Autonomous Landing Guidance Systems

All weather tactical aircraft recovery and high sortie generation rates from forward, possibly battle damaged landing areas will reqire autonomous landing guidance systems which are independent of ground-based cooperative aids. A recently completed study has examined the operational requirements and assessed current and near term technology for an answer to this need. The Landing Systems Requirements/Synthesis Study has defined the Pilot/vehicle Interface and imaging sensor suite required, based on the concept of augmenting pilot forward vision with sensor imagery and guidance symbology on a HUD during low visibility landings. Image processing technology was also assessed for potential enhancement of the information presented to the pilot. This paper summarizes the final report of the Study, which is in publication.     

Integrated design systems — capturing, reusing and optimizing design methods in new millennium

An important goal of New Millennium is to research new methods of performing spacecraft and mission design. We have completed the first phase of our effort on how to make design tools such as analysis programs more available. We are now embarking with Stanford University on discovering methods to allow more project history and knowledge to be automatically captured and reused and with Ames Research Center on how to use virtual reality to enhance the visualization of new missions before any hardware exists. We are also trying to capture the design process in an electronic form so that computer aided optimization may lead to a vastly greater search of the possible designs which meet the design requirements.     

A short history of the European Transonic Wind Tunnel ETW

This paper is written as a contribution to the celebration of 50 years of Progress in Aerospace Sciences and of the centenary of the birth of its founder, Dietrich Küchemann. It reviews the evolution of the European Transonic Wind Tunnel, ETW, from early conceptual studies to its entry into service and its current capabilities and achievements. It traces the development, from the earliest days, of experimental aerodynamics and of the basic aerodynamic understanding that gave rise to the main periods of wind tunnel building before and after World War II. By about 1960, this activity appeared to have come to a natural halt. The paper gives an account of the role of Küchemann in arguing the need in 1968 for a further step in wind tunnel capability, to provide transonic testing at high Reynolds numbers. It describes his leading role in gaining acceptance of the concept, formulating the specification and promoting studies of alternative, radical design options for the co-operative European project that became ETW. The progress of ETW through design, construction, commissioning and into full operation is recorded. The paper discusses the many technical innovations that have been introduced in order to meet customer requirements in the challenging field of aerodynamic testing in a cryogenic environment and, finally, looks to the future and the further technical challenges that it holds.     

What Might GRACE Contribute to Studies of Post Glacial Rebound?

The NASA/DLR satellite gravity mission GRACE, launched in March, 2002, will map the Earth's gravity field at scales of a few hundred km and greater, every 30 days for five years. These data can be used to solve for time-variations in the gravity field with unprecedented accuracy and resolution. One of the many scientific problems that can be addressed with these time-variable gravity estimates, is post glacial rebound (PGR): the viscous adjustment of the solid Earth in response to the deglaciation of the Earth's surface following the last ice age. In this paper we examine the expected sensitivity of the GRACE measurements to the PGR signal, and explore the accuracy with which the PGR signal can be separated from other secular gravity signals. We do this by constructing synthetic GRACE data that include contributions from a PGR model as well as from a number of other geophysical processes, and then looking to see how well the PGR model can be recovered from those synthetic data. We conclude that the availability of GRACE data should result in improved estimates of the Earth's viscosity profile. This revised version was published online in August 2006 with corrections to the Cover Date.     

High-Power Wide-Band RF Amplifiers

The theory and procedures pertinent to the design of wide-band high-power amplifiers and the classical theory of broadband voltage amplifiers is briefly reviewed; the differences between the design constraints for voltage amplifiers and for power amplifiers are pointed out. The requisite changes in analytical models of the amplifier are inferred; an analytical model appropriate to the design of high-power wide-band amplifiers is constructed. The observed characteristics of an amplifier are presented and compared with competitive devices. Differences between wide-band voltage amplifiers and wide-band power amplifiers are inferred directly from voltage and power gain; a procedure for designing efficient wide-band power amplifiers is presented; and application of this procedure is shown to be adequate for the design of VHF amplifiers providing average power output of 1 kW over a 50 percent bandwidth with overall efficiency of 33 percent and a power gain of 15 dB.     

Stepping stones to the future: Achieving a sustainable lunar outpost

The current emphasis in the US and internationally on lunar robotic missions is generally viewed as a precursor to possible future human missions to the Moon. As initially framed, the implementation of high level policies such as the US Vision for Space Exploration (VSE) might have been limited to either human lunar sortie missions, or to the testing at the Moon of concepts-of-operations and systems for eventual human missions to Mars [White House, Vision for Space Exploration, Washington, DC, 14 January, 2004. [1]]. However, recently announced (December 2006) US goals go much further: these plans now place at the center of future US—and perhaps international—human spaceflight activities a long-term commitment to an outpost on the Moon.Based on available documents, a human lunar outpost could be emplaced as early as the 2020–2025 timeframe, and would involve numerous novel systems, new technologies and unique operations requirements. As such, substantial investments in research and development (R&D) will be necessary prior to, during, and following the deployment of such an outpost. It seems possible that such an outpost will be an international endeavor, not just the undertaking of a single country—and the US has actively courted partners in the VSE. However, critical questions remain concerning an international lunar outpost. What might such an outpost accomplish? To what extent will “sustainability” be built into the outpost? And, most importantly, what will be the outpost's life cycle cost (LCC)?This paper will explore these issues with a view toward informing key policy and program decisions that must be made during the next several years. The paper will (1) describe a high-level analytical model of a modest lunar outpost, (2) examine (using this model) the parametric characteristics of the outpost in terms of the three critical questions indicated above, and (3) present rough estimates of the relationships of outpost goals and “sustainability” to LCC. The paper will also consider possible outpost requirements for near-term investments in enabling research in light of experiences in past advanced technology programs.