The color image captured by NASA's Mars rover Curiosity on Tuesday, August 7, has been rendered about 10% transparent so that scientists can see how it matches the simulated terrain in the background. 
This image comparison shows a view through a Hazard-Avoidance camera on NASA's Curiosity rover before and after the clear dust cover was removed. Both images were taken by a camera at the front of the rover. Mount Sharp, the mission's ultimate destination, looms ahead. 
The four main pieces of hardware that arrived on Mars with NASA's Curiosity rover were spotted by NASA's Mars Reconnaissance Orbiter (MRO). The High-Resolution Imaging Science Experiment (HiRISE) camera captured this image about 24 hours after landing. 
This image is a 3-D view in front of NASA's Curiosity rover. The anaglyph was made from a stereo pair of Hazard-Avoidance Cameras on the front of the rover. Mount Sharp, a peak that is about 5.5 miles high, is visible rising above the terrain, though in one "eye" a box on the rover holding the drill bits obscures the view. 
This view of the landscape to the north of NASA's Mars rover Curiosity was acquired by the Mars Hand Lens Imager on Monday afternoon, the first day after landing. 
NASA's Curiosity rover and its parachute were spotted by NASA's Mars Reconnaissance Orbiter as Curiosity descended to the surface on Sunday. The rover landed early on August 6 (ET). 
A camera on Curiosity snapped this image of the rover's heat shield falling away about two and a half minutes before landing. 
This is one of the first pictures taken by Curiosity after it landed. It shows the rover's shadow on the Martian soil. 
Another of the first images taken by the rover. The clear dust cover that protected the camera during landing has popped open. Part of the spring that released the dust cover can be seen at the bottom right, near the rover's wheel. 
This image shows Curiosity's main science target, Mount Sharp. The rover's shadow can be seen in the foreground. The dark bands in the distances are dunes. 
Another of the first images beamed back from NASA's Curiosity rover on August 6 is the shadow cast by the rover on the surface of Mars. 
NASA's Mars Curiosity Rover, shown in this artist's rendering, touched down on the planet on August 6. 
Water-ice clouds, polar ice and other geographic features can be seen in this full-disk image of Mars from 2011. 
This image was captured in 1976 by Viking 2, one of two probes sent to investigate the surface of Mars for the first time. NASA's Viking landers blazed the trail for future missions to Mars. 
The Valles Marineris rift system on Mars is 10 times longer, five times deeper and 20 times wider than the Grand Canyon. This composite image was made aboard NASA's Mars Odyssey spacecraft, which launched in 2001. 
The Nili Fossae region of Mars is one of the largest exposures of clay minerals discovered by the OMEGA spectrometer on Mars Express Orbiter. This image was taken in 2007 as part of a campaign to examine more than two dozen potential landing sites for NASA's new Mars rover, Curiosity, also known as the NASA Mars Science Laboratory. 
NASA's Mars Phoenix Lander descends to the surface of Mars in May 2008. Fewer than half of the Mars missions have made successful landings. 
Phoenix's robotic arm scoops up a sample on June 10, 2008, the 16th Martian day after landing. The lander's solar panel is seen in the lower left. 
In 2006, NASA's Mars Exploration Rover Spirit captured a 360-degree view known as the McMurdo panorama. The images were taken at the time of year when Mars is farthest from the sun and dust storms are less frequent. 
The European Space Agency's Mars Express captured this view of Valles Marineris in 2004. The area shows mesas and cliffs as well as features that indicate erosion from flowing water. 
This view is a vertical projection that combines more than 500 exposures taken by Phoenix in 2008. The black circle on the spacecraft is where the camera itself is mounted. 
A portion of the west rim of the Endeavour crater sweeps southward in this view from NASA's Mars Exploration Rover Opportunity in 2011. The crater is 22 kilometers (13.7 miles) across. 
A photo captured by NASA's Mars Global Surveyor in 2000 offers evidence that the planet may have been a land of lakes in its earliest period, with layers of Earth-like sedimentary rock that could harbor the fossils of any ancient Martian life. 
A U.S. flag and a DVD containing a message for future explorers of Mars, science fiction stories and art about the planet, and the names of 250,000 people sit on the deck of Phoenix in 2008. 
