
Mars Helicopter Attached to NASA's Perseverance Rover - caution
https://www.nasa.gov/feature/jpl/mars-helicopter-attached-to-nasas-perseverance-rover
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tectonic
I think it's interesting that it uses a Snapdragon processor running Linux and
communicates over commercial Zig-Bee 900 MHz links. Tons of technical details
here:
[https://rotorcraft.arc.nasa.gov/Publications/files/Balaram_A...](https://rotorcraft.arc.nasa.gov/Publications/files/Balaram_AIAA2018_0023.pdf)

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mappu
Thanks for the link -

The Snapdragon 801 was used in 2014-era flagship smartphones like the LG G3,
Nexus 5, and the Samsung Galaxy S5. (The paper is from Jan 2018.)

Publicly available vendor BSPs for msm8974 on CodeAurora topped out at kernel
3.4, but there are some independent people porting the mainline kernel to it.

It's also 28nm and not rad-hardened at all (a separate always-on FPGA is rad-
hardened).

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Ididntdothis
I think they should do more "cool" stuff in general. The rovers are great for
science but to get the public engaged they also need to do exciting and novel
stuff like flying drones on other planets. That's what gets people excited. I
can't wait for the submarine under the ice of Europa

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mturmon
The helicopter was very controversial, because it’s a technology demo, and
adds mass and risk to the overall mission without addressing its science
goals. It was on the edge of being descoped for a long time.

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Ididntdothis
I am glad that they did it. I am pretty big science nerd but even I am getting
bored with the nth rover going to the same planet. NASA should be doing
science but I think they also have the important role to push the limits of
what we think is possible, inspire people and make the next generation
interested in science instead of selling ads or creating CDOs. Being too risk-
averse is not good for them in the long term.

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perl4ever
It's annoying to read "The helicopter, which weighs 4 pounds (1.8 kilograms)",
considering all the pedantic people who like to say weight and mass are
different two things, here is something that's genuinely ambiguous because
they don't bother to say if that's Mars weight or Earth weight. And it's NASA,
not some careless pop sci writer!

...I did a Ctrl-F for "mass" too, and nothing.

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chmod775
Kilogram is a unit for mass, not weight. Weight is a force and measured in
newton.

A kilogram of steel on earth is still a kilogram of steel on mars.

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perl4ever
Ok, so?

Stating the weight of something in pounds and kg is only more confusing if you
don't think either are valid units.

It wasn't my idea to measure weight that way.

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LeifCarrotson
You missed the point of your respondent. Weight and mass _are_ different
things, mass in kilograms usually translates through Earth's gravity into a
2.2 to 1 relationship with weight in pounds. Because 1.8 * 2.2 ~= 4 it's
unambiguously referring to Earth weight, on Mars the ratio is 0.83 pounds per
1 kg. The helicopter would weigh 1.5 pounds if you took a load cell calibrated
in pounds and measured it on Mars, but it would still have a mass of 1.8 kg.

There's no such thing as "Earth mass" and "Mars mass", they're the same.
Calling this helicopter a 1.5 pound Mars weight helicopter seems confusing.

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drran
Pound and kilogram are same thing at different scales. The sooner US will
abandon Imperial scale, the better.

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p_l
Welcome to the confusing short hands of pound-force and kg-force!

It's huge part of why Newtons were used in SI instead of gram-force in CGS.

Still persists in thrust calculations, especially as metric ton-force, due to
ease of calculating TWR and related.

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billfruit
As always the question is with Mars rovers, does it have a microphone, that we
can finally hear the winds of Mars?

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pieix
Perseverance is bringing two microphones [0] with it, one of which has the
secondary purpose of recording minutes of ambient sound including rover and
wind noise.

[0]
[https://mars.nasa.gov/mars2020/spacecraft/rover/microphones/](https://mars.nasa.gov/mars2020/spacecraft/rover/microphones/)

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oh_sigh
It's great to know that this mission wasn't pushed due to COVID or anything -
the next launch window is 3 years from now.

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dflock
Veritasium episode covering this:
[https://www.youtube.com/watch?v=GhsZUZmJvaM](https://www.youtube.com/watch?v=GhsZUZmJvaM)

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mongol
A video of it : [https://youtu.be/oOMQOqKRWjU](https://youtu.be/oOMQOqKRWjU)

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antpls
Is there a particular challenge about flying a drone on Mars? Why not an
already existing consumer drone?

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knorker
I see people have already told you that the atmosphere is thinner. But they've
not really said just how much thinner.

The atmosphere on Mars is about one hundred times thinner than on Earth. That
means that between "Earth atmosphere" and "vacuum", it's 99% of the way to
being a vacuum.

This means that the blades need to spin really _REALLY_ fast. Like "oh no,
we'll start having transonic effects on the blades" fast. It's really tricky
to build a craft where the propellers move faster than the atmosphere can
"move aside". It was a really big deal to go supersonic back in 1947 or
whatever, and that was with _planes_ and did not use propellers. Transonic
effects is why modern airplanes have swept wings.

But yes, gravity is like a third, so it's got that going for it.

So this is really cool, and I even found it unrealistic in the Mars TV series
that they had drones, because how could that possibly be effective? Shows what
I know.

I saw some videos on this drone on youtube. It can't really fly on Earth. So
no, a drone off the shelf really can't fly on Mars.

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Ididntdothis
Titan is much easier, just a little cold:
[https://en.wikipedia.org/wiki/Dragonfly_(spacecraft)](https://en.wikipedia.org/wiki/Dragonfly_\(spacecraft\))

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cryptica
Too much human intelligence is spent on space missions. Imagine what we could
achieve if this intelligence was spent on useful things which affect regular
people in our society.

The costs vs benefits of space exploration are not balanced at all.

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mschuster91
Quite the other way around: Many if not most progresses in human tech history
came from such endeavours.

Space travel was helped/made possible by military research (beginning with the
Nazi regime), and then over the decades each r&d helped the other side to
advance. Internet? Military origin. Some forms of long range comms? Space.

Or, when we want to generalize to all forms of r&d deemed "wasteful", much
research in the car space was being done in the Formula 1 and later trickled
down to consumer cars - the only case in which trickle down politics actually
work. Many antibiotics and other medical agents came from researching rare
animals in remote countries.

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cryptica
This argument is highly speculative and very likely misleading too. Common
sense would say that the best way to hit a target is to be aiming at it. If
you're aiming all over the place, it's possible that you could end up with a
few bullseyes but how many shots have you wasted? How many bullseyes would
have been achieved if you had been aiming right at the target?

My point still stands that it's a wasteful way to reach those targets.

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p_l
By concentrating you risk getting over focused and boxed into some small
branch. Having many, many directions with cooperation across them means you
get significant interdisciplinary benefits, from just "someone looked at it
the other way" to (quite common!) "we need some fancy material, fortunately
space R&D already prototyped one that fits!"

