Curious Mars

CuriousMars: Rover's SAM organic and CheMin Labs Outrun Computer Snafu For Extra Rock Analysis

Organic carbon atoms can align in different ways. In these three depictions the carbon atoms are green, hydrogen is pink and oxygen is red. Credit: Journal of Molecular Graphics.

Scientists with the $2.5 billion Mars rover Curiosity will reveal potentially historic discoveries about Mars next week in Washington D. C.

There are indications that the planned March 12 NASA Headquarters briefing could reveal the finding of organic carbon on Mars - "key ingredients" for life on Mars, as the space agency reinforced this week.

In what may - or may not - be a coincidence, the day prior to announcing the rover science briefing that will be broadcast on NASA Television, the agency's Curiosity web site posted a new video titled: "Why is Curiosity Looking for Organics?"

The video opens with the narrator saying, "Organics are carbon-based molecules-key ingredients to life".

After an organics related geology discussion, the video concludes by saying, "If Curiosity finds organics, it wouldn't prove life existed, but it sure would improve the odds that Mars once had the right ingredients for life".

Previous Curiosity rover science briefings have simply been telecons based at JPL. But 9 years ago when the rover Opportunity made the historic finding that water had flowed on Mars - that announcement was also made during a televised briefing in Washington.

The Curiosity drilled rock sample briefing comes as BAE Systems and Jet Propulsion Laboratory computer experts complete fixes to the two BAE RAD750 computers systems. One of the rover's two computers, the A-side processor and memory malfunctioned February 28 requiring more than a week of work to fully program the B-side backup to take full command, while the A-side problem was diagnosed and corrected so it could become the new backup.

Two different configurations for BAE Systems RAD750 computer motherboards are shown. The malfunction of one of two RAD750s on Curiosity is causing great concern to NASA, the Manassas Va. company's customer. Credit: BAE Systems

Although not widely known, just before the computer problems struck Curiosity's robotic arm was able to deliver a second dose of powdered subsurface rock to the mission critical; organic sensing Sample Analysis at Mars (SAM) laboratory, said Richard Cook, rover project manager.

The Goddard SAM instrument heated the second sample of rock powder to nearly 2,000 deg. F (1,093 deg. C), using a more diverse temperature profile than used initially by SAM to analyze the gray/greenish tinted rock powder drilled from within a flat rock that appears to be a mudstone or siltstone formed in abundant water.

The different heating profile and SAM instrument settings used for the second processing run were designed to more precisely measure when specific molecules of different rock constituents baked out of the sample, SAM principal investigator Paul Mahaffy told CuriousMars after the laboratory's first run.

The SAM organic chemistry laboratory was able to receive and process a second sample of drilled rock that had been stored in the robot arm's instrument turret. Credit GSFC

Before the computer snafu, Curiosity was also able to transmit to Earth the results from SAM's second run along with the data from a second CheMin Chemistry and Mineralogy analysis of its original sample, the rover Project Manager told CuriousMars.

As a direct result of these four laboratory runs on the Martian surface - two by SAM and two by CheMin - investigators Mahaffy from the Goddard Space Flight Center and David Blake, with CheMin from the Ames Research Center, will be featured at the televised briefing at NASA Headquarters on Tuesday March 12, at 1 p.m. EDT.

Curiosity's wheels, belly and four center mounted front hazard cameras, two focused toward the left and the other two toward the right are imaged by the Mars Hand Lens Imager on the robotic arm. Credit: NASA/JPL-Caltech/MSSS

When the same two instruments, SAM and CheMin, found nothing unusual last fall when they analyzed their very first mission samples of dust from Martian sand the team only conducted a telephone briefing from the Jet Propulsion Laboratory.

But this is different. The fact this latest briefing is being held in Washington and televised by NASA is another indication that the two laboratories have found provocative evidence relating to Martian habitability - possibly even organic carbon. NASA would not be going
to these lengths to announce routine findings.

There are, however, different kinds of organic carbon. If SAM has detected any carbon molecules, a key step will be to precisely identify whether it could have been delivered to Mars by a meteorite, created by geologic processes or rather formed during an ancient Martian life process.

The Sun imaged March 5 by the NASA Solar Dynamics Observatory in an Iron wavelength shows a series of bright active regions like those that were responsible for the solar flare and coronal mass ejection fired toward Mars that day. Credit GSFC/SDO.

Mahaffy and Blake will be joined by John Grotzinger, Curiosity project scientist from Caltech and Michael Meyer, the lead scientist at NASA Headquarters for the Mars Exploration Program.

The NASA video about organics posted near simultaneously with the announcement of the briefing also noted that, "A great place to look for ancient organics today is in rock layers. Organics that were quickly trapped and buried in layers of mud or in sediments that sank to the bottom of a body of water could have an especially good chance of being preserved," the NASA video says.

"Scientists think Curiosity's landing site, Gale Crater , contains those special layers, created in ancient times when water was present." The mudstone/siltstone rock drilled, sampled and processed by the rover has exactly the same characteristics described in the NASA video.

