Editorial: Space Robotics Special Issue, Part 1

Space robots routinely provide compelling demonstration of the remarkable advance of robotic technology and show that the most advanced capabilities are moving from the laboratory to the field. Early space robots used the most simple and reliable technologies: welded aluminum, relays, brushed motors, hardened microprocessors, and assembly code, to mitigate the extreme effects of the space environment and the reliability risks associated with complex systems. Today we see state-of-art composites, flexible linkages, rare-earth brushless motors, multi-processors, and adaptive, high-level programming in space. These robots are extensively tested in simulation and at the component and system level in environments that are analogous to their ultimate destination. Their functions are validated before they begin their mission. One recurring result seems to be that not only do these robots succeed but they survive beyond any prediction. Indeed one could say that space robots are thriving on orbit and on the planets. This is the fourth special issue on space robotics published by the Journal of Field Robotics. Our previous issues in March-May 2007, March-April 2009, and May-August 2012 documented robotics technologies for space applications. In the previous Space Robotics special issue the editorial anticipated both the arrival of the Robonaut2 humanoid on the International Space Station and the landing of the Curiosity rover on the surface of Mars. Today these systems are in operation and are producing remarkable achievements. Robonaut2 is operational and performing increasingly sophisticated experiments with astronauts. In the coming year legs will enable it to move throughout the space station interior and to perform regular maintenance tasks. Curiosity has traveled nearly 2 km on Mars and under the guidance of scientists has measured 2000 targets and returned nearly 200 gigabytes of data. To do this it is acting more autonomously than any previous space robot, navigating from place to place, to selecting targets and acquiring measurements. In Europe the work on ExoMars, a large two-mission project to search for biosignatures of Martian life, past or present, including a Martian rover, is moving forward with the design, manufacturing and verification phase approved. The ExoMars rover scenario has been a stimulus for various research and development activities in robotic technologies including field testing. Space robotics in Asia include recent successes in China, Japan and India with launch of orbital systems destined for the Moon. The coming years hold exciting results of these development activites. This Space Robotics special issue appears in two parts, the first in November/December 2013 and the second in January/February 2014. Each issue provides a diverse mix of articles on robotic applications in space. Before the Mars Science Laboratory rover Curiosity arrived at Mars extensive testing of its chassis was undertaken by Heverly et al. A rover with mass reduced to match Mars loads was developed and evaluated in consolidated and unconsolidated soils at a variety of slopes. These results have informed what Curiosity can do on Mars and results from the rover have thus far agreed with what the authors have predicted and measured. The algorithms and software used to control the drill of Curiosity rover are described in Helmick et al. One of the most important components of the algorithm used for drilling is a force feedback control system used to regulate the force applied to the rock during drilling. This algorithm and all of the other algorithms and software used to enable the process of robustly, efficiently, and autonomously drilling into rocks with a priori unknown and widely varying properties are described in detail. Inotsume et al. presents a technique to improve mobility of rovers traversing across steep sandy slopes such as crater rims by using an actively reconfigurable suspension to adapt to the terrain. Terramechanics models are presented which describe the tractive performances under these conditions. Control strategies to reduce longitudinal and lateral slip have been developed and implemented on a four-wheeled rover El-Dorado-II-B. Results of tests of the effectiveness of the control scheme on a natural sand dune are presented. A rock climbing robot is presented by Parness et al. that can free climb on vertical, overhanging, and inverted rock faces. This type of system has applications to extreme terrain on Mars or for sustained mobility on microgravity bodies. The robot grips the rock using hierarchical arrays of micro-spines. Micro-spines are compliant mechanisms made of sharp hooks and flexible elements that allow the hooks to move independently and opportunistically grasp roughness on the surface of a rock. This paper presents many improvements to early micro-spine grippers, and the application of these new grippers to a 4-limbed robotic system, LEMUR IIB. The paper by Stenning et al. describes the use of a network of reusable paths as a novel approach to navigation of a rover on a planetary surface. It allows a mobile robot to autonomously seek distant goals in unmapped, GPS-denied environments generated via a visual teach and repeat