Martian Dust Storm May Spell Doom for Rover

Everyone knows that space is an incredibly inhospitable place, but the surface of Mars isn’t a whole lot better. It’s a dim, cold, and dry world, with a wisp of an atmosphere that provides less than 1% of Earth’s barometric pressure. As the planet’s core no longer provides it with a magnetosphere, cosmic rays and intense solar flares bathe the surface in radiation. Human life on the surface without adequate environmental shielding is impossible, and as NASA’s fleet of rovers can attest, robotic visitors to the planet aren’t completely immune to the planet’s challenges.

Opportunity Mission Patch

As a planet-wide dust storm finally begins to settle, NASA is desperately trying to find out if the Red Planet has claimed yet another victim. The agency hasn’t heard from the Opportunity rover, which landed on Mars in 2004, since before the storm started on June 10th; and with each passing day the chances of reestablishing contact are diminished. While they haven’t completely given up hope, there’s no question this is the greatest threat the go-kart sized rover has faced in the nearly 15 years it has spent on the surface.

Opportunity was designed with several autonomous fail-safe systems that should have activated during the storm, protecting the rover as much as possible. But even with these systems in place, its twin Spirit succumbed to similar conditions in 2010. Will Opportunity make it through this latest challenge? Or has this global weather event brought the long-running mission to a dramatic close?

A Fair-Weather Rover

Conditions on the surface of Mars were fairly well understood even before Viking 1 touched down on the surface in 1976. Due to the fact that the surface of Mars only receives around 40% of the sunlight that Earth does, early missions used radioisotope thermoelectric generators (RTGs) to provide power rather than relying on the inefficient solar panels of the era. Unfortunately Opportunity does not have an RTG and must rely on solar to recharge batteries.

But even as solar panels got smaller and more efficient in time for later missions to Mars, the constant accumulation of dust on them meant they would provide less energy over time. Accordingly, anything that uses solar panels on Mars needs to be designed with certain safeguards if it’s to have any chance of surviving. When the Opportunity and Spirit rovers were being designed, the possibility of them experiencing long periods of darkness was anticipated.

When the rover detects that the batteries are running low and the solar panels are not producing enough energy to recharge them, it will trigger a low-power fault. This causes the rover to shut down systems and go into a “hibernation” mode until such time that the solar panels begin producing power again. This mode is sufficient to protect the rover during the occasional dust storms that kick up on Mars, but this is no regular dust storm.

View of dust storm from Mars Reconnaissance Orbiter (MRO)

Unprecedented Event

NASA knows that Opportunity would have put itself into hibernation shortly after the storm started, sometime in the middle of June. This would be expected behavior, and normally once the storm cleared and the panels started receiving sunlight, the rover would resume normal operations. But at this point the rover has been in darkness for so long that NASA theorizes the batteries are at or near zero, meaning all systems have completely shut down.

This complicates matters, but still doesn’t mean Opportunity is unrecoverable. Eventually, enough sunlight should hit the panels that the system will power itself back up. But the time spent with no power will have caused the onboard clock to reset. If this happens, the rover will attempt to use the Martian sunrise and sunset to get a basic sense of time. The reality of this scenario is that the scheduled transmissions from Opportunity won’t be happening when NASA expects them. It will take very careful observations with the Deep Space Network to try to pick up a transmission from Opportunity if NASA doesn’t know when it’s going to happen.

Even worse, after enough time has passed without contact from Earth, the rover will begin doubting itself. Eventually an “uploss” fault will be registered, which will trigger Opportunity to begin going through diagnostics of its communication systems and attempt to use alternate modes of transmission. This will make it even harder to receive the rover’s call home, as NASA won’t know when or even how it will be made.

An Uncertain Future

Unless its been literally buried during the storm, NASA is confident that Opportunity will wake up once light levels have returned to their seasonal normal. Receiving its signal may prove difficult, but with the agency’s resources on Earth and in Mars orbit, it’s not necessarily a mission-ending challenge. Granted this is about as close to a worst case as things can get, but that’s never stopped NASA before.

Though even if everything goes right, and NASA is able to reestablish two-way communication with Opportunity, the rover may have received a fatal blow. There is growing concern that such an unprecedented deep discharge combined with the frigid temperatures during the storm may have had a negative effect on the rover’s lithium-ion batteries. If the capacity of the battery banks have been diminished, they may no longer be able to run mission critical systems. There’s especially concern about running the rover’s onboard heaters during the upcoming Martian winter.