Meanwhile at JPL, the objective is to find out exactly what happened to Curiosity's primary RAD750 computer in late February. The rover's A-side processor and memory was wounded by an apparently powerful cosmic ray strike. Then during the ongoing recovery March 6, both the A and B-sides were deliberately put to sleep by JPL controllers to avoid damage when bathed in radiation from a solar flare aimed toward Mars.

Rover Project Manager, Richard Cook (right) and Craig Covault, Editor of CuriousMars, examine JPL's Scarecrow rover (because it doesn't have a brain). Exactly the same size as the rover on Mars and used for early mobility tests, it shows how big the Curiosity rover really is. Credit: Craig Covault.

Curiosity was reawakened late March 7 when less solar radiation than feared passed by Mars and normal computer changeover tasks could be resumed. Ground controllers were aiming toward fully restored operations next week commanded by the B-side with the A-side now as backup.

Curiosity has substantially more powerful computers than does Opportunity (and Spirit, before it died), but yet less than the average laptop or even smart phones, said Mark W. Maimone, a lead computer and robotics engineer for the MSL and MER rovers.

The big differences are the years of efforts that go into the radiation hardening of computer chips that keep space-qualified electronics a decade behind off-the-shelf commercial chips.

MSL has a central processing unit 5 times faster than Opportunity, Maimone told me earlier at JPL. "Curiosity can perform at 100 MHz compared with only 20 MHz for Opportunity. In comparison, a low end desktop home computer will have 2,000 MHz (2 GHz) of power or more, but is not radiation hardened," Maimone told me earlier.

RAD750 computer is pictured in a third more integrated motherboard configuration. Credit: BAE Systems.

Controllers switched the rover to the "B-side" computer, early Thursday morning February 28 when the "A-side" computer that the rover had been using demonstrated symptoms of a corrupted memory location starting late Wednesday night February 27.

The spacecraft remained in communications at all scheduled communication windows on February 27, but did not send recorded data, only current status information. The status information revealed that the computer had not switched to the usual daily "sleep" mode when planned. Diagnostic work in a testing simulation at JPL indicates the situation involved corrupted memory at an A-side memory location used for addressing memory files. Cook said that was like having the table of contents zapped, instead of the contents itself.

The intentional side swap put the rover, as anticipated, into minimal-activity safe mode.

Curiosity exited safe mode on March 2 and resumed some operations using its high-gain antenna on March 3. But on March 5 the Sun gave off a flare and coronal mass ejection aimed at Mars forcing use of a precautionary sleep mode on both computers until that was lifted by March 7.

The Mars Reconnaissance Orbiter spacecraft continues to aid both the Curiosity and Opportunity rovers. But it is also continues to make discoveries in its own right. This illustration schematically shows where the Shallow Radar instrument on MRO detected flood channels that had been buried by lava flows in the Elysium Planitia region of Mars.. The associated Marte Vallis consists of multiple perched channels formed around streamlined islands. These channels feed a deeper and wider main channel. Note the color code. In this illustration, the surface has been elevated, and scaled by a factor of one to 100 for clarity. The color scale represents the elevation of the buried channels relative to a Martian datum, or reference elevation. The reason the values are negative is because the elevation of the surface of Mars in this region is also a negative -- below average global elevation. SHARAD was provided by the Italian Space Agency. Its operations are led by Sapienza University of Rome, and its data are analyzed by a joint U.S.-Italian science team.

Cook told CuriousMars that the key things that had to be completed to fully restore the computing system and reduce the chances of a similar problem happening again include:

- Providing the B-side, now primary computer, with everything it needs to know from software to run rover robotics including imaging navigation capabilities and drive system, as well as complex arm and turret motions and instrument operations and data acquisition and transmission tasks.

- Assessing the true post-event state of the A-side computer hardware "trying to understand if the memory is ok to give us an idea if the A-side will still be a good backup," said Cook.

- Developing options for software updates to immunize ourselves against this kind of problem in the future, since the design of the software is supposed to be tolerant to problems with the memory and generally is, said Cook.

"But if there is an actual hole burned in the A-side memory we are trying to put a patch in place prior to conjunction with the Sun, so that we know that while we are not in view of the spacecraft it will still be "in a good place" from a computer standpoint for that period of time," Cook told CuriousMars.

He said the event that triggered the computer problem is now an increased worry for the future however, since some type of space radiation apparently pierced the BAE chip's robust defenses when they were not supposed to.

As journalist William Harwood of CBS wrote in a CNET article just after the rover landed last August, "The RAD750s also meet lifetime dosage standards that are up to a million times more extreme than those considered fatal for a human being. As a result, over a 15-year period, the RAD750 chips aboard Curiosity would not be expected to suffer more than one external event requiring intervention from Earth.

"The RAD750 card is designed to accommodate all those single event effects and survive them," Vic Scuderi, BAE business manager for satellite electronics, said in an interview with Harwood. "The ultimate goal is one upset is allowed in 15 years. An upset means an intervention from Earth - one 'blue screen of death' in 15 years. We typically have contracts that (specify) that."

Curiosity's computers have only been on the surface for 6 months - far too soon for the "blue screen of death".

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