Date: June 11, 2010
Title: Spirit Won’t Give Up The Ghost
Podcaster: Bob Hirshon, AAAS
Description: The Spirit and Opportunity Mars Rovers have performed for years beyond their life expectancy. When Spirit’s wheels got trapped in some soft soil in January, and NASA scientists were unable to free it, you might have thought Spirit’s mission was finally over. But the NASA team has now improvised a new set of research studies the robot can perform as a stationary platform by using its instruments in novel ways. So while Spirit’s roving days are over, its mission is about to begin a new chapter.
Bio: Bob Hirshon is Senior Project Director at the American Association for the Advancement of Science (AAAS) and host of the daily radio show and podcast Science Update. Now in its 23rd year, Science Update is heard on over 300 commercial stations nationwide. Hirshon also heads up Kinetic City, including the Peabody Award winning children’s radio drama, McGraw-Hill book series and Codie Award winning website and education program. He oversees the Science NetLinks project for K-12 science teachers, part of the Verizon Foundation Thinkfinity partnership. Hirshon is a Computerworld/Smithsonian Hero for a New Millenium laureate.
Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by the Education and Outreach team for the MESSENGER mission to planet Mercury. Follow the mission as the spacecraft helps to unlock the secrets of the inner solar system at www.messenger-education.org.
Additional sponsorship for this episode of 365 Days of Astronomy has been provided by Kylie Sturgess and the Token Skeptic podcast, a weekly show about superstition, science and why we believe – at www.tokenskeptic.org.
365 Days of Astronomy Podcast
June 11, 2010
Spirit Won’t Give Up the Ghost
by Bob Hirshon, AAAS
Welcome to 365 Days of Astronomy podcast. I’m Bob Hirshon, host of the AAAS Radio show and podcast, Science Update. Just over a year ago, the Mars rover Spirit got stuck in some extremely soft dirt in an area known as Troy. But unlike previous, similar mishaps, this time, despite many attempts, the mission team could not get it free.
Dave Lavery is NASA Program Executive for Solar System Exploration and oversees the Mars rover program.
And we basically had a choice to make: Do we want to spend a lot more time and energy and keep working to back the rover out of its current position, or do we want to take advantage of the fact that it’s still, it’s in one location that’s a known place and it’s not moving, to actually do a different type of science than we did before?
In February, with Martian winter fast approaching, that’s what they decided to do.
Now considering the amazing history of Spirit and its sister vehicle Opportunity, this wasn’t exactly sad news. The rovers were originally intended to perform for about 30 days. That was over six years ago. So both vehicles have long since completed their primary science missions, and gone on to conduct a long series of additional, improvised science missions that have added a vast amount of information to what is known about the planet.
Still, being stuck uselessly in the sand would have been an ignominious end to such a heroic machine. So Dr. Lavery has high hopes for this new, stationery mission for Spirit.
So what we’re doing is transitioning into a radio science program, use the fact that we have a live, active science investigation platform sitting in one static location on the surface of the planet for a long period of time and that will allow us to do a lot of radio science that will allow us to more accurately measure what the interior of the planet mars is like—whether there is a molten core, how big it is, how active it is, things like that. So that’s the science plan that we’re transitioning into.
He says this sort of mission wasn’t possible when the rover was roving.
What we want to do is get a very specific, very precise measurement from the same spot on Mars over and over and over again for about six to nine months. And it’s actually that accumulation of data from a known location that’s repeatable over many many iterations that actually gives us the information we need about what the interior of the planet is actually like. When the rover is driving around and moving, you can’t differentiate the differences in the signal that are caused by the planet versus those that are caused by the movement of the rover. So what we want to do is take advantage of the fact that the rover is not moving and pull that part of the (?) noise and signal out, and all that remains are the effects created just by the planet.
These sorts of measurements weren’t a part of the original plan. And, in fact, Spirit has no instruments designed to perform this sort of data collection: Lavery says they’re using the rover’s radio as the instrument.
What we’re doing is making great use of the radio signal itself and the precise amount of time it takes for the radio signal to get from Mars back to Earth and timing that signal, in addition to the other instruments that are actually on board. For example, we don’t really have a seismometer on board the rover itself. However we do several accelerometers, and we can use that information, interpolate that information to sort of crudely create the effect of a seismometer to measure the effects of the planet and gravity.
And how does that tell you anything about the planet’s core?
What you’re looking at are differences in the radio signal and the time of flight as well as the exact amplitude of some of the fluctuations in the frequency that may be caused as the core of the planet, based on how big it is, has effects on the radio signals. And so as the core rotates, if it’s still active and liquid and rotating—it’ll actually have an effect on the radio frequency, the amplitude, and the frequencies, as well as the time of flight back. And—just very minute and small amounts. And what we’re looking at is can we aggregate those small amounts over enough time to pull a real signal out of it.
He says that collecting that many readings will take between six and nine months, depending on how strong a signal they can generate. But they can’t start right away.
Because right now Spirit is in the depths of local Mars winter. So she’s actually hibernating right now. But as soon as the hibernation period is over, we start to get more sunlight back on the solar arrays, the rover wakes up, then we begin to starting to do this static science radio astronomy program in earnest.
That will be sometime in July or August.
But once that signal starts to come back up, then we’ll start monitoring on a daily basis to see how much power we’re getting and once we get sufficient power, then we’ll start the radio science campaign.
Despite Lavery’s optimism, it’s not a sure thing that Spirit will emerge from hibernation. The rover has already put in thousands more hours than it was built for, it’s now experiencing temperatures at the lower limit of its tolerance, its solar panels are dusty and they’re not oriented optimally toward the sun.
On the other hand, this is a robot that has beaten the odds many times already, so it certainly wouldn’t be wise to bet against it now.
We’re in a completely unknown realm as far as how well these machines can continue to function. We’re just looking at every single new day literally as precious resource that we want to take advantage of for as long as they happen to last.
We’ll check back with Dave and the Spirit team later this year to see if Spirit wakes up and cheats death yet again. For the 365 Days of Astronomy Podcast, I’m Bob Hirshon.
End of podcast:
365 Days of Astronomy
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