“机遇”号准备要进入Victoria crater 了！
NASA to Send Mars Rover into Crater 2007-06-29 09:58:36 ReutersNASA will send its Mars rover Opportunity into a gaping Martian crater in July to seek clues about the planet's bygone environment despite risks to the plucky little vehicle, officials said on Thursday.There is the chance the six-wheeled fact-gathering robot will be unable to handle the terrain inside Victoria Crater or get out once it gets in, they said.
But U.S. space agency officials said they did not view this as a suicide mission for Opportunity and looked forward to the potential for a deeper understanding of Earth's planetary neighbor. It is one of two rovers now on the Martian surface.
Opportunity is due to enter the crater either July 7 or July 9, according to John Callas, rover project manager at NASA's Jet Propulsion Laboratory in Pasadena, California.
"We know that the rewards are worth the risk," added Alan Stern, associate administrator of NASA's science mission office. "Entering this crater does come with some unknowns."
"We can't be certain about the terrains and the footing down in the crater until we go there. We can't guarantee, although we think we're likely to come back out of the crater," Stern told reporters.
Victoria Crater, near the Martian equator, is about half a mile wide and was formed by the primordial impact by a space rock on the planet's surface.
Mission scientists have been directing Opportunity to roll around the rim of the crater, exploring layered rocks and looking for the easiest place to make its entrance. They settled on a rock-paved slope on an alcove dubbed Duck Bay.
Callas said Duck Bay has entry slopes of no more than 20 degrees, with the rover able to handle a slope as steep as 32 degrees. Callas said there is confidence the rover can travel safety at least 330 feet into the crater.
NOW OR NEVER
The rover, originally intended to operate for three months, has kept going strong for 12 times as long. The scientists have carefully plotted its mission to explore Victoria's secrets to enable an eventual exit but acknowledge that the rover could become trapped inside or lose some capabilities.
With the rover aging, it was now or never for this descent into the crater, they said.
The scientists want Opportunity to gather data on the composition of material in the crater's depths that may provide further evidence about an ancient environment on Mars that many experts think was wet and potentially habitable by at least microbial life forms.
As it goes deeper into the giant hole, it will be able to examine more ancient rocks in the crater's exposed walls.
"The rovers have been amazingly resilient to date. They're hardy little vehicles. We're quite confident," Callas said.
The crater is about five times wider than Endurance Crater, which Opportunity devoted more than six months exploring in 2004. Victoria Crater is about 4 miles south of the spot where Opportunity landed in January 2004.
Callas said the Victoria Crater mission was an easier jaunt for Opportunity than going into Endurance Crater because the initial slopes are somewhat less steep and the scientists have more experience guiding it in such terrain.
The robot's discoveries in Endurance Crater revealed evidence of the water-rich ancient history of Mars. Opportunity started rolling toward Victoria from Endurance 30 months ago.
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哈哈！消息最佳来源：
NASA的航天任务：http://www.nasa.gov/missions/highlights/index.html
NASA的最新公布：http://www.nasa.gov/news/highlights/index.html
航天飞机专页：http://www.nasa.gov/mission_pages/shuttle/main/index.html
这些都比路透社要强多了。 Dwayne Brown/Tabatha Thompson
Headquarters, Washington
202-358-1726/3895
Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
June 28, 2007
RELEASE: 07-146
NASA Mars Rover Ready for Descent Into Crater
WASHINGTON - NASA's Mars rover Opportunity is scheduled to begin a descent down a rock-paved slope into the Red Planet's massive Victoria Crater. This latest trek carries real risk for the long-lived robotic explorer, but NASA and the Mars Rover science team expect it to provide valuable science.
Opportunity already has been exploring layered rocks in cliffs around Victoria Crater. The team has planned the descent carefully to enable an eventual exit, but Opportunity could become trapped inside the crater or lose some capabilities. The rover has operated more than 12 times longer than its originally intended 90 days.
The scientific allure is the chance to examine and investigate the compositions and textures of exposed materials in the crater's depths for clues about ancient, wet environments. As the rover travels farther down the slope, it will be able to examine increasingly older rocks in the exposed walls of the crater.
"While we take seriously the uncertainty about whether Opportunity will climb back out, the potential value of investigations that appear possible inside the crater convinced me to authorize the team to move forward into Victoria Crater," said Alan Stern, NASA associate administrator, Science Mission Directorate, NASA Headquarters, Washington. "It is a calculated risk worth taking, particularly because this mission has far exceeded its original goals."
The robotic geologist will enter Victoria Crater through an alcove named Duck Bay. The eroding crater has a scalloped rim of cliff-like promontories, or capes, alternating with more gently sloped alcoves, or bays.
