EA3HMJ Blog

Proyectos, ideas, trabajos & demás cosas

Mars, how to tracking with high precision

with 2 comments

Mars-2016-Mikhail-Chubarets-Ukraine1-e1454016334245

Hace un tiempo comentando con Iban Eb3FRN la posibilidad de poder seguir sondas con mi sistema de seguimiento lo descarte, en esos momentos lo vi fuera de mi alcance.

Ahora con las ultimas modificaciones en mi sistema y las que tengo pensadas hacer, veo realizable esa misión.

Como el guru en el tema es Iban Eb3FRN, me recomendó para empezar usar los datos que proporciona JPL’s HORIZONS system en cualquier de sus múltiples formatos, el WEB es el mas fácil de manejar.

Aqui os pego un volcado de datos de marte

*******************************************************************************
 Revised: Sep 28, 2012                 Mars                             499 / 4
 
 GEOPHYSICAL DATA (updated 2009-May-26):
  Mean radius (km)      = 3389.9(2+-4)    Density (g cm^-3)     =  3.933(5+-4)
  Mass (10^23 kg )      =    6.4185       Flattening, f         =  1/154.409
  Volume (x10^10 km^3)  =   16.318        Semi-major axis       =  3397+-4
  Sidereal rot. period  =   24.622962 hr  Rot. Rate (x10^5 s)   =  7.088218
  Mean solar day        =    1.0274907 d  Polar gravity ms^-2   =  3.758
  Mom. of Inertia       =    0.366        Equ. gravity  ms^-2   =  3.71
  Core radius (km)      =  ~1700          Potential Love # k2   =  0.153 +-.017
 
  Grav spectral fact u  =   14 (x10^5)    Topo. spectral fact t = 96 (x10^5)
  Fig. offset (Rcf-Rcm) = 2.50+-0.07 km   Offset (lat./long.)   = 62d / 88d
  GM (km^3 s^-2)        = 42828.3         Equatorial Radius, Re = 3394.0 km 
  GM 1-sigma (km^3 s^-2)= +- 0.1          Mass ratio (Sun/Mars) = 3098708+-9
  
  Atmos. pressure (bar) =    0.0056       Max. angular diam.    =  17.9"
  Mean Temperature (K)  =  210            Visual mag. V(1,0)    =  -1.52
  Geometric albedo      =    0.150        Obliquity to orbit    =  25.19 deg
  Mean sidereal orb per =    1.88081578 y Orbit vel.  km/s      =  24.1309
  Mean sidereal orb per =  686.98 d       Escape vel. km/s      =   5.027
  Hill's sphere rad. Rp =  319.8          Mag. mom (gauss Rp^3) = < 1x10^-4 
*******************************************************************************
 
