Multibody Interplanetary Swingby Trajectories /MIST-1/

Computer program incorporates new isolation procedure to determine interplanetary trajectories which utilize a maximum of three flybys. Program also computes singe planet flybys and direct transfer trajectories. The three principle systems employed in MIST-1 use as their fundamental plane the mean plane of the earth's orbit around the sun

A Fluid Generalization of Membranes

In a certain sense a perfect fluid is a generalization of a point particle. This leads to the question as to what is the corresponding generalization for extended objects. The lagrangian formulation of a perfect fluid is much generalized and this has as a particular example a fluid which is a classical generalization of a membrane, however there is as yet no indication of any relationship between their quantum theories.Comment: To appear in CEJP, updated to coincide with published versio

A microgravity isolation mount

The design and preliminary testing of a system for isolating microgravity sensitive payloads from spacecraft vibrational and impulsive disturbances is discussed. The Microgravity Isolation Mount (MGIM) concept consists of a platform which floats almost freely within a limited volume inside the spacecraft, but which is constrained to follow the spacecraft in the long term by means of very weak springs. The springs are realized magnetically and form part of a six degree of freedom active magnetic suspension system. The latter operates without any physical contact between the spacecraft and the platform itself. Power and data transfer is also performed by contactless means. Specifications are given for the expected level of input disturbances and the tolerable level of platform acceleration. The structural configuration of the mount is discussed and the design of the principal elements, i.e., actuators, sensors, control loops and power/data transfer devices are described. Finally, the construction of a hardware model that is being used to verify the predicted performance of the MGIM is described

On the complexion of pseudoscalar mesons

A strongly momentum-dependent dressed-quark mass function is basic to QCD. It is central to the appearance of a constituent-quark mass-scale and an existential prerequisite for Goldstone modes. Dyson-Schwinger equation (DSEs) studies have long emphasised this importance, and have proved that QCD's Goldstone modes are the only pseudoscalar mesons to possess a nonzero leptonic decay constant in the chiral limit when chiral symmetry is dynamically broken, while the decay constants of their radial excitations vanish. Such features are readily illustrated using a rainbow-ladder truncation of the DSEs. In this connection we find (in GeV): f_{eta_c(1S)}= 0.233, m_{eta_c(2S)}=3.42; and support for interpreting eta(1295), eta(1470) as the first radial excitations of eta(548), eta'(958), respectively, and K(1460) as the first radial excitation of the kaon. Moreover, such radial excitations have electromagnetic diameters greater than 2fm. This exceeds the spatial length of lattices used typically in contemporary lattice-QCD.Comment: 7 pages, 2 figures. Contribution to the proceedings of the "10th International Symposium on Meson-Nucleon Physics and the Structure of the Nucleon (MENU04)," IHEP, Beijing, China, 30/Aug.-4/Sept./0

Proper Motions of Ionized Gas at the Galactic Center: Evidence for Unbound Orbiting Gas

We present radio continuum observations of the spiral-shaped ionized feature (Sgr A West) within the inner pc of the Galactic center at three epochs spanning 1986 to 1995. The VLA A-configuration was used at $\lambda$2cm (resolution of 0\dasec1$\times$0\dasec2). We detect proper motions of a number of features in the Northern and Eastern Arms of Sgr A West including the ionized gas associated with IRS 13 with V(RA)= 113 \pm 10, V(Dec)=150 \pm15 km/s, IRS 2 with V(RA)= 122 \pm 11, V(Dec)=24 \pm 34 km/s and the Norther Arm V(RA)= 126 \pm 30, V(Dec)=--207 \pm 58 km/s. We also report the detection of features having transverse velocities > 1000 km/s including a head-tail radio structure, the ``Bullet'', $\approx4''$ northwest of Sgr A$^*$ with V(RA)= 722 \pm 156, V(Dec)=832 \pm 203 km/s, exceeding the escape velocity at the Galactic center. The proper motion measurements when combined with previous H92$\alpha$ radio recombination line data suggest an unambiguous direction of the flow of ionized gas orbiting the Galactic center. The measured velocity distribution suggests that the ionized gas in the Northern Arm is not bound to the Galactic center assuming a 2.5 million solar mass of dark matter residing at the Galactic center. This implies that the stellar and ionized gas systems are not dynamically coupled, thus, supporting a picture in which the gas features in the Northern Arm and its extensions are the result of an energetic phenomenon that has externally driven a cloud of gas cloud into the Galactic center.Comment: 11 pages, three figures (one color) and one table. Astrophysical Journal Letters in pres

Strong D* -> D+pi and B* -> B+pi couplings

We compute g_{D* D pi} and g_{B* B pi} using a framework in which all elements are constrained by Dyson-Schwinger equation studies of QCD, and therefore incorporates a consistent, direct and simultaneous description of light- and heavy-quarks and the states they may constitute. We link these couplings with the heavy-light-meson leptonic decay constants, and thereby obtain g_{D* D pi}=15.9+2.1/-1.0 and g_{B* B pi}=30.0+3.2/-1.4. From the latter we infer \hat-g_B=0.37+0.04/-0.02. A comparison between g_{D* D pi} and g_{B* B pi} indicates that when the c-quark is a system's heaviest constituent, Lambda_{QCD}/m_c-corrections are not under good control.Comment: 5 pages, 1 table, 2 figure

Survey of heavy-meson observables

We employ a Dyson-Schwinger equation model to effect a unified and uniformly accurate description of light- and heavy-meson observables, which we characterise by heavy-meson leptonic decays, semileptonic heavy-to-heavy and heavy-to-light transitions - B -> D*, D, rho, pi; D -> K*, K, pi, radiative and strong decays - B(s)* -> B(s) gamma; D(s)* -> D(s) gamma, D pi, and the rare B-> K* gamma flavour-changing neutral-current process. We elucidate the heavy-quark limit of these processes and, using a model-independent mass formula valid for all nonsinglet pseudoscalar mesons, demonstrate that their mass rises linearly with the mass of their heaviest constituent. In our numerical calculations we eschew a heavy-quark expansion and rely instead on the observation that the dressed c,b-quark mass functions are well approximated by a constant, interpreted as their constituent-mass: we find M_c=1.32 GeV and M_b=4.65 GeV. The calculated heavy-meson leptonic decay constants and transition form factors are a necessary element in the experimental determination of CKM matrix elements. The results also show that this framework, as employed hitherto, is well able to describe vector meson polarisation observables.Comment: 32 pages, 7 figures, REVTEX. Some quantitative modification of tables and figures: calculation of additional processes. To appear in Phys. Rev.