The Truth Behind Opportunity's Last Message and It's Final Days On Mars

hello it's Scott Manley here it's been a better week since Mars Exploration Rover B better known as opportunity was declared dead and lost after an epic Odyssey over the Martian surface and for many people the last message has stood up as a poignant epitaph to this plucky little Explorer my batteries are low and it's getting dark and I'll admit that it even took me a couple of tries to record that without getting misty-eyed since then we've seen images art t-shirts and even this person who got a tattoo with it and I'm not sure how to tell them this but that is curiosity and not opportunity despite all the romanticism over these final words most people are probably aware that these words are not exactly what the rover sent they were paraphrased by a human in Mission Control turning the engineering data into something poetic and I certainly don't want to take away from this anthropomorphism that helped connect so many people to this robot any cold distant world but I'd like to talk about the actual last message and how the last days of the rover played out the last messages weren't sent directly to earth they were relayed via the Mars Reconnaissance Orbiter sending data directly to earth was slower and it took more energy so as the dust storm closed in the engineers arranged for communications to happen via the omnidirectional UHF antenna on June 10th our Sol 51:11 M are all passed over the site an opportunity transmitted a report on its status the storm had been building and there had been any science data collected but opportunity's science instruments were an idol they were used to collect information on the amount of light that was making it to the surface just before the pass the rover had turned its panoramic camera to the sky folded a solar filter into place and snapped a picture of where the Sun was so the engineers would be able to determine just how much light was making it through to the surface and this image is what was being when communications ceased so this noisy grayscale image of the Sun completely occluded by the Martian storm is really the last message that was sent by opportunity the reason it was never fully downloaded wasn't because there are over ran out of power at that instant but simply because Mars Reconnaissance Orbiter had moved beyond the horizon and was no longer visible in all during this pass the rover uploaded about four megabits of data from there it would take about 34 minutes for Mars Reconnaissance Orbiter to forward the data and for it to arrive back on earth after that message opportunity would have been instructed to store its camera go to sleep and unsolved 51:12 it would wake for just long enough to send nothing more than a beep to acknowledge that it was still alive the beep wasn't heard and we can only surmise that by then the battery charge had dropped so low they were unable to sustain both the computer and the transmitter that partially downloaded image wasn't even the last image taken by the rover either there was a pair of images taken using just regular red and blue filters they were taken at 4:30 p.m. Universal Time on June 10th those were only delivered in the form of thumbnails rather than complete images but you don't need to have the full resolution image to just show how dark it had become but the real inspiration for the popular message came in the form of the engineering data collected but from the battery control boards these were separate from the main computer they were connected directly to the batteries and the solar panels and they're kind of like the reptile brain of opportunity they would always work and even when the rest of the systems were shut down and the computer was asleep these would still be monitoring systems and collecting data they would collect a telemetry every 10 minutes things like temperatures voltage charge for the batteries solar panels and power buses and all this would have been included in that final pass and that really told us that the batteries were law and the skies were dark the raw data is not yet public but some of the aggregate numbers from the final few days can be gleaned from the regular mission reports these are published on NASA's planetary data system along with all the other data from the mission and yeah there's the science operations working group uplink report which was primarily dealing with figuring out what commands to send to the rover to satisfy the science objectives and then there was the mission managers downlink report which was a weekly summary of the rule for her status the mission managers report for Sol 111 starts with the ominous notice how value is not a typographical error the tower value is a measure of the atmospheric scattering and it was estimated to have a value of 10.8 and what that meant was sun's brightness was reduced by a factor of e to the power 10.8 which is roughly equivalent to taking the brightness of the midday Sun and turning it into a full moon the report also told us that the solar array was generating 22 what hours of energy per day compared to 900 watt hours of energy during the early parts of the mission to be clear the solar array power production wasn't directly affected by tow because some of the light scattered by the Sun would still reach the rovers it would just be scattered across the whole sky so how much is 22 watt hours of energy well for comparison the battery in my iPhone X is about 10 watt hours and that's just powering modern ultra efficient silicon whereas the processor an opportunity was an IBM rad 6000 irradiation hardened version of a PowerPC processor which is more or less what went into the very