Keep the shuttle flying: Fwd: Engineers troubleshoot Curiosity

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From: "Gary Johnson" <gjohnson144@comcast.net>
Date: March 7, 2015 at 5:27:39 PM CST
To: "Gary Johnson" <gjohnson144@comcast.net>
Subject: FW: Engineers troubleshoot Curiosity

Engineers troubleshoot glitch with Mars rover
03/04/2015 12:33 PM
By WILLIAM HARWOOD
CBS News

Engineers are running tests to pinpoint an apparent short circuit somewhere in the complex electronics aboard NASA's Curiosity Mars rover that triggered fault protection software and interrupted robot arm science operations last week, officials said Wednesday.

Jim Erickson, the Curiosity project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif., told CBS news engineers should get the results of an initial round of tests shortly, "and then we'll move on."

"But it's going to be a series of things that we use to try and figure out exactly where the short is occurring, whether it's transient or permanent, all the things you need to know in order to decide what to do about it," he said in a telephone interview
A "selfie" taken by the Curiosity Mars rover near a target rock called "Telegraph Peak" where rock samples were collected by the spacecraft's drill. An apparent short circuit has interrupted robot arm operations pending an engineering analysis. (Credit: NASA)

The problem cropped up last Friday as a mechanism in Curiosity's robot arm was in the process of shaking powder from a drilling sample into a tray so it could be sifted and transferred to experiments in the body of the spacecraft for detailed analysis.

A percussive mechanism was working at the time, impacting the drill to help shake loose rock powder, a technique successfully used with five previous drilling samples.

While that was going on, telemetry indicates a short was detected, which in turn triggered on-board fault-protection software that halted arm operations. Erickson said engineers do not yet know whether the short was in the drill circuitry or somewhere else in the rover.

"In looking at the initial diagnostics that we are doing and what the possible root causes are, nothing shows up as a show stopper," he said. "We could be surprised, and that's one of the reasons we're doing more analysis and looking at all the data we're getting down. We're going to start out very gentle, so to speak, and very low risk and gradually move to where the data shows us we should be moving."

The $2.5 billion Curiosity successfully landed in Gale Crater in August 2012. Since then, it's been slowly making its way to the base of Mount Sharp, a towering mound of layered terrain in the center of the crater, stopping frequently to examine interesting soil and rocks.

The rover has already accomplished the mission's primary goals, detecting organic compounds like those necessary for life as it is known on Earth and showing Mars once featured a habitable environment. A major long-range objective is to climb up the lower slopes of Mount Sharp to reach a transition zone that might hold clues about what caused the red planet to dry out.

The short circuit detected last week was not Curiosity's first.
A closeup of Curiosity's robot arm drilling mechanism. (Credit: NASA)

"One of the things we've seen before, and we're not saying this is the problem (now), it's just on our list of possibles, we'd previously seen an RTG short," Erickson said, referring to the rover's radioisotope thermoelectric generator. "It could have been another one, perfectly timed to look like it was related to the drilling."

The RTG generates the rover's electricity. The previous short cleared itself up when "eventually, there was enough current that it blew the little whisker that was growing in the RTG and that ended the short," Erickson said.

"One of the options is that this thing might be something that happened just at the same time as we started transferring the drill powder ... for further processing, that's one of the possibilities," he said. "Another possibility is that it's something in the drill itself."

Before launch, engineers had problems with the drill's percussive mechanism, designed to "basically pound on the drill to get more progress through the drilling cycle." But the drill is used so sparingly, a failure would "be sort of a surprise," Erickson said.

"To put it frankly, it is a surprise no matter what," he added. "Something has happened, and we have to figure out exactly what."

Curiosity will simply stay where it is while engineers carry out tests and study telemetry.

"Then, after we've gotten as much information as we can in that position, then we're going to finish getting the powder out of the drill, do the sample drop off ... and then we'll be in position where we can move to the next location while we do testing and analysis to isolate the problem."

