An overview of the communications technology satellite project: Executive summary

An overview of the Communications Technology Satellite (CTS) project, a joint venture between NASA and the Canadian Department of Communications is given. A brief technical description of the CTS spacecraft and its cognate hardware and operations, a history of the CTS project, and a list of the CTS experiments and demonstrations conducted during the course of the project are given

A Third Planet Orbiting HIP 14810

We present new precision radial velocities and a three-planet Keplerian orbit fit for the V = 8.5, G5 V star HIP 14810. We began observing this star at Keck Observatory as part of the N2K Planet Search Project. Wright et al. (2007) announced the inner two planets to this system, and subsequent observations have revealed the outer planet planet and the proper orbital solution for the middle planet. The planets have minimum masses of 3.9, 1.3, and 0.6 M_Jup and orbital periods of 6.67, 147.7, and 952 d, respectively. We have numerically integrated the family of orbital solutions consistent with the data and find that they are stable for at least 10^6 yr. Our photometric search shows that the inner planet does not transit.Comment: ApJL, accepte

The communications technology satellite and the associated ground terminals for experiments

General spacecraft operational characteristics of the Communications Technology Satellite are discussed with particular emphasis on communication system parameters. Associated used ground terminals are reviewed. Wideband communications are also discussed

Studies in a transonic rotor aerodynamics and noise facility

The design, construction and testing of a transonic rotor aerodynamics and noise facility was undertaken, using a rotating arm blade element support technique. This approach provides a research capability intermediate between that of a stationary element in a moving flow and that of a complete rotating blade system, and permits the acoustic properties of blade tip elements to be studied in isolation. This approach is an inexpensive means of obtaining data at high subsonic and transonic tip speeds on the effect of variations in tip geometry. The facility may be suitable for research on broad band noise and discrete noise in addition to high-speed noise. Initial tests were conducted over the Mach number range 0.3 to 0.93 and confirmed the adequacy of the acoustic treatment used in the facility to avoid reflection from the enclosure

Metastable helium molecules as tracers in superfluid liquid 4^{4}He

Metastable helium molecules generated in a discharge near a sharp tungsten tip operated in either pulsed mode or continuous field-emission mode in superfluid liquid $^{4}$He are imaged using a laser-induced-fluorescence technique. By pulsing the tip, a small cloud of He$_{2}^{*}$ molecules is produced. At 2.0 K, the molecules in the liquid follow the motion of the normal fluid. We can determine the normal-fluid velocity in a heat-induced counterflow by tracing the position of a single molecule cloud. As we run the tip in continuous field-emission mode, a normal-fluid jet from the tip is generated and molecules are entrained in the jet. A focused 910 nm pump laser pulse is used to drive a small group of molecules to the vibrational $a(1)$ state. Subsequent imaging of the tagged $a(1)$ molecules with an expanded 925 nm probe laser pulse allows us to measure the velocity of the normal fluid. The techniques we developed demonstrate for the first time the ability to trace the normal-fluid component in superfluid helium using angstrom-sized particles.Comment: 4 pages, 7 figures. Submitted to Phys. Rev. Let

Ultrasonic Evaluation of Polymers and Composites Using Air-Coupled Capacitance Transducres

It is often necessary to evaluate materials using non-contact ultrasonic techniques, for example when the test sample is hot, moving, or highly absorbent to conventional fluid couplants. Several non-contact methods are available, such as various optical techniques [1–3], which are generally expensive and require the sample to have optimized optical characteristics. Electro-magnetic acoustic transducers (EMATs) [4,5] and capacitance devices [6] may be used, but require an electrically conductive sample, and a small stand-off distance of a few millimeters or less. There has been much interest recently in the use of air-coupled transducers [7], which may be piezoelectric, using piezopolymers such as PVDF [8], piezocomposites of PZT and epoxy [9,10], or piezoceramics with impedance matching layers on the transducer face [11]. Another type of device is the electrostatic or capacitance transducer [12,13], which consists of a metallized polymer membrane against a backplate electrode to which a bias voltage is applied. Motion of the membrane causes the charge on the backplate to change, which may be detected using a suitable charge amplifier. These devices in general have a wider bandwidth than their piezoelectric counterparts, and improved sensitivity. The backplates are usually mechanically roughened metal, and it is therefore difficult to manufacture two identical devices. However, using a silicon backplate [14–17] and standard etching techniques, the surface of the backplate may be precisely controlled. Such a device is shown schematically in Figure 1. The backplate consists of a silicon wafer into which pits 40μm in diameter and 80μm apart have been anisotropically etched to a depth of approximately 40μm. A gold electrode is then evaporated onto the backplate, and a thin metallized polymer membrane is then placed next to the plate