The scientific understanding of key physical processes between the Sun and Earth require simultaneous measurements from many vantage points in space. Nano-satellite technologies will enable a class of constellation missions for the NASA Space Science Sun-Earth Connections theme. These technologies will also be of great benefit to other NASA science enterprises. Each nano-satellite will weigh a maximum of 10 kg including the propellant mass. Provisions for orbital maneuvers as well as attitude control, multiple sensors and instruments, and full autonomy will yield a highly capable miniaturized satellite. All onboard electronics will survive a total radiation dose rate of 100 krads over a two year mission lifetime. Nano-satellites developed for in-situ measurements will be spin-stabilized, and carry a complement of particles and fields instruments. Nano-satellites developed for remote measurements will be three-axis-stabilized, and carry a complement of imaging and radio wave instruments. Autonomy both onboard the nano-satellites and at the ground stations will minimize the mission operational costs for tracking and managing a constellation. Partnerships with private industry and academic institutions will be utilized for the development, manufacturing, and testing of the nano-satellites. Key technologies under development will be described, which include: advanced, miniaturized chemical propulsion; miniaturized sensors; highly integrated, compact electronics; autonomous onboard and ground operations; miniaturized onboard methods of orbit determination; onboard RF communications capable of transmitting data to the ground from far distances; lightweight, efficient solar array panels; lightweight, high output battery cells; a miniaturized heat transport system; lightweight yet strong composite materials for the nano-satellite and deployer-ship structures; and simple, reusable ground systems