Spirit Update : Brush, Brush, Brush, Then Step Back

sol 55, Feb 29, 2004

This image of the rock called "Humphrey" was taken by Spirit’s navigational camera on its 54th sol on Mars. The rock’s name was inspired by Humphries Peak – the tallest peak in Arizona and part of the San Francisco volcanic complex. Standing approximately .6 meters (about 2 feet) tall, "Humphrey" is one of the largest blocks of what scientists believe is ejected material from one of the rover’s long-term targets, the crater dubbed "Bonneville." Likely a basaltic rock, the fractures in "Humphrey" are thought to have been caused by the impact as it was hurled from the crater to its current resting place. Scientists are eager to investigate ejecta rocks, as they give a glimpse of the composition of what lies beneath the martian surface. The engineering and science teams are preparing to brush and then grind "Humphrey" with Spirit’s rock abrasion tool. The hope is to remove as much dust as possible so they can examine the coating and then the exposed undersurface after grinding with the cameras and the miniature thermal emission spectrometer.


Spirit used its rock abrasion tool for brushing the dust off three patches of a rock called "Humphrey," during its 55th sol on Mars, ending at 5:53 p.m. Saturday, PST. Before applying the wire-bristled brush, the rover inspected the surface of the rock with its microscope and with its alpha particle X-ray spectrometer, which identifies elements that are present. Brushing three different places on a rock one right after another was an unprecedented use of the rock abrasion tool, designed to provide a larger cleaned area for examining.

Afterwards, Spirit rolled backward 85 centimeters (2.8 feet) to a position from which it could use its miniature thermal emission spectrometer on the cleaned areas for assessing what minerals are present. Due to caution about potential hazards while re-approaching "Humphrey," the rover moved only part of the way back. Plans for sol 56, ending at 6:33 p.m. Sunday, PST, call for finishing that re-approach and further inspecting the brushed areas. If all goes well, the rock abrasion tool’s diamond-toothed grinding wheel will cut into the rock on sol 57 to expose fresh interior material.

For wake-up music on sol 55, controllers chose "Brush Your Teeth," by Cathy Fink and Marcy Marxer, and "Knock Three Times," by Tony Orlando and Dawn.

More Updates On Spirit

Opportunity Update: "Guadalupe" Under the Microscope

sol 35, Feb 29, 2004

During its 35th sol on Mars, ending at 6:14 a.m. Sunday, PST, Opportunity manipulated the microscopic imager at the tip of its arm for eight observations of the fine textures of an outcrop-rock target called "Guadalupe." The observations include frames to be used for developing stereo and color views.

Opportunity also used its Moessbauer spectrometer and, after an overnight switch, its alpha particle X-ray spectrometer to assess the composition of the interior material of "Guadalupe" exposed yestersol by a grinding session with the rock abrasion tool.

The panoramic camera up on the rover’s mast captured a new view toward the eastern horizon beyond the crater where Opportunity is working, for use in evaluating potential drive directions after the rover leaves the crater.

Jimmy Cliff’s "I Can See Clearly Now," was played in the mission support area at JPL as Opportunity’s sol 35 wake-up music.

Plans for sol 36, ending at 6:54 a.m. Monday, PST, called for finishing the close-up inspection of "Guadalupe," then backing up enough to give the panoramic camera and miniature emission spectrometer good views of the area where the rock interior has been exposed by grinding.

More Updates On Opportunity