NASA'sMars Reconnaissance Orbiter is suffering science-reducing glitches, althoughthe spacecraft is nearing a milestone in churning out record-setting levels ofdata.
Thespacecraft carries six instruments for probing Mars' atmosphere [video], surface andsubsurface to characterize the red planet and how it changed over time.
Twoinstruments onboard the Mars Reconnaissance Orbiter (MRO)--the super-powerful HighResolution Imaging Science Experiment (HiRISE) and the Mars Climate Sounder--are not in prime-time, science taking status. The problems were flaggedFebruary 7 by officials at the Jet Propulsion Laboratory (JPL) in Pasadena, California, manager of MRO's mission.
Whileengineers wrestle with MRO's anomalies, JPL noted that the orbiting probe thismonth is set to eclipse the record for the "most science data" returned by anyMars spacecraft.
Therate of data return is projected to increase over the coming months as therelative motions of Earth and Mars in their orbits around the Sun shrink thedistance between the planets. That Mars-Earth positioning means MRO shouldrelay more than 30 terabits of science data--equal to more than 5,000 information-packedCD-ROMs.
MROobservations are an essential element of on-going studies of potentialexploration sites for future missions to that time-weathered world--such as thePhoenix Mars lander to launch this coming August.
MRO'sMars Climate Sounder (MCS) is built to map the temperature, ice clouds and dustdistributions in the Mars' atmosphere on each of the spacecraft's nearly 13orbits around the planet per day.
Butin late December, the sounder appeared to skip steps sporadically--a problemthat put the equipment's field of view slightly out of position. Followinguplink of new scan tables to the instrument, the position errors stopped andthe instrument operated nominally.
Lastmonth, however, the position errors reappeared, becoming more frequent.
Dueto the problem, the MCS has been temporarily stowed while the science teaminvestigates the root cause of the trouble.
HiRISEis one of three cameras that are part of MRO's science payload--the largest-diametertelescopic camera ever sent to another planet.
TheHiRISE instrument holds an array of 14 electronic detectors, each covered by afilter in one of three wavelength bands: 400 to 600 nanometers (blue-green),550 to 850 nanometers (red), or 800 to 1000 nanometers (near infrared). Ten reddetectors are positioned in a line totaling 20,028 pixels across to cover thewhole width of the field of view.
Inlate November 2006, the HiRISE team noticed a significant increase in noise,such as bad pixels, in one of its 14 camera detector pairs. Another detectorthat developed the same problem soon after MRO's launch in August 2005 hasworsened. Images from the spacecraft camera last month showed the first signsof this problem in five other detectors.
Whilethe current impact on image quality is small, explained a JPL statement, thereis concern as to whether the problem will continue to worsen. The camera stayson duty and is returning outstanding images of the martian landscape.
"Fornow we are using a slightly extended warm-up period before each image,"explained Alfred McEwen, Director of the Planetary Image Research Lab at the University of Arizona in Tucson, Arizona. He is MRO's HiRISE principal investigator.
Thatwarming, McEwen told SPACE.com, is sufficient to reduce the HiRISEproblem to minor dropouts--easily interpolated--in RED 9, and no problems at allin other charge couple devices within the instrument except an infraredreceiver channel (IR10 channel 1), where instrument specialists first saw thisproblem after MRO's blastoff from Florida in August 2005.
"Whenwe have evaluated whether or not the extended warm-up has potential long-termdetrimental effects, then we can decide to extend this warm-up period in thefuture if the problem continues to worsen," McEwen said.
"HiRISEhas been performing beautifully," said Richard Zurek, MRO's project scientistat JPL. "That's why any possible degradation in its performance concerns us,"he told SPACE.com.
Zurekadvised that the principal concern is not the present performance of HiRISE,but whether or not the noise will intensify, impacting the image quality ofchannels for which the noise is now hardly noticeable, if present at all.
"Fortunately,the two detectors--out of 14--for which the noise is often significant are on theedges of the panchromatic (black and white) and color fields of view, so thatthey leave no obvious gaps when they are too noisy," Zurek said.
Theissue with HiRISE does appear, Zurek added, to have an "operationalwork-around". By operating the instrument a few degrees warmer, still in itsnominal operating range, appears to significantly reduce, and often eliminate,the noise, he said.
"Agoal of the present troubleshooting effort is to confirm that this mode doesnot have some unforeseen side effects," Zurek noted. "We are of course tryingto understand the cause of the noise to help define other mitigation proceduresand to help us know if we need to conserve the number of images we canultimately take."
WhileHiRISE is acting up, Zurek observed that the instrument's three months ofscience gathering to date has yielded roughly 1,000 images--more than 1.5terabits (1,500 gigabits) of image data.
Aspart of that output, for example, HiRISE has redirected the landing site forthe Phoenix Mars mission to a safer, boulder-free area, Zurek said, "and it hasshown us Mars at a level of detail as good or better than you could see from alow-flying plane."
"Ourexpectation is that HiRISE will continue to do this for a long time once weunderstand the noise problem better and craft our operations proceduresaccordingly," Zurek concluded.
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