"This team has a very strong bond with the rover, a very tight emotional connection with it", said John Callas, Opportunity project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
And while there's a chance the hardest-working rover on Mars won't make it through the storm, scientists are still hopeful. As of June 10, it covered more than 15.8 million square miles (41 million square kilometres) - about the area of North America and Russian Federation combined. Luckily, NASA has since made contact with the rover, which is encouraging sign.
A NASA rover on Mars has been knocked out by big dust storm that envelops the planet and blots out the sun.
An animation showing the dust storm, highlighted in an exaggerated red, expanding to cover most of Mars.
The opacity of the storm, an indication of how effectively it is blocking out sunlight, is at record levels for Opportunity, making it hard for the rover's solar arrays to fully charge its batteries.
If the rover's power dips even lower than it is now, it's possible that Opportunity's clock could turn off, meaning that NASA will need to remain vigilant to listen for any pings from the rover that would come at somewhat random intervals if it's able to come back online, Callas said.
NASA's Curiosity rover - the agency's other functioning rover on Mars - is also seeing some haze in the atmosphere due to the dust storm, but it isn't experiencing any ill effects from the storm, NASA said.
The solar-powered Opportunity rover landed on Mars in 2004 and was supposed to last 90 days, though it has operated for more than 14 years.
Engineers are also concerned that freezing temperatures caused by the storm could damage the rover, as cold is thought to be what led to the breakdown of NASA's Spirit rover - Opportunity's twin - in 2010.
The NASA team has used the rover more than 50 times longer than originally planned and it survived such a storm before in 2007.
Whereas the previous storm had an opacity level (tau) of about 5.5, this new storm has an estimated tau of 10.8. If the batteries are insufficiently charged, the computer will again enter a sleep mode, the same mode used each night to power down the rover.
'This latest data transmission showed the rover's temperature to be about minus 20 degrees Fahrenheit (minus 29 degrees Celsius). The dust storm is actually keeping it relatively warm on Mars, so Opportunity will likely stay warm enough to turn back on when the dust clears. "The same swirling dust that blocks out sunlight also absorbs heat, raising the ambient temperature surrounding Opportunity". That wind kicks up yet more dust, creating a feedback loop that NASA scientists are still trying to understand. Such storms last for weeks, sometimes months, but stop when the air temperatures equalize. NASA ceased Opportunity's science operations on June 4 as engineers prepared to secure the craft against the storm, Callas said. "The rover hits a steady-state temperature", NASA's Jim Watson told reporters, "at which point there's a balance between what little energy is coming out of the rover and what's lost to the environment". And if there's one thing Opportunity has proven, it is that it's capable of enduring! At this rate, it could have many more years of life left in it!