And the weather on Mars is… really very pleasant

Preliminary weather reports from the Curiosity rover’s Remote Environment Monitoring Station (REMS) are showing some surprisingly mild temperatures during the day. 

The mercury’s risen above freezing on more than half the Martian days – known as Sols – since REMS started recording data. Average daytime air temperatures have reached a peak of 43 degrees Farenheit at 2pm local time and – most excitingly of all – it’s looking as if temperatures might hit the seventies later in the summer.

Martian explorers will still need their thermal undies at night, though, when temperatures can sink to -94 degrees F.

“That we are seeing temperatures this warm already during the day is a surprise and very interesting,” says Dr Felipe Gómez of the Centro de Astrobiología in Madrid.  

“It’s very early days and we are only now being able to test our models against REMS observations.  If this warm trend carries on into summer, we might even be able to foresee temperatures in the 20s [Celsius] – and that would be really exciting from a habitability point of view.”

At these temperatures, of course, liquid water could be seen on a regular basis. But, says Gómez, “It’s too soon to tell whether that will happen or whether these warm temperatures are just a blip.”

REMS pressure sensors have also been recording slightly higher pressures than expected. In winter, Mars becomes cold enough for carbon dioxide at the poles to freeze, forming seasonal ice caps – and removing it from the atmosphere means atmospheric pressure varies through the year.

“The pressure data show a very significant daily variation of pressure, following a fairly consistent cycle from Sol-to-Sol. The minimum is near 685 pascals and the maximum near 780 pascals,” says Javier Gómez-Elvira, principal investigator of REMS.

“The majority of the variation is due to large scale waves in the atmosphere called tides. These tides are different from tides in the Earth’s ocean because they are forced by heating due to the sun rather than the gravitational pull of the moon. The tides are sensitive to the distribution of cloud and dust in the atmosphere, and also the large scale pattern of winds – rather like the jet streams on Earth.”