Aug 15, 2012
Hollywood has had its crack at the Red Planet with Civil War veterans, flying saucers and The Governator, now it’s NASA’s turn to tackle Mars and a communications challenge that dwarfs the just-completed “Twitter Olympics.” This takes Big Data to a whole new level.
Launched last November 26, the Mars Science Laboratory space probe mission landed Curiosity, a 1,980-lb mobile research lab, just over a week ago on August 6 to study its climate and geology in preparation for a manned mission to the planet. A part of NASA’s Mars Exploration Program, the $2.5 billion vehicle (rover) is to explore for at least 687 Earth days (1 Martian year) over a range of 3.1 by 12 miles. Curiosity carries 17 cameras, 10 scientific instruments, two computers with four processors and a whopping 4.5 gigabytes of data storage.
Obviously communications is both critical and complex. Curiosity landed less than two miles from its target, after a journey of 350 million miles. At its closest approach, the distance between Mars and Earth is 34.8 million miles, and 250 million miles at its farthest, with the average being 140 million miles. It takes approximately 14 minutes for a signal to travel between the two planets.
Curiosity can communicate with Earth directly in speeds up to 32 kbit/s, but the bulk of the data transfer will be relayed through the the two satellites orbiting the planet, the Mars Reconnaissance Orbiter and Odyssey, which provide more power and have better antennas. Each orbiter can only communicate with the rover for about 8 minutes per day, but data transfer speeds may reach 2 Mbit/s and 256 kbit/s, respectively. Odyssey is capable of relaying UHF telemetry back to Earth in real time, with the transmission taking just under 14 minutes during the landing.
Calling home is via NASA’s Deep Space Network (DSN) antennas at Goldstone, in California’s Mojave Desert; near Madrid, Spain; and near Canberra, Australia. There are three types of traffic: telemetry to report temperature, power and other onboard conditions; computer process reporting; and the actual science data.
Expecting a surge of interest for the August 6th landing, NASA partnered with Amazon Web Services to handle the temporary demand peak via the Cloud. Shortly before the landing, NASA provisioned stacks of AWS infrastructure, each capable of handling 25 gigabits/sec of traffic and used Amazon CloudWatch to monitor spikes in traffic volume and to add more capacity based on regional demand.
The bottom line is that the Mars mission features technology, including data communications capabilities, that were state-of-the-art years ago. However, given that the expedition is set to last two years and a service call would involve a 700-million-mile round trip, reliability and durability are a lot more important than the latest bells and whistles.