Finding Attitude of a Spin Axis from Roll Angles

2011 ◽  
Author(s):  
Andrew A. Thompson
Keyword(s):  
Spin Axis

Models of comets with strongly variable nongravitational effects

1999 ◽  
Vol 173 ◽  
pp. 381-387
Author(s):  
M. Królikowska ◽  
G. Sitarski ◽  
S. Szutowicz
Keyword(s):  
Cometary Nucleus ◽  
Spin Axis ◽  
Reactive Force ◽  
Orbital Elements ◽  
Cometary Nuclei ◽  
Short Period ◽  
Basic Parameters ◽  
Polar Radius ◽  
Cometary Activity ◽  
Nongravitational Effects

AbstractThe nongravitational motion of five “erratic” short-period comets is studied on the basis of published astrometric observations. We present the precession models which successfully link all the observed apparitions of the comets: 21P/Giacobini-Zinner, 31P/Schwassmann-Wachmann 2, 32P/Comas Solá, 37P/Forbes, and 43P/Wolf-Harrington. We used the Sekanina's forced precession model of the rotating cometary nucleus to include the nongravitational terms into equations of the comet's motion. Values of six basic parameters (four connected with the rotating comet nucleus and two describing the precession of spin-axis of the nucleus) have been determined along the orbital elements from positional observations of the comets. The solutions were derived with additional assumptions which introduce instantaneous changes of modulus of reactive force,Aand of maximum of cometary activity with respect to perihelion time. The present precession models impose some contraints on sizes and rotational periods of cometary nuclei. According to our solutions the nucleus of 21P/Giacobini-Zinner with oblateness along the spin-axis of about 0.32 (equatorial to polar radius of 1.46) is the most oblate among five investigated comets.

Development of a Small-spin-axis Controller and Its Application to a Solar Sail Subpayload Satellite

2009 ◽  
Vol 7 ◽  
pp. 25-32 ◽  
Author(s):  
Takanao SAIKI ◽  
Koji NAKAYA ◽  
Takayuki YAMAMOTO ◽  
Yuichi TSUDA ◽  
Osamu MORI ◽  
...  
Keyword(s):  
Solar Sail ◽  
Spin Axis

Spin axis orientation of Ajisai determined from Graz 2kHz SLR data

2010 ◽  
Vol 46 (3) ◽  
pp. 251-256 ◽  
Author(s):  
D. Kucharski ◽  
T. Otsubo ◽  
G. Kirchner ◽  
F. Koidl
Keyword(s):  
Spin Axis ◽  
Axis Orientation

scholarly journals Dynamics of Spin Bowling: The Normalized Precession of the Spin axis Analysed with a Smart Cricket Ball

2015 ◽  
Vol 112 ◽  
pp. 196-201 ◽  
Author(s):  
Franz Konstantin Fuss ◽  
Batdelger Doljin ◽  
René E.D. Ferdinands ◽  
Aaron Beach
Keyword(s):  
Spin Axis ◽  
Cricket Ball

Spin-axis estimation of the Radiation Belt Storm Probes spacecraft using RF Doppler data

2012 ◽  
Vol 73 ◽  
pp. 30-37 ◽  
Author(s):  
Dipak K. Srinivasan ◽  
Gene A. Heyler ◽  
Timothy G. McGee
Keyword(s):  
Radiation Belt ◽  
Spin Axis ◽  
Doppler Data ◽  
Radiation Belt Storm Probes

Spin-axis stabilisation of underactuated rigid spacecraft under sinusoidal disturbance

2008 ◽  
Vol 81 (12) ◽  
pp. 1901-1909 ◽  
Author(s):  
H.-H. Zhang ◽  
F. Wang ◽  
Pavel M. Trivailo
Keyword(s):  
Spin Axis ◽  
Rigid Spacecraft ◽  
Sinusoidal Disturbance

Initial Ball Flight Characteristics of Curve and Instep Kicks in Elite Women’s Football

2012 ◽  
Vol 28 (1) ◽  
pp. 70-77 ◽  
Author(s):  
Alison Alcock ◽  
Wendy Gilleard ◽  
Nick A.T. Brown ◽  
John Baker ◽  
Adam Hunter
Keyword(s):  
Regression Models ◽  
Three Dimensional ◽  
Spin Axis ◽  
Vertical Coordinate ◽  
Ball Flight ◽  
Launch Angle ◽  
Target Center ◽  
Women's Football

