Cosmic dust analog simulation in a microgravity environment: the STARDUST program.

We have undertaken a project called STARDUST which is a collaboration with Italian and American investigators. The goals of this program are to study the condensation and coagulation of refractory materials from the vapor and to study the properties of the resulting grains as analogs to cosmic dust particles. To reduce thermal convective currents and to develop valuable experience in designing an experiment for the Gas-Grain Simulation Facility aboard Space Station Freedom we have built and flown a new chamber to study these processes under periods of microgravity available on NASA's KC-135 Research Aircraft. Preliminary results from flights with magnesium and zinc are discussed.     

An Extension of Viterbi's Analysis of the Cycle Slipping in a First-Order Phase-Locked Loop

The phenomenon of cycle slipping in a first-order phase-locked loop is reconsidered and a simple expression for the expected number ? of cycles slipped per second is given in the form of a rapidly converging series. In this way the computation of ? becomes much easier than with previously known formulas. A formula allowing the computation of the expected number of cycles gained or lost per second is also given. These results are obtained by extending a technique used by Viterbi. The outcome of experimental verifications of the theory is also reported.     

Accurate solution of proportional navigation for maneuveringtargets

An accurate solution is presented of the nonlinear differential equations describing motion under proportional navigation when the target is laterally maneuvering. A quasilinearization (QL) approach is used, followed by a perturbation technique to obtain closed-form solutions for trajectory parameters. An explicit expression for the pursuer lateral acceleration is derived and shown to contain contributions due to initial heading error and target maneuver, with a coupling between the two effects. The solution is shown to be a substantial and consistent generalization or an earlier accurate solution for nonmaneuvering targets and also of classical linear solutions for maneuvering targets. The generalized QL solution presented provides very accurate estimates of pursuer lateral acceleration over a much broader range of engagement geometries and target maneuvers than presently available closed-form solutions     

ISEE-1 observations in the magnetosphere of VLF emissions triggered by nonducted coherent VLF waves during VLF waveinjection experiments

Recent data from the ISEE-1 spacecraft indicates that VLF emissions triggered by nonducted coherent VLF waves can differ in important aspects from VLF emissions triggered by ducted VLF waves.     

An experimental system for determining the influence of microgravity on B lymphocyte activation and cell fusion.

The influence of microgravity on lymphocyte activation is central to the understanding of immunological function in space. Moreover, the adaptation of groundbased technologies to microgravity conditions presents opportunities for biotechnological applications including high efficiency production of antibody forming hybridomas. Because the emerging technology of microgravity hybridoma generation is dependent upon activation and cultivation of B lymphocytes during flight, we have adapted mitogen-driven B lymphocyte stimulation and culture that allows for the in vitro generation of large numbers of antibody forming cells suitable for cell fusion over a period of 1-2 weeks. We believe that this activation and cultivation system can be flown on near-term space flights to test fundamental hypotheses about mammalian cell activation, cell fusion, metabolism, secretion, growth, and bio-separation.     

Stratospheric trace gas distributions observed in different seasons

A newly developed balloon-borne cryogenic sampler has been used to collect large air samples in the midlatitude stratosphere (44° N). The samples were analysed for their content of several longlived trace gases. The vertical profiles of N₂O, CH₄, and CF₂Cl₂ derived from two balloon flights in winter 1982 and, as part of the MAP Globus Project, in fall 1983 indicate variations that are caused by large scale dynamic processes. Significant features of the profiles are discussed and compared with averaged profiles that were derived from a series of balloon sampling flights performed previously over the same location during the summer season. The temporal variation of the individual profiles is more detailed than predicted by model calculations.     

European materials science investigations and associated experimental equipment within the Spacelab demonstration missions

This paper reviews shortly the results obtained by a preliminary call for experiment proposals for future Spacelab flights issued by the European Space Agency in April 1978. The results of this call indicate clearly the trend towards experiments performing studies on the state and the evolution of fluid media. The instrumentation used are mainly multipurpose instruments (furnaces, process chambers) already under development for the first Spacelab flight and new equipment currently under study.     

Shaping a legal framework for the commercial use of outer space: recommendations and conclusions from Project 2001

Private and commercial activity in outer space still poses challenges to space law and policy. Within ‘Project 2001’—a legal research project by the University of Cologne's Institute of Air and Space Law and the German Aerospace Center (DLR)—six international expert working groups examined international and national laws, in order to identify gaps and, where necessary, propose improvements to the present legal framework for private space activities. The results were presented and discussed at an international colloquium in May 2001 in Cologne, Germany, where final conclusions have been drawn. This report presents a summary of the project's work and main conclusions, which are documented in full in a comprehensive book to be published in May 2002.