A rock outcrop dubbed Longhorn and the sweeping plains of the Gusev crater are seen in a 2004 image taken by the Mars Exploration Rover Spirit. 
Although it is 45 kilometers (28 miles) wide, countless layers of ice and dust have all but buried the Udzha crater on Mars. The crater lies near the edge of the northern polar cap. This image was taken by NASA's Mars Odyssey Orbiter in 2010. 
NASA's Opportunity examines rocks inside an alcove called Duck Bay in the western portion of the Victoria crater in 2007. 
Pictured is a series of troughs and layered mesas in the Gorgonum Chaos region of Mars in 2008. This photo was taken by Mars Orbiter Camera on the Mars Global Surveyor. 
An image captured in 2008 by NASA's Mars Reconnaissance Orbiter shows at least four Martian avalanches, or debris falls, taking place. Material, likely including fine-grained ice and dust and possibly large blocks, detached from a towering cliff and cascaded to the gentler slopes below. 
This 2008 image spans the floor of Ius Chasma's southern trench in the western region of Valles Marineris, the solar system's largest canyon. Ius Chasma is believed to have been shaped by a process called sapping, in which water seeped from the layers of the cliffs and evaporated before it reached the canyon floor. 
Pictured is the Martian landscape at Meridiani Planum, where the Mars Exploration Rover Opportunity successfully landed in 2004. This is one of the first images beamed back to Earth from the rover shortly after it touched down. 
An image from the Mars Global Surveyor in 2000 shows potential evidence of massive sedimentary deposits in the western Arabia Terra impact crater on the surface of Mars. 
The Mars Reconnaissance Orbiter captures a dust devil blowing across the Martian surface east of the Hellas impact basin in 2007. Dust devils form when the temperature of the atmosphere near the ground is much warmer than that above. The diameter of this dust devil is about 200 meters (650 feet). 
Soft soil is exposed when the wheels of NASA's Mars Exploration Rover Spirit dig into a patch of ground dubbed Troy in 2009. 
An image from NASA's Mars Reconnaissance Orbiter shows the floor of the Antoniadi Crater in 2009. 
The larger of Mars' two moons, Phobos, is seen in 2008 from the Mars Reconnaissance Orbiter. 
Earth and the moon are seen in 2007 from the Mars Reconnaissance Orbiter. At the time the image was taken, Earth was 142 million kilometers (88 million miles) from Mars. 
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Follow @CNNLightYears on Twitter for updates on Curiosity.
(CNN) -- Hey Mars! We're back! Hope you don't mind if we cruise around in our scientific SUV to grab some historic data and snap some breathtaking images. Oh, and we might do some Martian doughnuts in your front yard.
Now that the Mars rover Curiosity is safely parked, NASA's unmanned planet crawler appears ready to roll. A car salesman would have a ball selling this beauty. It's loaded with an array of sophisticated cameras, a "rocker bogie" suspension, a robotic arm, 2 gigs of flash memory, a rock-vaporizing laser (!!!!) and a plutonium-fueled power system. It operates by remote control from millions of miles away and has a blazing top speed of 1.5 inches per second.
Sticker price (including delivery): $2.6 billion.
During its expected lifespan of 23 months, all this cool hardware could help solve big mysteries: Has life ever existed on Mars? What can Mars tell us about our own planet? Can we benefit from Martian resources?
Mars rover Curiosity's descent 
First images sent from Curiosity 
Curiosity tweets Mars landing But there are less romantic questions swirling around the fourth rock from the sun: Is the price tag really worth it? Who will pay for the first manned mission to Mars? Could manned space missions be replaced by robotic exploration?
The answers may be hard to see amid all the rover revelry. And this isn't the first time rovers have churned up this kind of excitement.
In 1997, a smaller NASA robot on Mars -- Sojourner -- lit up the Web.
"Back when the Internet was young, it was the largest Internet event in the history of that medium," Curiosity team member James Bell told CNN on Monday. The little rover found clues suggesting that Mars once had a thicker atmosphere and liquid water. Sojourner and its parent spacecraft Pathfinder cost $265 million (PDF).