© 2015 William Harwood/CBS News

Glitch on Curiosity rover traced to drill mechanism
March 7, 2015 by Stephen Clark
The mast camera on the Curiosity Mars rover captured this raw color view of the craft's drill after collecting a rock powder sample Feb. 24. Credit: NASA/JPL-Caltech/MSSS
Officials are assessing how to adjust operations to collect future rock core samples with NASA's Curiosity Mars rover after identifying its drill as the likely source of a short circuit that stopped the rover's movement in late February.
The rover ran into the problem Feb. 27 as it tried to transfer a drill sample to its on-board instruments for analysis. Curiosity's fault-protection software automatically detected the glitch — described by NASA as a fluctuation in an electrical current — and halted movement of the robotic arm, which holds the drill and sampling mechanism.
The rover has kept still since the problem occurred, as engineers on Earth analyze the cause of the short circuit.
"Diagnostic testing this week has been productive in narrowing the possible sources of the transient short circuit," said Jim Erickson, Curiosity's project manager at NASA's Jet Propulsion Laboratory. "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."
Curiosity drilled into a rock at the base of Mount Sharp — a towering peak on Mars where layered sediments could hold clues of an ancient habitable Martian environment — in late February.
NASA says the drill unit uses rotation and a hammering motion to push into rocks. Powder from rocks drilled by Curiosity is captured in the grooves of the drill, then shaken into a mechanism to sift the sample before it is dropped into the rover's miniature laboratory.
Curiosity uses a percussive mechanism to clear the powder off the drill's grooves.
Engineers this week repeated the motion of the drill that led to the short circuit as part of testing to determine the cause.
"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," NASA said in a status report Friday. "Though small and fleeting, it would have been enough to trigger the fault protection that was active (Feb. 27) under the parameters that were in place then."
The rover gathered five previous drill samples with no problems.
Ground controllers plan to move the rover's robotic arm and check if the short circuit goes away when the appendage is in a different orientation.
"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," status report said. "Next, Curiosity will resume climbing Mount Sharp."

© 2015 Spaceflight Now Inc.

NASA Finds Likely Source of Mars Rover Curiosity's Short Circuit
by Mike Wall, Space.com Senior Writer | March 06, 2015 06:31pm ET

NASA's Curiosity Mars rover held its arm in the same position for several days after a transient short circuit triggered onboard fault-protection programming to halt arm activities on Feb. 27, 2015.
Credit: NASA/JPL-Caltech/MSSS View full size image
The short circuit that has stalled some of the science work by NASA's Mars rover Curiosity apparently originated in the robot's rock-boring drill, mission team members say.
Curiosity experienced a current fluctuation on Feb. 27 while delivering some sample powder from the drill to instruments on the robot's body. The drill sits on the rover's 7-foot-long (2.1 meters) robotic arm. The rover hasn't moved the arm or its six wheels since, as engineers have focused on running tests to figure out what exactly happened.
Those diagnostic tests have been productive, Curiosity Project Manager Jim Erickson, of NASA's Jet Propulsion Laboratory in Pasadena, California, said Friday (March 6). [Amazing Mars Photos by NASA's Curiosity Rover]
"The most likely cause is an intermittent short in the percussion mechanism of the drill," Erickson said in a statement. (Curiosity's drill doesn't simply rotate; it hammers into rock, via that percussion mechansism, as well.) "After further analysis to confirm that diagnosis, we will be analyzing how to adjust for that in future drilling."
A brief short occurred during a test on Thursday (March 5) that used the drill's percussive action, NASA officials explained.
"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," they wrote in the statement. "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."
Curiosity may start moving its arm again as early as next week, NASA officials said.
The 1-ton Curiosity rover landed on Mars in August 2012, on a mission to determine if the Red Planet has ever been capable of supporting microbial life. The rover's drill is key to this quest, allowing Curiosity to collect powdered samples from up to 2.5 inches (6.5 centimeters) deep within rocks.
Indeed, Curiosity's analysis of drilled samples enabled mission scientists to determine that an area near the rover's landing site called Yellowknife Bay was a habitable lake-and-stream system billions of years ago.
Curiosity snagged its latest sample from a rock dubbed Telegraph Peak, which lies at the base of the huge Mount Sharp in a region called Pahrump Hills. The rover has drilled into three separate rocks from Pahrump Hills, which Curiosity reached in September 2014.
Mission scientists plan to send Curiosity up through the foothills of Mount Sharp, which rises about 3.4 miles (5.5 kilometers) into the Martian sky. Reading the rocks along the way should reveal a great deal about how the Red Planet's environmental conditions have changed over time, Curiosity team members say.
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