Initial ball flight characteristics of curve and instep kicks were investigated. Fifteen international female footballers performed curve and instep kicks from a distance of 20 m from goal and at a 1 m2 target. Seventeen Vicon cameras tracked three-dimensional coordinates of four reflective markers adhered to the ball. Ball flight characteristics were quantified, and the coordinates of the ball relative to the target center were recorded. The lateral launch angle and the angle of the spin axis relative to the horizontal best predicted the horizontal placement of the ball relative to the target. The vertical launch angle, antero-posterior velocity and amount of backspin best predicted the vertical coordinate. Regression models demonstrated how carefully controlled the flight characteristics must be with launch angles constrained within 3° to hit the target. Curve kicks were characterized by significantly greater lateral and vertical launch angles, increased sidespin and spin about the antero-posterior axis, and a more vertical spin axis. This information is beneficial for coaches in training players to achieve the characteristics required to score a goal and avoid a defensive wall. For example, if players consistently kick above or below the target, these findings identify the variables that will help rectify that error.

scholarly journals Magnetohydrodynamic simulations of a Uranus-at-equinox type rotating magnetosphere

2020 ◽  
Vol 633 ◽  
pp. A87 ◽  
Author(s):  
L. Griton ◽  
F. Pantellini
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Supersonic Flow ◽  
Magnetic Dipole ◽  
Stellar Wind ◽  
Rotation Axis ◽  
Spin Axis ◽  
Mhd Equations ◽  
Field Lines ◽  
The Magnetic Field

Context. As proven by measurements at Uranus and Neptune, the magnetic dipole axis and planetary spin axis can be off by a large angle exceeding 45°. The magnetosphere of such an (exo-)planet is highly variable over a one-day period and it does potentially exhibit a complex magnetic tail structure. The dynamics and shape of rotating magnetospheres do obviously depend on the planet’s characteristics but also, and very substantially, on the orientation of the planetary spin axis with respect to the impinging, generally highly supersonic, stellar wind. Aims. On its orbit around the Sun, the orientation of Uranus’ spin axis with respect to the solar wind changes from quasi-perpendicular (solstice) to quasi-parallel (equinox). In this paper, we simulate the magnetosphere of a fictitious Uranus-like planet plunged in a supersonic plasma (the stellar wind) at equinox. A simulation with zero wind velocity is also presented in order to help disentangle the effects of the rotation from the effects of the supersonic wind in the structuring of the planetary magnetic tail. Methods. The ideal magnetohydrodynamic (MHD) equations in conservative form are integrated on a structured spherical grid using the Message-Passing Interface-Adaptive Mesh Refinement Versatile Advection Code (MPI-AMRVAC). In order to limit diffusivity at grid level, we used background and residual decomposition of the magnetic field. The magnetic field is thus made of the sum of a prescribed time-dependent background field B0(t) and a residual field B1(t) computed by the code. In our simulations, B0(t) is essentially made of a rigidly rotating potential dipole field. Results. The first simulation shows that, while plunged in a non-magnetised plasma, a magnetic dipole rotating about an axis oriented at 90° with respect to itself does naturally accelerate the plasma away from the dipole around the rotation axis. The acceleration occurs over a spatial scale of the order of the Alfvénic co-rotation scale r*. During the acceleration, the dipole lines become stretched and twisted. The observed asymptotic fluid velocities are of the order of the phase speed of the fast MHD mode. In two simulations where the surrounding non-magnetised plasma was chosen to move at supersonic speed perpendicularly to the rotation axis (a situation that is reminiscent of Uranus in the solar wind at equinox), the lines of each hemisphere are symmetrically twisted and stretched as before. However, they are also bent by the supersonic flow, thus forming a magnetic tail of interlaced field lines of opposite polarity. Similarly to the case with no wind, the interlaced field lines and the attached plasma are accelerated by the rotation and also by the transfer of kinetic energy flux from the surrounding supersonic flow. The tailwards fluid velocity increases asymptotically towards the externally imposed flow velocity, or wind. In one more simulation, a transverse magnetic field, to both the spin axis and flow direction, was added to the impinging flow so that magnetic reconnection could occur between the dipole anchored field lines and the impinging field lines. No major difference with respect to the no-magnetised flow case is observed, except that the tailwards acceleration occurs in two steps and is slightly more efficient. In order to emphasise the effect of rotation, we only address the case of a fast-rotating planet where the co-rotation scale r* is of the order of the planetary counter-flow magnetopause stand-off distance rm. For Uranus, r*≫ rm and the effects of rotation are only visible at large tailwards distances r ≫ rm.

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