An Advocate for Gusev Crater

Image credit: Seth Shostak
Dr. Nathalie Cabrol spoke with me about her experiences as a scientist working with the Spirit team. This is a personal story, a snapshot taken in the midst of the swirl of events as Spirit prepares to rove the surface of Mars. She’s been at JPL since the Spirit rover landed. When asked if it’s been hard to sleep, Nathalie replied, “If this is a dream, don’t wake me up! I’ve been waiting for 15 years to see this place we’ve been dreaming about. It’s as beautiful as I expected! I’m excited and eager to step off the lander and explore Gusev Crater.”

For more than a decade, Dr. Nathalie Cabrol has been going to Mars every morning as she pursued her dreams of exploring Gusev Crater. She’s a planetary geologist with the SETI Institute and NASA Ames Research Center. In a unique scientific partnership with her husband, Dr. Edmond Grin, Cabrol studied and successfully proposed, and promoted Gusev Crater as a landing site for the martian rovers. Gusev may hold an ancient lakebed; Spirit is seeking evidence of water on Mars.

Cabrol’s dreams came true when Spirit successfully landed in Gusev Crater on January 3, 8:35 PM PST. Cabrol described the landing with excitement: “These first few days are baby steps in our giant leap toward understanding the environment of Mars. The rover landing went perfectly. We had only one tense moment after the 4th bounce when we lost contact, but we regained contact after a few minutes, and all was well. Actually, Spirit landed 32 times as it bounced across Gusev before coming to rest in the vast plain encompassed by the crater. It was a fantastic achievement! The engineers are doing the checkout now. For them, it’s business as usual, and all seems to be going well.”

After coming to a stop, the lander paused; its great balloons deflated. The rover came to life, unfolded, and phoned home. Like any good tourist, it sent a postcard home. It’s the first view of a new place, a new terrain on Mars.

Cabrol said that she felt “at home” when she saw the first views of Gusev Crater. Here on Earth, she considers herself to be a “desert rat”. She does field research in some of the most inhospitable locations on the planet such as the Atacama Desert and Lincancabur volcano in South America, extreme environments that offer Earth-analogs for Mars. Viewing Gusev through the eyes of Spirit, Nathalie sees “landscapes we know on Earth. Mars is really an Earth-like planet. But, it’s a new place on Mars. Gusev is very different from the Viking and Pathfinder landing sites. At Gusev we see lots of smaller rocks. There are fewer boulders than we saw at the other landing sites. We’re in new terrain with Spirit.”

How does she feel about where Spirit finally landed? “We landed in the sweet spot. Gusev is known to be dusty, but we landed where most of the dust has been removed in places by winds and dust devils. Some rock looks clean enough, and this will make our scientific work much easier. We’ll spend less energy cleaning and scraping the surfaces of rocks we wish to study because there appears to be little dust on them,” said Cabrol. And there are lots of rocks to study; everywhere around the lander the plain is strewn with rocks.

She’s interested in understanding the population of stones: the distribution of their shapes and sizes, the morphology and composition of the rocks, and how they were transported to their present locations. As the new, hi-resolution panoramas stream in over the next few days, she’s eagerly looking forward to seeing both the visible and infrared images as these will begin to reveal the mineralogy of the rocks.

There are other great targets for Spirit: as they retracted, the airbags scraped the surface and revealed differently colored soil that is intriguing in both its color and apparent stickiness. It’s a puzzle that requires closer inspection. There’s a nearby depression that could be an impact crater, Sleepy Hollow that offers the opportunity to get a close-up look as subsurface materials. Cabrol explained, “With the 3-D glasses, Sleepy Hollow was a blast! It just jumped out and looked a lot like as an impact crater with a solid rim armored with rock. It’s spectacular! That depression makes our lives as geologists easier. It’s like an excavated surface–so we can see what’s below.”

Why Gusev? The scientific motive for the Mars Exploration Rovers is to seek evidence of water and life, extant or extinct, on Mars. Gusev may be an ancient lakebed, and Spirit’s onboard scientific instrument package provides the virtual tools to Earth-bound geologists to look for evidence of sediments and water in the past. Where to look? There’s a team of about 50 scientists assembled at JPL. “Ideas and hypotheses are flying about the room as we actually see Gusev Crater. We are discussing and debating the best targets for Spirit as the images come back to us on Earth. It is so exciting!” said Cabrol.

Beyond the immediate terrain, there are hills and mesas. Until the stereoscopic panoramas arrive at Earth in the next few days, it is difficult to determine the distance to these features. So, it is not known whether Spirit can travel to these hills and, perhaps, come to the shore of an ancient lake. Mission success is defined as at least 90 sols (Mars days) of exploration and science, but how long can Spirit continue to rove? “As long as the rover and the scientists remain healthy, we’ll keep exploring. It’s so challenging to get to Mars, and land successfully that we have to go on as long as possible.”

Today, Cabrol is making her first virtual steps on the Martian surface. In the future, she dreams of going to Mars. When asked about the Saturday night landing, she said, “There’s only one thing that didn’t land on Mars, and that’s me!” For now, she’s there virtually and she just finds Gusev Crater “beautiful. It’s simply beautiful.”

Original Source: Astrobiology Magazine