How will the Curiosity Mars rover phone home? (+video)
A pair of orbiters circling the Red Planet will help signals from NASA's Curiosity Mars rover on their long journey to Earth.
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Mission managers back on Earth will be eagerly awaiting news of the $2.5 billion Mars Science Laboratory rover, which is due to land at 10:30 p.m. PDT on Aug. 5 (1:30 a.m. EDT, 0530 GMT, Aug. 6), beginning a two-year mission. In fact, for the first 90 days of the mission, controllers will work together as if each day were 24 hours and 40 minutes long — the approximate length of a Martian day.
"It's to get the most use possible for the rover while it's fresh and new on Mars," says Ashwin Vasavada, MSL's deputy project scientist. "Ideally, we'd do it for the next 10 years, but the reality is, after 90 days it's better for everyone to go back to Earth time."
Controllers on Earth will have three ways of hailing Curiosity as it trundles around Gale Crater. Two are direct links through NASA's Deep Space Network, a worldwide collection of antennas. It provides both a fixed low-gain antenna, best for basic commands and emergencies, and a pointable high-gain antenna for complex commands. [11 Amazing Things NASA's Mars Rover Can Do]
Curiosity also has a higher-speed ultra-high frequency (UHF) communications system that can send signals to spacecraft orbiting Mars, which in turn would relay them to Earth.
To send back imagery, Curiosity must stay in touch with the Mars Reconnaissance Orbiter and Mars Odyssey spacecraft, two probes orbiting Mars that each can talk to the rover twice a day. (Odyssey is currently recovering from the loss of one of its three reaction wheels.)
"The high-gain antenna only gives us a moderate amount of bandwidth," Vasavada told SPACE.com. "We can transmit a series of commands every morning. But it's not enough to transmit hundreds of images every day."
For navigation purposes, the rover has two guidance systems on board. One keeps the rover apprised of its position on the Red Planet, which is needed to find Earth in the sky and keep in contact with NASA. The other system calculates how close Curiosity is to rocks and other obstacles.