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Raumfahrt - Mars-Chroniken - Curiosity Mars-Rover nach Elektrischen Störung lahm gelegt - Update

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5.03.2015

The Mars Curiosity rover was in the processing of transferring a sample of powder it had drilled out of a rock when an electrical short triggered an automated shutdown.
NASA/JPL-CALTECH
Engineers at NASA’s Jet Propulsion Laboratory are scrambling to figure out the cause of an electrical glitch on the Mars rover Curiosity which stopped science operations cold.
The rover had finished drilling a sample from a rock known as “Telegraph Peak” and was transferring the powder into laboratory instruments when an abnormal electrical current was detected, NASA said in a statement posted on its website on Tuesday.
“We are running tests on the vehicle in its present configuration before we move the arm or drive,” Curiosity project manager Jim Erickson said in the statement. “This gives us the best opportunity to determine where the short is.”
NASA said that the short could have little impact on rover operations, or it could be more significant.  Analysis to determine the cause of the problem and assess what, if any, changes need to be made is expected to take several days.
Curiosity was in the early stages of transferring the powdered rock from a drill located on the rover’s arm to instruments for analysis.
“With the drill bit pointed up and the the drill’s percussion mechanism turned on, the rock powder was descending from collection grooves in the bit assembly into a chamber in the mechanism the sieves and portions the sample powder,” when the electrical short occurred,” NASA said.
The rover, which had performed the same transfer operation five times previously, automatically put itself into a safe mode.
Curiosity is exploring the base of a three-mile-high mountain of layered sediment inside its Gale Crater landing site. It already has returned evidence that Mars, the planet most like Earth in the solar system, had all the ingredients necessary for microbial life. It is assessing other niches for environmental and chemical habitability, as well as looking for places suitable to preserve organic matter.
Quelle: D-News
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Mars Science Laboratory Mission Status Report
NASA's Curiosity Mars rover is expected to remain stationary for several days of engineering analysis following an onboard fault-protection action on Feb. 27 that halted a process of transferring sample material between devices on the rover's robotic arm.
Telemetry received from the rover indicated that a transient short circuit occurred and the vehicle followed its programmed response, stopping the arm activity underway at the time of the irregularity in the electric current.
"We are running tests on the vehicle in its present configuration before we move the arm or drive," said Curiosity Project Manager Jim Erickson, of NASA's Jet Propulsion Laboratory in Pasadena, California. "This gives us the best opportunity to determine where the short is."
A transient short in some systems on the rover would have little effect on rover operations. In others, it could prompt the rover team to restrict use of a mechanism.
When the fault occurred, the rover was conducting an early step in the transfer of rock powder collected by the drill on the arm to laboratory instruments inside the rover. With the drill bit pointed up and the drill's percussion mechanism turned on, the rock powder was descending from collection grooves in the bit assembly into a chamber in the mechanism that sieves and portions the sample powder. The sample powder is from a rock target called "Telegraph Peak."  The same transfer process was completed smoothly with samples from five previous drilling targets in 2013 and 2014.
NASA's Mars Science Laboratory Project is using Curiosity to assess ancient habitable environments and major changes in Martian environmental conditions.  JPL, a division of the California Institute of Technology in Pasadena, built the rover and manages the project for NASA's Science Mission Directorate in Washington.
Quelle: NASA
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Update: 6.03.2015
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Use of Rover Arm Expected to Resume in a Few Days
This March 4, 2015, image from the Navcam on NASA's Curiosity Mars rover shows the position in which the rover held its arm for several days after a transient short circuit triggered onboard fault-protection programming to halt arm activities on Feb. 27.
Image Credit: NASA/JPL-Caltech/MSSS
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Mission Status Report
Managers of NASA's Curiosity Mars rover mission expect to approve resumption of rover arm movements as early as next week while continuing analysis of what appears to be an intermittent short circuit in the drill.
A fluctuation in current on Feb. 27 triggered a fault-protection response that immediately halted action by the rover during the mission's 911th Martian day, or sol. Since then, the rover team has avoided driving Curiosity or moving the rover's arm, while engineers have focused on diagnostic tests. Science observations with instruments on the rover's mast have continued, along with environmental monitoring by its weather station.
"Diagnostic testing this week has been productive in narrowing the possible sources of the transient short circuit," said Curiosity Project Manager Jim Erickson of NASA's Jet Propulsion Laboratory, Pasadena, California. "The most likely cause is an intermittent short in the percussion mechanism of the drill. After further analysis to confirm that diagnosis, we will be analyzing how to adjust for that in future drilling."
The sample-collection drill on Curiosity's robotic arm uses both rotation and hammering, or percussion, to penetrate into Martian rocks and collect pulverized rock material for delivery to analytical instruments inside the rover.
The short on Sol 911 occurred while the rover was transferring rock-powder sample from the grooves of the drill into a mechanism that sieves and portions the powder. The percussion action was in use, to shake the powder loose from the drill.
Engineers received results Thursday, March 5, from a test on Curiosity that similarly used the drill's percussion action. During the third out of 180 up-and-down repeats of the action, an apparent short circuit occurred for less than one one-hundredth of a second.  Though small and fleeting, it would have been enough to trigger the fault protection that was active on Sol 911 under the parameters that were in place then.
The rover team plans further testing to characterize the intermittent short before the arm is moved from its present position, in case the short does not appear when the orientation is different.
After those tests, the team expects to finish processing the sample powder that the arm currently holds and then to deliver portions of the sample to onboard laboratory instruments. Next, Curiosity will resume climbing Mount Sharp.
NASA's Mars Science Laboratory Project is using Curiosity to assess ancient habitable environments and major changes in Martian environmental conditions.  JPL, a division of the California Institute of Technology in Pasadena, built the rover and manages the project for NASA's Science Mission Directorate in Washington.  For more information about Curiosity,
Quelle: NASA

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