WASHINGTON, D.C. -- NASA is not wasting time in moving forward on its next rover that will strut its stuff across the far-flung sands of the red planet.

The space agency released mid-month an "Announcement of Opportunity" that calls for science gear and related ideas that could wind up onboard the Mars Science Laboratory -- or MSL, for short.

Slated for a 2009 liftoff, MSL is the first mobile machinery to follow in the wheel tracks of those two worker-bee Mars Exploration Rovers: Spirit and Opportunity. The MSL rover would depart from the NASA Kennedy Space Center Eastern Test Range during a 20-day launch period, opening as early as October 2009 and closing in November 2009.

Given its potential to be nuclear-energized through radioisotope power sources, MSL is being designed to out-live, out-distance, and out-produce its earlier sister ships.

This roving, long-duration science laboratory mission is to conduct unprecedented surface measurements. MSL would also pave the way for future martian surface and sample return spacecraft.

The flight hardware for MSL is expected to showcase technology for an accurate landing, possibly utilizing hazard and detection avoidance sensors. That equipment would be needed to reach promising but otherwise tough to get to martian real estate.

Where on Mars MSL will find itself is anybodys guess at the moment. MSLs landing site could be picked as late as the final year prior to launch, thereby accommodating a touchdown zone responsive to discoveries from the Mars Reconnaissance Orbiter -- to be launched in 2005, as well as all previous Mars missions.

Making MSL a more capable rover than its forerunners is just one challenge, said Michael Meyer, Senior Scientist for Astrobiology here at NASA Headquarters. He is Program Scientist for the Mars Science Laboratory.

"This is an analytical laboratory on wheels," Meyer told SPACE.com. "How you get the whole package of instruments to work together and with each other and give you the information youre really afterthats going to be a major challenge."

Meyer said the just-issued Announcement of Opportunity was written with the idea that MSL would explore an area on Mars that was potentially habitable -- either in the long-gone past or present-day.

Already finding a cozy home aboard MSL is an active neutron spectrometer provided to NASA through a cooperative agreement with Russia's Federal Space Agency. Also to be mounted on the MSL rover is a sensor to assess the radiation environment at the local Martian surface -- data valuable to better determine how future human crews can cope with radiation doses during their stays on Mars.

Furthermore, there is an analysis of the landing site environment to be done by a meteorology station that gauges temperature, pressure, wind speed and direction, humidity, ultraviolet dose to certain levels, atmospheric dust, and local fluctuations in magnetic field. That equipment will be provided to NASA through a cooperative agreement with Spain's Ministry of Science and Technology.

The current best estimate of the total mass for science gear still to be picked for MSL is roughly 105-pounds (48-kilograms). Proposals from researchers are due in mid-July.

Once down and dirty on Mars, the Mars Science Laboratory is to perform science chores related to biology, climatology, geology and geochemistry in terrain which could include -- depending on the site selected -- sedimentary, hydrothermal, ancient and/or ice-bearing deposits.

MSL science is to done by its Sample Acquisition, Processing, and Handling System. Instruments or suites of devices are to be mounted on the MSL rover mast. Additionally, instruments are to be carried on the rovers robotic arm, or arms.

"Mars Science Laboratory is an essential scientific element of NASAs ongoing Mars Exploration Program," said James Garvin, NASA Lead Scientist for Mars and Lunar Exploration in the Office of Space Science here at NASA Headquarters.

MSL was born in the eyes of science, Garvin told SPACE.com, when the overarching scientific strategy was finally codified. That is, intensified sightseeing of Mars from both orbit using the soon-to-be-launched Mars Reconnaissance Orbiter (MRO) and ground rovers, such as Spirit and Opportunity.

Garvin said this combination allows NASA "to make highly selective and informed decisions about targeting the next wave of Mars exploration," starting with on-the-spot analytical science and then transitioning to the first sample return.  

Meyer noted that the Spirit and Opportunity Mars rovers that are now alive, doing well and working fine on the planet have provided some valuable lessons in preparing for MSL. "We want to make some major improvements in our efficiency in exploration," he said.

Meyer said that the more MSL autonomy the better for science operations. Much faster characterization of valuable science targets is expected.

"Think of how long Opportunity spent in Eagle crater analyzing that outcrop. All that going up and down and doing a few key measurementsthat took a long time," Meyer said. "The more autonomy you can put in so theres less stops in the process of obtaining the science the greater your efficiency is," he added.

Having super-smart robots running on Mars is seen as a confidence building step toward a future Mars return sample effort. Having one rover that can spend a couple years looking for thingsselecting the key rocks that should be brought back to Earthis sure to be an important ingredient for such a task.

"That is one of the things where having nuclear power would be a real benefit," Meyer explained.

MSL has evolved to have a set of essential characteristics: 

• Precision landing, on the order of 3 to 6 miles (5 to 10 kilometers) landing error ellipses versus 31 to 37 miles (50 to 60 kilometers) used by earlier landers;
• Access to higher latitudes and thereby higher absolute elevations than Spirit and Opportunity since all latitudes south of 15 degrees are much higher in relief (above the martian "sea level"). Doing so opens up nearly 70% to 80% of the planet, if needed, to the MSL;
• Longer-range mobility, wheeling from 3 to 16-plus miles (5 to 10-plus kilometers) during a nominal mission;
• Analytical measurements of martian materials suitable for assessing some aspects of "life inference".

Garvin said MSL has been tagged as a "gateway" mission. "It builds as it must upon the Mars Exploration Rover experience and lessons-learned. It also brings a higher level of adaptability and more definitive tools to bear on how to read martian materials: rocks, soils, maybe ices, atmosphere," he said.

Furthermore, MSLs suite of instruments will look for the geochemical signatures of potentially life-hospitable past environments, and begin to help sort out the potential for Mars being habitable right now.

Important to Mars researchers is being able to send MSL to the most scientifically-compelling places on the red planet with precision targeting made possible by Mars Reconnaissance Orbiter observations. And building on the skills shown by Spirit and Opportunity by using MSLs suite of highly precise analytical instruments, the mega-rover can be capable of examining what some call "biological building blocks", Garvin said.

For MSL, the aim is to quantitatively investigate a potential habitat on Mars in place, "before having to decide we have to return such materials to Earth via sample return," Garvin noted.

"Today, MSL is a keystone in our strategy of being scientific discovery-responsive," Garvin pointed out.

Indeed, there has been a continual stream of new discoveries at Mars.

For one, there are the recent discoveries by Opportunity at Meridiani Planum. Then there are the sharp-eyed observations by the Mars Global Surveyor of the planets Holden region "delta", as well as spotting thousands of martian gullies. Still-to-come are the prospects of sleuthing out other discoveries utilizing the Mars Reconnaissance Orbiter.

"MSL has the opportunity to build on the twin Mars rover findings by visiting deposits such as these -- or even better ones discovered by Mars Reconnaissance Orbiter -- and assessing their biogeochemical preservation possibilitiesand whether there are any organic materials at parts per billion," Garvin said. "Of course, the competition for MSLs actual payload is only just beginning," he stated.

"We see MSL as the key next step before much more challenging science missions such as sample return and our conceptualized Astrobiology Field Laboratory (AFL)," Garvin said. AFL would be a possible follow-on rover to MSL, and is being actively discussed by NASA scientists.