An 18-day period began a transition into solar conjunction on sol 241, when the Sun partially obscured the communications path between Earth and Mars, making communications sessions unreliable. Engineers were able to successfully command Spirit on sol 241, and they had partial commanding success on sol 242.

Engineers will attempt to command Spirit on sol 243 also. From sol 244 through sol 255, sequences already safely on board will perform a set of science activities on a daily basis. On sols 256 through 258, the last three days of conjunction, the rover team will attempt normal operations again.

On sol 242, engineers sent Spirit a set of coordinated commands to use the miniature thermal emission spectrometer and panoramic camera for observations of possible future science targets. A new set of 12 conjunction master sequences was also transmitted successfully to Spirit. This new set of conjunction master sequences will use less energy than previous sequences.

For the conjunction period, the rover team has placed the Moessbauer spectrometer on one of the two magnets on the rover deck. Spirit will activate the Moessbauer instrument every day during conjunction in order to characterize the dust that has collected on the magnet. However, a wrinkle has developed in this plan.

Before placing the Moessbauer spectrometer on the magnet, Spirit placed it on the soil in front of its current location. That soil touch was done to leave a soil impression that would be studied after conjunction for changes. Images taken after the touch indicate that Spirit inadvertently picked up some soil and likely sandwiched that soil onto the magnet with the Moessbauer. It's the team's first inadvertent sample acquisition!

Engineers and scientists decided to leave the Moessbauer in place on the magnet and will evaluate the status and effect of the dirt clod after conjunction. The dirt does not pose any threat to the rover from an engineering perspective.

Since Spirit arrived at its solar-conjunction resting place, its science activities have focused on gathering data from the surrounding area for use in planning post-conjunction sols. Navigation camera images in Spirit's drive direction have been used to develop traverse maps.

These maps show areas that allow Spirit to maintain a north-facing tilt; these areas will provide significantly more solar energy and will therefore be favored as the team plans the traverse to Spirit's next science target.

During conjunction, Spirit will transmit five-minute "beep" tones, and engineers will send "No-operation" commands to the rover to characterize effects that the conjunction has on radio transmissions between Mars and Earth.

RAT is Rearin' For Another Opportunity To Go At It

Opportunity is healthy and continuing to explore a rock called "Escher" on the southwestern slope of "Endurance Crater."

Sol 211: Opportunity awoke from deep sleep at 7 a.m. local solar time. It re-enabled survival heaters on its miniature thermal emission spectrometer and re-started a Moessbauer spectrometer examination of a target called "Kirchner."

The rover made observations with its panoramic camera and its miniature thermal emission spectrometer from about 11 a.m. to 2 p.m. local solar time, focusing on getting thermal inertia measurement of the dunes at different times of day.

A planned tool change to the alpha particle X-ray spectrometer in the afternoon failed due to a sequencing error in retracting the Moessbauer spectrometer from the surface. A conditional sequencing check prevented the overnight alpha particle X-ray spectrometer integration from occurring as desired in such fault cases.

Sol 212: A calibration of the rock abrasion tool calibration was completed successfully. The tool is healthy and ready for action! An aggressive plan acquired 80 microscopic images of the rock Escher.

As part of the team's efforts to increase operational flexibility, a test was conducted involving operating the miniature thermal emission spectrometer in parallel with arm operations.

Unfortunately, this resulted in some corrupted data from the miniature thermal emission spectrometer due to vibrations as the rover arm moved. The rover used its Moessbauer spectrometer in the afternoon before going into deep sleep overnight.

Sol 213: Opportunity awoke from deep sleep and re-started the Moessbauer integration. The rover performed some remote sensing during the day and then changed tools to the alpha particle X-ray spectrometer for an overnight integration. Later it completed a midnight thermal inertia observation with the miniature thermal emission spectrometer, which required an hour of actuator preheating.

Sol 214: Opportunity completed the alpha particle X-ray spectrometer observation and successfully used the rock abrasion tool to brush clean two targets on Escher ("EmilNolde" and "Kirchner_RAT").

Then it made observations with its microscopic imager, hazard-avoidance camera and panoramic camera. The Moessbauer spectrometer was then positioned on Kirchner_RAT, where it analyzed the rock's mineral composition until the rover went into deep sleep overnight. Sol 214 ended on Aug. 31.

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