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Articolo che parla dei motivi tecnici del ritardo si MSL. Un paio di estratti:

After the success of MER, JPL engineers dreamed big. Talking to planetary scientists, they heard concerns about the relatively small areas of Mars where the MER rovers could land. MER was restricted to within 15 degrees of the equator because it needed solar power to survive, and required moderate temperatures for its stainless steel actuator motors. Scientists wanted more of the planet to be available: some of the most geologically interesting landing sites were outside the equatorial landing envelope (for example, possible delta deposits had been spotted by orbital imagery nearly 30 degrees south of the equator). JPL engineers looked into what they could do to get MSL into these challenging landing sites.

One of the first restrictions they sought to lift was that surrounding the MER lubrication system. Actuators on MER used a “wet lubrication” system to enable motors to move joints, instruments, and other components. This lubrication system was suspect in the very cold temperatures further from the Martian equator. MSL was to get a brand new type of lubrication—a dry, titanium-based actuator system—in order for it to operate in really low latitudes, up to 35 degrees south of the equator. In 2006, the JPL engineers got to work on testing out their ideas.

By 2007–08, as the launch date drew closer, things were not working out with the new actuators. Required braking and torques were not being achieved with the new dry lubricants. A decision to change course had to be made, because work was being held up on other components that relied on the actuators.

A total of 51 actuators and 54 stand-alone motors are required for MSL, including both engineering models and the flight models that will launch with the rover2. These are spread throughout the rover. JPL outsourced the work to a highly capable company, Aeroflex of Long Island2, which has historically produced actuators for space missions very successfully.

In 2008, a decision was finally made to change back to the old “wet type” stainless steel actuators, and the order was passed to Aeroflex. But the actuator redesign set back actuator development by about nine months2. As it turned out, this change of course came too late. Despite their best efforts, including working double and triple shifts, Aeroflex was not able to deal with such a large order of such complex components while maintaining schedule and quality2. By October 2008, this was becoming apparent to Doug McCuistion, the head of the Mars Exploration Program (MEP) and NASA HQ, who managed the purse strings for the MSL budget.

MSL has been billed as the most capable scientific mission every sent to another planet. Almost every instrument is a unique, cutting-edge item never used before on a space mission. Sample Analysis at Mars (SAM) is the heart of the sample analysis suite: it takes small amounts of rock or soil collected by the rover arm and runs it through a gas chromatograph, a quadrupole mass spectrometer, and a tunable laser spectrometer to completely determine the chemical (and especially organic) content of the sample. For those following the Phoenix instrument last year, NASA has recently found out how challenging this sort of work is. SAM is the instrument the Phoenix team would have loved to have onboard, but that’s the difference between a Scout and a Flagship mission.

CHEMCAM is a laser used to burn into rocks and detect plasma lines emitted by excited electrons and thus tell the chemistry of rocks at a distance. CHEMIN is an ingeniously miniaturized x-ray diffractometer that will determine the mineralogy of rocks and soil collected by the rover arm. Then there are an array of cameras: a descent imager (MARDI), a hand lens (MAHLI,) and panoramic camera (MASTCAM). There is a Russian-built neutron detector (DAN), and a Spanish-built atmospheric monitoring package (REMS). For future Martian astronauts, there is a radiation detector designed to monitor the Martian radiation environment (RAD). An old standby with a large heritage from Pathfinder and MER, the Alpha Proton X-Ray Spectrometer (APXS), is also mounted on the MSL robot arm.