Unmitigated Success

Opportunity (Left) and Curiosity (Right)

Opportunity is currently the longest running Mars rover, outlasting its original mission lifetime nearly 60 times over. Even if it never wakes up, or if it only returns to a partially functional state, the mission will still go down in history as one of the most successful interplanetary explorations ever conducted. In that light, the potential loss of Opportunity should not be thought of as a disappointment. If anything, the fact that Mars had to throw everything it had at the veteran rover to knock it out of commission is perhaps a fitting retirement.

In any event, science will continue on the surface of Mars. The larger and more modern Curiosity rover uses an evolved version of the RTG technology that powered the Viking landers, and as such has been able to work through the storm. Before the end of the year it will be joined by the InSight lander, and depending on who you believe, we might have boots on the ground within a decade. It’s a very exciting time for Mars exploration, and no matter what happens, Opportunity will forever be remembered as an important milestone on humanity’s journey to the Red Planet.

65 thoughts on “Martian Dust Storm May Spell Doom for Rover

  1. I think the fact that it’s being doomed due to insufficient light reaching the solar panels is a form of success in it’s own right, not because it’s dying but because it proved it was worth putting RNGs in future rovers. NASA’s original martian rover is laughable now because of the huge evolutionary steps in rover design and deployment that we’ve taken.

    Hat’s off to NASA for really designing the most advanced rover and rover deployment system.

    1. There has been a dearth of breeder reactors in the US since President Carter decided to do away with moth breader research to show leadership in counterproliferation efforts despite the US being neck deep in modernizing the actual nuclear arsenal.
      I am not aware of any production of Pu328 and I know that there were less than ten RTG or system heater pellets around y2k.
      I don’t even know of there being an alternate source from another free to experiment with nuclear reactors country.

      1. An alternative to Pu-238 could be Sr-90 not as long half life or Am-241 which only has 1/4 as much heat output.
        The most idea solution would be to ramp up Pu238 production as these type of missions are generally too small for a full blown fission reactor.

        1. AM-241? so my smoke detector is selfheating? Should try to stick a thermometer in my jar of ion sources from 20 or so old detectors or glue them on a teg module. Maybe just stuff them in a 12V Peltier cooler to get a nuclear powered garden light?

    2. “I think the fact that it’s being doomed due to insufficient light reaching the solar panels is a form of success in it’s own right, not because it’s dying but because it proved it was worth putting RNGs in future rovers. ”

      I don’t agree. Opportunity lasted for 14+ years, which is (coincidentally) exactly as long as the MMRTG in Curiosity will last.

      The MMRTG was used in the MSL mission because the power (well, technically, energy) requirements were high enough that the MMRTG was significantly lower weight than the solar panel + battery solution you would need. Plus it restricts the landing area as well.

      MSL’s power source was chosen well before it was known how long a solar powered rover would last on Mars. In fact, it turns out that some of the arguments against solar power back in 2006 when they made the decision were *wrong* – they expected solar panels to only last a few years on Mars. In fact, Opportunity’s solar panels were producing nearly 80% of their peak 900W power output even after 14 years.

          1. It was so much worse for me, I’m aware that bingo halls have RNGs but i couldn’t think of what it was, I was also aware that in this thread RNG is obviously some form of nuclear alternative power supply, then in a moment of confused logic, I suddenly realised that bingo halls have nuclear alternative power supplies lest the game of bingo be interrupted.
            I’m only sharing this because a problem shared is a problem halved and this kind of logic is clearly a problem, so thanks.

          1. They’re not *that* heavy. The MMRTG design is ~50 kg. I mean, it’s heavy, but not crazy heavy – the entire MSL rover (Curiosity) itself is 900 kg, so it’s a small portion of the weight. You’re definitely right about the ‘short supply’ part, though, NASA only has enough plutonium for a handful.

  2. “There is growing concern that such an unprecedented deep discharge combined with the frigid temperatures during the storm may have had a negative effect on the rover’s lithium-ion batteries. ”

    I have to say, I’ve seen this reported places, but I wish I knew who from NASA is actually saying it, because I don’t understand it. The MER design has radioisotope heaters right on the battery, and a passive thermal control system designed for Martian (clear sky) night, so I don’t understand how the system ends up getting too cold in this situation. It doesn’t need power to stay warm, and it shouldn’t be nearly as cold as a normal night on Mars. Yeah, the heaters are a bit weaker than when they started out, but not much, I think: Spirit’s were still at 95% capacity after ~7-8 years, so you’d expect like 90% capacity for Opportunity now.

    With Spirit they just attributed it to the fact that the rover lost power completely during the winter (which was actually outside the design environment for the rovers – again, only a 90 sol design lifetime, so they didn’t design for winter), in an unfavorable orientation, and the fact that the rover was just crazy old. Obviously the crazy old part still applies, but I don’t see how the “cold” part could really be comparable. If the two rovers end up with a similar failure point (extended no-power operation) I’d have to wonder if something else was the actual cause.

