Short, high current electrodynamic tether

An electrodynamic tether experiment, to be carried out in the Russian spacecraft Almaz, is proposed. A 10 km tether would be deployed downwards; the lower 8 km would be nonconductive, the upper 2 km would be conductive, bare, and 2.2 mm in diameter, and would act as a thruster, with power supply at the top. This hybrid arrangement allows for other, onelectrodynamic experiments,reducing costs; it also limits the induced electromotive force, reducing the power to be handled. The current-voltage characteristic of contactors would be measured. With the anode switched off, the wire itself should collect a current over 5 A at day conditions, providing a thrust of 0.11 N at a 0.77 kW power

Some results of cislunar plasma research

The main results of plasma cislunar investigations, carried out during Luna-19 and Luna-22 spacecraft flights by means of dual frequency dispersion interferrometry, are briefly outlined. It is shown that a thin layer of plasma, with a height of several tens of kilometers and a maximum concentration of the order 1,000 electrons/cu cm exists above the solar illuminated lunar surface. A physical model of the formation and existence of such a plasma in cislunar space is proposed, taking into account the influence of local magnetic areas on the moon

A Novel, Free-Space Optical Interconnect Employing Vertical-Cavity Surface Emitting Laser Diodes and InGaAs Metal-Semiconductor-Metal Photodetectors for Gbit/s RF/Microwave Systems

Emerging technologies and continuing progress in vertical-cavity surface emitting laser (VCSEL) diode and metal-semiconductor-metal (MSM) photodetector research are making way for novel, high-speed forms of optical data transfer in communication systems. VCSEL diodes operating at 1550 nm have only recently become commercially available, while MSM photodetectors are pushing the limits of contact lithography with interdigitated electrode widths reaching sub micron levels. We propose a novel, free-space optical interconnect operating at about 1Gbit/s utilizing VCSEL diodes and MSM photodetectors. We report on development, progress, and current work, which are as follows: first, analysis of the divergent behavior of VCSEL diodes for coupling to MSM photodetectors with a 50 by 50 m active area and second, the normalized frequency response of the VCSEL diode as a function of the modulating frequency. Third, the calculated response of MSM photodetectors with varying electrode width and spacing on the order of 1 to 3 m as well as the fabrication and characterization of these devices. The work presented here will lead to the formation and characterization of a fully integrated 1Gbit/s free-space optical interconnect at 1550 nm and demonstrates both chip level and board level functionality for RF/microwave digital systems

Autofluorescent polarimetry in diagnostics of endometriosis and infertility

A new information about optical technique in diagnostics for the endometrium structure has been proposed. The model of Mueller-matrix description of mechanisms responsible for optical anisotropy of these objects (optical activity, birefringence as well as linear and circular dichroism) has been suggested. The ensemble of informationally topical azimuthally stable Mueller-matrix invariants has been determined. Using the statistical analysis of the distribution parameters, the objective criteria for differentiation of endometrium taken from healthy women and patients with endometriosis were determined. From the viewpoint of probative medicine, the operational characteristics (sensitivity, specificity and accuracy) of the information-optical method applied to Mueller-matrix mapping of endometrium histological section have been found and its efficiency in diagnostics of endometriosis and infertility has been demonstrated

Optical Cloaking by Aberation Correction

Light incident on a material is scattered and then continues its propagation in seemingly random directions. If one can force light to pass through a material and not scatter, however, then one could “see” through the material. This scattering of light can be described as aberration within the light. A technique used for “Aberration Correction” is adding phase-shifts to regions of light allowing for all wave fronts of light to interfere in a constructive manner. This is accomplished in the use of a Spatial Light Modulator (SLM). The SLM, an array of linearly aligned crystals, allow for added phase shifts to light incident on the SLM. By shifting the phase of light, it is possible to allow light to pass through some material without having the light be scattered by the material. This case allows for one to “see” through the material, on account of the light passing through the material rather than being scattered by it. This technology has potential to be used for non-invasive surgeries as well as being a strong starting point for research into optical cloaking. If a procedure for allowing light to pass through a material is developed, then the procedure could be used for the purpose of Optical Cloaking. By expanding the region in which one “sees” through a material so that one encloses the entire material, one would cloak the entire material rather than “see” through some region of it. This procedure would have applications in both medical and military technology

Free-Space Optical Interconnect Employing VCSEL Diodes

Sensor signal processing is widely used on aircraft and spacecraft. The scheme employs multiple input/output nodes for data acquisition and CPU (central processing unit) nodes for data processing. To connect 110 nodes and CPU nodes, scalable interconnections such as backplanes are desired because the number of nodes depends on requirements of each mission. An optical backplane consisting of vertical-cavity surface-emitting lasers (VCSELs), VCSEL drivers, photodetectors, and transimpedance amplifiers is the preferred approach since it can handle several hundred megabits per second data throughput.The next generation of satellite-borne systems will require transceivers and processors that can handle several Gb/s of data. Optical interconnects have been praised for both their speed and functionality with hopes that light can relieve the electrical bottleneck predicted for the near future. Optoelectronic interconnects provide a factor of ten improvement over electrical interconnects

The nighttime ionosphere of Mars from Mars-4 and Mars-5 radio occultation dual-frequency measurements

Dual frequency radio sounding of the Martian nighttime ionosphere was carried out during the exits from behind the planet of the Mars-4 spacecraft on February 2, 1974 and the Mars-5 spacecraft on February 18, 1974. In these experiments, the spacecraft transmitter emitted two coherent monochromatic signals in decimeter and centimeter wavelength ranges. At the Earth receiving station, the reduced phase difference (or frequencies) of these signals was measured. The nighttime ionosphere of Mars measured in both cases had a peak electron density of approximately 5 X 1,000/cu cm at an altitude of 110 to 130 km. At the times of spacecraft exit, the solar zenith angles at the point of occultation were 127 deg and 106 deg, respectively. The height profiles of electron concentration were obtained assuming spherical symmetry of the Martian ionosphere