In clear morning skies over central Florida, NASA launched an Atlas Five rocket carrying the Mars Science Lab and a rover the size of a small automobile called Curiosity Saturday.
Eight months from now, after landing on Mars, Curiosity will be used to search for evidence that the red planet could support microbial life, a project that could pave the way for a human mission to Mars in the decades ahead.
Once the Mars vehicle is in space and on its designated flight path it will take eight months to arrive at its destination, more than 566 million kilometers from Earth.
More than 13,000 people viewed the launch at the Kennedy Space Center, but many more people around the world saw it in television broadcasts and through streaming video on the Internet.
This is the first launch of a rover for Mars exploration in eight years, and scientists say Curiosity, officially known as the Mars Science Laboratory, will go well beyond the comparatively simple exploration carried out by previous vehicles.
The one-ton Curiosity is approximately the size of a subcompact automobile and is equipped with a mechanical arm that can stretch out more than two meters to take samples of rock and soil, which can then be analyzed by 10 instruments in the main body of the rover.
In addition to grabbing material from the planet's surface, Curiosity can drill into rock to obtain samples and break up rocks with a laser attached to its mast, which also holds a camera that will allow researchers back on earth to see what is being done.
The rover also has various instruments to measure weather conditions, providing scientists with daily updates about temperature, humidity and atmospheric conditions as well as radiation.
In its long-range plans, NASA envisions a human mission to Mars and information gathered by this science laboratory will help in the planning and preparation for that.
But many scientists argue that these unmanned missions, utilizing sophisticated robotic devices, may be able to answer most of the tantalizing questions they have about the planet in our solar system that comes closest to being like Earth.
This mission, which cost $2.5 billion, comes at a time of a budget crisis in the U.S. federal government that could affect NASA's future plans. While defenders of the program say it costs only pennies from each dollar in the federal budget, lawmakers in Congress may consider cuts if faced with the prospect of reducing programs that more directly benefit citizens.
NASA is hoping that all goes well on this mission, that the Mars Science Laboratory arrives as planned in early August, that the descent vehicle succeeds in its complicated maneuver to lower the rover onto the surface of Mars and that all the instruments then work, sending signals back to Earth with valuable information about the planet's soil.
The goal is to find out if Mars does or ever did have the capability of sustaining life as we know it.
The main requirements for life are water, energy and organic carbon. Previous missions have already found evidence of the first two, so Curiosity will concentrate on finding carbon.
Curiosity is to carry out its exploration for two years in a place scientists call the Gale Crater, which features a gently sloping mountain of sedimentary rock. By moving up the surface, Curiosity can provide information about the geologic makeup of the rock and how it was formed over time.