Phoenix Robotic Arm Camera

Abstract

[1] The Phoenix Robotic Arm Camera (RAC) is a variable-focus color camera mounted to the Robotic Arm (RA) of the Phoenix Mars Lander. It is designed to acquire both close-up images of the Martian surface and microscopic images (down to a scale of 23 mm/pixel) of material collected in the RA scoop. The mounting position at the end of the Robotic Arm allows the RAC to be actively positioned for imaging of targets not easily seen by the Stereo Surface Imager (SSI), such as excavated trench walls and targets under the Lander structure. Color information is acquired by illuminating the target with red, green, and blue light-emitting diodes. Digital terrain models (DTM) can be generated from RAC images acquired from different view points. This can provide high-resolution stereo information about fine details of the trench walls. The large stereo baseline possible with the arm can also provide a far-field DTM. The primary science objectives of the RAC are the search for subsurface soil/ice layering at the landing site and the characterization of scoop samples prior to delivery to other instruments on board Phoenix. The RAC shall also provide low-resolution panoramas in support of SSI activities and acquire images of the Lander deck for instrument and Lander check out. The camera design was inherited from the unsuccessful Mars Polar Lander mission (1999) and further developed for the (canceled) Mars Surveyor 2001 Lander (MSL01). Extensive testing and partial recalibration qualified the MSL01 RAC flight model for integration into the Phoenix science payload.

Water and Brines on Mars: Current Evidence and Implications for MSL

“…The impingement of the Fig. 3 Phoenix Robotic Arm Camera (Keller et al 2008) images of a strut on Sols 8, 31, and 44. The "smoking gun" that spheroids like that encircled in red must have been liquid, is the fact that they grew in proportion to their initial volume as predict by Raoult's Law, that they darkened just before disappearing (likely dripping off as predicted by stability analysis), and that growth was subsequently suppressed only over the material that appear to have dripped off, carrying the deliquescent salts with them.…”

Curiosity’s Mars Hand Lens Imager (MAHLI) Investigation

“…In the mid-to late-1990s, the deployable hand lens concept was adapted for spacecraft headed to Mars in the form of the RAC aboard Mars Polar Lander and Phoenix (Keller et al 2001(Keller et al , 2008, and the MER MI cameras aboard the rovers Spirit and Opportunity . Arriving in January 2004, the MER MI cameras quickly revolutionized Mars science, ending a 30-year discussion (e.g., Sharp and Malin 1984) as to whether sand-sized, windblown particles actually occur on Mars (Herkenhoff et al 2004a).…”

The Mars Astrobiology Explorer-Cacher (MAX-C): A Potential Rover Mission for 2018

“…Microimaging capability-in the form of a geologist's hand lens-has long been an essential tool for terrestrial field geology. Imagery at the hand-lens scale (several cm field of view resolved to several tens of microns) provided by the Microscopic Imagers on the MERs and the Robotic Arm Camera (Keller et al, 2008) on the Phoenix lander has proven so vital to the success of these missions and to the Mars Exploration Program (Herkenhoff et al, 2004) that a microimager is one of the two instruments now recognized as essential for Mars surface missions (MEPAG ND-SAG, 2008). The microtextures of rocks and soils, defined as the microspatial interrelationships between constituent mineral grains, pore spaces, and secondary (authigenic) phases (e.g., cements) of minerals, provide essential data for inferring both primary formational processes and secondary (postformational) diagenetic processes.…”