Ingenious

April 19, 2021 6:23 AM

"We can say human beings have flown a rotorcraft on another planet." On April 19th the Ingenuity copter, part of the Perseverance rover mission, took off from the Martian surface, hovered, took a photo of its shadow, then safely landed. It is the first time a human-built craft has flown on another world.

Ingenuity's project lead is Burmese-American MiMi Aung.

Ingenuity carries a small piece of the Wright brother's Flier 1.

More from Ars Technica.

NASA video.

Perseverance previously.

posted by doctornemo (36 comments total)

That's just so cool! [And everybody's so excited in that room!]
posted by chavenet at 6:34 AM on April 19, 2021

This was amazing news to wake up to. Way to go! I can't wait to see what else they will do with it!
posted by turtlebackriding at 6:42 AM on April 19, 2021

Looking at that shadow photo makes me wonder what the exposure value for full sunlight on Mars is. I'm pretty sure the sunny 16 rule wouldn't apply.
posted by TedW at 6:57 AM on April 19, 2021

That's fairly impressive camera to stop the motion of the blades spinning 2400 rpm.
posted by Mitheral at 6:58 AM on April 19, 2021 [6 favorites]

The Onion is really dropping the ball here by not publishing the headline "MARS DRONE SUCCESSFULLY LIFTS OFF AND IMMEDIATELY GETS STUCK IN TREE"
posted by JoeZydeco at 7:07 AM on April 19, 2021 [24 favorites]

Wright Brothers first flight: 120 feet, 12 seconds. Earth.
Ingenuity first flight: 10 feet, 39 seconds. Mars.
posted by CheeseDigestsAll at 7:14 AM on April 19, 2021 [7 favorites]

For those who may want to head straight to the catharsis, excitement starts infecting the voices of everyone on-mic as data starts rolling in around 35:00, though definitely stick around to see an engineer rip up the contingency plans at 42:00.
posted by range at 7:17 AM on April 19, 2021 [8 favorites]

...the Martian atmosphere is just 1% as dense as that of Earth at sea level, so there's not much air for helicopter blades to push against. This disadvantage outweighs the benefits that aircraft gain from Mars' lower gravitational pull, which is just 38% as strong as Earth's.

Can someone explain to me how it works? My intuition is that lift should be proportional to air density and that seems to be true, so lift should be a hundred times less than it would get on Earth, but the gravity is only about third of Earth's.

Does the blade rotate much faster? Is the limiting factor on a rotor blade primarily drag, so it can rotate much faster than on Earth for a similar power output? Or does it just have much bigger blades and more power than the Earth equivalent would need?
posted by TheophileEscargot at 7:20 AM on April 19, 2021

It's way faster. From a comment elsewhere: "The two rotor blades are just under 4 feet long, and spin in opposite directions at 2,500rpm. The rotor tips are moving at about 2/3 of the speed of sound on Mars. (For ref, Ingenuity weighed 4 pounds on Earth, so about 1.5 pounds in Martian gravity.)"
posted by JoeZydeco at 7:27 AM on April 19, 2021 [5 favorites]

It's way faster.

Yep. Lift gets very complicated for rotors, but you can see in the basic lift equation that lift is proportional to velocity squared. (Drag, too.)
posted by clawsoon at 7:52 AM on April 19, 2021 [2 favorites]

I'm not a scientist. I'm a dreamer. I grew up reading Asimov and Heinlein and Niven. Y'all, I started to ugly cry around the 43 minute mark. It seems like so many things have been terrible in the last year-plus, but a bunch of tool-using primates just flew a helicopter on another planet from a small room in the United States.
posted by gwydapllew at 8:01 AM on April 19, 2021 [22 favorites]

NASA Rotorcraft publications are publicly available.

Mars Helicopter Technology Demonstrator (Balaram 2018) discusses design considerations and testing.

A Study of Past, Present, and Future Mars Rotorcraft is exactly what it sounds like.
posted by zamboni at 8:15 AM on April 19, 2021 [3 favorites]

It's not way faster. Similarly scaled Earth RC rotorcraft have roughly the same head speed. It's a lot faster than full sized helicopters, sure, but the limiting factor is more or less the speed of sound - go too fast with too long a rotor blade and you break the speed of sound and bad things happen. I wonder how close earthen RC copters are getting to the speed of sound though, if 2500rpm on a 600mm blade is 2/3rds the speed of sound in Mars' atmosphere, what's 2200rpm on a 700mm blade in Earth's denser atmosphere?

(To be fair, that's all back of the envelope and lord knows I might have missed a scale somewhere? But Ingenuity's 4' blade diameter is 1200-ish mm and RC helicopter scale classes are measured in blade radius. So maybe the t-rex 600 is more appropriate? Then the head speed is almost identical to Iggy's - 2470rpm at idle.)

That said, it looks like it has a significantly thicker chord than earthen atmospheric RC helicopters which makes sense given the atmosphere they're trying to push around. But 2000-2500 RPM is more or less child's play for the bigger electric helicopters.
posted by Kyol at 8:51 AM on April 19, 2021 [2 favorites]

Isn't there no need to qualify the statement with "a rotorcraft"? Isn't this the first time human beings have flown anything on another planet?
posted by thewumpusisdead at 8:57 AM on April 19, 2021 [1 favorite]

first time human beings have flown anything on another planet?
The qualifiers are probably necessary. We've "flown" plenty of rockets on other planets. We've done parachutes too, which can be considered "gliding". But this is something different, and awesome.
posted by Popular Ethics at 9:11 AM on April 19, 2021 [1 favorite]

Welllllllll what about rocket propelled landers and sample return craft? Is that flying, or is that something else? This feels like the sort of thing that maybe language struggles with...
posted by Kyol at 9:14 AM on April 19, 2021 [3 favorites]

That's fairly impressive camera to stop the motion of the blades spinning 2400 rpm.

