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Nasa’s Mars Rover Opportunity Concludes a 15-Year Mission

nytimes.com

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Re: Nasa’s Mars Rover Opportunity Concludes a 15-Year Mission

#171

Post by [deleted] »

proactivesvcs wrote: post #164
Retric wrote: post #159

Earlier quoted context omitted.

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…

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.

[deleted]

Re: Nasa’s Mars Rover Opportunity Concludes a 15-Year Mission

#172

Post by trothamel »

Retric wrote: post #87
slg wrote: post #23

Opportunity's and Spirit's original missions were planned to last 90 Martian days each. They ended up lasting over 8,000 combined. That is almost as impressive as getting the rovers to Mars in the first place.

That story is very much over sold. They defiantly designed the things with a longer lifespan in mind. NASA simply had more reasonable minimum specks so if they died on day 220 nobody would call the program a failure.

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.

Re: Nasa’s Mars Rover Opportunity Concludes a 15-Year Mission

#173

Post by kumarharsh »

greglindahl wrote: post #162
slg wrote: post #99

Earlier quoted context omitted.

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 la…

> 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?

Re: Nasa’s Mars Rover Opportunity Concludes a 15-Year Mission

#174

Post by m3at »

justinator wrote: post #139
m3at wrote: post #129

Earlier quoted context omitted.

You're likely joking, but just in case: on earth the second is not defined as a fraction of the day, it's a SI unit defined as a constant count of energy level variations of an caesium-133 atom.

What came first, the definition/concept/time span of a second, or the discovery of the Caesium-133 atom?

Good question.

Counting minutes obviously came first as devices likes hourglass and water clocks are old (2000 BCE).

Regarding their precision, I got interested and per this paper [1] and the wikipedia page about traditional Chinese timekeeping [2], water clocks from two millennia ago might have around 15min precision.

For second level precision, it seems modern mechanical clocks were required, and they only precede the discovery of caesium by a few centuries.

[1] https://www.cambridge.org/core/services/aop-cambridge-core/c... [2] https://en.m.wikipedia.org/wiki/Traditional_Chinese_timekeep...

Re: Nasa’s Mars Rover Opportunity Concludes a 15-Year Mission

#175

Post by Ianworld »

brandonjm wrote: post #138
jessriedel wrote: post #109

Earlier quoted context omitted.

What's the limiting factor on just running with reduced staff support? (Honest question.)

I had the same question, I don't imagine it takes too many people to decide what it should do and give the robot commands while monitoring it.

Looks like according to an old article linked on wikipedia they spent another $100+ million over 5-6 years to keep it going. So not wildly expensive, but not cheap either.

https://web.archive.org/web/20120504171453/http://www.msnbc....

Re: Nasa’s Mars Rover Opportunity Concludes a 15-Year Mission

#176

Post by torpfactory »

You know the craziest thing about all of the mars exploration programs is to me?

The first time there is an entire full-up test of the system is live, AT MARS. There isn't a good way to test the entire entry descent and landing sequence because the earth's atmosphere is so different than mars. I know NASA works hard to test parts of it in the vicinity of earth, but I can't imagine designing something so complicated (especially the system for curiosity) and then not being able to test it completely before the real thing.

Re: Nasa’s Mars Rover Opportunity Concludes a 15-Year Mission

#177

Post by gizmo686 »

Rebelgecko wrote: post #146
jessriedel wrote: post #109

Earlier quoted context omitted.

What's the limiting factor on just running with reduced staff support? (Honest question.)

A small handful of people can still easily cost millions of dollars per year. And DSN time to talk to the rovers is expensive, probably in the neighborhood of $2,000 per hour.

How much DSN time do you need. Given the deley, I assume the only use is batch transfers, so cost per bit seems like the more useful metric (along with how much data is involved)

Re: Nasa’s Mars Rover Opportunity Concludes a 15-Year Mission

#178

Post by lilott8 »

tzs wrote: post #125
luizfzs wrote: post #82

Earlier quoted context omitted.

I saw a video once saying that SpaceX uses general purpose computers on the rockets instead of specific purpose hardware. If I'm not mistaken, they amount to 6 and have a checking system to assure the output of them is the same.

Those "have N copies and compare them" systems then have the issue that whatever does the comparison is a single point of failure. You could use multiple comparison units and have a second level comparison check them, but then that is your single point of failure, and so on. I've been told, but never actually looked it up, that there is a theorem that proves you always have to have at least one single point of failur…

I'm curious if this SPoF theory stops at computer/real world interfaces (such as the control surface computers). Or if this generalizes into purely computational models. In my mind I can't find any purely computational model using distributed techniques that succumbs to the SPoF "theory." But the computer/real world interface is trivially obvious in just about every context.

Re: Nasa’s Mars Rover Opportunity Concludes a 15-Year Mission

#179

Post by dbg31415 »

aspectmin wrote: post #141

Steven Squyres, the Principal Scientist of the program came to Microsoft to give a talk. One of the best talks I’ve been to. So many interesting tidbits like the parts about the rovers expected short lifetime due to the dust, and how (if I remember correctly) they fixed this by shaking the solar panels like wings. He talked about the rover drivers, and how they all had to live in special light cycle controlled buildi…

I was really fortunate to have him as an astronomy professor right around the time of the launch. He's great at making complex things easy to understand, and his enthusiasm is contagious. Highly recommend his book, but if you've only got an hour here's a good video conversation.

* Roving Mars with Steve Squyres - Conversations with History - YouTube || https://www.youtube.com/watch?v=NI6KEzsb26U

Re: Nasa’s Mars Rover Opportunity Concludes a 15-Year Mission

#180

Post by gizmo686 »

JohnJamesRambo wrote: post #126
slg wrote: post #23

Opportunity's and Spirit's original missions were planned to last 90 Martian days each. They ended up lasting over 8,000 combined. That is almost as impressive as getting the rovers to Mars in the first place.

I’ve never found it impressive, it’s a horrible padded estimate meant to cover NASA and make them look good. A real estimate needs to be useful and somewhat close to the actual outcome. There’s no way they were this off without it being on purpose. Imagine if your retirement planner or accountant was off by 44X in their number crunches for you. Would you say they were good at estimating?

No one predicted that the rover would break on day 91. They designed it to last at least 90 days. Between standard rocket-science safty factors and preparing for the pessimistic end of all the uncertain risks, there is much room to go beyond your original mission.

Imagine you design a bridge to support 100 tons. No one would accuse you of mispredicting if it holds up at 200 tons. They will accuse you of negligence if it collapses at 105 tons.

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