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Wikipedia's Mars Helicopter Ingenuity says:

It could potentially cover a distance of up to 300 metres (980 ft) per flight.

Perseverance is somewhat similar to Curiosity which drove about 22970 meters in 2839 sols, which is only 8 about meters per day.

Question: How long could the Mars helicopter Ingenuity keep up with the Perseverance rover if it wanted to?

Is Ingenuity capable of keeping up with Perseverance for years if it wanted to? It seems like it could fly as little as once a week and still keep up on average, but there may be a problem with the batteries since Ingenuity has to cycle its batteries every night to stay warm.

Of course that begs the question Could Ingenuity stay warmer at night by landing on (or near) Perseverance's RTG? so I've asked it.

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  • $\begingroup$ About two and a quarter hours. There was another question about landing Ingenuity on Perseverence $\endgroup$ – JCRM Aug 20 '20 at 14:33
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    $\begingroup$ Baring battery/helicopter hardware degradation, Ingenuity is faster on average than Perseverance even with its charge cycle, so theoretically forever. That said though, an extended dust storm might be able to kill Ingenuity if it can't collect enough sunlight to keep the batteries and electronics warm overnight or in the winter. $\endgroup$ – Dragongeek Aug 20 '20 at 14:48
  • $\begingroup$ @Dragongeek ya that's why I wondered: Could Ingenuity stay warmer at night by landing on (or near) Perseverance's RTG? $\endgroup$ – uhoh Aug 20 '20 at 14:54
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There are two parts to this question. The first is, can it physically keep up? As you mentioned, the range of 300 m per flight is specifically stated. From this page, we can deduce that one 90 second flight per day will cover the 300 meter distance. No doubt some of that power will be reserved for the first few seconds of flight, but it seems quite likely that Ingenuity could easily keep up with Perseverance, with an average distance likely of only maybe 10-20 m/ day likely on that front.

The second part is how long can that be kept up? Well, this is a bit harder to know for sure. NASA has released a paper that details some of the system, including the power system, so let's take a look! The end-of-life battery power is estimated at 35.75 Wh. Of this. 10.73 Wh is reserved for improved battery life and emergencies, 21 Wh is reserved for night time heater use. This leaves 10 Wh for flight per day, assuming flight is done to still allow some charge. Using those values, a 90 second flight is still possible at EOL. The batteries spec sheets show about a 20% degradation after 500 charges.

There are still a few unknowns in that. One will note that the total power budget for a day is 41, while the estimated EOL batter power is actually 36 Wh. I believe this will be accomplished with mid-day flights every other day when things are starting to get tougher.

The bottom line, however, is at least 31 Wh are needed just to ensure enough power to survive, as is currently planned. I believe that will happen after about 1000 charges. Even without a flight, the amount of discharge per day is quite significant. I believe that Ingenuity cannot survive longer than about 4 years, unless an optimal heating strategy is determined at some future date.

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    $\begingroup$ That's the number I'm the most unsure about. I'm basically basing that off of my cell phone, which I expect to be at about 50% charge after 2 years. It seems like that is a bit pessimistic still, so maybe a better number would be 15 or so. Will edit appropriately. That is still likely pessimistic, but... $\endgroup$ – PearsonArtPhoto Aug 20 '20 at 16:31
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    $\begingroup$ My 4.5 year old tablet is now around 400-500 cycles and lost about 10%. Reports from Tesla batteries suggest something in the same order ("10% after 160Mm"). That's 1%/40 cycles. Low temperatures and slow charging on Mars even reduce aging further. $\endgroup$ – asdfex Aug 20 '20 at 17:12
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    $\begingroup$ Could this article be useful ? rotorcraft.arc.nasa.gov/Publications/files/… G Power & Energy systems $\endgroup$ – Cornelisinspace Aug 20 '20 at 19:12
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    $\begingroup$ MSL could manage 140 m/hour. With improved autonomy and not stopping for experiments Perseverence could probably outrun it if they had a falling out... $\endgroup$ – JCRM Aug 21 '20 at 0:04
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    $\begingroup$ just driving is quite a waste @Cornelisinspace. stopping to take pictures and do science is what the platform is meant for. If they wanted to outrun the 'copter they probably could - but why would they want to? using the flyer as a pathfinder is far more use. $\endgroup$ – JCRM Aug 21 '20 at 9:32

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