Martian dust storm silences NASA's rover, Opportunity

A massive dust storm raging across Mars has overcome NASA's aging Opportunity rover, putting the unmanned, solar-powered vehicle into sleep mode and raising concerns about its survival, the US space agency said on Wednesday.

The unusually severe dust storm has blocked out the Sun over one quarter of the Red Planet, blanketing an area spanning 35 million square kilometers (14 million square miles), NASA said.

Opportunity, located in a spot called Perseverance Valley, "has fallen asleep and is waiting out the storm," said John Callas, Opportunity project manager at NASA's Jet Propulsion Laboratory.

"We are concerned but we are hopeful that the storm will clear and the rover will be able to communicate with us."

The storm was first detected on May 30, and grew worse in recent days.

The rover has shut everything down except its master clock, and last communicated with Earth on June 10.

Callas declared a "spacecraft emergency" due to low power.

"In this point we are in a waiting mode. We are listening every day for possible signals from the rover," he said, likening the atmosphere among colleagues to having a family member in a coma.

Opportunity, along with its twin named Spirit, launched in 2003 and landed on Mars a year late to hunt for signs of past life.

Its mission was initially meant to last just 90 days.

The rover "has made a number of discoveries about the Red Planet including dramatic evidence that long ago at least one area of Mars stayed wet for an extended period and that conditions could have been suitable for sustaining microbial life," NASA said in a statement.

Its partner rover, Spirit, became stuck in soft soil on the Red Planet in 2009, and its mission was formally declared over in 2011.

Callas said he is hopeful Opportunity will not fully shut down because the approaching Martian summer means temperatures should not dip below the rover's minimal operating temperature, -55°C (-167 Fahrenheit).

The coldest NASA expects it to get is -36°C (-60 F).

"So we should be able to ride out the storm," he told reporters.