A meteor impact millions of years ago excavated Victoria, which lies approximately 4 miles south of where Opportunity landed in January 2004. The impact-created bowl is half a mile across and about five times as wide as Endurance Crater, where Opportunity spent more than six months exploring in 2004.
The rover began the journey to Victoria from Endurance 30 months ago. It reached the rim at Duck Bay nine months ago. Opportunity then drove approximately a quarter of the way clockwise around the rim, examining rock layers visible in the promontories and possible entry routes in the alcoves. Now, the rover has returned to the most favorable entry point.
"Duck Bay looks like the best candidate for entry," said John Callas, rover project manager, NASA's Jet Propulsion Laboratory, Pasadena, Calif. "It has slopes of 15 to 20 degrees and exposed bedrock for safe driving."
If all of its six wheels continue working, engineers expect Opportunity to be able to climb back out of the crater. However, Opportunity's twin rover Spirit lost the use of one wheel more than a year ago, diminishing its climbing ability.
"These rovers are well past their design lifetimes, and another wheel could fail on either rover at any time," Callas said. "If Opportunity were to lose the use of a wheel inside Victoria Crater, it would make it very difficult, perhaps impossible, to climb back out."
"We don't want this to be a one-way trip," said Steve Squyres, principal investigator for the rovers' science instruments, Cornell University, Ithaca, N.Y. "We still have some excellent science targets out on the plains that we would like to visit after Victoria. But if Opportunity becomes trapped there, it will be worth the knowledge gained."
The Jet Propulsion Laboratory manages the Mars Exploration Rover project for NASA's Science Mission Directorate.
For more information on the Mars Rovers, visit:
http://www.nasa.gov/rovers
Visuals describing this decision and the anticipated science can be viewed at:
http://www.nasa.gov/mission_pages/mer/070628
- end - http://www.nasa.gov/mission_pages/mer/mer-20070703.html
Dust Delays Mars Crater Entry
07.03.07
A giant dust storm brewing for more than a week on Mars has become worse and is affecting surface operations of the Mars Exploration Rovers, Spirit and Opportunity. Because the rovers depend on solar energy for survival, and the dust is partially blocking the sun, the storm is being watched closely by the rover scientists and engineers. Opportunity's entry into Victoria Crater is delayed for at least several days.
The storm, the most severe storm yet to hit the rovers, is expected to continue for at least another week. Opportunity is perched near "Duck Bay" as it readies to descend into Victoria Crater, but operations were scaled back on Saturday, June 30, to conserve power.
Image right: The route followed by NASA's Mars Exploration Rover Opportunity from its landing site through the 1,215th Martian day (or sol) of its mission (June 24, 2007), is marked on this map. Image credit: NASA/JPL/Cornell/MSSS/Ohio State University
+ Full image and caption
http://www.nasa.gov/images/content/181637main_pia09691-330.jpg
"The storm is affecting both rovers and reducing the power levels on Opportunity," said John Callas, Mars Exploration Rover project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We are keeping an eye on this as we go forward, but our entry into Victoria Crater will be delayed until no sooner than July 13."
"We have some data that show the atmospheric opacity is decreasing, so the storm might have peaked and we may have passed the worst of this. The situation could improve quickly from here, but we will have to wait and see," said Callas.
Weather reports from NASA's Mars Reconnaissance Orbiter Mars Color Imager camera are helping track the storm and plan rover operations.
Pictures from the orbiter's Mars Color Imager show the storm is regional in extent, and includes several local areas of especially high dust activity. The storm has been moving eastward and toward mid-latitudes, and is now also causing an increase in atmospheric dust at Spirit's location, on the opposite side of the planet at Gusev Crater. Dust levels at Gusev remain much lower than at the Opportunity site, however.
Both rovers take daily measurements estimating the amount of dust in the atmosphere. The less dust the better, because it means more sunlight reaches the rover's solar panels, which power the vehicles. In the last week, Opportunity has broken its dust record, with the opacity level rising from 1.0 to 3.3. Solar array energy on Opportunity dropped from 765 watt-hours to 402 watt-hours over the same period of time.
"While this only represents enough dust to coat the planet to about the thickness of a human hair, it is enough to decrease the brightness of the noon sun by 96 percent compared to a completely clear atmosphere," said Steve Squyres, principal investigator, Cornell University, Ithaca, N.Y. "Of course, the solar arrays also receive light that is scattered from the dust, so the decrease in power is not nearly that great."
"We have not seen dust measurements this high on either rover before. If the dust levels were to increase further and stay elevated for several days, there is a risk to how well Opportunity could continue to work in this darkened environment," said Callas.
Media contact: Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
[ 本帖最后由 worren 于 2007-7-4 19:50 编辑 ] 如果两个Rovers 是核能驱动的就好了！那样就不依赖阳光的强度了！ 核能有可能污染火星环境
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