Dante II, an eight-legged walking robot developed by the Dante project, explored the active volcanic crater of Mount Spurr in July 1994. In this paper, we describe the operator interfaces and the network-based participation methods used during the Dante II mission. Both virtual environment and multi-modal operator interfaces provided mission support for supervised control of Dante II. Network-based participation methods including message communications, satellite transmission, and a World-Wide Web server enabled remote science and public interaction. We believe that these human-machine interfaces represent a significant advance in robotic technologies for exploration.