 
*******************************************************************************
Ephemeris / WWW_USER Tue Jun 28 00:21:50 2016 Pasadena, USA      / Horizons    
*******************************************************************************
Target body name: Mars (499)                      {source: mar097}
Center body name: Earth (399)                     {source: mar097}
Center-site name: (user defined site below)
*******************************************************************************
Start time      : A.D. 2016-Jun-28 00:00:00.0000 UT      
Stop  time      : A.D. 2016-Jun-29 00:00:00.0000 UT      
Step-size       : 60 minutes
*******************************************************************************
Target pole/equ : IAU_MARS                        {East-longitude -}
Target radii    : 3396.2 x 3396.2 x 3376.2 km     {Equator, meridian, pole}    
Center geodetic : 2.01392859,41.5695213,0.3200000 {E-lon(deg),Lat(deg),Alt(km)}
Center cylindric: 2.01392859,4779.09766,4210.1644 {E-lon(deg),Dxy(km),Dz(km)}
Center pole/equ : High-precision EOP model        {East-longitude +}
Center radii    : 6378.1 x 6378.1 x 6356.8 km     {Equator, meridian, pole}    
Target primary  : Sun
Vis. interferer : MOON (R_eq= 1737.400) km        {source: mar097}
Rel. light bend : Sun, EARTH                      {source: mar097}
Rel. lght bnd GM: 1.3271E+11, 3.9860E+05 km^3/s^2                              
Atmos refraction: NO (AIRLESS)
RA format       : HMS
Time format     : CAL 
EOP file        : eop.160627.p160918                                           
EOP coverage    : DATA-BASED 1962-JAN-20 TO 2016-JUN-27. PREDICTS-> 2016-SEP-17
Units conversion: 1 au= 149597870.700 km, c= 299792.458 km/s, 1 day= 86400.0 s 
Table cut-offs 1: Elevation (-90.0deg=NO ),Airmass (>38.000=NO), Daylight (NO )
Table cut-offs 2: Solar Elongation (  0.0,180.0=NO ),Local Hour Angle( 0.0=NO )
*******************************************************************************
 Date__(UT)__HR:MN     Azi_(a-appr)_Elev            delta      deldot
*********************************************************************
$$SOE
 2016-Jun-28 00:00  m  225.8739  12.9656 0.56149068474203   6.6938959
 2016-Jun-28 01:00  m  236.9469   4.1683 0.56165246386162   6.7478427
 2016-Jun-28 02:00  m  246.8866  -5.7555 0.56181530607983   6.7818111
 2016-Jun-28 03:00 Am  256.2001 -16.4210 0.56197870496587   6.7939124
 2016-Jun-28 04:00 Cm  265.4892 -27.5187 0.56214212650134   6.7837558
 2016-Jun-28 05:00 *m  275.5699 -38.7578 0.56230504566574   6.7524754
 2016-Jun-28 06:00 *m  287.8089 -49.7676 0.56246698239898   6.7026521
 2016-Jun-28 07:00 *m  304.9288 -59.8633 0.56262753447732   6.6381366
 2016-Jun-28 08:00 *m  332.0390 -67.4103 0.56278640505207   6.5637850
 2016-Jun-28 09:00 *m   10.3380 -69.1919 0.56294342296686   6.4851270
 2016-Jun-28 10:00 *m   43.7003 -63.9658 0.56309855446391   6.4079860
 2016-Jun-28 11:00 *m   64.8529 -54.7889 0.56325190547941   6.3380811
 2016-Jun-28 12:00 *m   78.9591 -44.0961 0.56340371437137   6.2806352
 2016-Jun-28 13:00 *    89.8475 -32.9104 0.56355433557773   6.2400169
 2016-Jun-28 14:00 *    99.3923 -21.7078 0.56370421532195   6.2194416
 2016-Jun-28 15:00 *   108.6106 -10.8006 0.56385386102851   6.2207508
 2016-Jun-28 16:00 *   118.1822  -0.4805 0.56400380654125   6.2442860
 2016-Jun-28 17:00 *   128.6537   8.9096 0.56415457552647   6.2888647
 2016-Jun-28 18:00 *   140.4829  16.9300 0.56430664556847   6.3518616
 2016-Jun-28 19:00 *   153.9441  23.0324 0.56446041541938   6.4293883
 2016-Jun-28 20:00 C   168.9049  26.6260 0.56461617765014   6.5165597
 2016-Jun-28 21:00 A   184.6433  27.2606 0.56477409857957   6.6078289
 2016-Jun-28 22:00     200.0442  24.8471 0.56493420685945   6.6973676
 2016-Jun-28 23:00     214.1705  19.7087 0.56509639149903   6.7794658
 2016-Jun-29 00:00     226.6549  12.4064 0.56526040946456   6.8489230
$$EOE
*******************************************************************************
Column meaning:
 
TIME

  Prior to 1962, times are UT1. Dates thereafter are UTC. Any 'b' symbol in
the 1st-column denotes a B.C. date. First-column blank (" ") denotes an A.D.
date. Calendar dates prior to 1582-Oct-15 are in the Julian calendar system.
Later calendar dates are in the Gregorian system.

