The Pioneer spacecraft as a probe carrier

Requirements for Pioneer 10 and 11 designs are provided that are adequate to carry the probes for Jupiter and Saturn explorations. For a Uranus probe mission, additional spacecraft modifications are necessary. Considered are weight availability for carrying the probe, aspects of probe to bus link communications and onboard navigation

FUSE Observations of Galactic and Intrinsic Absorption in the Spectrum of the Seyfert 1 Galaxy 2MASX J21362313-6224008

We present the far-ultraviolet spectrum of the Seyfert 1 galaxy 2MASX J21362313-6224008 obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). The spectrum features absorption from Galactic OVI at two velocities and redshifted HI Lyman beta and gamma, CII, CIII, and O VI. The redshifted absorption features represent a single kinematic component blueshifted by ~310 km/s relative to the AGN. We use photoionization models to derive constraints on the physical parameters of the absorbing gas. An alternative interpretation for the absorption lines is also proposed, whereby the absorbing gas is associated with an intervening galaxy cluster.Comment: Astrophysical Journal, in pres

A Corollary for Nonsmooth Systems

In this note, two generalized corollaries to the LaSalle-Yoshizawa Theorem are presented for nonautonomous systems described by nonlinear differential equations with discontinuous right-hand sides. Lyapunov-based analysis methods are developed using differential inclusions to achieve asymptotic convergence when the candidate Lyapunov derivative is upper bounded by a negative semi-definite function

Swimming in curved space or The Baron and the cat

We study the swimming of non-relativistic deformable bodies in (empty) static curved spaces. We focus on the case where the ambient geometry allows for rigid body motions. In this case the swimming equations turn out to be geometric. For a small swimmer, the swimming distance in one stroke is determined by the Riemann curvature times certain moments of the swimmer.Comment: 19 pages 6 figure

Atmospheric effects on remote sensing of non-uniform temperature sources

The effects are considered of an absorbing, emitting, and scattering atmosphere upon the remote sensing of surface areas having non-uniform intensity. These atmospheric effects may be significant in determination, by remote sensing, of non-uniform surface temperature distributions, and the results of the investigation are applicable in such cases. Analytical methods and a digital computational program are presented, expressing the results in terms of contrast and contrast transmittance between two adjacent emitting areas having unequal intensities, in the presence of a additional disturbing emitters. In the computational procedure, emitting areas are replaced by point-source emitters, each assigned and effective intensity based upon the intensity of the area it replaces. Absorbing, emitting, and scattering behavior of the atmosphere may be specified in the computational procedure either by means of analytical atmospheric models or by means of calibrating ground level emitters

Spinning test particles and clock effect in Schwarzschild spacetime

We study the behaviour of spinning test particles in the Schwarzschild spacetime. Using Mathisson-Papapetrou equations of motion we confine our attention to spatially circular orbits and search for observable effects which could eventually discriminate among the standard supplementary conditions namely the Corinaldesi-Papapetrou, Pirani and Tulczyjew. We find that if the world line chosen for the multipole reduction and whose unit tangent we denote as $U$ is a circular orbit then also the generalized momentum $P$ of the spinning test particle is tangent to a circular orbit even though $P$ and $U$ are not parallel four-vectors. These orbits are shown to exist because the spin induced tidal forces provide the required acceleration no matter what supplementary condition we select. Of course, in the limit of a small spin the particle's orbit is close of being a circular geodesic and the (small) deviation of the angular velocities from the geodesic values can be of an arbitrary sign, corresponding to the possible spin-up and spin-down alignment to the z-axis. When two spinning particles orbit around a gravitating source in opposite directions, they make one loop with respect to a given static observer with different arrival times. This difference is termed clock effect. We find that a nonzero gravitomagnetic clock effect appears for oppositely orbiting both spin-up or spin-down particles even in the Schwarzschild spacetime. This allows us to establish a formal analogy with the case of (spin-less) geodesics on the equatorial plane of the Kerr spacetime. This result can be verified experimentally.Comment: IOP macros, eps figures n. 2, to appear on Classical and Quantum gravity, 200

Classical String in Curved Backgrounds

The Mathisson-Papapetrou method is originally used for derivation of the particle world line equation from the covariant conservation of its stress-energy tensor. We generalize this method to extended objects, such as a string. Without specifying the type of matter the string is made of, we obtain both the equations of motion and boundary conditions of the string. The world sheet equations turn out to be more general than the familiar minimal surface equations. In particular, they depend on the internal structure of the string. The relevant cases are classified by examining canonical forms of the effective 2-dimensional stress-energy tensor. The case of homogeneously distributed matter with the tension that equals its mass density is shown to define the familiar Nambu-Goto dynamics. The other three cases include physically relevant massive and massless strings, and unphysical tahyonic strings.Comment: 12 pages, REVTeX 4. Added a note and one referenc