THE NASA rover ‘Opportunity’, which is stationed on Mars, has fallen silent as a gigantic dust storm enveloped the Red Planet in the past 24 hours.

The storm is so large — an estimated 40 million kilometres squared — that it has completely obscured the planet and blotted out the Sun.

Flight controllers tried late on Tuesday night to contact Opportunity, but the rover did not respond.

The storm has been growing since the end of May and now covers one-quarter of the planet.

Controllers expect it will be several more days before there is enough sunlight to recharge Opportunity’s battery through its solar panels.

NASA says the battery is likely so low that only a clock is still working, to wake the spacecraft for periodic power-level checks.

NASA launched the twin rovers Opportunity and Spirit in 2003 to study Martian rocks and soil.

Spirit hasn’t worked for several years. Opportunity, however, has kept exploring well past its expected mission lifetime.

NASA will host a media teleconference at 1:30pm. EDT Wednesday, June 13, to discuss a massive Martian dust storm affecting operations of the agency’s Opportunity rover and what scientists can learn from the various missions studying this unprecedented event.

The storm is one of the most intense ever observed on the Red Planet.

As of June 10, its size was comparable to the geographical span of North America and Russia combined — and may grow larger.

The storm has blocked out so much sunlight that it has effectively turned day into night for Opportunity, which is located near the centre of the storm, inside Mars’ Perseverance Valley.