  Time tags refer to the same instant throughout the solar system, regardless
of where the observer is located. For example, if an observation from the
surface of another body has an output time-tag of 12:31:00 UTC, an Earth-based
time-scale, it refers to the instant on that body simultaneous to 12:31:00 UTC
on Earth.

  The Barycentric Dynamical Time scale (TDB) is used internally as defined by
the planetary equations of motion. Conversion between TDB and the selected
non-uniform UT output time-scale has not been determined for UTC times after
the next July or January 1st. The last known leap-second is used as a constant
over future intervals.

  NOTE: "n.a." in output means quantity "not available" at the print-time.
 
SOLAR PRESENCE (OBSERVING SITE)
  Time tag is followed by a blank, then a solar-presence symbol:

        '*'  Daylight (refracted solar upper-limb on or above apparent horizon)
        'C'  Civil twilight/dawn
        'N'  Nautical twilight/dawn
        'A'  Astronomical twilight/dawn
        ' '  Night OR geocentric ephemeris

LUNAR PRESENCE (OBSERVING SITE)
  The solar-presence symbol is immediately followed by a lunar-presence symbol:

        'm'  Refracted upper-limb of Moon on or above apparent horizon
        ' '  Refracted upper-limb of Moon below apparent horizon OR geocentric
             ephemeris
 
 Azi_(a-appr)_Elev =
   Airless apparent azimuth and elevation of target center. Adjusted for
light-time, the gravitational deflection of light, stellar aberration,
precession and nutation. Azimuth measured North(0) -> East(90) -> South(180) ->
West(270) -> North (360). Elevation is with respect to plane perpendicular
to local zenith direction.  TOPOCENTRIC ONLY. Units: DEGREES
 
 delta  deldot =
   Range ("delta") and range-rate ("delta-dot") of target center with respect
to the observer at the instant light seen by the observer at print-time would
have left the target center (print-time minus down-leg light-time); the
distance traveled by a light ray emanating from the center of the target and
recorded by the observer at print-time. "deldot" is a projection of the
velocity vector along this ray, the light-time-corrected line-of-sight from the
coordinate center, and indicates relative motion. A positive "deldot" means the
target center is moving away from the observer (coordinate center). A negative
"deldot" means the target center is moving toward the observer.
Units: AU and KM/S


 Computations by ...
     Solar System Dynamics Group, Horizons On-Line Ephemeris System
     4800 Oak Grove Drive, Jet Propulsion Laboratory
     Pasadena, CA  91109   USA
     Information: http://ssd.jpl.nasa.gov/
     Connect    : telnet://ssd.jpl.nasa.gov:6775  (via browser)
                  telnet ssd.jpl.nasa.gov 6775    (via command-line)
     Author     : Jon.Giorgini@jpl.nasa.gov

*******************************************************************************

A partir de aquí ya podemos apuntar nuestro sistema de seguimiento a marte, pero hay que tener en cuenta los eclipses de marte con las sondas que hagamos seguimiento.

Iban EB3FRN lo excplica en este articulo.

Una vez controlado el tema el paso siguiente es ser autónomo y poder disponer en mi ordenador de esos datos en tiempo real. Para ello existe el tool kit cspice  que permite en programar en varios lenguajes y sistemas operativos, en mi caso linux y C.

Iban EB3FRN me paso un source basado en sus investigaciones para poder conseguir los datos en el PC.

Este es un volcado del cálculo de Marte.