    1. Maybe the heat lost by conduction (when the rover is buried in dust) is bigger than the heat lost by radiation (when the rover is clean). Other way said, the heaters have enough power to heat the rover alone, but not enough power to heat the rover and the dust.

      1. This is a seeking more info comment informed only by my impressions from space geek reading, I know the fine powder can make drifts and dunes but I believe that it would take many years to bury even the wheels much less than the body of the rover. Is there any though that even the mid 70s Viking landers are anywhere near buried in dust?

      2. The rover wouldn’t actually be *covered* in dust. If it was, you’re screwed no matter what since the panels wouldn’t be getting power, period. But the dust storm won’t really deposit any significant amount of dust at all.

        It doesn’t work from a thermal design standpoint, either. Anything that blankets the WEB will improve the heating, because you’re reducing the overall heat loss. The heat that gets out of the WEB is already lost – it’s trying to heat the Martian atmosphere, which has a way bigger thermal mass than a layer of dust. Add on dust, and that heat actually raises the temperature of the dust, which means you see a smaller thermal difference at the WEB boundary, meaning less heat transfer. (tl;dr version – covering yourself with a blanket keeps you warmer).

      3. I’m pretty sure dust in a dry environment acts as insulator in all scenarios, but then again it would be impossible to ever get the batteries charged again if we are talking feet of material. Maybe Matt Damon scavenged the panels for his habitat?

    2. The rover has RHU’s onboard, but they are small (less than 1 watt each) and have never been relied on as a primary heat source before. They have always been a supplement to reduce the energy requirements of the primary electrical heaters.

      It’s not Martian winter yet, and the storm actually raised surface temps a bit, so the temperatures likely never got into the fatal lows. But this is still an unprecedented event in terms of the thermal control system.

      1. “The rover has RHU’s onboard, but they are small (less than 1 watt each) and have never been relied on as a primary heat source before.”

        There’s 6 of them at a designed capacity of 1 W each, and they’re strapped right on the battery. As for not being used as a “primary heat source,” you’re wrong – in fact, Opportunity’s been going into ‘deep sleep’ for over a decade for multiple hours at night due to a malfunctioning heater switch on the Mini-TES. In this mode, the only heat sources for the instrument are the RHUs.

        The only reason why deep sleep was considered safe is because, in fact, the survival heaters on the batteries and REM weren’t needed (the Mini-TES heater, however, was needed, and so deep sleep pushed its temperature well below its designed operation limit).

        To quote the thermal design paper from 2005, “In fact, the only survival heater that came on during the entire course of the mission (so far) was that for the Mini-TES instrument.” The battery survival heater, as of 2005, had never been used, and the minimum battery temperature ever recorded was -17C, during the winter. During the summer the battery temps level off at night at around 5-10 C.

        That’s why I really kinda doubt that the batteries would ever get too cold, and I’m pretty sure NASA would know if they do (they’ve got a really good thermal model for the rover). I think the deep discharge is more what they’re worried about.

      1. Those are warmup heaters, not survival heaters. According to the thermal design report, all external hardware was designed to survive Martian night without heaters (allowable flight temperature limits of -105 to +50 C). The warmup heaters are just there to allow extended operations when there was enough energy.

  3. >> If this happens, the rover will attempt to use the Martian sunrise and sunset to get a basic sense of time.

    That’s pretty slick. With all the thought that went into these it seems odd that there isn’t a prescribed transmit time after a fault recovery. I get that the internal clock is unreliable but I don’t see why local noon or sunset can’t be used. We know where the rover’s last position is, we understand Mars’ orbit well enough to calculate a time to be listening for Opporunity’s transmissions.

    1. I’m imagining Wall-E’s solar recharge right now.

      Opportunity wakes up.
      Where am I?
      Oh this is Mars.
      What time is it?
      Oh no, the sun’s up. I have to go to work.

    2. Yeah, seems exagerated that the broadcast time would be that critical, with all the antennas that could be used. There seems to havet been little problem receiving the past comms so should be alright.. Maybe i should read the linked article tho. But listening to the scheduled broadcasts or listening for them to start at any time should “only” come down to a cost issue, depending on using the receiver part time or for i guess a martian day? So the question is probably if its deemed worth it after all this time, have it outlived its usefullness vs more costs?

        1. After an uplink loss fault, it uses the LGA, which is a fixed monopole antenna. Not directional. The HGA is directional and articulated (it moves), but obviously you don’t use that since you don’t know where Earth is.

          1. This happened to Spirit after its crash. The fallback position is to use the low gain antenna. I think I remember only having a few watts of transmit power. The signal is phase-shift keyed at 31 bits per second.

