|Apr 21, 2013, 12:09 AM||#351|
Mars rover Curiosity back in action after engineers fix technical glitch
NASA’s Mars rover Curiosity is back in action, after engineers have fixed the software snag which put the robot on a precautionary ‘standby’ mode earlier this week.
“We expect to get back to sample-analysis science by the end of the week,” said Curiosity Mission Manager Jennifer Trosper of NASA’s Jet Propulsion Laboratory (JPL), Pasadena, California.
Curiosity went into a precautionary ‘safe mode’ on March 16, after being sidelined by a computer glitch for the second time in three weeks.
The safe-mode entry was triggered when a command file failed a size-check by the rover’s protective software. Engineers detected a software bug that appended an unrelated file to the file being checked, causing the size mismatch.
Engineers diagnosed the software issue and know how to prevent it from happening again, according to a JPL statement.
Next steps will include checking the rover’s active computer, the B-side computer, by commanding a preliminary free-space move of the arm.
The B-side computer was provided information last week about the position of the robotic arm, which was last moved by the redundant A-side computer.
The rover was switched from the A-side to the B-side by engineers on February 28 in response to a memory glitch on the A-side. The A-side now is available as a back-up if needed.
However, Curiosity only has about two weeks to continue analysing the drill sample it recently collected from a Yellowknife Bay rock, before it is forced to take another break.
Beginning April 4, all commands to the rover will be suspended for four weeks due to solar system geometry of Mars passing nearly directly behind the Sun from Earth’s perspective.
The suspension is a precaution against interference by the Sun corrupting a command sent to the rover.
|May 5, 2013, 03:59 AM||#352|
Back From Far Side of the Sun, Curiosity Rover Gets Ready to Resume Science
A beautiful mosaic stitched together from Curiosity images from before the Mars conjunction, showing the rover’s arm and Mount Sharp in the distance
After a long period of silence, NASA has reestablished its link with the Curiosity and Opportunity rovers and is getting ready to resume science operations on Mars.
The Red Planet has been hidden behind the sun for most of the month of April, meaning that signals sent from here to there could get interrupted or scrambled. The Mars flotilla — which includes the two rovers, two orbiting satellites, the Mars Reconnaissance Orbiter and Mars Odyssey, and ESA’s Mars Express spacecraft – have been on their own for this duration. The rovers have been banned from driving and have mostly been taking routine measurements. Curiosity, for instance, has monitored radiation and atmospheric changes from its position at Gale Crater.
But now the wait is over. Both rovers are reporting healthy status. The smaller and older Opportunity rover, which has been on Mars since 2004, is out of standby mode and executing new instructions from NASA. The first thing in store for Curiosity is a software update.
“From time to time on your laptop, you need to update your operating system,” said geologist John Grotzinger of Caltech, the rover’s project scientist. “Every couple of months we also upload a new version of Curiosity’s flight software and, when it’s convenient, we transition to it.”
The newest 225-million-kilometer software patch will improve the rover’s efficiency. Certain operations, like making sure the robot’s ChemCam wasn’t pointed at the sun, previously required a human at mission control to be in the loop. Such processes are now automated.
The software update won’t go as quickly as getting the newest version of an iPhone app. It will take the rest of the week to make sure everything is properly installed. After that, Curiosity will be ready to resume doing science.
Grotzinger said the science team is looking to document their drill site, perhaps getting some close-up photos and X-ray measurements inside the drill hole. After that, they will probably look to bore another hole about one or two meters from the original drill site to see if there are any mineral variations in the rock.
“Then we’ll make sure there aren’t some last minute things to wrap up and begin our plan to head to Mount Sharp,” said Grotzinger, referring to the 5.5-km-high peak at the center of Gale Crater that is Curiosity’s main target.
The rover hopes to investigate the mountain in order to better understand its watery history and whether or not it could have definitively supported life in the past. Curiosity moves slowly, about the same speed as a crawling baby, so it will take a while to reach Mount Sharp, likely after a few stops at areas of geologic interest. Grotzinger is optimistic that the long trek will begin this summer.
|May 9, 2013, 01:37 PM||#353|
Curiosity Mars rover to investigate classic rock type
Nasa's Curiosity rover will soon return to a spectacular set of rocks on Mars to confirm their deposition in water billions of years ago.
The Shaler outcrop pictured with Mount Sharp in the distance. This panorama was built from pictures taken by the rover's navigation cameras, and assembled by Ken Kremer and Marco Di Lorezo
This conjunction, as it is known, plays havoc with communications and the robot was forced to park up while the celestial mechanics took their course. But the ability to send commands has now been restored, and scientists have a heavy schedule of tasks they want the rover to work through.
The vehicle is currently sitting in a small depression on the floor of Gale Crater known as Yellowknife Bay. Just before conjunction, it drilled into a mudstone in a rock unit referred to as Sheepbed and found further compelling evidence for a watery past in Gale - sediments that possibly once formed a lakebed.
Curiosity is due to turn its drill again in this mudstone for further analysis before climbing out of Yellowknife Bay and heading for the crater's big central mountain, Aeolis Mons (Mount Sharp).
But almost as soon as it starts that journey, the robot is going to stop at some of the most spectacular rocks seen so far on the mission.
Scientists have mentioned the so-called Shaler outcrop but haven't yet spoken about it in great detail.
Shaler is a classic example of cross-stratification - a structure produced from thin, inclined layers of sediment.
You'll have seen examples in a river or on a beach.
The turbulent flow of water creates undulations in the bed sediments - a series of ripples or dunes that slowly migrate in the direction of the water current.
The sediment grains bouncing along the bed get pushed up the rearward-facing slope (stoss) and then avalanche down the other side (lee).
As they cascade downwards, they form discrete layers that can be preserved over geological time as laminations in the rock.
If you look at the pictures of Shaler taken by Curiosity, you can see how subsequent erosion has taken its toll on this preserved bedform. Layers just a few millimetres thick are now falling out. Thin plates of rock are strewn over the ground.
For anyone about to begin their study of geology, cross-stratification, or cross-bedding, will be one of the first topics to be covered in "sedimentary processes", and Shaler is a beautiful example.
"It's textbook; you could use the Shaler pictures of cross-bedding in an intro-textbook," Prof John Grotzinger, the project scientist on the Curiosity mission, told me.
"For a while Shaler really was a contender to drill. We were discussing it as a team and then we drove down into Sheepbed and thought 'wow, well let's put Shaler off to the side'."
Sedimentary processes at work on Earth are also seen in play on the Red Planet
But scientists will now get a chance to study Shaler in more detail in the coming weeks, using the rover's cameras and survey instruments.
They're keen to establish for sure how those thin layers were built.
At first glance, it might seem obvious that it was through the action of flowing water (fluvial), but the Curiosity team needs to rule out the possibility that these rocks were deposited by the wind (aeolian) or by some kind of surge, such as the fast-moving clouds of gas and rock that will often plummet down the sides of particular types of volcano (a pyroclastic surge).
"Aeolian. That's the one you always have to falsify on Mars because it's a windy planet," says Prof Grotzinger.
This can be done by looking at the size of the rock grains in the layers; and from the pictures taken of Shaler on the way into Yellowknife Bay, it seems the particles are simply too big to have been carried in the wind. Further imagery will confirm that.
There are ways to discount the base surge idea, also, explains Dr Lauren Edgar from Arizona State University.
"If you're migrating faster than you're accumulating, you just preserve the lee side because you're eroding on that stoss side. However, in a pyroclastic surge environment, you often have high rates of accumulation relative to migration, so as the bedform is migrating it is also rapidly accumulating more sediment. This means you tend to get the full stoss-side and lee-side preserved," she told BBC News.
Another check is to look for a diversity of flow directions. A surge deposition will tend to move radially away from a point source. Cross-stratification from water currents, on the other hand, will likely show movement in assorted directions.
To be honest, it's hard to think where a surge might have come from in Gale. There are no volcanoes around.