./jose mars "2016 JUN 28, 17:50:00" "2016 JUN 28, 18:10"
2016 JUN 28 17:51:00, , ,138.5523, 15.7987, 84415726.00251, 6.341385, 4.693106
2016 JUN 28 17:52:00, , ,138.7586, 15.9226, 84416106.52000, 6.342532, 4.693128
2016 JUN 28 17:53:00, , ,138.9655, 16.0460, 84416487.10642, 6.343683, 4.693150
2016 JUN 28 17:54:00, , ,139.1728, 16.1689, 84416867.76204, 6.344838, 4.693172
2016 JUN 28 17:55:00, , ,139.3805, 16.2912, 84417248.48711, 6.345998, 4.693194
2016 JUN 28 17:56:00, , ,139.5887, 16.4131, 84417629.28187, 6.347162, 4.693216
2016 JUN 28 17:57:00, , ,139.7974, 16.5344, 84418010.14658, 6.348329, 4.693238
2016 JUN 28 17:58:00, , ,140.0065, 16.6552, 84418391.08148, 6.349501, 4.693260
2016 JUN 28 17:59:00, , ,140.2161, 16.7755, 84418772.08682, 6.350677, 4.693282
2016 JUN 28 18:00:00, , ,140.4261, 16.8952, 84419153.16284, 6.351858, 4.693304
2016 JUN 28 18:01:00, , ,140.6366, 17.0144, 84419534.30980, 6.353042, 4.693325
2016 JUN 28 18:02:00, , ,140.8476, 17.1331, 84419915.52793, 6.354230, 4.693347
2016 JUN 28 18:03:00, , ,141.0590, 17.2513, 84420296.81748, 6.355422, 4.693369
2016 JUN 28 18:04:00, , ,141.2709, 17.3689, 84420678.17868, 6.356619, 4.693391
2016 JUN 28 18:05:00, , ,141.4833, 17.4859, 84421059.61178, 6.357819, 4.693413
2016 JUN 28 18:06:00, , ,141.6961, 17.6025, 84421441.11702, 6.359023, 4.693435
2016 JUN 28 18:07:00, , ,141.9094, 17.7184, 84421822.69463, 6.360231, 4.693457
2016 JUN 28 18:08:00, , ,142.1232, 17.8339, 84422204.34484, 6.361443, 4.693479
2016 JUN 28 18:09:00, , ,142.3374, 17.9487, 84422586.06790, 6.362659, 4.693501
2016 JUN 28 18:10:00, , ,142.5521, 18.0631, 84422967.86403, 6.363879, 4.693523
root@nlsu4:/home/jas/cspice/jas#

Pero en rojo he marcado un mismo punto y vemos que hay una diferencia entre los datos de horizons y los calculados por mi.

Az=0.0568 El=0.0348

Bueno, después de volverme loco con esa diferencia Iban me explico que Horizons tenia un pequeño delay en los cálculos que no se visualiza al no devolver datos en segundos que jugando con los valores de segundos se consigue minimizar la diferencia.

En mi caso resulto que fueron 16.2s para obtener datos casi iguales.

  ./jose mars "2016 JUN 28, 17:59:16.2" "2016 JUN 28, 18:01"
2016 JUN 28 18:00:16, , ,140.4829, 16.9275, 84419256.06552, 6.352177, 4.693309
2016 JUN 28 18:01:16, , ,140.6935, 17.0465, 84419637.23167, 6.353362, 4.693331
root@nlsu4:/home/jas/cspice/jas#

Az=0.0 El=0.0025

Esa diferencia es asumible 🙂 por lo que puedo validar los datos calculados.

El programa usado se base en el publicado por Dr. Willian Thompson escrito en IDL para el seguimiento de las naves stereo.

SSC_WRITE_STATION

Aquí podéis encontrar ejemplos de programación en IDL.

 

 

 

 

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Written by qlfecv

28 de junio de 2016 a 22:07

2 comentarios

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  1. Lo primero felicidades por el blog y todo el trabajo. ¡Es tremendo!

    Hay un wrapper en Python del Spice que lo mismo es más agradable de usar: http://systemssignalsandmore.blogspot.com.es/2015/10/jpl-spice-in-python.html

    Me gusta

    Francisco Gallardo López

    3 de abril de 2017 at 8:33

  2. Gracias por la info, pero de Python ni idea. De todas formas espero que liberen la versión N66 que promete.

    Me gusta

    qlfecv

    3 de abril de 2017 at 12:18


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