NASA communications with Mars rovers soon to go silent

Solar conjunction will interrupt communications with Curiosity, orbiters for the month

Within days, NASA's robotic rovers and orbiters working on Mars will go silent.

Starting today, communication with all machines working on Mars will become spotty -- and within about a week should stop all together, according to Richard Zurek, chief scientist in the Mars Program Office at NASA's Jet Propulsion Laboratory.

NASA is dealing with a solar conjunction, which is when the Sun is almost directly in the path between Earth and Mars, knocking out communications between the two planets.

The solar conjunction has just begun. Communications between Earth and Mars will be minimal for the next week or so and then go dark until around May 1.

Radio beams, carrying instructions to the rovers or orbiters and carrying data and images back to Earth, travel between the two planets in a straight line. During the conjunction, which happens nearly every two years, the Sun won't be directly blocking the path that the communication signals need to travel, but its atmosphere and magnetic field will cause enough static in the communications to garble them or render them undecipherable.

"The sun produces noise in our radio transmissions and that noise gets pretty bad as the path of our radio beam gets close to the Sun," said Zurek. "When you have a noisy signal, sometimes you don't get all the words. We don't want to leave a word like "no" out of a command. We need to get un-corrupted commands to the crafts."

Zurek noted that NASA scientists have given the two working robotic rovers, Curiosity and Opportunity, as well as the orbiters, Odyssey and the Mars Reconnaissance Orbiter, instructions to do minimal work during the time they will be out of contact.

The orbiters will be taking very few measurements as they circle the planet since they don't have the storage capacity to store large amounts of data until it can be downloaded in early May.

The two rovers will remain stationary for the month and will not be using their robotic arms. Curiosity will periodically take some temperature, pressure and wind measurements to monitor the environment, however.

Zurek said he's not nervous about being out of contact with the Mars spacecraft for so long.

"We have been through this before," he said. "We've simplified the activities they'll be doing during this period. We have programs that are tested and we take precautions.... All the working spacecraft on the planet will operate on their own."

The newest rover to work on Mars, Curiosity, won't get back to drilling in its search for water or chemicals that might have enabled Mars to support life, until the solar conjunction is over.

Curiosity has had two computer glitches in the past month. However, Zurek said Curiosity can function normally now and NASA's computer specialists will use the quiet time to try to figure out what caused trouble for the rover's A-side computer and how to keep it from recurring.

He also noted that if there is another computer problem during the solar conjunction, the spacecraft are all configured to automatically put themselves in safe mode and wait until engineers can fix the problem.

Sharon Gaudin covers the Internet and Web 2.0, emerging technologies, and desktop and laptop chips for Computerworld. Follow Sharon on Twitter at  @sgaudin, on Google+ or subscribe to Sharon's RSS feed . Her email address is

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