Engineers at the Jet Propulsion Laboratory in California are nearly finished assembling and testing the Mars Science Laboratory before shipping hardware to Cape Canaveral for final launch preparations.

The $2.5 billion mission is due for launch as soon as Nov. 25 on an Atlas 5 rocket, beginning a nearly nine-month journey to Mars, where the spacecraft will deploy a massive rover named Curiosity to the surface.

Earlier this year, the rover was put through vibration testing to simulate the intense shaking it will experience during blastoff. NASA also placed Curiosity inside a thermal vacuum chamber to test the rover in the environmental conditions of Mars, including cold temperatures of -202 degrees Fahrenheit and a low atmospheric pressure.

Workers have been gradually putting together the Curiosity rover over the last year, and NASA released photos this week showing the craft almost as it will appear when traversing the surface of Mars.

The rover's six wheels and camera mast were added in 2010, and Curiosity has since received its scientific sensors built to determine whether conditions at Mars were once favorable to support microbial life. Its 10 instuments include a comprehensive analysis tool to study soil samples on-board, a suite of panoramic and microscopic cameras, a laser beam to burn off the skin of rocks, and payloads to measure radiation and soil composition.

Spain provided a weather station for the rover and Russia supplied an instrument to detect underground water ice.

Stretching about 10 feet long, Curiosity is twice as big and five times as heavy as the Spirit and Opportunity rovers sent to Mars in 2003. Curiosity is about the size of a Mini Cooper, according to NASA.

NASA plans to ship the Curiosity rover, its heat shield, descent system and cruise stage to Florida in May and June for final assembly and packaging for launch.

A powerful Atlas 5 rocket, boosted by four strap-on solid motors, must launch the spacecraft between Nov. 25 and Dec. 18 to reach the Red Planet in August 2012.

The images below show Curiosity in its nearly flight-ready state at JPL, including views inside the vacuum chamber and detailed shots of the rover's mast camera suite and robot arm.

Photo credit: NASA/JPL-Caltech