AkaSci 🛰️
Good news from JPL - the Mars helicopter team managed to reestablish contact with Ingenuity after its comm loss since the middle of Flight 72. The team is reviewing data to better understand the root cause of the comm outage.
This was accomplished by "instructing Mars rover Perseverance to perform long-duration listening sessions for Ingenuity’s signal."
Let's take a look at what that means.
#Mars #Ingenuity
3/n
AkaSci 🛰️
The solution to this problem caused by unsynchronized clocks is obvious - configure Perseverance to keeps its comm. system continuously turned on for a few hours!
That's what they did on May 5, 2022. A few hours later, Percy received Ingenuity's call, exchanged status info. and promptly set Ingenuity's clock to the correct value.
This is what JPL must have done today - "instructing Perseverance to perform long-duration listening sessions for Ingenuity’s signal."
I doubt they use NTP 🕰️
6/n
AkaSci 🛰️
FYI - the Ingenuity team did not know in May 2022 that time-sync loss was the problem and not something more catastrophic, but they had anticipated such events and had a bag of solutions to try.
Also, part of the solution to the May 2022 problem was to lower Ingenuity's thermostat at night, so that the heating system consumed less power and the electronics could stay up (in low power mode) all night. The thermostat setting was restored once solar insolation levels rose to normal levels.
7/n
AkaSci 🛰️
Mars Helicopter Ingenuity was just a 30-day technology demonstration mission to test powered, controlled flight on another world.
Ingenuity completed its tech demo phase after the 3rd flight on April 25, 2021. After another 2 flights, it transitioned to a new operations demonstration phase.
Almost 3 years later, Ingenuity has completed 72 flights and is still going strong in support of the overall mission.
Overachiever much?
👏
https://mars.nasa.gov/technology/helicopter/#Flight-Log
#Ingenuity #Mars
8/n
AkaSci 🛰️
This incident sounds very similar to a comm. outage that occurred in May 2022.
Then, increased atmospheric dust caused a reduction in solar panel output. One night, battery capacity fell low enough that a controller chip was automatically powered off as a safety measure.
Consequently, Ingenuity's time-of-day clock get reset.
That led to a failure to communicate with Perseverance, when power levels came back to normal.
Why?
AkaSci 🛰️
Ingenuity and Perseverance turn on their comm systems and talk during certain pre-determined periods of the day (e.g., at the top of the hour), to conserve power. Ingenuity initiates the call.
For this to work, both systems need to have "wall-clocks" (i.e., the date/time counter) whose values match closely.
Since Ingenuity's clock got reset and restarted due to the low power condition, the times when Ingenuity and Perseverance attempted to communicate with each other no longer matched.
5/n
aburka 🫣 #SaveChandra
@AkaSci it could be the same thing this time... but the latest dropout started *during* a flight. If the battery hit the critical "enter low-power mode NOW" level while above the ground it may not be in a 100% flyable state anymore :/
[source: am drone engineer on Earth, have accidentally cut motor power in flight before and observed the effects]
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