"Later, in 2004, when the Spirit and Opportunity rovers landed, it became one of the largest worldwide Internet sensations," said Bell, who also worked on that mission. "It slammed NASA's website." The rovers scored several discoveries including evidence of an ancient wet environment on Mars. Price tag for Spirit and Opportunity: $800 million (PDF).
CNN commenter
Nowadays -- at least for some space travel fans -- Martian robots aren't so cool anymore. Curiosity "is just another box with wheels on Mars," says CNN commenter It_could_always_be_worse. "Develop useful technology -- not this shooting of boxes with wheels all over the place. SEND PEOPLE, and I will be proud."
CNN commenter Max Lewes disagrees. "This really was a HUGE leap from previous missions."
Related story: Curiosity's wild ride
After the initial excitement of Monday's landing, even the Curiosity team jokingly acknowledged the first dusty black and white photos from the rover have already lost their luster.
"It's not such a great picture anymore," a smiling Mike Watkins told reporters. He promised color and panorama photos in the coming days.
Seriously, no matter how successful unmanned missions might be, robots will never replace the need for human space exploration, says Bell.
In a sense, Curiosity is performing a scouting mission for a manned U.S. mission to Mars that President Barack Obama predicts will happen in his lifetime.
NASA administrator Charles Bolden gets even more specific: Manned missions to Mars are at least 18 years away -- sometime in the 2030s.
But first, mission planners need more information about the Martian surface so they can choose the best landing sites.
"We don't want astronauts to be surprised," says Bell. Robot missions, such as Surveyor, preceded the Apollo moon landings, and these Martian probes are performing similar tasks.
Putting a monetary value on space exploration is impossible, experts say, because there are too many unanswered questions, such as whether Mars, the moon or asteroids hold precious minerals, water and cheap energy resources that could be mined and brought back to Earth.
"The reason to send humans will be because we have to," Bell says. "If some things can be done by robots, they should be done by robots. But sending a drill rig to Mars or Jupiter's moon Europa to tap into an aquifer that may have living organisms in it -- those kinds of things will require people."
Then there's the unknown value of newly discovered knowledge. Scientists want to know what Mars can tell us about our own planet's climate and geology. That knowledge, experts say, could help solve difficult environmental problems on Earth.
Jim Bell, Curiosity team member
"It's human nature to explore," says Bell. "By going to difficult or dangerous places, we carry the rest of our species along with us. These stories become part of part of our culture, part of our heritage, part of our shared need to explore the worlds around us. it's a human endeavor that is part science, part inspiration."
Related story: Earth loves Mars -- why we're crushing on the red planet
By the way, Curiosity has fostered jobs, says NASA; more than 7,000 people have worked on the project across 31 states.
What's next? NASA plans test flights for Orion -- a spacecraft designed to carry astronauts outside low Earth orbit -- as soon as 2014. In 2017, NASA plans to launch Orion with a new heavy-lift rocket NASA calls the Space Launch System.
But big questions remain: How would NASA pay for development of a landing vehicle? Or a vehicle for astronauts to travel on the Martian or lunar surface? Or how would it develop an astronaut habitat suitable for the months it would take to travel to Mars or to asteroids?
NASA's proposed budget for 2013 is $17.7 billion -- $59 million less than 2012 (PDF). It includes a "lower cost program" for unmanned missions to Mars (PDF). For perspective, the Mars rover's $2.6 billion price tag equals about 14.7% of NASA's proposed 2013 budget.
However, the budget also calls for more money for manned deep space programs, including almost $3 billion for Orion and the Space Launch System.
In May, something happened right above our heads that gave us a glimpse into the future of Mars exploration. That's when the private firm SpaceX successfully docked its Dragon spacecraft with the orbiting international space station.
NASA is studying a proposal -- referred to as Red Dragon -- that would use a SpaceX rocket for less-expensive unmanned missions to Mars.
But robot missions are just stepping stones to what many experts say is a foregone conclusion.
"Humans are going to live on Mars in the president's expected lifetime," says commercial space consultant Charles Miller, a former NASA executive. "It will happen as a partnership between U.S. entrepreneurs and private industry and NASA."
So what do you think? Are billion-dollar, planet-crawling robots worth the money? Do you think astronauts will set foot on Mars within your lifetime? Share your opinion in the comments section below.
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