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The Ingenuity folks at NASA and lots of viewers on the internet I'm sure were pleased to see the first data from "the first flight of powered aircraft on another planet" (by humans at least); the output of the helicopter's altimeter.

Question: How does Ingenuity measure its altitude when flying? How does its altimeter work? Air pressure? Lidar? Laser displacement? Radar? Gamma rays? Something else?

Screenshot from the new NASA video First Flight of the Ingenuity Mars Helicopter: Live from Mission Control

enter image description here

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From multiple sites, but for the following quote, ScienceMag.org references a laser altimeter: (emphasis mine)

The data began to trickle in at 6:40 a.m. ET, relayed by the Perseverance rover to orbiters above and back to Earth. Cheers erupted 12 minutes later among Ingenuity’s small team of engineers and scientists when confirmation of a successful flight came, first from a laser altimeter showing that the helicopter had risen about 3 meters in the air. That data was followed by a picture from a camera on the helicopter's belly, showing its shadow directly below on the surface.

Additional research would indicate that the laser altimeter is a Garmin LIDAR-Lite V3. From the linked site:

So how is Garmin involved? Our technology — LIDAR-Lite v3 — will be measuring the distance from the helicopter to the ground. Ingenuity’s flight altitude goal is to get up to 15 feet (or 5 meters) from the surface of Mars for a flight lasting up to 90 seconds.

The link internal to the quote points to a purchase-related webpage: LIDAR-Lite v3 image

  • Weight: 22 g (0.77 oz)
  • Resolution: 1 cm
  • Accuracy: +/- 2.5 cm at distances greater than 1 meter. Refer to operating manual for complete operating specifications.
  • Range: 5 cm to 40 meters
  • Update rate: up to 500 Hz
  • Interface: I2C or PWM
  • Power (operating voltage): 4.75-5 VDC; 6 V Max
  • Current consumption: 105ma, idle; 130ma, continuous
  • Operating temperature: -20 to 60° C
  • Laser wave length/Peak power: 905 nm/1.3 watts
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  • $\begingroup$ Thanks for the edit, pretty cool! I hope you don't mind that I added a few of the relevant specifications, feel free to roll back or edit further. $\endgroup$
    – uhoh
    Apr 19, 2021 at 22:57
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    $\begingroup$ I guess that's part of the "off-the-shelf" strategy. Makerspace NASA (or rather JPL). Pretty cool. $\endgroup$ Apr 20, 2021 at 1:41
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    $\begingroup$ So this would be distance from the ground being measured, rather than distance above sea-level, as we're used to from typical earth-bound altimeters. (Makes sense since what would "sea-level" mean on Mars anyhow?) $\endgroup$ Apr 20, 2021 at 14:40
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    $\begingroup$ @DarrelHoffman Altitude above sea-level would depend on the distance between Earth and Mars. $\endgroup$
    – Barmar
    Apr 20, 2021 at 15:04
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    $\begingroup$ Relying on a hobby robotics grade LIDAR on a $3 billion space mission is really cool! ;-) $\endgroup$
    – Kozuch
    Apr 26, 2021 at 13:25

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