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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

#151

Post by mehrdadn »

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…

This is something I'd always wondered about and never gotten a straight answer to. You're the first person I've seen who explicitly confirmed my suspicion that every system has a single point of failure. Would love to find a reference for this...

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

#152

Post by mehrdadn »

m3at wrote: post #129
Evidlo wrote: post #97

Earlier quoted context omitted.

It just depends on what your definition of a Martian minute is. If you define it as 1/(24*60) of a Martian day, it is different from an Earth minute.

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.

They said minute, not second. Even on Earth a minute isn't always 60 seconds.

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

#153

Post by teslaberry »

it's ALL ABOUT POWER. the 800 pound gorilla is the lack of power IN martian orbit and moreso on the surface of mars. no nuclear reactor of any major size can be launched into orbit let alone deep space and solar panels get less powerful as you travel away from the sun. we can imagine a bunch of chemical energy technologies will be invented to be launched to mars and then reach its surface, but realistically a satellite with solar panels around venus can generate massive power , over 4.5 times the power of that satellite around mars according to basic solar irradiance calculations. and probably even more than that ,

people love the idea of touching down on a solid surface on mars, but why? especially when the prospects of launching heat tolerant robots to venus might open up a world of possibilities. i'd sooner believe longrun humans find a way to colonize a world with a tremendous amount of energy easily available to harness, than one without. and also, consider how much more of our attention mars has gotten than venus, isn't it maybe worth thinking about that venus might deserve some more attention , relatively speaking?

http://em01.powweb.com/sciencetoday/solar_constants_%20plane...

TABLE 2. Solar Irradiance at the Planets Planet Solar Irradiance, W/m-2

                   Mean       Perihelion       Aphelion
Mercury 9116.4 14447.5 6271.1 Venus 2611.0 2646.4 2575.7 Earth 1366.1 1412.5 1321.7 Mars 588.6 715.9 491.7 Jupiter 50.5 55.7 45.9 Saturn 15.04 16.76 13.53 Uranus 3.72 4.11 3.37 Neptune 1.510 1.515 1.507 Pluto 0.878 1.571 0.560

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

#154

Post by HALtheWise »

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.

JPL wrote a fascinating reflection on what engineering practices allowed this to happen. For any of you who have not experienced the NASA Knowledge Gateway, I would recommend. https://llis.nasa.gov/lesson/1743

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

#155

Post by teslaberry »

let's go to venus.

satellites get almost 5 times more solar energy at venus than mars. and venus has been extremely neglected relative to mars as a target of study. the delta V to get to orbit around venus is about the same as mars. if future energy STOREAGE systems are improved dramatically, we can simply store more energy by being closer to the sun, so a mission to orbit venus would have a far easier time RETURNING to earth than an equivalent one to mars orbit, all things being equal.

launching a substantial power source into space isn't happening anytime soon.

http://em01.powweb.com/sciencetoday/solar_constants_%20plane...

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

#156

Post by spyspy »

droithomme wrote: post #131
Ianworld wrote: post #105

Earlier quoted context omitted.

I remember talking to a high up on the program at a FIRST robotics event who complained about them running so long. They weren't making any major new discoveries and sucking up resources and mindshare stopping him for kicking off and focusing on new projects. He said nobody would take the PR hit to decide to just end a mission like this so he was stuck.

> I remember talking to a high up on the program at a FIRST robotics event who complained about them running so long. Not surprising at all. Coached a FIRST team for several years. At this point they sell licensed robotics kits with canned instructions for kids to put together and those kids win because of time limitations. The teams that build from scratch and actually contribute discover or learn anything at all ar…

...what? They've always given out the Kit Of Parts and I don't recall those teams that relied on them ever winning anything substantial.

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

#157

Post by classicsnoot »

mos_basik wrote: post #101
classicsnoot wrote: post #92

Earlier quoted context omitted.

Your recollection is correct. Consider too the dust accumulation predictions for the moon landing. It would appear that we (as humans) are not very good at dust estimates (dustimates?). This is reinforced by the continuing struggle/inability to manufacture dirt. As an avid composter with a ton (lol sorry) of experience, I can make you hummus for days. I can turn 90% of your organic household waste into growth medium,…

Kim Stanley Robinson's Mars trilogy talks a lot about the "can't make dirt fast" problem, and I was surprised and impressed at how fascinating such a mundane-appearing problem could be. I had never thought about it before. Note: I think you mean humus. Hummus is "a Levantine dip or spread made from cooked, mashed chickpeas... blended with tahini, olive oil, lemon juice, salt and garlic."

Autocorrect has outed me as a desirer of dips and spreads more so than an urban farmer. The shame and ignominy is overwhelming.

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

#158

Post by classicsnoot »

bitwize wrote: post #110
classicsnoot wrote: post #92

Earlier quoted context omitted.

Your recollection is correct. Consider too the dust accumulation predictions for the moon landing. It would appear that we (as humans) are not very good at dust estimates (dustimates?). This is reinforced by the continuing struggle/inability to manufacture dirt. As an avid composter with a ton (lol sorry) of experience, I can make you hummus for days. I can turn 90% of your organic household waste into growth medium,…

Hummus? Or humus? Because one I'd like to eat with pita bread and a nice shawarma.The other...not so much :)

You are correct. Incidentally, humus is a delightful compliment to a sound horticultural spread, not unlike it's etymological cousin. It can make things better, but it cannot be the main course.

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

#159

Post by Retric »

sramsay wrote: post #137
Retric wrote: post #87

Earlier quoted context omitted.

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.

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.

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

#160

Post by goatherders »

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.

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.
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