But Curiosity should nail all this with its return visit to Shaler.
Here's the really clever thing, though, I think. Cross-stratification is one of those rock structures that is so well understood, you can use it to pull out some amazing information about the past environment in which it occurred.
I've mentioned the direction of flow, but you can also determine the depth of the water and the speed of the water - not precisely, but to a good approximation.
Ponder that for a moment. That's information about an environment that existed on another planet millions of kilometres away.
"The other really nice thing," says Prof Sanjeev Gupta, a Curiosity science team-member from Imperial College London, "is that what you're recording at Shaler is perhaps just a few minutes to hours of migration in those dunes, and then that activity has been preserved for billions of years. That's stunning."
Edgar, Grotzinger and Gupta presented their latest thinking about Shaler on a poster at the recent European Geosciences Union General Assembly. Two of their colleagues on the work have some particularly nice web resources related to cross-stratification.
Prof Dawn Sumner from the University of California at Davis describes how the layers are built in a YouTube video. Dr Dave Rubin, at the US Geological Survey, has a collection of animations to show the different forms. And click here to see a tank experiment. Watch the ripples migrate into view from the left.
After landing on the floor of Gale Crater last August, Curiosity drove east. It passed Shaler on its way into Yellowknife Bay. When the rover drives back out in the coming weeks, it will stop at Shaler for a closer look
|May 11, 2013, 02:25 PM||#354|
Curiosity rover team selects second drilling target on Mars
This map shows the location of "Cumberland," the second rock-drilling target for NASA's Mars rover Curiosity, in relation to the rover's first drilling target, "John Klein," within the southwestern lobe of a shallow depression called "Yellowknife Bay." Cumberland, like John Klein, is a patch of flat-lying bedrock with pale veins and bumpy surface texture. The bumpiness is due to erosion-resistant nodules within the rock, which have been identified as concretions resulting from the action of mineral-laden water.
This second drilling target, called "Cumberland," lies about nine feet (2.75 meters) west of the rock where Curiosity's drill first touched Martian stone in February. Curiosity took the first rock sample ever collected on Mars from that rock, called "John Klein." The rover found evidence of an ancient environment favorable for microbial life. Both rocks are flat, with pale veins and a bumpy surface. They are embedded in a layer of rock on the floor of a shallow depression called "Yellowknife Bay."
This second drilling is intended to confirm results from the first drilling, which indicated the chemistry of the first powdered sample from John Klein was much less oxidizing than that of a soil sample the rover scooped up before it began drilling.
"We know there is some cross-contamination from the previous sample each time," said Dawn Sumner, a long-term planner for Curiosity's science team at the University of California at Davis. "For the Cumberland sample, we expect to have most of that cross-contamination come from a similar rock, rather than from very different soil."
This patch of bedrock, called "Cumberland," has been selected as the second target for drilling by NASA's Mars rover Curiosity. The rover has the capability to collect powdered material from inside the target rock and analyze that powder with laboratory instruments. The favored location for drilling into Cumberland is in the lower right portion of the image.
Although Cumberland and John Klein are very similar, Cumberland appears to have more of the erosion-resistant granules that cause the surface bumps. The bumps are concretions, or clumps of minerals, which formed when water soaked the rock long ago. Analysis of a sample containing more material from these concretions could provide information about the variability within the rock layer that includes both John Klein and Cumberland.
Mission engineers at NASA's Jet Propulsion Laboratory in Pasadena, Calif., recently finished upgrading Curiosity's operating software following a four-week break. The rover continued monitoring the Martian atmosphere during the break, but the team did not send any new commands because Mars and the sun were positioned in such a way the sun could have blocked or corrupted commands sent from Earth.
Curiosity is about nine months into a two-year prime mission since landing inside Gale Crater on Mars in August 2012. After the second rock drilling in Yellowknife Bay and a few other investigations nearby, the rover will drive toward the base of Mount Sharp, a 3-mile-tall (5-kilometers) layered mountain inside the crater.
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