September 6, 2004
Salar Grande, Atacama Desert, Chile

Agenda
• Continue checkout of the position estimator
• Rebuild hard drive in the environmental station
• Grab images with the fluorescence imager
• Test onboard spectrometer with 1° foreoptic
• Verify tuning of motion controller
• Navigate autonomously
• Finalize science site

Status and Progress

Imaged fluorescence in daylight. The onboard Fluorescence Imager (FI), which passed its initial mechanical and electronic checkout a few days ago, imaged samples placed in its field of view. Color images were created by imaging with red, green, and blue band-pass filters with full-spectrum illumination from the underbody flash lamp. Fluorescence is the property of some molecules to emit light at longer wavelength that the wavelength that illuminates them; it is caused by the absorption and emission of energy by electrons composing the molecule. With the FI on Zoë we detected fluorescence, in daylight under the shade of the rover solar panels. This required special filters and a very high sensitivity camera because fluorescence is usually overwhelmed by sunlight. Using 450 +/- 25 nm (blue) excitation and 740 +/- 70 nm detection (infrared) we imaged the fluorescence of chlorophyll and possibly some minerals in a sample. The images below show the composite color image (left) and just the 740nm fluorescence emission (right).

Tested visible near-infrared (VNIR) spectrometer. The spectrometer, its fiber optics and, and foreoptic are installed in Zoë. The instrument is working although we are having some intermittent difficulties communicating with its interface electronics. It is typically used in conjunction with a dedicated laptop computer but we are testing a prototype interface that allows Zoë’s computers to control and collect data from the instrument.

Tuned steering control. Steering performance on Zoë is not well tuned through most of its operating range but as expected its ability to turn tightly (2.5m radius) will be limited at the top speeds. Hyperion’s top speed was 0.25m/s, about 1kph, but Zoë is able to move nearly 4 times that speed, at 1.0m/s. This is necessary so that Zoë has ample time to stop at science sites and acquire observations from its instruments. It sprints from location to location on its daily traverse, to maximize the time available for observation. We are now very satisfied with the drive and steering capability and have me the design specifications coming out of the 2003 field experiment.

Finalized science operations site. We’ve chosen a region in the coastal to conduct the remote science operations, in which daily commands for Zoë will be developed by a team in Pittsburgh using satellite imagery and rover observations. Ground truth will be measured by scientists in Chile, who will measure spectra and collect samples after Zoë has moved on.

Upcoming
• Continue checkout of the position estimator
• Rebuild hard drive in the environmental station
• Test onboard spectrometer with 1° foreoptic
• Navigate autonomously
• Set up long range VHF and 802.11 wireless communication

Weather
Morning: Overcast, moderate 12.5C, humidity 70%, no dew
Afternoon: Clear, light breeze 5kph, moderate 24C, humidity 55% (beautiful day)
Evening: Overcast, breeze 15kph at sunset, cool 10C, humidity 65%

Quote of the Day
“CHI, LE, CHI, LE, CHI, CHI, CHI, LE, LE, LE, VIVA CHILE!”