first power Mac's twenty-five years ago based on that number and the power in this battery is the team estimated that it would be about two weeks before the battery charge dropped so low that even the battery charge boards would and the clock would go offline finally the report showed that the final odometer reading was 45,000 won sixty-one point all four metres the last time the rover had moved was almost four weeks earlier when it had spun a wheel to kick a stone out from underneath it and in the process had moved about a centimeter and going back to that time shows just how well things have been going the downlink report for the week ending 50 87 described the rover's energy situation as solar a groovy meaning the solar panels power was sufficient to conduct science operations without drawing any power from the batteries opportunity was generating 670 what hours per day and testing communications with the trace gas orbiter the first sign of the storm was on Sol 50 104 and the last time the Sun was visible to the cameras was Sol 50 106 sites were suspended and the focus switched to rover management and survival unfortunately the rover's chances of survival were hampered by one of the very first faults discovered at the very start of the mission a heater in the instrument arm would get stuck on when temperatures got too low and it could account for one third of the power consumption in the early mission the rogue heater was dealt with by having the computer turn off the main power bus cutting power to the heater and everything else on the bus including the computer but the battery control board was connected directly to the batteries in the solar panel so those would continue to operate so in this mode the heater wouldn't run and practically nothing else would run and that would save a lot of power at the risk of letting temperatures drop to law this was called deep sleep mordant was used for a large parts of the mission to conserve power the way it would wake up is the battery control board had a check when the power coming to the panel's changed by a significant amount it would look at the status of the system and it would notice that power bus was on line and then bring it back on line so in the morning when the Sun came up the power to the panel's would rise and the battery control board would turn the power bus back on and eventually the computer would come up but this also would happen at night when the Sun set the battery control board would bring the bus back up regardless so this meant the computer cane had to sneak around in sleep deep sleep mode it would wait until it got dark and then it would wake up when the battery control board wasn't expecting and only then would it cut power and enabled deep sleep mode but if we look at how this would affect the recovery if the rover well after the storm began to clear the battery control board would come back online but so with that instrument heater meaning that after the rover shut down it would take a lot more power coming in to bring it back to life and it's very likely during the first restarts the battery Control Board would come up the heater would come up and then everything would eventually be depleted down to nothing and the batteries would get deeply discharged several times and that would not be good for them but whatever happened opportunity had lived to a ripe old age but the years had taken their toll some instruments used radioactive sources which had decayed it took twice as long to collect data from the alpha particle x-ray spectrometer and the Mossberg spectrometers gamma-ray source had become so weak that hadn't been useful since 2011 the non-volatile memory that was used to store science data before it was transmitted was no longer reliable so data was stored in RAM but that meant that if it wasn't up linked before the rover went into deep sleep it would be lost and there aren't like thumbnails for images in the planetary data system that were deleted they never made it to the ground there was the mini thermal emission spectrometer and that instrument was completely dead by the end of the mission not all the wheels which turned correctly are steer correctly and the instrument arm had been unable to store for a good amount of time and the microscope would just fail randomly which made one of my favorite images from the final months of opportunity just that little bit harder for the engineers to pull off the rover self a the team took back on Sol 5000 we've seen curiosity taking many selfies of itself using the camera it's instrument arm but opportunity didn't have a regular camera on its arm the camera on the mast was used to take some great pictures of its solar panels ensure that they'd been cleaned but to get a proper selfie of the rover sitting on the surface the team decided to use the microscope on the instrument arm now the focus obviously wasn't perfect by any means but the image mosaic showed the rover in all its glory sitting on Mars less than four months before the skies would darken and the rover would go into deep sleep for the last time but we have 5000 Sol's worth of science from the rover and anyone can now go and download that data to analyze and process for themselves there's a pretty good chance that there are things hidden in there that nobody's yet seen and this will extend opportunities legacy long past its operational life I'm Scott Manley fly safe [Music] [Music]

Channel: Scott Manley

Views: 339,497

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Keywords: mars, nasa, opportunity, rover, mer-b, jpl, jet propulsion laboratory, spirit, curiosity

Id: TS7S8T8vExM

Length: 12min 24sec (744 seconds)

Published: Tue Feb 26 2019