The Dark Ars Tribunus Angusticlavius
8y
11,841
The lander's four shock-absorbing legs have some give, sort of like the crush zone of a car, according to Will Coogan, Firefly's chief engineer for the Blue Ghost lander. The legs have an aluminum honeycomb material inside, and they connect to bowl-shaped footpads with a ball-socket joint to give the spacecraft some flexibility in case it comes down on a slope or a rock.

That's basically a copy of the Apollo landers. Apollo had crushable aluminum honeycomb in the legs and bowl-shaped feet attached to the legs with ball joints. The statistical analysis was that Apollo's system had a 99.9% of not fully crushing the honeycomb as long as the landing velocity was below 4 feet per second horizontally and 7 feet per second vertically (1.22 m/s and 2.13 m/s). All of the landings were well under those velocities:

https://arstechnica.com/civis/attachments/1740667805423-png.103726/

NASA Technical Note TN D-6850 Apollo Experience Report - Lunar Module Landing Gear Subsystem by William F. Rogers (June 1972).

D-6850 Apollo Experience Report - Lunar Module Landing Gear Subsystem

https://ntrs.nasa.gov/api/citations/19730010151/downloads/19730010151.pdf. //

EarendilStar Wise, Aged Ars Veteran
8y
148
SkyeFire said:
Lunar conditions are brutal. Two weeks of brutal daylight (plus unfiltered solar radiation) followed by 2 weeks of total darkness. A few lunar probes have managed to survive the night and reboot once they got some sunlight again, but none of them survived more than a few day/night cycles. The thermal swings tend to destroy the electronics and power systems.

This entire bath and forth made me realize I don’t know how the temperature swings of the moon and Mars differ. I was reading thinking “How is this thermal swing different than Mars, a place we operate electronics for far more heat cycles than this?”.
Allow me to share what I found:

Commonly accepted average temps for Luna:
-180°C to 105°C
Mars:
-130°C to 22°C

That’s quite the difference!
Does anyone know why Mars nights are warmer? Is it mostly due to ground surface absorption of radiation, and not losing most of it until the next day cycle? The (limited) atmosphere retaining some heat? ///

Shorter nights on Mars