These missions have limited expected lifespans, but they do seem to routinely exceed these timelines. Generally, the landers and rovers are not built to last much longer and the extra time is considered a bonus. To put a solar cell cleaner on the craft would cost weight that the scientists want to use for instruments and experiments. Think of it as doubling the amount of fuel on an airplane (rather than only fuel for an extra 45 minutes plus an amount to reach an alternate airport) in order to assure that it reaches its destination; there would be less available weight left over to fly the payload. When everyone agrees to the mission lifespan, they are grateful for extensions rather than upset that the mission had to eventually come to an end.

Longer missions, such as Curiosity or Perseverance, tend to be designed with other power sources so that longevity is assured. They, too do not have a backup power source, such as solar arrays.

When creating the financial budget for the mission, they don’t really budget for longer missions and to extend a mission must request them in order to receive additional budget for additional data collection, such as ground controllers and Deep Space Network time to collect the data, and for additional scientist salaries to write the additional papers explaining the data.

It is a shame that we have lost our only seismometer on Mars, but it would have been lost eventually anyway and lasted longer than planned, meaning hat it is a gain, not a loss.

Perhaps one of these years someone will design a solar array cleaner that is lightweight and effective so that these longer missions can use solar arrays rather than the other power sources. Perhaps one of these years we will have plenty of alternate power sources that we can include them on all missions. With Starship, we may be able to afford greater weight budgets due to the vastly reduced cost of launch, heavier missions with more instruments due to the vastly greater capacity of this launcher, and more of these missions due to the vastly greater availability of launches. But today, as in the past, we have limited resources for space exploration.

Richard M: You make a good point that I had forgotten. When it comes to its planetary missions, NASA in general has been doing a reasonably good job in the past two decades getting them built on time and on budget (more or less). NASA’s failures have been connected to its manned program (specifically SLS and Orion), and its astronomy program (specifically Webb and Roman and all the big telescopes proposed in the past two decades).

As you say, the problem with InSight had to do with farming it out to the Europeans, whose expertise in planetary work is weak. They showed it here.

Well, that would have more than doubled mission cost, and….NASA just had (and still has) a severely limited stock of RTG’s. So, they’re trying to use them only when they feel they absolutely must, until the stockpile is built back up.

Dragonfly is the next mission up that will use one, and it’s because there’s just no way they can get sufficient power via solar on the surface of Titan.

I think the problem was the outsourcing of the seismometer to the less experienced CNES, which I think was a combination of…CNES was offering it cheaper, and international involvement as good politics.

The mole failed, it seems, because they had the bad luck to land on a spot where the surface soil was particularly bad. I think (based admittedly on limited information) that there was concern in some quarters that they ought to have estimated such an eventuality as being higher probability than they did….they rolled the dice, and they didn’t get the numbers. So, maybe there is room for criticism here, but it sounds like luck was part of it, too.

It should be noted that there were other instruments on InSight besides these two: RISE, an x-band radio experiment (intended for precise measurements of planetary rotation to better understand the interior of Mars), and TWINS, which measures local wind and termperature. These ain’t nearly so important as SEIS and the mole, but they’not without significant value, and they did work: it’s the one site on Mars where we have such a long record of local climate data.

I wouldn’t call InSight the greatest Discovery success, but I think it turned out to be reasonably successful, even in spite of the delay and the cost overrun. On my list of NASA outrages, I think this rates low on my list; but others’ mileage may vary.

Lee S: No need to strain your memory. I provide links above to the past stories about InSight’s problematic development.

Twas not my intention to pick out NASA especially, you guys have the best robotic space program a planet could hope for! But I wonder what and where the last mission that came to fruition early and under budget was?

( It would be interesting to be a fly on the wall during China’s space budget discussions… I can only presume that inevitable budget overruns occur…)

Lee S: It was a NASA project except that its two main instruments were being built by the French and the Germans. The German instrument failed to work on Mars, and the French instrument failed on Earth, causing a two year delay, budget overruns, and a takeover by JPL.

I am certainly not a booster for NASA, but in this case the problems mostly stemmed from Europe, combined with lax management at NASA (but only in the beginning).

Regarding solar Vs nuclear power… Plutonium is expensive and problematic, and Mars receives enough sunlight to make solar practical IF the panels can be kept clean. It seems to me that some kind of windshield wiper brush or compressed air blower shouldn’t be too hard to implement, and surly without adding a huge amount of mass to any mission. Why we haven’t seen such a device yet on any Mars mission puzzles me…

1) (We should have already known it, but an array of) seismographs placed around the planet are enormously important towards figuring out what’s going on within Mars; and

2) Important instruments placed on the planet should be provided with RTG (nuclear) power – which cannot be blocked out by a little dust settling on the solar panels – much like Curiosity, Perseverence, and Viking.

Lee S: Your point is well taken, but I also note that the mission was two years late, and significantly overbudget. Also, had NASA not taken the seismometer away from the French and give it to JPL, it would have failed as well.

The success here should not blind us to the overall poor management and engineering of this mission.

I am as peeved as anyone about the failure of the mole probe ( it always sounded a bit dodgy to me…. Even if it worked as planned, what happens when it hits a big rock?) , But the seismology results have changed our understanding of the Mars interior.
Call it what you like, but “failure” wouldn’t be a word I would use.