Curiosity Mars rover takes some downtime

This panorama prepared by Ken Kremer and Marco Di Lorenzo shows the rover's robot arm with Gale Crater's central mound, Mount Sharp, in the background (www.kenkremer.com)

The US space agency's Curiosity Mars rover is entering several weeks of low activity as the Red Planet moves behind the Sun as viewed from Earth.

The alignment interferes with normal communications.

Curiosity will remain stationary throughout the rest of April, collecting only weather and other environmental data.

Periodically, the robot will send a beep via its low-gain antenna to inform controllers on Earth that all is well.

"It's a very simple signal, like a 'yes' or a 'no', and that will tell us that the vehicle is OK, or at least doesn't believe it has any problems," Jim Erickson, the Curiosity deputy project manager at Nasa, told BBC News.

The rover landed on Mars in August last year and has been exploring the floor of the equatorial Gale Crater ever since.

Locked off

So-called solar conjunctions that put Mars and Earth on opposite sides of the Sun occur roughly every 26 months.

Radio transmissions become highly degraded during these periods.

Messages sent from Mars, such as pictures, can suffer data gaps. Of greater concern, however, is the possibility that commands from Earth sent up to spacecraft could become corrupted. Nasa will not even attempt such practice as this could confuse the computers on the spacecraft.

Instead, Curiosity has been sent a series of instructions in advance to hold it over. The robot will not be commanded again until 1 May.

Curiosity has been being put in a parking mode with its camera mast and robotic arm locked in safe positions.

Only the REMS meteorological station and the RAD experiment, which senses the radiation environment around the rover, will be left collecting data.

This information will be transmitted to Nasa's two satellites at Mars.

But because the orbiters are also affected by the same radio interference, they will not get a clean data relay until after solar conjunction.

Team relief

The Odyssey satellite may be able to get some information back to Earth, but the Mars Reconnaissance Orbiter will simply store Curiosity data until the conjunction is over.

Nasa's other Mars rover, Opportunity, has already gone through four solar conjunctions since landing on the Red Planet in 2004.

It, too, will engage in some low-level science activity that does not involve driving.

Jim Erickson said the next three weeks offered some important downtime for engineering and science teams, especially on the Curiosity project.

"We're telling the troops, 'you've really done a great job, you've been pushing hard since landing, but now's the time to go home and remember what your families look like. And we'll see you again in May'."

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