Rover nets Mars climate secrets

Nasa has two rovers on the planet

The US space agency's robotic Mars explorer Spirit has sent back vital new information on the Martian atmosphere.

The data could help scientists plan safer entry, descent and landing stages for future Mars missions, particularly if those missions are to be manned.

Temperatures show huge fluctuations of up to several degrees in a minute.

"The rovers are giving us good profiles of the temperature structure of the atmosphere," mission scientist Don Banfield told a news conference.

"We didn't have very good data on the atmosphere prior to this."

Temperature measurements were taken using the Miniature Thermal Emission Spectrometer (Mini-Tes).

"This is a new way to use the instrument that we hadn't thought about until we got to the surface," Dr Banfield explained to journalists in Pasadena, US.

It's going to help us maybe in the future put rovers safer on the ground Don Banfield, Nasa

"We realised that what we could is stare up at the sky and take a spectrum every two seconds and from that spectrum get a temperature profile every two seconds.

"Mini-Tes was originally designed to look down at the minerals, but it can also look 30 degrees above the rover deck, or even a little bit higher.

"It's going to help us maybe in the future put rovers safer on the ground," he added.

Temperature jump

Temperatures near the Martian surface show huge jumps within the space of a minute.

"[There are] these huge jumps of something like four Kelvin or seven degrees Fahrenheit that come intermittently on a roughly minute timescale," said Dr Banfield.

Round grains litter the floor of Opportunity's landing site

"If you were to set your thermostat in your house up by seven degrees, you would certainly feel that."

This is due to convection. As the ground heats up in the morning, it transmits the heat to the atmosphere.

"The fact that we're seeing these temperature profiles will allow us to get these better for future attempts at Mars."

There were grave concerns before the rovers landed safely that wind shear in the Martian atmosphere would wreak havoc during entry, descent and touchdown.

The Spirit rover has broken its own one day distance record on the surface of Mars, driving 24.4 metres (80 feet) to a group of rocks dubbed Stone Council.

Meanwhile, Spirit's twin Opportunity sent back more pictures of the strange round soil grains that seem to be falling from the rocky outcrop that sticks out of the rim of the crater where it landed.

Opportunity is continuing to map out a outcrop of intriguing layered rocks sticking out of the rim of the crater where it has landed.

The rover had run into trouble driving up the rim of the crater.

But engineers studied the problem on Earth using dry sand and learned that they needed to set the controls to overshoot their target while going uphill, while undercompensating when going down.