After a long, sustained series of traverses (with a few stops along the way to see the sights) Opportunity has reached "Vostok Crater." The rover began a set of in-situ measurements on the soil and rock of Vostok. The miniature thermal emission spectrometer instrument seems to be showing some symptoms of its age, resulting in some failed images; diagnostic observations using the instrument will be performed shortly. Opportunity otherwise continues to be in excellent health.
Sol-by-sol summaries:
Sols 396 and 397 (March 5 and 6) were designed as a two-sol plan, with two sols of driving toward Vostok. The intent was to cover about 130 meters (427 feet) through combined directed-drive segments and autonomous-navigation segments on sol 396, followed by another 60-meter (197-foot) autonomous-navigation drive on sol 397. However, due to a partially misdefined waypoint (correct coordinates, but with too small a radius) on the first sol, Opportunity drove farther in its directed drive than intended. A safety timeout was triggered, and no driving took place on sol 397. The issue was quickly analyzed and fully understood by the mobility team and the rover planners, so nominal traverse planning resumed on sol 398.
In the meantime, the miniature thermal emission spectrometer failed some command executions, and a command was uplinked on sol 396 to prevent further use of this instrument until diagnostic testing is completed.
Sol 398 was primarily a drive sol, with Opportunity covering 95 meters (312 feet) via a combination of directed drives and autonomous navigation.
At the end of a 35-meter (115-foot) traverse, Opportunity finally reached Vostok during sol 399. The crater is almost completely buried in sand.
On sol 400, thanks to fortuitous positioning of the rover, in-situ targets were already in the work volume of the robotic arm, eliminating the need for an approach sol. Opportunity proceeded to examine a soil target, "Laika," and a rock, "Gagarin," with its microscopic imager, then positioned the alpha particle X-ray spectrometer for later measurements on Gagarin. After taking a panoramic image of Vostok, the rover took a long nap, waking up for its afternoon downlink and to begin taking data with the alpha particle X-ray spectrometer. Opportunity awoke again before midnight to stop the integration, and then went into the deep-sleep mode until morning.
Since the plan called for Opportunity to continue in-situ measurements, the team chose to combine sols 401 and 402 as a two-sol plan. For sol
401, the plan is to use the brush of the rock abrasion tool brush on Gagarin and capture a microscopic imager mosaic afterwards. This will be followed by an evening alpha particle X-ray spectrometer measurement of the brushed surface, and then by a mini-deep sleep. On sol 402, ending on March 11, the rover will grind Gagarin for two hours with the rock abrasion tool, then perform an early morning alpha particle X-ray spectrometer integration on the resulting hole.