NASA mission managers are tweaking the landing target for the new Mars rover, which is on track to touch down shortly after 1:30 a.m. EDT on Aug. 6.
Mars Science Laboratory is headed to a large crater that has a 3-mile-high mound of what appears to be layers of sediment inside. Scientists aren't sure how the mound, recently named Mount Sharp, formed, but they believe it is what is left over from debris that once filled the 96-mile-wide pit, known as Gale Crater.
With confidence growing that the rover, nicknamed Curiosity, is on track for a precision landing, NASA decided to aim to for a smaller spot, which would lop off months of driving time if successful. The new zone also is closer to the Mount Sharp's central peak which has more high-priority science targets.
The point of the mission, expected to last two years, is to probe Mount Sharp and the surrounding area for chemical and geologic evidence that would support life and keep it preserved.
The new landing target, pictured above in black, is 12 miles long and 4 miles wide. The previous zone was 12 miles long and 16 miles wide.
A successful landing depends on a newly designed rocket-powered sky crane, which is expected to gently lower the car-sized rover onto the surface of Mars.
"We've done everything we can to ensure the greatest probability of success," NASA manager Dave Lavery told reporters during a conference call Monday.
"The reality is, this is a very risky business. Historically, only about 40 percent of the missions to Mars have been successful," he said.
Curiosity has been racing toward Mars since its launch on Nov. 26, 2011, from Cape Canaveral Air Force Station in Florida.
Because of the distance between Mars and Earth, communication signals indicating whether the rover landed safely will take at least 14 minutes to arrive.
Image: NASA's new Mars probe is expected to touch down inside a 96-mile-diameter crater located just south of the equator. The oval circle is the targeted landing zone. Credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS