How NASA Designed a Helicopter That Could Fly Autonomously on Mars • Hacker News Board

Re: How NASA Designed a Helicopter That Could Fly Autonomously on Mars

#91

Post by mlindner » Fri, Feb 19, 2021, 12:12 AM UTC

donquichotte wrote: post #48

nuccy wrote: post #46

Earlier quoted context omitted.

Actually the computing power of Ingenuity surpasses one of the Perseverance rover (and probably by a lot). The rover has a radiation hardened RAD 750 CPU (based on PowerPC 750 architecture, which was introduced in 1997 to compete with Intel's Pentium II [1,2]) with 250-150nm technology process operating at 200Mhz[3]. Ingenuity's Snapdragon 801 can reach up to 2.5 GHz and is based on more energy-efficient 28nm modern…

Do you know why radiation hardening is not needed for the Ingenuity? Is there a mechanical shield? Or is it just the shorter runtime that makes the use of an off-the-shelf processor acceptable?

My entirely uninformed opinion is that radiation hardened silicon is something that comes from government that isn't actually needed for most purposes. It's something you do when cost is no object.

Re: How NASA Designed a Helicopter That Could Fly Autonomously on Mars

#92

Post by [deleted] » Fri, Feb 19, 2021, 12:18 AM UTC

amelius wrote: post #42

gambiting wrote: post #39

Earlier quoted context omitted.

I do remember reading about this - a balloon would work, but it would be absolutely enormous, far larger than anything we can bring into Mars currently. Maybe some day.

Another thing I'm wondering: the drones can probably carry only a small (light) camera, whereas a satellite can carry much more and thus also a much better camera. Wouldn't a satellite+camera be a better option?

[deleted]

Re: How NASA Designed a Helicopter That Could Fly Autonomously on Mars

#93

Post by retSava » Fri, Feb 19, 2021, 9:12 AM UTC

teraflop wrote: post #68

nynx wrote: post #59

Earlier quoted context omitted.

I'm a little surprised they didn't go for three separate computers and compare them for every operation, or something like that, but I'm sure they have their reasons.

I've never seen an off-the-shelf processor that has hardware support for doing that kind of cross-checking on every instruction. And doing it in software would probably add so much overhead that the error-checking would be much more likely to fail than the application code. If you're willing to relax your real-time constraints a bit, and risk a brief period of incorrect behavior before the error is caught, the proble…

Perhaps the double-memory-and-checking is only done on the control algos and not on sensor fusion/object detection etc?

Kind of "Ok if we for a brief moment believe there's an obstacle in front of us, since it'll be gone next tick, but not ok to turn off motors".

Re: How NASA Designed a Helicopter That Could Fly Autonomously on Mars

#94

Post by RapidFire » Sat, Feb 20, 2021, 10:24 AM UTC

foobarbecue wrote: post #18

RapidFire wrote: post #16

Earlier quoted context omitted.

This is the coolest part of the mission IMO. My big question is where does it land? Does it dock with the rover? It seems to power itself via a solar array. About 100 days into the mission they plan on launching the helicopter for the tiny lifespan window. I think the limit on its lifespan is really, "How long until destroyed by wind/dust". And then how long until it cannot charge its own batteries/sustain itself.

I agree, this is the coolest part, but the most useful part for humanity is MOXIE. It lands on the ground. And yes, dust on the panels is a big concern. (I work at JPL but not on Perseverance / Ingenuity)

That's really cool; thanks for your work!!

I cant wait to see how Y'all figure out how to get those rock samples back to earth; that's gonnna be nuts XD

Re: How NASA Designed a Helicopter That Could Fly Autonomously on Mars

#95

Post by manicdee » Sun, Feb 21, 2021, 8:22 PM UTC

tkinom wrote: post #71

ryan_j_naughton wrote: post #52

Can someone who understands aeronautical engineering explain why they went with a helicopter over a winged aircraft? My guess is that takeoff would be too difficult for a traditional winged aircraft and VTOL was way too complicated. But given the thin nature of the atmosphere, a helicopter seems even more difficult to get lift than a winged aircraft. Can someone explain or link to the science between lift and air den…

Wonder the same thing, I have the impression that Quad or Hex copter would be more stable/reliable with more redundancy build in.

The propellers are huge in order to get this tiny helicopter to fly. A quadcopter would be larger than Perseverance, unless you devise some zero-mass hinges to make the entire thing fold into the same space that was available for Ingenuity.