Martian dust storm causes loss of contact with Opportunity rover

Lack of access to sunlight means solar panels are unable to recharge rover's weakening batteries.
By Laurel Kornfeld | Oct 03, 2018
Enveloped by a dust storm that has been raging near it since late May, NASA's Opportunity rover failed to make contact with Earth during a planned check-in, indicating its power levels may be dangerously low.

One of two identical rovers that arrived on the Red Planet in 2004 on a 90-day mission, Opportunity has been exploring Mars for more than 14 years. Its twin, Spirit, functioned until June 2010, when one of its wheels got stuck in Martian terrain, putting it in a position where it could not get the necessary sunlight to recharge its batteries during winter.

In its near decade-and-a-half on the Red Planet, Opportunity has survived several dust storms, including a powerful one in 2007, when mission control halted communications for four days to save power.

First observed by NASA's Mars Reconnaissance Orbiter (MRO) on May 30, the current dust storm started near Perseverance Valley, Opportunity's current location. It rapidly spread and became more powerful to the point that it now covers a quarter of the entire planet.

Within a week of the storm's start, the rover was engulfed in dust. Opportunity is now in perpetual darkness, as its solar panels are not getting the necessary sunlight to recharge its batteries.

Between June 2 and 10, the rover's power levels plummeted from 645 watt-hours to 22-watt hours. The power drop triggered Opportunity to put itself in "low power fault mode," shutting down everything but its internal clock.

Once the storm abates and its solar panels get sufficient sunlight to recharge its batteries, Opportunity will emerge from this low-power state and automatically attempt to contact Earth.

Additional power depletion could cause Opportunity to shut down its internal clock. If that happens, it will still be able to contact Earth when conditions improve, but the timing of its contact attempts will be much less predictable.

The fact that the rover failed to make its last scheduled contact indicates it likely has shut off its internal clock, putting itself in a state where communication is not possible.

Scientists now expect the dust storm to continue growing and envelop the whole planet within the next several days.

During contact with mission control last week, Opportunity measured its internal temperature at minus 20 degrees Fahrenheit (minus 29 degrees Celsius). Cold temperatures could damage and even possibly destroy Opportunity's batteries.

While the dust around Opportunity is thicker than it was during any previous dust storm, Martian seasonal changes could save it from freezing. Summer is approaching, meaning temperatures are warming. Temperatures are unlikely to drop below minus 33 degrees Fahrenheit (minus 36 degrees Celsius).

Opportunity is capable of withstanding temperatures as low as minus 67 degrees Fahrenheit (minus 55 degrees Celsius).

John Callas of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, and Opportunity project manager, said he remains optimistic about the rover's ability to survive the storm.

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