And over this past week, that "trouble" has been a Martian dust storm that's larger than the continent of North America, spanning 7 million square miles (18 million square kilometers) when it passed over Opportunity's current location in Mars' Perseverance Valley. It's critical to the rover's survival - NASA believes its rover Spirit failed after it could not harvest enough sunlight to power its survival heaters.
"Full dust storms like this one are not surprising, but are infrequent", NASA said. On Mars, dust storms can crop up suddenly, NASA said in a statement, but it could take weeks or even months for them to subside. NASA has suspended the science operations which are carried by NASA's Opportunity rover, and they are now waiting for the storm to pass. The updrafts of dust can trigger more winds, triggering a feedback loop that fuels the birth of a dust storm.
This storm has affected the Opportunity's solar panels, and it uses to recharge its batteries and helps to give power to the heaters which allow the rover to function in the extremely cold conditions of Mars.
NASA said, "There is a threat to Opportunity if the tempest continues for too long and rover gets freeze while lingering for the skies to clear". This required the team to shift the rover to minimal operations while the massive dust storm rages on.
Having said that, scientists hope that Opportunity can sustain the Martian dust storm because it has seen worst days.
By Sunday night (10 June), the situation had worsened, with NASA noting that the dust storm had intensified in the past several days and that a dark, perpetual night has now settled over Opportunity's location. However, the tau rating of that storm was just 5.5. The measured opacity level of the current storm is 10.8, almost double that of the 2007 event and temperatures in the region have dropped to minus 20 degrees Fahrenheit (minus 29 degrees Celsius).
"Engineers will monitor the rover's power levels closely in the week to come".
Despite limited sunlight to charge its battery, Opportunity also needs to deal with sub-freezing temperatures on Mars.
Despite this, Opportunity did call home yesterday through a communications relay with the Mars Reconnaissance Orbiter - a positive sign despite the worsening dust storm.
NASA's instrumentation shows that the rover's current temperature is around -29 degrees Celsius (-20 degrees Fahrenheit).
The unmanned Curiosity rover has also found increasing evidence for seasonal variations of methane on Mars, indicating the source of the gas is likely the planet itself, or possibly its subsurface water.