            Curious if anyone knows… does this mean the rovers are running ham-style PSK31, QRP no less? What is the gain of the 70m dishes at 8 GHz? And did I read in a tech report, maybe from DSN, that the receiver first IF is 432.1 MHz? Because these are all (except 8GHz) pretty obvious “ham-type numbers”. Which makes me wonder if W6JPL (W6VIO?) has a hot rod 70 cm rig laying in the spares pile. “You’re 59, good luck on mars.”

      1. As the Kevin Spacey character said in K-Pax, it wouldn’t be concern on Earth to beam back to his home planet, but with all the other K-Paxians (?) returning from all the other places, there was a critical time frame for him to beam back.

        NASA has multiple missions ongoing right now, and the number of receive antenna on Earth is limited.
        Couple that with the rotations of the Earth and Mars with a single point on Mars (the rover) being optimal for transmissions with only a few places on Earth.

        To give you an idea of the scheduling, here is a recent NASA article.

    3. “That’s pretty slick. With all the thought that went into these it seems odd that there isn’t a prescribed transmit time after a fault recovery. I get that the internal clock is unreliable but I don’t see why local noon or sunset can’t be used.”

      That’s exactly what they said it does…? You use sunrise/sunset to get a sense of time, and then transmit at the prescribed time based off that. That’s exactly the idea. The prescribed transmit time is 11:00 LST (local solar time).

      After even more time has passed, it’ll get even more daring, using more windows and even attempting to communicate with orbiters, which gets rid of the concern of Earth’s relative position.

      1. I didn’t read the actual NASA details, I was going off of the HAD article where they mentioned this:

        >>The reality of this scenario is that the scheduled transmissions from Opportunity won’t be happening when NASA expects them.

        So if Opportunity transmits regularly at 11:00LST why is NASA not expecting the signals? Or are they and it just got lost in the write up? Figuring out when 11:00LST (with a margin for error) for Opportunity is and turning on your receiver seems pretty trivial.

        1. Detection of sunset and sunrise depends on local geography and dust/weather conditions. It’s not a precise process and can probably deviate as much as 15 to 30 minutes either way. That means the signal can be anywhere within a 1 hour time span. Which is actually quite a wide window if you need to tie down the DSN for it.

          1. I’m pretty sure it’s worse than that, because I think Opportunity figures out local sunrise from when it wakes up due to sunlight on the panels. So if dust coverage is high, it could be *way* off.

    4. So maybe a stupid question but I didnt find an answer with a quick search, why wouldn’t the Opportunity be listening for a signal from Maven or one of the other orbiters that are there? Having Maven send a sync signal and listen for an ack whenever it passes overhead should be much more efficient then trying to make contact directly.

      1. It does, after it’s tried and failed to communicate with Earth for a while. Direct to Earth communication is actually usually easier since the DSN is crazy-capable (whereas the orbiters are obviously spacecraft that have fixed capabilities), and if the rover’s in fault mode it’s trying to conserve its efforts.

  4. Maybe one of those people in the bathrobes standing among the rovers (in the picture in the article) could use one of the bathrobes to dust off the solar panels.

  5. ” If anything, the fact that Mars had to throw everything it had at the veteran rover to knock it out of commission is perhaps a fitting retirement.”

    At least the Martians have stopped swiping the wheels.

    1. B^)

      Red Skelton had a skit shortly after Apollo 11 of moon men picking up the scientific gear left behind and tossing it in a garbage can. A sign on the garbage can said something to the effect. Keep Moon Clean, Don’t Litter!

  6. “Or has this global weather event brought the long-running mission to a dramatic close?” Uh-oh. Now we have global climate change on Mars too. Gotta stop using that fossil fuel, it’s messing up the entire universe!

  7. Overall a very good article. However, since the article includes a decent amount of factual data, some of the speculative comments that are probably meant to encourage discussion, are obviously being taken as facts and thus debated in the comments. Even with that, the article is written well and makes some really good points about the success of NASA’s rovers. How many new cars can last 14 years with just scheduled maintenance.

    1. “How many new cars can last 14 years with just scheduled maintenance.”
      A huge proportion of them… people lie about doing all the scheduled maintenance.

      But you’re making the wrong point, how many new cars could survive 14 years in a harsh environment with no hands on maintenance would be closer to the mark.

    1. Or some way to tilt them down and vibrate them a bit to shake the dust off. How about a fan or a compressor and nozzles to blow the dust off? There’s atmosphere on Mars so it should be possible to mechanically use it to blow off dust.

      What has extended the rover’s life several times are “cleaning events” where apparently a stong enough breeze has worked up (when NASA wasn’t observing the panels) to blow most of the accumulated dust off the PV panels.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.