31–40 of 95 posts
One thing that I have been wondering, if the atmosphere is so thin, then how does the RTG cool? I seem to have nerd-sniped myself. It needs a temperature differential to generate electric current and it looks to have fins for convective cooling but the atmospheric pressure is a few % of that of sea level Earth.
Seems shortsighted to end this mission after 30 days. I imagine it's purely for mission planning complexity reasons. But a more sensible approach seems to be to say "after 30 days you have to limit comms to 100 bytes/sec back to earth and stay 100 meters from the rover". In the future I could imagine the more modern processor on the helicopter might become handy... Some neural network based navigation system might ru…
If you just want images from a different angle, why not tether it to the rover? Also can't you use a kind of balloon instead to save power?
One thing that I have been wondering, if the atmosphere is so thin, then how does the RTG cool? I seem to have nerd-sniped myself. It needs a temperature differential to generate electric current and it looks to have fins for convective cooling but the atmospheric pressure is a few % of that of sea level Earth.
mars is freezing cold, it's like dust covered ice ball.
from the episode summary:
> "Friend of the podcast Doug Ellison from NASA's Jet Propulsion Lab stops by to give us the lowdown on the newest Mars rover Perseverance, which will be landing on the red planet in just a few weeks, plus all kinds of fun info about Lagrange transceivers, making oxygen out of thin air, flying helicopters on other planets, and recording home movies at mach 25."
https://techpod.content.town/episodes/71-curiosity-and-perse...
Unfortunately the article does not talk about how this helicopter would fare in a sandstorm. Are the winds strong enough to tip it over?
There is practically no wind on Mars. The wind speed is super high, but the air density is so low it won't impact anything more than dust.
Could they use it to try blow dust off the Opportunity rover's solar panels to see if it'll boot again?
https://mars.nasa.gov/resources/24729/map-of-nasas-mars-land...
If you just want images from a different angle, why not tether it to the rover? Also can't you use a kind of balloon instead to save power?
I would think the atmosphere is too light to support a balloon.
Can someone explain the phyics of flying a helicopter in such low density atmosphere? It must be less efficient than on earth, but evidently efficiency isn't proportional to density or else it could not fly at all.
No it mustn't. You'd expect efficiency to be higher, all else being equal, since there's less drag to overcome - aircraft can generally fly more efficiently at high altitude on Earth (up to a point). The limiting factor is that helicopter flight only works while the rotor tips are subsonic, so as the air gets thinner the "IAS" that a pitot tube on the rotor (that's going as fast as you safely can) would experience gets lower and lower, and so the flight dynamics will be like a helicopter with a slow rotor, but speeded up. But for a small helicopter the square-cube law is on your side and so a low "IAS" is quite doable.