I'm guessing they use healthy-sized CCDs for all their cameras.
posted by RobotVoodooPower at 9:24 AM on April 19, 2021

That's fairly impressive camera to stop the motion of the blades spinning 2400 rpm.

It is using a global shutter not a rolling shutter. The specs are in the document zamboni linked above.
posted by vacapinta at 9:27 AM on April 19, 2021 [6 favorites]

Isn't there no need to qualify the statement with "a rotorcraft"? Isn't this the first time human beings have flown anything on another planet?

FWIW, in the NASA video at 38:26 the flight control person qualifies it a bit less, calling it "the first flight of a powered aircraft on another planet".
posted by mstokes650 at 9:27 AM on April 19, 2021

How about "first flight using another planet's atmosphere for lift"? Too detailed? Or is that the same thing as "aircraft"?
posted by JoeZydeco at 9:32 AM on April 19, 2021

Somewhere on Mars, a Martian is telling the authorities that they were NOT drinking, they really did see a UFO.
posted by AugustWest at 9:36 AM on April 19, 2021 [16 favorites]

Oh HELL yes. Well done, humans. Very well done, human-created machines.
posted by rmd1023 at 9:39 AM on April 19, 2021 [1 favorite]

First powered, aerodynamic, flight on another planet. First powered flight of any kind to take off from the surface of another planet, if the Moon isn't a planet. However you finesse it, it's the first of its kind by some measure or other!

I'd been wondering why they went with a (complex, delicate) collective+cyclic setup, rather than a (simple, robust) multirotor, but then they did the full speed rotation test before going for flight, and it seemed to make sense...
posted by rhamphorhynchus at 9:40 AM on April 19, 2021

I wonder if this success changes plans for the "Fetch Rover" that Nasa / ESA are planning to go pick up sample canisters that the Perseverance rover will be filling and dropping over the next few years. A helicopter could round up the canisters pretty quick :)
posted by Popular Ethics at 9:42 AM on April 19, 2021

I'd been wondering why they went with a (complex, delicate) collective+cyclic setup, rather than a (simple, robust) multirotor

That question came up during Derek Muller's youtube interview of Mimi Aung. Short answer - coaxial rotors (with swash plates) are more efficient than quadcopters because they have a greater disc area for a given weight (even though they are more mechanically complex). For Mars, they needed every bit of efficiency they could find.
posted by Popular Ethics at 9:47 AM on April 19, 2021 [8 favorites]

Perseverance's video of the flight.
posted by rhamphorhynchus at 11:19 AM on April 19, 2021 [8 favorites]

I wonder how close earthen RC copters are getting to the speed of sound though

Not very close; they tend to crumble before reaching any kind of speed.
posted by acb at 2:07 PM on April 19, 2021 [2 favorites]

I think the question is about tip-speed of the rotors though... Reading some random RC helicopter forums, it sounds like target tip-speed for a copter is 200m/s, which will be around 1/3 the speed of sound. According to the linked comment, RC copters seem to be in the range of 100-150 m/s.
posted by kaibutsu at 3:35 PM on April 19, 2021

hovered, took a photo of its shadow,

… and thereby indicated that there would be six more weeks of Martian winter.
posted by Joe in Australia at 8:11 PM on April 19, 2021 [7 favorites]

Oooh, this is so cool! The Fetch Rover concept is also interesting, and I'm guessing there are all kinds of uses for a drone on Mars.
posted by Harald74 at 2:14 AM on April 20, 2021

I love that there's a postage-stamp-sized piece of canvas from the wing of the Wright Brothers' 1903 plane on board Ingenuity.
posted by mediareport at 4:27 AM on April 20, 2021 [3 favorites]

A CNES/Soviet partnership loated two balloons in the Venusian atmosphere during the 80's Vega missions.

Ingenuity is the first heavier-than-air aircraft to fly on another planet--the rotorcraft qualification is necessary.

Rockets aren't really considered "flying" since they are on ballistic trajectories.
posted by head full of air at 8:26 AM on April 20, 2021 [2 favorites]

Isn't there no need to qualify the statement with "a rotorcraft"? Isn't this the first time human beings have flown anything on another planet?

The First Flight On Another World Wasn’t on Mars. It Was on Venus, 36 Years Ago
posted by ActingTheGoat at 8:14 PM on April 20, 2021 [3 favorites]

Using a speed of sound of 343 m/s I get the mach number of the blade tips to be

m = 0.3 (r/1m) (f/1000rpm)

meaning 1 meter radius blades going 1000 rpm are at 0.3x the speed of sound. With that formula you can scale accordingly for different r and f
posted by secretseasons at 12:54 PM on April 21, 2021

GitHub added a badge for every developer who contributed code to any of the projects used by Ingenuity.
posted by rhamphorhynchus at 3:23 PM on April 23, 2021 [2 favorites]

That badge is so cool! Be still, my nerdy heart!
posted by Harald74 at 3:54 AM on April 30, 2021 [1 favorite]