Feasibility of mining lunar resources for earth use: Circa 2000 AD. Volume 1: Summary

The feasibility of obtaining lunar minerals for terrestrial uses is examined. Preliminary results gave indications that it will not be economically feasible to mine, refine, and transport lunar materials to Earth for consumption. A broad systems approach was used to analyze the problem. It was determined that even though the procedure was not economically advisable, the concept for the operations is technically sound

Wireless Command-and-Control of UAV-Based Imaging LANs

Dual airborne imaging system networks were operated using a wireless line-of-sight telemetry system developed as part of a 2002 unmanned aerial vehicle (UAV) imaging mission over the USA s largest coffee plantation on the Hawaiian island of Kauai. A primary mission objective was the evaluation of commercial-off-the-shelf (COTS) 802.11b wireless technology for reduction of payload telemetry costs associated with UAV remote sensing missions. Predeployment tests with a conventional aircraft demonstrated successful wireless broadband connectivity between a rapidly moving airborne imaging local area network (LAN) and a fixed ground station LAN. Subsequently, two separate LANs with imaging payloads, packaged in exterior-mounted pressure pods attached to the underwing of NASA's Pathfinder-Plus UAV, were operated wirelessly by ground-based LANs over independent Ethernet bridges. Digital images were downlinked from the solar-powered aircraft at data rates of 2-6 megabits per second (Mbps) over a range of 6.5 9.5 km. An integrated wide area network enabled payload monitoring and control through the Internet from a range of ca. 4000 km during parts of the mission. The recent advent of 802.11g technology is expected to boost the system data rate by about a factor of five

Solar-Powered Airplane with Cameras and WLAN

An experimental airborne remote sensing system includes a remotely controlled, lightweight, solar-powered airplane (see figure) that carries two digital-output electronic cameras and communicates with a nearby ground control and monitoring station via a wireless local-area network (WLAN). The speed of the airplane -- typically <50 km/h -- is low enough to enable loitering over farm fields, disaster scenes, or other areas of interest to collect high-resolution digital imagery that could be delivered to end users (e.g., farm managers or disaster-relief coordinators) in nearly real time

Long-term survivorship and crown area dynamics of tropical rainforest canopy trees

Lateral shading of direct-beam irradiation among neighboring canopy tree crowns in a nonequatorial tropical rain forest canopy was modeled as a function of solar position using a photogrammetric database derived from large-scale color aerial stereopairs (1:1500–1:3000 scale) acquired in 1976. The interception of direct-beam irradiation by the orthogonally projected crown area of each tree was computed at hourly intervals over a full calendar year using a Parameterization model of cloud-attenuated direct-beam availability. The annual totals of intercepted direct-beam irradiation (Ib) ranged from 1.81 to 4.13 GJ·m−2·yr−1. Expressed as a percentage of the available incident direct-beam irradiation, these values ranged from 44% to 100%. Approximately 20% of the sample population intercepted <70% of the available annual direct-beam irradiation. The long-term effects of lateral shading and the intertree differences in Ib were assessed using repeat aerial stereophotography of the same section of forest 18 yr later in 1994 for the determination of the mortality, survivorship, and crown growth of the canopy trees delimited in the 1976 stereopairs. Mortality over the 18-yr period amounted to 27.2%. Based on the lateral shading simulations, the mean annual Ib totals of the survivors and those that died were significantly different (P < 0.001). Approximately 40% of the survivors experienced crown area reductions. Although there was no significant difference in the Ib of survivors with crown growth and those with crown reductions, a relationship was established between Ib and the extent of crown area change. Canopy trees that intercept the most direct-beam irradiation and experience the least lateral shading have higher probabilities of survivorship and significant crown area changes that may be in the form of crown growth or crown reduction. Their laterally shaded neighbors have a lower survivorship probability, and those that survive persist in an inhibited state with limited crown area change. We conclude that the effects of lateral shading are not limited to the margins of treefall gaps and that lateral shading determined by crown position in the uneven upper canopies of nonequatorial tropical rain forests has a detectable effect on the long-term fates of neighboring canopy trees.\u