Mars Weather Report At Gale Crater
September 29, 2012

Martian Weather Report – Gale Crater Set For Possible Heat Wave

Lee Rannals for - Your Universe Online

NASA's Curiosity rover has sent back a Martian weather report, showing surprisingly mild daytime temperatures.

The rover's Remote Environment Monitoring Station (REMS) is the latest Martian meteorologist, and it has been keeping NASA updated with the weather on the Red Planet around Gale Crater.

The latest data shows the average daytime air temperatures have reached a peak of 42 degrees Fahrenheit on Mars around Curiosity.

Temperatures have risen above freezing during the day now for more than half of the Martian Sols since REMS started recording data.

Because Mars' atmosphere is much thinner than Earth's, and its surface is drier, the effects of solar heating are more pronounced.

While the daytime temperatures seem tolerable, at night the lows get to around -94 degrees Fahrenheit.

The southern hemisphere of Mars is approaching springtime, so the temperatures for the height of the Martian summer could be even higher.

“That we are seeing temperatures this warm already during the day is a surprise and very interesting,” said 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."

He said if this warm trend continues, temperatures in the summer could rise as high as 68 degrees Fahrenheit.

"In the daytimes, we could see temperatures high enough for liquid water on a regular basis. But it´s too soon to tell whether that will happen or whether these warm temperatures are just a blip," Gómez said in the release.

Curiosity's REMS instruments have also recorded slightly higher pressures than expected. The pressure has risen from a daily average of around 730 pascals during the first three weeks after landing, to around 750 pascals. This is considered just a tiny fraction of the average pressure at sea level on Earth.

"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," said Javier Gómez-Elvira, the Principal Investigator of the REMS Instrument. "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."

Another instrument onboard Curiosity called the Dynamic Albedo of Neutrons (DAN) is designed to detect the location and abundance of water. The instrument works because when neutrons hit heavy particles, they bounce off with little loss in energy. But, when they hit hydrogen atoms, they lose half of their energy.

DAN fires a pulse of neutrons at the ground beneath the rover and detects the way it is reflected. The intensity of the reflection depends on the proportion of water in the ground.

“The prediction based on previous measurements using the Mars Odyssey orbiter was that the soil in Gale Crater would be around 6% water," Maxim Mokrousov of the Russian Space Research Institute and the lead designer of the instrument, said in a press release. "But the preliminary results from Curiosity show only a fraction of this."

Over the small distance that Curiosity has rolled, DAN has observed variations in the detector counting rates that may indicate different levels of hydrogen in the ground.

Curiosity's ability to probe the water content in the Martian soil in specific locations allows for a more precise and detailed understanding of water ice on Mars.