NASA's helicopter survives first freezing night on Mars
edition.cnn.com
edition.cnn.com
https://www.jpl.nasa.gov/news/nasas-mars-helicopter-survives...
More and more designs are choosing the latter, although notable exceptions are LED light bulbs (which use special components rated to operate for years at ~150 Celcuis)
Thermal design can be both surprisingly easy and surprisingly difficult. If the mission profile is cold-biased it's an "easy" matter of judiciously adding heating and insulation (to retain heat). Here "easy" is in quotes because nothing is trivial or truly easy in space.
If you have to deal with temperatures beyond the maximum thermal range of the design, sometimes the "easy" solution (again, in quotes) is to schedule shutdowns or duty cycle around thermal conditions. The power-down storage temperature of most devices is much higher than operating limits. Yes, you would need hardware that can deal with extremes in order to wake everything back up. That's where the rad-hard $300K microprocessors come into the fold.
At the same time, you'd be surprised how well some non-rad hard hardware can do in space. There are imaging satellites that basically use qualified COTS imaging sensors quite successfully.
The case is similar for dealing with radiation. Don't turn things on until you have to and, when you do, if you can, limit operating time to the absolute minimum.
There's a lot more to the art and science of making things for space, of course. Everything out there is actively trying to kill everything you send out there 100% of the time.
Maybe JPL has overcome those with some new battery tech, but extreme temperatures have always been the vain of engineers who have to design technology for cold weather.
It'll be interesting to see if multiple cold-weather days or years eventually kill the batteries off. This helicopter only flies for 90 seconds at a time already. If the batteries degrade by 30%, we are talking about sub-minute flight times.
Other information about the tech; camera & landing, energy use for heating, flight in low pressure atmosphere, the system to actually land the thing, is also really interesting.
Indeed, we don't have any video from the skycrane after touchdown, because I believe that data was fed over an umbilical to the rover before being sent to the low orbit (I'd typed LEO, but I guess I mean "LMO") satellites and back to Earth.
I also don't see why they are waiting so long to do the flight, why risk even waiting until nightfall for the batteries to get too cold or for dust to get into the electronics/mechanics?
An amazing one. Most of driving along at 1MPH on a barren landscape is incredibly boring, but...
https://youtu.be/4czjS9h4Fpg?t=10
> I also don't see why they are waiting so long to do the flight
Because there's a couple dozen steps that are each irrevocable involved in uncovering, unfolding, deploying, and then flying this thing... and that they want to make sure everything is perfect between each one and that comms still worked before cutting umbilicals, etc, because you can't just plug it back in.
Maybe, just maybe, the domain experts involved know something you don't. Just a theory.
Or perhaps there are regional variants of English where this is a normal way to ask a question. There are probably lots of idioms that work in one area but would be offensive in another, and it's not always easy to predict.
> During the first flight, the helicopter will attempt to rise about 10 feet (3 meters) in the air from the middle of its flat 33-by-33-foot (10-by-10-meter) airfield...
p.s. -90°C
I happen to easily remember that 20°C = 68°F and usually use that when mapping the temperatures back and forth which works for the usual ranges where I've had to do so by just adding/subtracting 5/9 on each side.
I once translated literally on the run (running the Boston marathon) for a foreigner who asked about the temperature and got a Fahrenheit response.
When I've been in other countries that use C, I've always had to translate from C back to F in my head to make sense of the temperature. The longest I've ever been any place outside the US is 10 days, and that hasn't been enough time for me to get a feel of what temps are in C.
It's a thing in Northern climes where the temperatures can get that cold. Everyone living in such places will know the term and you'll hear it frequently when talking about the weather or listening to weather forcasts.
I've got a few references in my head -40C = -40F (because magic), 0C = 32F (water freezing), 37C = just under 99F which I'm mostly approximate to 100F (body temp). 92C ~= 198F (espresso brewing temp), and 100C ~= 212F (boiling).
I use those to interpolate other F temps to whatever precision I need.
Brewing espresso I care about maybe half a degree C precision. Deciding what clothes to wear I only need to be within maybe 5 degrees C (so to me, 60F is "about 20% under halfway between 100F/37C and 32F/0C, so ~20% less than 18.5C - call it 15 = cold enough to take a jacket). For cooking I don't need to care to much about anything better +-20 degrees.
When some youtuber is camping out in 'sub-zero' temps, I smile. We call it 'warm' in Iowa when it gets above freezing in winter.
New York city is fun to visit, but I'd never live there...
https://en.wikipedia.org/wiki/Lowest_temperature_recorded_on...
