by Maggi Glasscoe
Geophysicist

For those of us living in southern California, the risk of earthquakes is a constant fact of life. In fact, small earthquakes occur daily, we simply may not notice them. It’s the larger, more damaging earthquakes that are cause for concern. The infamous San Andreas fault twists its way through much of California, posing significant risk to southern and northern California both-- and as many scientists have said, it’s not a question of if, it’s a question of when, a large earthquake will occur.

Even though the risk of earthquakes is always present, I am sure most people are not thinking about this on the way to work, or as they are watching TV at night, or just generally going about their daily lives. Establishing an earthquake preparedness plan probably doesn’t even come to mind, except possibly when there is a major earthquake elsewhere, or a minor earthquake nearby.

We here at JPL are working on ways to extend our ability to forecast earthquakes. We are combining the state of the art in high performance computing resources and modeling software with satellite observations made from space of small scale motion on Earth. This will enhance our understanding of the fundamental earthquake processes. With projects like NASA/JPL’s QuakeSim, which aims to improve our ability to forecast earthquakes, much as we do the weather, we will also be able to help prepare ourselves for the inevitable.

This is a portion of the 1,200-kilometer (800-mile) San Andreas fault, the longest fault in California. Image credit: NASA/JPL

Unfortunately, should a large earthquake catch us unprepared-- and remember, it’s not a question of if, it’s a question of when-- this could have disastrous consequences. According to FEMA, the annualized loss due to earthquakes is $5.3 billion per year, with 66% ($3.5 billion) concentrated in the state of California alone. A moderate-sized earthquake in the metropolitan Los Angeles region could lead to loss of vital infrastructure-- water via the aqueduct, freeways, possibly even the ports or the airports, rendering us isolated and without resources for not days, but possibly months.

We are told to be prepared in case of an earthquake with 72 hours’ worth of water and food and other necessary emergency provisions. That will certainly see us through the first few days, but if the vital infrastructural resources like our water distribution, sewers, freeways, and other pipelines are taken out, we could be looking at much more than 72 hours without proper services, especially water and power. Are you prepared for such a circumstance?

On November 13, 2008, the United States Geological Survey will lead a disaster preparedness scenario called “The Great Southern California Shakeout.” It will be based on a magnitude 7.8 earthquake along the southern San Andreas fault. Shaking from an earthquake of this size is projected to last up to two minutes, and the modeling that they have done has predicted that sediments in the various basins around the Los Angeles area will trap and magnify seismic waves, amplifying ground motions, much like what occurred in the Northridge earthquake. (To learn more about the “Great Shakeout,” please visit: www.shakeout.org)

This earthquake scenario will also be the basis for the statewide emergency response exercise, Golden Guardian 2008. These complementary exercises are meant to demonstrate our ability to deal with an earthquake scenario in which there would be 1800 deaths, 50,000 injuries, and $200 billion in damage. An earthquake of this magnitude could produce destruction on the scale of the recent Gulf Coast hurricanes or worse.

One thing to keep in mind, though, is that we need to be proactive, rather than simply reactive. That way, when the inevitable moderate to large earthquake does hit, we will be as ready as we can be to deal with it. Exercises like the ShakeOut certainly help to keep the community more aware of the ever-present risk of earthquakes, but we as individuals also need to take the time to make sure that we are disaster prepared as well. That way we can be not only prepared, but resilient.

by Ashley Stroupe
Robotics Engineer

The Mars Exploration Rovers, Spirit and Opportunity, have been exploring the geology of Mars for nearly five years - well beyond their expected lifetime of three to six months. In that time they have made amazing discoveries, most importantly finding proof that Mars was once a much wetter planet that may have been capable of supporting life. Spirit has been exploring a region around a small mountain range that seems to have once had hot water or steam, the very kind of place life might have originated on Earth. Opportunity has been investigating craters in the plains that provide views deep underground and show evidence of flowing water in the ancient past.

I am a roboticist at JPL, and just one member of the large team of people who work together to enable Spirit and Opportunity to explore. My work focuses on getting robots to do things intelligently, both by developing software for robot autonomy and by operating our two spacecraft on the surface of Mars.

Spirit and Opportunity have become like old friends to the operations team. Every day we are anxious to hear the latest news and see the snapshots taken from the new places they are visiting. Working with the rovers never gets routine as each new location brings new circumstances and new problems to solve.

The white-capped Von Braun hill in the distance is Spirit’s next destination.

The challenges of operating Spirit and Opportunity have continued to grow and change as they age, and we have had to develop new ways of driving and operating the robotic arm as capabilities decrease. We are discovering how to operate these rovers in ways for which they were never designed. The discovery process requires a lot of imagination and a lot of practice, both on Earth with our engineering rover and on Mars. It’s this kind of completely new and unanticipated problem that is the most fun for engineers like myself to solve.

Both rovers are now starting to show their old age of 4¾ years (that’s at least 300 in rover-years!), and some parts do not function quite as well as they used to. Spirit has to drive more slowly and constantly monitor her progress to make sure she is staying on the right path to compensate for a broken right front wheel that tends to dig into the soil. Opportunity has limited reach with her instrument arm due to a failed shoulder joint, and has to approach science targets in a very precise way. Despite these limitations, both rovers are now about to embark on difficult journeys which will require them to set new milestones and we will need to learn new ways of driving yet again.

After surviving a very difficult winter, Spirit is soon going to be heading south toward some interesting geological features: a hill called von Braun and a depression called Goddard. Scientists hope investigating these unique features will provide insights into the Martian past. They are looking for additional evidence of hot springs or steam vents that have been hinted at by other observations in this region. Based on comparisons to similar locations on Earth (like deep sea vents), this could be an ideal place for life. Reaching these exciting features requires a long drive through sandy terrain in a very short period of time before next winter arrives. This will mean pushing Spirit to new levels of performance.

Opportunity is getting ready to head for “Endeavour” crater, having finished up its study of “Victoria.”

Opportunity is finishing up her observations of the 800-meter Victoria crater and then will begin a 12-kilometer, two-year odyssey toward a huge crater (about 22 kilometers across) to the southeast. As this means more than doubling the total distance Opportunity has driven in her lifetime, we are excited to be developing new methods to make record distance drives safely. This will require relying on the rover’s onboard autonomy to keep her safe more than ever before as we drive each day well past what we can see.

Spirit and Opportunity’s story of continued exploration - boldly striking out after one new goal after another, far beyond their design lifetimes - is a genuinely inspiring one. It’s as if Magellan circumnavigated the Earth, then paused and said, ‘You know, that’s not good enough. Let’s go to the moon, too.’