Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

nytimes.com

Post reply on HN
Print view View original

111–120 of 235 posts

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

#111

Post by jessriedel »

DevX101 wrote: post #62
sanj wrote: post #31

Is it possible for someone other than NASA to send a message to the rover? I'd be happy throwing a little money at a project to ping it monthly to see if there is a response.

It's physically possible but I'd have to imagine there's a security key required for the Rover to accept a message and there's no way in hell NASA would give you that key.

I was shocked to read that, apparently, there is no key?

https://security.stackexchange.com/questions/18225/mars-curi...

I get the argument for why nuclear weapons aren't physically locked -- there's always people guarding them -- but not having security on a remotely operated billion-dollar device seems crazy to me, even if the technical barriers to establishing a link are high.

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

#112

Post by lozaning »

ChuckMcM wrote: post #60
sanj wrote: post #31

Is it possible for someone other than NASA to send a message to the rover? I'd be happy throwing a little money at a project to ping it monthly to see if there is a response.

Yes and unlikely :-) The protocols are all documented but the ability to receive signals from the rover requires a pretty sensitive receiver and antenna combination. If you have the resources to build a 10m or 15m steerable radio antenna parabolic dish then you could probably manage it.

I wonder if the Stanford Radio club could talk SRI into borrowing The Dish for a bit.

Pinging a mars rover would be one hell of a DX, even if Opportunity won't be sending you a QSL card.

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

#113

Post by buboard »

fivefive55 wrote: post #108
buboard wrote: post #42

Earlier quoted context omitted.

the cost of sending humans is disproportionately larger

The cost of failure is even higher.

the mars rover missions cost $2.5 billion. sending humans has an estimated cost 500 billion

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

#114

Post by xenadu02 »

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.

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.

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

#117

Post by gus_massa »

ragebol wrote: post #103
bad_alloc wrote: post #94

Earlier quoted context omitted.

If found in the current state, I'd speculate they'd conclude it's a planetary explorer: * Lots of sensors * Lots of communcation equipment * No external controls * Parts built without maitenance access * Solar power * Found on a mostly empty planet, with only a few other rovers around * A planet next door littered with similar technology

How would you recognize this and reach that conclusion if you were a different species, with different technology?

Wheels and axis are probably universal. Don't believe in sci-fi moves about floating transports.

A cooper wire around a iron core makes a good electromagnet. Deducing from there that it is a motor is not difficult. (It's even connected to the wheels.)

I'm not sure about the battery. I guess it's guessable because it has some unusual metals.

The lens (a clear piece of glass, thin, with a rounded surfaces) are also probably universal. If you have a few of them in line connected with moving parts with gears will confirm that it's the zoom of the camera.

Probably at the end of the camera is the sensor, I don't know how long it will keep the photo sensibility. It is connected by wires with the big chunk of wires and weird electric parts, so it must be the main board. The main board is also connected to the motors of the wheels.

The high gain antena is not parabolic (IIUC), it would have been an easy task to recognize it if it were parabolic :( . The low gain antena is a stick. By this time they already know the technology level of the motors and they will deduce that the communication is electromagnetic waves. So a big metal stick connected to wires is a good low gain antena candidate. The other weird thing has similar conections. And is orientable (they can see the inner gears of the support arm) and perhaps if you open it the inner structure also help. They will deduce that it is another antena.

[I personally think that for long distance transmission (specially in space) the electromagnetic waves are irremplazable. They may have a better encoding and filtering methods, but I guess they will mainly use electromagnetic waves.]

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

#118

Post by ChuckMcM »

jacquesm wrote: post #98
ChuckMcM wrote: post #60

Earlier quoted context omitted.

Yes and unlikely :-) The protocols are all documented but the ability to receive signals from the rover requires a pretty sensitive receiver and antenna combination. If you have the resources to build a 10m or 15m steerable radio antenna parabolic dish then you could probably manage it.

That can't be that expensive unless you want it to be storm proofed. But it wouldn't be super cheap either, the receiver is probably going to be a bigger problem. http://www.astrosurf.com/luxorion/dish-antenna-building.htm Would be a good starting point. But keeping it stable under wind load is going to be the major challenge. That would be one heck of a project, it would likely take a few years of your time to pull…

This quora answer (https://www.quora.com/What-bands-signals-and-protocols-are-u...) claims that even the 70m DSN antennas have a hard time hearing the rover to earth transmissions. That is 10x the diameter so 1000x the surface area of a 4.8m dish like the one the guy built.

That said, there are no doubt interesting hacks you can do to help this but steerability is always going to be a concern to maximize the SNR of the very weak signal coming from the rover.

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

#119

Post by mturmon »

felipemnoa wrote: post #73
Will_Parker wrote: post #46

Earlier quoted context omitted.

Also a testament to the value of under-promising. :)

If I remember correctly the reason they did not expect the mission to last longer than that was because they expected the solar panels to get covered with dust and thus render them useless. I don't think they had banked on martial winds to regularly clean them.

Yes. For more:

https://en.wikipedia.org/wiki/Cleaning_event

and:

https://www.jpl.nasa.gov/missions/mer/images.cfm?id=1823

The second link shows about 18% power drop after 90 sols ~= 90 days.

Post reply on HN