Six Things About Opportunity's Recovery Efforts
The global dust storm on Mars could soon let in enough sunlight for the Opportunity rover to recharge.
NASA's Opportunity rover has been
silent since June 10, when a planet-encircling dust storm cut off solar power
for the nearly-15-year-old rover. Now that scientists think the global dust
storm is "decaying" -- meaning more dust is falling out of the
atmosphere than is being raised back into it -- skies might soon clear enough
for the solar-powered rover to recharge and attempt to "phone home."No one will know how the rover is doing until it speaks. But
the team notes there's reason to be optimistic: They've performed several
studies on the state of its batteries before the storm, and temperatures at its
location. Because the batteries were in relatively good health before the storm,
there's not likely to be too much degradation. And because dust storms tend to
warm the environment -- and the 2018 storm happened as Opportunity's location
on Mars entered summer -- the rover should have stayed warm enough to survive.What will engineers at NASA's Jet
Propulsion Laboratory in Pasadena, California, be looking for -- and what will
those signs mean for recovery efforts?A tau below 2Dust storms on Mars block sunlight
from reaching the surface, raising the level of a measurement called
"tau." The higher the tau, the less sunlight is available; the last
tau measured by Opportunity was 10.8 on June 10. To compare, an average tau for
its location on Mars is usually 0.5.JPL engineers predict that
Opportunity will need a tau of less than 2.0 before the solar-powered rover will
be able to recharge its batteries.A wide-angle cameraon NASA's Mars
Reconnaissance Orbiter will watch for surface features to become visible as the
skies clear. That will help scientists estimate the tau.Updates on the dust storm and tau
can be foundhere.Two Ways to Listen for OpportunitySeveral times a week, engineers
use NASA'sDeep Space
Network, which communicates between planetary probes and Earth,
to attempt to talk with Opportunity. The massive DSN antennas ping the rover
during scheduled "wake-up" times, and then search for signals sent
from Opportunity in response.In addition, JPL's radio science
group uses special equipment on DSN antennas that can detect a wider range of
frequencies. Each day, they record any radio signal from Mars over most of the
rover's daylight hours, then search the recordings for Opportunity's "voice."Rover faults outWhen Opportunity experiences a
problem, it can go into so-called "fault modes" where it
automatically takes action to maintain its health. Engineers are preparing for
three key fault modes if they do hear back from Opportunity.Low-power fault: engineers assume the rover went into
low-power fault shortly after it stopped communicating on June 10. This mode
causes the rover to hibernate, assuming that it will wake up at a time when
there's more sunlight to let it recharge.Clock fault: critical to operating while in hibernation is
the rover's onboard clock. If the rover doesn't know what time it is, it
doesn't know when it should be attempting to communicate. The rover can use
environmental clues, like an increase in sunlight, to make assumptions about
the time.Uploss fault: when the rover hasn't heard from Earth in a
long time, it can go into "uploss" fault -- a warning that its
communication equipment may not be functioning. When it experiences this, it
begins to check the equipment and tries different ways to communicate with
Earth.What happens if they
hear back?After the first time engineers hear from Opportunity, there
could be a lag of several weeks before a second time. It's like a patient
coming out of a coma: It takes time to fully recover. It may take several
communication sessions before engineers have enough information to take action.The first thing to do is learn more about the state of the
rover. Opportunity's team will ask for a history of the rover's battery and
solar cells and take its temperature. If the clock lost track of time, it will
be reset. The rover would take pictures of itself to see whether dust might be
caked on sensitive parts, and test actuators to see if dust slipped inside,
affecting its joints.Once they've gathered all this data, the team would take a
poll about whether they're ready to attempt a full recovery.Not out of the woodsEven if engineers hear back from Opportunity, there's a real
possibility the rover won't be the same.The rover's batteries could have discharged so much power --
and stayed inactive so long -- that their capacity is reduced. If those
batteries can't hold as much charge, it could affect the rover's continued
operations. It could also mean that energy-draining behavior, like running its
heaters during winter, could cause the batteries to brown out.Dust isn't usually as much of a problem. Previous storms
plastered dust on the camera lenses, but most of that was shed off over time.
Any remaining dust can be calibrated out.Send Opportunity a
postcardDo you miss Opportunity as much as the rover's team? You can
write a message sharing your thoughtshere.Read more about
Opportunity at:https://mars.nasa.gov/mer/highlights/