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| NASA's Mars rover Opportunity examined this 3-foot-wide rock, dubbed Wopmay (after a legendary Canadian bush pilot), inside Endurance crater on Oct. 7. The image was discussed by the mission's scientific principal investigator, Cornell astronomy Professor Steve Squyres, in a telephone press conference with national media from Cornell's Space Sciences Building on Nov. 4. Evidence from the rover's spectrometers and its microscopic imager (MI), Squyres said, is consistent with scientists' earlier hypothesis that rocks near the bottom of the crater were affected by water both before and after the crater formed. The false-color image accentuates iron-rich spherical concretions as bluish dots, dubbed "blueberries," embedded in the rock and on the ground around it. The panoramic camera (Pancam) image was analyzed and calibrated in Cornell's MarsLab. Inset is a close-up of Wopmay combining four frames taken by the MI. The image, a 2.4-inch section of the rock, shows surface crevices and the "blueberries." NASA/JPL/Cornell; Inset: NASA/JPL/Cornell/USGS |
By Thomas Oberst
Since NASA's Mars rovers Spirit and Opportunity landed on the red planet last January, researchers and students on the Cornell rover team have gone from living and working on Mars time at the Jet Propulsion Laboratory (JPL) in Pasadena, Calif., to running their operations from Cornell's Space Sciences Building on a hybrid Earth-Mars time.
The planning and operations that must occur twice each day -- between the time when "yester-sol's" data reach Earth until commands for the next sol's activities are sent off to the rovers -- have been streamlined to just six or seven hours on average, compared with the 17 hours it once took. (A sol, a Martian day, is 39 minutes, 35 seconds longer than an Earth day.)
On Nov. 4, media representatives crowded into the small, fourth-floor conference room that has become one of the Mars mission's operations centers to watch the Cornell team help plan the following sol's operations for Opportunity. Reporters from newspapers and TV and radio stations in Ithaca and Syracuse, together with journalists from the Associated Press and U.S.News & World Report, sat at a table with the team as members conducted the Science Operations Working Group (SOWG) video-conference meeting, held twice daily, once for each rover, with colleagues from JPL and other scientific institutions around the world.
The reporters quickly learned that no end to the mission is in sight. The original "warranty" assigned to the rovers was 90 sols, which expired seven months ago, and on Oct. 1 NASA extended the mission for a further six months.
That presents a challenge to the 29 people -- they like to refer to themselves as "Martians" -- who, since last August, have been working long hours in the Cornell operations center. Their number includes 12 working undergraduates and three graduate students.
"What sets this mission apart from almost every other planetary mission that has ever flown is that every time a rover moves, you're someplace new in an unexplored terrain, and you have to use that information to inform the decision process for the coming sol," said astronomy Professor Steve Squyres, the Mars mission's principal investigator.
The rovers are commanding the Cornell staff's attention almost around the clock -- even though the deepest, darkest part of the Martian winter began in October, and the original plan was to allow the rovers to spend more time idling in the weak winter sunlight to recharge their batteries. Nor have operations missed a step due to power losses from the thickening layer of windborne dust that has been collecting on the rovers' solar-array panels. NASA planners had assumed that the rovers would last only 90 days because of the dust buildup. However, said Squyres, "We had enough margin built into the design that even with the lower power output, we're still able to do operations."
"The rate of dust buildup has slowed," he noted, "and when you combine that with the fact that we've gotten clever about parking these things on north-facing slopes where the sunlight is stronger, we've found that we don't need recharge sols. Both rovers have been active throughout the Martian winter, and soon we'll start to see spring coming on."
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| The Mars rover mission's scientific principal investigator, Cornell astronomy Professor Steve Squyres, discusses rover scheduling in a video-conference with his colleagues at NASA's Jet Propulsion Laboratory in Pasadena, Calif., from his operations center on the fourth floor of the Space Sciences Building on Nov. 4. Squyres was closely watched by Ithaca and Syracuse media who had been invited to the Science Operations Working Group session. Robert Barker/University Photography |
Detailed instructions still must be sent to the rovers, said Squyres, although planning that would typically take months for some planetary missions must be compressed into a few hours. After much refining, the rover team has streamlined the planning process into a daily regimen of 10 meetings, five for each rover, which are now conducted remotely from home institutions. Planners at Cornell and JPL communicate -- via Polycom, a Web-, tele- and video-conferencing system -- with scientists who operate the rovers' onboard instruments and cameras at Arizona State University, Honeybee Robotics in New York City, the U.S. Geological Survey in Flagstaff, Ariz., Washington University in St. Louis, the Max-Planck-Institut für Chemie in Germany and the Neils Bohr Institute in Denmark.
In addition, every day dozens -- sometimes hundreds -- of never-before-seen images of the Martian frontier pour into the MarsLab, also on the fourth floor of the Space Sciences Building. These are the images captured as little as 12 hours previously by the rovers' panoramic cameras, or Pancams. Led by Jim Bell, associate professor of astronomy, the Cornell Pancam team then analyzes and calibrates the images, which, with data from the rovers' other instruments, enable the science team to send the rovers their instructions for the following sol.
Bell's team also is in charge of writing the computer commands that direct the Pancams. "Sometimes it's really simple, and sometimes it's really tricky," mission support specialist Miles Johnson was quoted in The Post-Standard (Syracuse). "[We] spend 30 seconds deciding we'll drive and look at this rock, and then we spend hours trying to figure out: Where is that rock going to be and what's the best way to image it."
On a given day there are 16 specific job assignments that must be filled for each rover by science team members at Cornell or one of the other institutions, not including NASA engineers. Squyres keeps a spreadsheet schedule weeks in advance of who will fill what position on a given day. "Nobody works two rovers on the same sol: It is absolutely flat out impossible," said Squyres.
The 16 positions are:
A typical day in the life of a Cornell rover scientist begins at about 11 a.m. with a "science kick-off"meeting at which the previous day's data are reviewed and the next day's plan for Spirit or for Opportunity is roughed out.
At the midday SOWG meeting -- the most important of the day -- the chair, documentarian, Pancam PDL and PUL and other science team members gather in the Cornell operations center to create the main rover plan for the next sol. The center has a 3-foot-by-4-foot flat-screen TV, dubbed the MERboard, used to display the daily rover plan. As participants dial into the Polycom, the Cornell center becomes linked to similar rooms at JPL and at other science team institutions. When someone in one of the conference rooms starts to speak, the LCD projector automatically switches to a view of the speaker.
At 1:30 p.m., JPL engineers and the PULs take the SOWG plan and create a highly detailed computer model of the rover's activities for the day. Squyres must be available to answer questions and to troubleshoot. The documentarian at his side keeps careful track of the changes to the SOWG plan.
At 2 p.m. there is a briefing by a JPL engineer on such things as power and time status. With approval given by all, the team starts building the plan's computer programs. By now the PULs have built their individual "submaster" computer sequences, which need to be strung together into a "master sequence." Finally, the sequence integration engineer makes sure the master sequence makes sense.
At 3 p.m. the master and submaster programs are triple-checked. By this time the only people left are the SOWG chair, the documentarian and the engineers. The engineers run a software simulation of the rover to make sure they don't "break" anything when they run the master program on the rover.
At 6 p.m. the command approval meeting provides one last chance to catch mistakes. With assurances given, the SOWG chair and the JPL mission manager give their thumbs up.
Then, and only then, are the commands sent to NASA's Deep Space Network and on to the waiting rovers on Mars 235 million miles away.
Thomas Oberst is a science writer intern with the Cornell News Service.
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