Buffeted by ethereal whirlwinds and twisters, the Curiosity Mars rover is wrapping up initial soil analysis operations at a sandy drift where it's been parked for more than a month, project scientists said today. The rover is now being prepared to move on in search of suitable targets for a compact rock drill, the final major sample acquisition system to be tested.
Ashwin Vasavada, the deputy project scientist for the Mars Science Laboratory rover at the Jet Propulsion Laboratory in Pasadena, Calif., told reporters that Curiosity's robot arm had completed five scoops of martian soil, using the sandy material to clean and scour the sampling system and to deposit samples into both of the rover's main internal instrument suites.
The Chemistry and Mineralogy package, or CheMin, uses X-ray diffraction to identify and analyze the minerals in samples collected by Curiosity's robot arm. The Sample Analysis at Mars, or SAM, package, uses a suite of three laser spectrometers to look for signs of organic compounds, a key element in the rover's search for signs of past or present habitability.
CheMin analyzed its first soil sample earlier while SAM initially was used to analyze samples of the martian atmosphere, in part to look for signs of methane. While earlier Earth- and space-based observations indicated methane might be present, Curiosity's initial results found no clearly measurable amounts at the Gale Crater landing site.
Vasavada said Thursday SAM now is processing its first soil samples and "based on a very brief look at that data, the team decided to run a couple of more SAM experiments, which are customized to this particular soil and we're currently in the midst of getting those results back."
"The rover really is doing incredibly well," he summarized. "We've had very, very few glitches to speak of... as we run this very complex piece of technological machinery. There's also the human side of it. The team also has been working very well. We have a lot of different protocols to make sure we don't make mistakes. We have to learn a lot as we operate this thing."
Curiosity landed in Gale Crater on August 6 and after initial tests and checkout, flight controllers directed it to an area known as Glenelg, where orbital photographs show three different rock and terrain types coming together.
For the past 40 or so martian days, Curiosity has been parked by a sand dune, collecting soil samples and giving the flight control team a chance to learn the intricacies of remotely operating the complex sample acquisition system.
Vasavada said engineers now are making plans to resume driving in a bid to find a suitable rock for initial drilling tests. That process is expected to take a month or more to complete.
"We're pretty excited," Vasavada said. "After more than 40 sols (martian days) being parked in front of this sand drift, we're actually going to start moving again. Frankly, the team is pretty excited about that even though it's been a wonderful campaign to analyze the soil."
In the next few days, he said, "I think you'll see us head on to our next site. We still would like to get a little further into this Glenelg region where we see this diversity of rocks and layered rocks and other really interesting terrain. And then we still have a goal in the next month or two of doing the big U-turn and heading up to Mount Sharp."
Mount Sharp is a 3-mile-high mound of layered terrain in the center of Gale Crater where Curiosity is expected to spend the bulk of its planned two-year mission.
In the meantime, the science team is having a field day with Curiosity's initial observations, including an ongoing analysis of the martian weather.
"Most of what we've talked about on this mission is the ancient habitability of Mars," Vasavada said. "But we also have some pretty important goals on this mission of studying the modern environment. And it's a pretty dynamic environment.
"If you were standing next to Curiosity, you'd realize you were on a planet with an atmosphere, an atmosphere that's thick enough that when the sun heats the ground every day, gusty winds rush up and down the slopes of Gale Crater and Mount Sharp and spawn whirlwinds that sweep across the landscape. But the atmosphere isn't thick enough to shield you from the harsh ultraviolet light and the natural high energy radiation coming in from space."
Manuel de la Torre Juarez, a co-investigator with the Rover Environmental Monitoring Station, or REMS, aboard Curiosity, said wind data indicates nearly two-dozen twisters, or dust devils, have nearby or directly over Curiosity.
But that's based on wind speed and direction data alone. The rover's cameras have not yet spotted any such twisters.
"Dust devils on Mars have been seen in missions before," he said. "We have images from previous rovers. Although we've been trying to find them here, we haven't gotten any imagery yet. But we have been able to measure all the environmental variables associated with dust devil activity."
The data show sudden changes in pressure and wind direction that are indicative of twisters. But Juarez said the whirlwinds would pose no threat to astronauts.
"The martian atmosphere is a very low-density atmosphere, the pressures (are what) you would have if you were flying at twice or three times the usual airplane height," he said. "So it would have almost no push on you. It might obscure your vision if it lifts dust, and that's what we're looking for. We're seeing all the signatures, but we're not seeing dust being lifted yet.
"These events are starting to occur more and more often. We have measured 21 thus far, but we are still out of the season where they occur. We expect to see more in the future."
Along with keeping tabs on the weather, another instrument aboard Curiosity is monitoring the radiation environment, a critical factor for engineers contemplating future manned missions.
Don Hassler, principal investigator for the Radiation Assessment Detector, or RAD, said radiation levels at the surface vary daily, rising when atmospheric pressure drops and decreasing with the pressure goes up.
"Basically, we're finding that the Mars atmosphere is acting as a shield for the radiation on the surface and as the atmosphere gets thicker, that provides more of a shield and therefore we see a dip in our radiation dose," he said. "This dip is on the order of 3 to 5 percent and it's very reliable, we see it every day."
But he said it's too early to draw any conclusions about what sort of shielding future astronauts might need, in large part because the effects of major solar storms are not yet known. While Earth's magnetic field acts as a protective shield during solar storms, Mars has no such protection.
"The astronauts can live in this environment," Hassler said. But the big question is how much radiation will an astronaut receive during an eight- to nine-month voyage to Mars, a six-month stay on the surface and then the long flight back to Earth.
"When you add up all those different contributions, you need to stay within your career limits," he said. "So over time, we're going to get those numbers. Since we've been on the surface, we have not yet seen a large solar flare or solar particle event like we saw during cruise (to Mars). When we do see one, that will be very interesting and very important."