Icy Soil Acquisition Device for the 2007 Phoenix Mars Lander  Philip Chu*, Jack Wilson*, Kiel Davis*, Lori Shiraishi** and Kevin Burke**  Abstract  The Icy Soil Acquisition Device is a first of its kind mechanism that is designed to acquire ice-bearing soil  from the surface of the Martian polar region and transfer the samples to analytical instruments, playing a  critical role in the potential discovery of existing water on Mars. The device incorporates a number of  novel features that further the state of the art in spacecraft design for harsh environments, sample  acquisition and handling, and high-speed low torque mechanism design.  Introduction   The Phoenix Mars Mission, currently en route to Mars, consists of a lander equipped with tools and  analytical instruments designed to assess the history of water and the habitability potential of the Martian  polar ice-bearing soil. Icy soil is believed to exist in these regions underneath a shallow layer of regolith.  The Phoenix lander includes a scoop mounted on the end of a robotic arm that will be used to remove the  layer of loose soil covering ice-bearing materials. Once these materials are encountered, an ice-sampling  tool within the scoop will penetrate and acquire icy soil samples that will then be delivered to analytical  instruments by the Robotic Arm to ascertain the existence of water ice. The scoop and ice sampling tool  is known as the Icy Soil Acquisition Device (ISAD). The ISAD is a first of its kind mechanism that will  support the Thermal Evolved Gas Analyzer (TEGA) and the Microscopy, Electrochemistry and  Conductivity Analyzer (MECA) experiments with critical soil samples.  The ISAD has two main functions; bulk digging of loose soil and precision sampling of hard ice-bearing  soils. It is partitioned into two main chambers. The front chamber is used as a scoop, and performs the  function of removing bulk material. The rear chamber contains a high-speed cutting tool, which penetrates  and acquires harder icy soil. The two main chambers are separated by a series of panels. These panels  prevent bulk material from filling the rear chamber of the ISAD during digging of loose soil, and also allow acquired icy soil to be transferred to the front chamber using a series of Robotic Arm wrist movements. A  funnel feature in the front chamber allows for precision delivery of loose and icy soil to analytical  instrument inlet ports. The ISAD also has two blades, the first attached to the front of the scoop, and the  second attached to the bottom of the scoop, which are utilized for scraping surface regolith and ice.   When acquiring icy soil, the ISAD is preloaded against the surface so that the cutting bit is retracted into  the scoop. The drivetrain is energized, rotating the cutting bit at high speed. Spring preload on the cutting  bit forces it into the soil. Icy soil is ballistically ejected from the surface, into the rear chamber of the ISAD,  where it is captured. Several samples can be acquired, after which the icy soil is transferred to the front  chamber of the scoop using a series of Robotic Arm wrist motions. The sample is then delivered to  science instruments by the Robotic Arm.  The ISAD is a first generation mechanism to be qualified for space flight. There are many aspects of the  design that are unique, and should be brought to the attention of the spacecraft mechanism community.  Many of these features will likely be used on subsequent missions, and this paper will provide details on  their design, and lessons learned. This paper will first discuss the highly constrained design space  dictated by the fact that the mechanism was a very late addition to the payload of the Phoenix Mars  Lander. It will then give an overview of the ISAD device and its operational usage. The paper will discuss  details of the design that are critical for understanding the lessons learned, and the unique features of the  mechanism. Solutions to the constrained design space and lessons learned during design, assembly and  testing will be presented in detail.                                                   * Honeybee Robotics Spacecraft Mechanisms Corporation, New York, NY   ** Jet Propulsion Laboratory, Pasadena, CA 

Proceedings of the 39th Aerospace Mechanisms Symposium, NASA Marshall Space Flight Center, May 7-9, 2008  289