Oversold?

A group of engineers put a working robot on a moving object 140 million miles away, and that robot trucked along for fourteen years.

I honestly do not see any aspect of this which is not totally and completely astonishing, marvelous, and awe-inspiring.

They designed it for a winter which means at least 687+ earth days days was considered achievable. Dust was expected to be a larger issue and in many ways they lucked out, but more so as a calculated risk than blind luck.

Distance makes little difference past the first day. Doing the same thing on the moon would not be easier becase it’s closer. It’s local conditions that make this hard more so than simply getting to that point.

I can assure you that the distance took its toll on the rovers, in my understanding. Their wheel surfaces eroded, oil pumps failed, bearings degraded and they ended up dragging dead wheels in the end.

Are you talking about the distance the rovers traveled while on mars? Because that's not what Retric is talking about. Retric is talking about the distance from the earth to mars (hence why they compared it to the moon).

Ah, my mistake; I misunderstood their comment.

To me, that they designed it to last that long, and it actually did, just makes it more impressive. Otherwise it would just be blind luck.

Sort of.

I think the book "Roving Mars" covers this the best. They were worried about a dust storm like the one that killed Opportunity, so they designed the rover to last 90 days even in the pitch darkness of a dust storm. To make sure they'd succeed even in this worst case, they added two additional petals worth of solar panels (IIRC, about a 50% increase in area) to the MERs.

Reading a contemporary description, they seemed to be very scared they wouldn't make the 90 days - hence this major and risky redesign. (The new panels had to open, and if one failed it would block off both the new solar panel, and one of the original ones.)

It worked, and so they had enough extra power to last through that first Martian year, where the winds blew the panels clean. And the rest is history.

I think they solve the power problem by bringing a nuclear reactor as the main power source.

Different rover. Spirit and opportunity aren’t RTG powered; curiosity is.

Yes, they probably designed it to last for a year. No one builds bridges for the exact expected load either.

There is no chance anyone involved in that program expected the rover to last for 5 years, let alone 15.

I disagree. Even without accounting for expectations, making a machine that works for years without regular scheduled maintenance in extreme conditions is a monumental feat. Ask people who work in the oilfield, extreme heats, extreme humidity, etc.

The discussion is about 90 days, not years. Years is awesome. 90 days was a planning goal used to set engineering priorities.

Kinda/sorta.

90 days was because they didn't think a rover would last over 90 days due to dust storms. They figured that after 90 days they'd encounter a bad dust storm that would cover the solar panels and make them unable to collect power, and thus the battery would be drained and unable to charge after 90 days.

They didn't account that the winds on mars would be able to clean the solar dust off the solar cells so well that it turned out dust storms weren't a huge issue until the latest one.

And from my understanding it wasn't the intensity of the latest storm that killed it but the part of the rover's computer that kept track of time was shot, so it wasn't able to optimize when to go to sleep and when to wake up properly, causing it to run out of charge while it was dark.

Expectation management is sometimes as important as the actual delivery.

It's pretty much what you do in any successful enterprise. Under promise, over deliver.

That's just startup and sales speak. I've found that delivering exactly as promised is more than enough to keep customers happy.

> That's just startup and sales speak.

Nah, it's a method for giving you a lot of wiggle room if you (or your business) fucks up in something.

I wasn't just commenting on the physical durability of the rovers themselves although that is a huge part of it. It is also impressive from both a political and an organizational standpoint to keep a program like this running successfully for so much longer than initial plans dictated.

NASA has numerous programs running for this length of time. One of the people working on Voyager showed up at my grad school to get a degree between Uranus and Neptune.

NSF, too. The VLA opened in 1978 and the first data recorded by it can be reduced by the current radio astronomy analysis software. In fact the software data format developed for the VLA (FITS) is now popular with high-end camera people... 41 years later.

> One of the people working on Voyager showed up at my grad school to get a degree between Uranus and Neptune.

So, did he make it beyond Pluto or not?

She.

Underpromise and over deliver :)

underpromise and way over deliver. This is unheard of.