NASA's Perseverance Mars Rover tweeted:

Ingenuity, the Mars Helicopter I carry, is working as expected. I’m currently charging it, but once I set it down, it’ll rely solely on its solar panels. If it survives the brutally cold Martian nights, the team will attempt flight.

Question: If survivability is in doubt, why not do the first test flight the same day that it's dropped? Presumably it would be fully charged from the rover, and in a few hours Perseverance could move a safe viewing distance away.


Wikipedia' Ingenuity (helicopter) links to Mars Helicopter Technology Demonstrator(Canham et al. 2018, AIAA Atmospheric Flight Mechanics Conference, archived) which says:

One challenge in using off-the-shelf assemblies for electronics systems to be used on Mars is the low temperatures expected on the surface. At night, the antenna and cable assemblies will see temperatures as low as −140 C. Electronics assemblies on both base station and helicopter will be kept “warm” (not below −15 C) by heaters as required...

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    $\begingroup$ I'm looking forward to the answer! My guess is that they need to check that the rest of the rover works well before deploying it. Isn't it deployed from the belly of the rover? So the rover needs to drop it off and then drive away? $\endgroup$ – ChrisR Feb 21 at 7:13
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    $\begingroup$ Of course Ingenuity has been tested at those low temperatures, "If it survives.." is just a way of speaking to make it a still more exiting event ! $\endgroup$ – Cornelis Feb 21 at 14:28
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    $\begingroup$ @Cornelisinspace A better way to maintain the hype would be to share more data publically, since from pathfinder to ingenuity, components stay roughly the same, so do brutally cold martian nights. $\endgroup$ – qq jkztd Feb 21 at 17:36

First of all, according to Fig. 2 from Multi-model Meteorological and Aeolian Predictions for Mars 2020 and the Jezero Crater Region the nighttime surface and atmospheric temperatures for Ingenuity will not drop below minus 90 degrees Celsius.
Also,this paper shows that Ingenuity has been tested in thermal vacuum at minus 90 degrees Celsius for 4 hours and the conclusion was that the helicopter successfully performed the functional tests.

From INGENUITY MARS HELICOPTER landing press kit:

Mars has beyond bone-chilling temperatures, with nights as cold as minus 130 degrees Fahrenheit (minus 90 degrees Celsius) at Jezero crater. These temperatures will push the original design limits of the off-the-shelf parts used in Ingenuity. Tests on Earth at the predicted temperatures indicate they should work as designed, but the team is looking forward to the real test at Mars. One of Ingenuity's first objectives when it gets to the Red Planet is just to survive the frigid Martian night for the first time.

(Emphasis by me)

From Mars Helicopter Technology Demonstrator:
IV.Mars Helicopter Engineering Development Model
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.

So Ingenuity has been designed and tested to survive many Martian nights, there's no need to hurry !

From INGENUITY MARS HELICOPTER landing press kit (page 21):

Once Ingenuity is deployed to the surface, it has 30 sols (31 Earth Days) to complete its activities. The first phase is a commissioning process that is expected to take about a week; then the first flight tests begin.
At the beginning of Ingenuity's surface operations, the helicopter will aim to hit the following milestones:

  • Autonomously keeping warm through the intensely cold Martian nights (as frigid as minus 130 degrees Fahrenheit, or minus 90 degrees Celsius).
  • Autonomously charging with its solar panel.
  • Confirming the communications link: between the helicopter and its base station; between the base station and the rover's communication system; and then between the rover and Earth, all the way back to the helicopter flight operators.
  • Unlocking its rotor blades, confirming blades can change their angle, or pitch, and then performing both low-speed (50 rpm) and high-speed (2,400 rpm) spin tests while still standing on the surface.

(Emphasis by me)

All these milestones take their time, just like the Perseverance rover needs some time to become fully operational !

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    $\begingroup$ Thanks for the well-sourced answer, this is helpful! I can see that thoroughly testing the communications as described could take a while, as could the run through of the rotor workout followed by sending the resulting data back home and all the engineering analysis and decision-making necessary to approve an autonomous flying machine with dangerous high speed propellors start doing its thing so close to a \$2.75 billion rover. $\endgroup$ – uhoh Feb 21 at 21:28
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    $\begingroup$ and those rotor and to a lesser extent communications test will likely deplete the battery, so at least one if not several recharge cycle would be necessary before flight testing. $\endgroup$ – uhoh Feb 21 at 23:30
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    $\begingroup$ @Cornelisinspace Just to dive in further, nothing in your answer says why flight cannot be attempted before the brutal night stresses the batteries and risks the entire venture. Only the last point, about unfolding and testing the propellers, makes any kind of delay understandable. That it can autonomously charge, and survive the night, are not put forward here with extra information which makes the reader say "aha, i see why that is more important than a first-day flight", so you have room for improvement there. $\endgroup$ – Innovine Mar 2 at 18:53
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    $\begingroup$ @Innovine Ingenuity is a test. Flying is only part of it, survival is another. If a test results in damage future tests are hampered. This is a guess, but to get the most science out of Ingenuity they're doing the lowest risk tests first. I wouldn't be surprised if flying is considered low priority, from a science perspective; the aerodynamics are well understood. $\endgroup$ – Schwern Mar 4 at 0:26
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    $\begingroup$ @Cornelisinspace thank you for the edit; excellent answer! $\endgroup$ – uhoh Mar 4 at 22:39

First of all, Ingenuity has to survive the nights until it can be properly deployed on the surface, although it has power from Perseverance to do so. This probably isn't a significant issue, it has a protected case to allow it to survive EDL which will be ditched prior to deployment. It should be fine there for a while.

Then it has to be deployed, and Perseverance has to move away. The movement rate of Perseverance is 100 m/ day, assuming they go full speed. Not sure how far away it will have to be, but I suspect at least 20 meters. We don't know if the deployment will use some of the battery power, it might well. Next the animations show some tests of the propellers prior to full flight, which will likely happen. Finally, the batteries need to be fully charged again prior to attempting flight.

I rather suspect that Perseverance will set Ingenuity down, move away, take some photographs, and then Ingenuity will do some tests on Mars prior to actual attempted flight. The operators will no doubt need to verify that it is in fact away from the rover before attempting flight, one does not want to ruin Perseverance with a budget drone! Only one flight per day is even possible, barely. All in all, it will take a few days between deployment and everything being ready for flight, thus it will have to survive a few days in the cold before it can try to take flight.

  • $\begingroup$ As most of the rest of the answer said, it needs to do some calibration, and the operators on the ground no doubt will need to ensure that it is in fact on the ground. The demo videos show it doing some blade tests without attempting flight when first on the surface, followed on another day by flight. $\endgroup$ – PearsonArtPhoto Feb 21 at 21:52
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    $\begingroup$ There was a bit of that in there, but I've made it better. I've been researching independently a bunch about Ingenuity, finding the sources for everything is tricky, but... $\endgroup$ – PearsonArtPhoto Feb 21 at 22:10

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