During pre-flight testing in March 2011, the Mars Hand Lens Imager (MAHLI) camera on NASA's Mars rover Curiosity took this image of the MAHLI calibration target under illumination from MAHLI's two ultraviolet LEDs (light emitting diodes).

One reference swatch on the target fluoresces in red as it is illuminated by the instrument's ultraviolet light source. The LED wavelength is 365 nanometers. Violet reflections of the ultraviolet LEDs are visible off the opal glass in the bar target section of the calibration target. The pigment in the fluorescent swatch was donated by Spectra Systems Inc., Providence, R.I.

This image can be compared to image PIA15287 which was taken from the same distance, 3.94 inches (10 centimeters), but using MAHLI's white-light LEDs rather than the ultraviolet ones. In white light, the fluorescent swatch is cream-colored.

The MAHLI adjustable-focus, color camera is one of the tools on the turret at the end of Curiosity's robotic arm. Its calibration target is attached to the rover at the arm's shoulder joint.

NASA's Mars Science Laboratory mission launched on Nov. 26, 2011, and will deliver the rover Curiosity to Gale Crater on Mars in August 2012. With MAHLI and nine other science instruments, Curiosity will investigate whether the area has ever offered environmental conditions favorable for microbial life.

Malin Space Science Systems, San Diego, supplied MAHLI and three other cameras for the mission. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, in Pasadena, manages the Mars Science Laboratory mission for the NASA Science Mission Directorate, Washington, and built Curiosity.