Teflon from the drill on NASA's Curiosity rover could contaminate Martian soil, say scientists, creating misleading evidence of an ancient alien civilization that had developed nonstick cookware.

An unexpected contamination problem has cropped up for NASA's next Mars rover, but scientists are confident the huge robot will still be able to complete its mission after it lands on the Red Planet in August.

NASA scientists discussed the contamination concern and a new Mars landing plan for the car-sizeCuriosity roverin a teleconference with reporters today (June 11). The contamination issue, they said, concerns the rover's drill.

When Curiosity ultimately bores into a Martian rock, small amounts of Teflon and other contaminants from the drill will likely seep into the sample, NASA officials said. These introduced materials may make it tougher for the Curiosity team to search for organic carbon the building blocks of life as we know it here on Earth on the Red Planet.

While researchers are still working to get a handle on the problem, they don't think it will significantly hinder the Curiosity rover or its $2.5 billion mission, which is officially known as the Mars Science Laboratory (MSL).

Right now, the overall sense on the mission team is that "it's not a serious problem, because we see so many potential ways to work around this that we could use," Curiosity lead scientist John Grotzinger, of Caltech in Pasadena, told reporters today. [Curiosity - The SUV of Mars Rovers]

Meanwhile, Grotzinger and his team also said today that they have trimmed down the landing zone for the Curiosity rover in order to bring it closer to its final target: a huge mountain inside Mars' giant Gale Crater.

Curiosity launched in late November and is due to touch down inGale Crateron the night of Aug. 5. After it lands, it will embark on a roughly two-Earth-year mission to determine if the Gale Crater area is, or ever was, capable ofsupporting microbial life.

The 1-ton rover will use10 science instrumentsto get at the question. One of those instruments, known as Sample Analysis at Mars, or SAM, is a chemistry laboratory stripped down to the size of a microwave oven.

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