Ingenuity survived, literally, a first freezing night. That is an accomplishment by itself, and is hardly sensationalist.
[1] As linked in the article: https://mars.nasa.gov/technology/helicopter/status/288/its-c...
For anyone reading this: -130F is -90°C
https://www.jpl.nasa.gov/news/press_kits/mars_2020/launch/mi...
Why didn't they test the survival of the freezing cold after testing the rotor blades, lift-off and perhaps a short flight in the vicinity of the rover?
For example: if you know that lift-off works, then that's a huge datapoint.
I don't know the actual list, but it's not hard to guess why they couldn't do everything, including ejecting it from the main rover and getting the main rover out of the way, in the ~12-14 hours a day that they have to do stuff.
https://www.nasa.gov/centers/johnson/pdf/639713main_Vibratio...
NASA knows what they’re doing.
Does it take a ton of power to heat. Or does it take very little power to fly?
I'd assume there is a ton of effort put into passive insulation? Since my non intuitive gut seem like it should be able to better insulate heat loss. I can't help but feel like there is probably a ton of effort and science to insulate. And this is even only possible because of that work. But is it just a much harder problem than I probably realize?
The power capacity metric isn't necessarily concurrent; one could imagine the chopper using its power to fly (which will generate heat as a byproduct) for a third of the sunlight time, and then using the rest of the day to charge for the night-time cold.
This is impossible; the flight duration is ~ 90 seconds.
I can't find numbers on the power system or materials so I can't speak to the thermal side or how much flight time that affords.
EDIT: Apparently there's enough energy to fly for 90 seconds (!) per sol.
"""H. Thermal System
The helicopter must survive the cold of the night on Mars where temperatures can drop to -100 C or lower. The most critical component is the battery which is kept above -15 C through the night as it powers Kapton film heaters attached to the battery cells. The avionics boards in the ECM surround the battery and are also kept at an elevated temperature by virtue of their proximity to the warm battery assembly. Insulation around the avionics boards is provided by a carbon-dioxide gap of 3 cm width. Additional insulation can be provided by replacing the carbon-dioxide gas with an Aerogel formulation. The outermost fuselage thermal coating is from Sheldahl with Solar absorptivity α = 0.8 and infra-red (IR) emissivity = 0.1.
In addition to thermal losses through the gas gap (or aerogel), additional losses occur due to conduction in the mast as well as through the copper wiring that penetrate the ECM from the mast. To minimize the latter, the wire gauges are selected to be of the thinnest gauges that can still support the current draw during operations without overheating. Prior to flight, under the control of the FPGA, the thermal system powers on heaters in the motor control boards that have been exposed to the ambient temperatures. The internal battery temperature is brought up to 5 C to allow hi-power energy extraction from the cells. During operation the ECM and battery warm up as a result of avionics operations and battery self-heating. However, the thermal inertia of the elements is such that for the short flights of the helicopter, there is no overheating."""
[0] "Mars Helicopter Technology Demonstrator" https://rotorcraft.arc.nasa.gov/Publications/files/Balaram_A...
EDIT: some detail on the battery capacity from section G:
"A de-rated end-of-life battery capacity of 35.75 Wh is available for use. Of this capacity, 10.73 Wh (30%) is kept as reserve, night-time survival energy usage is estimated at 21 Wh for typical operation in the northern latitudes in the spring season, and approximately 10 Wh is available for flight. Assuming that 20% of the power is at the peak load of 510 W and 80% is at a continuous load of 360 W, approximately 90 sec of flight is possible. These energy projections represent conservative worst-case end-of-mission battery performance at 0 C initial temperature. More moderate power loads will extend the flight time."
This video from Veritasium does a good job of covering the helicopter power system: https://www.youtube.com/watch?v=GhsZUZmJvaM&t=613s
https://www.jpl.nasa.gov/news/nasas-mars-helicopter-survives...
But I prefer to hear it directly from the engineers involved:
> "What was it like seeing that first image of Ingenuity on mars?"
> "Oh it was a dream come true. To see the culmination of the entire team's hard work really pay off. Being dropped - that's one huge milestone, but the massive one for us over the last few days has been realising not only did we drop, but we actually survived the first night. That is huge. That was one of the huge huge achievements that we've been looking forward to and now we can look forward to the rest of the mission. But being able to drop under our own energy, sustain ourselves, keep ourselves warm through the whole night and then wake up and talk with Perseverance and say "yep we're here alive and healthy" the team couldn't be happier."