft as monstrous as the Boeing 747, its wingspan longer than their very first flight, able to carry hundreds of passengers across whole oceans at speeds of 600 MPH. Who knows where we might wind up, and how soon, now that Ingenuity has shown what’s possible?
As the boffins at the Jet Propulsion Laboratory direct Ingenuity to attempt increasingly ambitious flights, they’re liable at some point to crash it. Or perhaps it will simply break down. No matter. Failure at this point is impossible.