Spacecrafts for Celestia

[gironde]

Toutatis,

Can you tell me how you set up HORIZON with DSCOVR to get your .xyzv file?

Because I do not get the same numbers.

[selden]

If you send a properly formatted email message to Horizons, it will return an xyz trajectory file which needs only minimal editing to be compatible with Celestia.

A commented version of such a message (which produces a Sun-centered trajectory) is available at https://www.classe.cornell.edu/~seb/celestia/horizons-template.txt

Here are its contents:

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Here's a sample template for an e'mail message to request xyz coordinates
from Horizons for use with Celestia. You will have to edit the returned
message into the format that Celestia uses.

The message must be mailed to the address "horizons@ssd.jpl.nasa.gov"
The subject must be "JOB" ( do not include the quotes in either )

The body of the message should consist of the following text which
is between the lines of =====. Don't include those lines.
The lines starting with "!$$" are required, however.
Replace the fields ending in "here" with appropriate values.
Don't touch any of the other lines until you've read and understood
Horizons' documentation.
==========================================================
!$$SOF (ssd)       JPL/Horizons Execution Control VARLIST       
 EMAIL_ADDR = 'your address here'        ! 'you@there.com'
 COMMAND    = 'object name or id# here'  ! e.g. 'TRITON'
 OBJ_DATA   = 'NO'
 MAKE_EPHEM = 'YES'
 TABLE_TYPE = 'VECTORS'
 CENTER     = '@10'
 REF_PLANE  = 'ECLIPTIC'
 SITE_COORD = '0,0,0'
 START_TIME = 'starting date here'    ! e.g. '1989-Aug-23 09:00'
 STOP_TIME  = 'ending date here'      ! e.g. '1989-Aug-27 09:00'
 STEP_SIZE  = 'sample period here'    ! e.g. '10m' or '2d'
 REF_SYSTEM = 'J2000'
 OUT_UNITS  = 'KM-D'
 VECT_TABLE = '1'
 VECT_CORR  = 'NONE'
 TIME_DIGITS = 'MIN'
 CSV_FORMAT = 'NO'
 VEC_LABELS = 'NO'
 ELM_LABELS = 'NO'
 R_T_S_ONLY = 'NO'
 CA_TABLE_TYPE= 'EXTENDED'
 CALIM_SB= '0.1'
 CALIM_PL= '.1, .1, .1, .1, 1.0, 1.0, 1.0, 1.0, .1, .003'
!$$EOF++++++++++++++++++++++++++++++++++++++++++++++++++++++
=======================================================


[toutatis]

If you send a properly formatted email message to Horizons, it will return an xyz trajectory file which needs only minimal editing to be compatible with Celestia.

Thanks very much Selden...

[toutatis]

Compton GR Observatory... alternative model...

Added after 11 minutes 12 seconds:

We learn every day.

Another subject: do you have a method to generate data .xyz files starting from the ephemeris data of the Horizon site? In this I think of the orbits of the satellites at the point of Lagrange.

Yes, Gironde... I have software which convert txt-file from HORIZONS to xyzv-file for Celestia...

We learn every day.

Yes, we learn every day...

[toutatis]

SSC-file for DSCOVR... was corrected date of beginning for orbit... Thanks to Croc...

[Croc]

Compton GR Observatory... alternative model...

Excellent choice of colors! The natural color of the case is metallic! Toutatis, thanks for perseverance!

[toutatis]

thanks for perseverance!

[toutatis]

Toutatis,

Can you tell me how you set up HORIZON with DSCOVR to get your .xyzv file?

Because I do not get the same numbers.

Gironde... Only such way... watch below...

[toutatis]

I will start work with "Gaia" from tomorrow...

[gironde]

The orbits defined until then for DSCOVR, LISA Pathfinder and SoHO did not satisfy me. While they placed these satellites in the right place but when we visualized the orbit in Celestia, it was drawn in parallel with that of the Earth around the Sun.
The problem comes from the reference point (Earth or Sun). These satellites orbit at Lagrange point L1. ( "Sol / Earth / Earth-L1")

I redid the .ssc files with this reference point and used Horizon's orbital data provided with Body Center "Earth".
In Celestia, we now see the orbiting satellites around L1 between the Sun and the Earth.

To use point L1, you need to have the addon cc_Lagrange_2012.ssc from Phil Batchelor that creates the Lagrange reference points for the main planets of the Solar System.
For those who do not, I put it in this pack.
The models and textures that have not changed are not included. Just copy the .ssc instead of the old ones. The file cc_Lagrange_2012.ssc can be put in a folder cc_Lagrange in "extras".


also see https://en.wikipedia.org/wiki/List_of_objects_at_Lagrangian_points

[toutatis]

I do not think that I will change SSC-files for DSCOVR and SOHO which I made before... all is well with orbits of these Spacecrafts in my Celestia space... I trust more NASA...

[toutatis]

I will start project GRAIL for Celestia... I got two 3ds files of spacecrafts.. GRAIL-A (Ebb) and GRAIL-B (Flow) and 3ds file of second stage of Delta-II... GRAIL-SS.... Need to make lot of work to prepare it for Celestia...(work with solar panels... texturing... etc..).. but it was interesting project of NASA... so I think we need it for Celestia...

[gironde]

Toutatis, it is not a problem of Nasa but a problem of Orbit Center: Earth-L1 instead of Sol or Earth.

[toutatis]

Gironde... Did I said about problem of NASA??? or about my problems? I know very well Astronomy... The Sun is the main object in the whole Solar System... so all is well... they gave the very correct positions of the spacecrafts in the space where the main object is the Sun at each period of time... so all is well and I trust them... sorry for my English, but hope you understand my opinion...

[gironde]

That's not what I'm challenging.
When we put a satellite around the Moon, we write:
"name of the satellite" "Sol / Earth / Moon" to say that it orbits around the Moon in the Solar System

When we put "name of the satellite" "Sol", it orbits around the Sun.


In our case, it has to orbit around L1

Coordinate points x, y, z are not involved.

[toutatis]

Pre-launch planning trajectory for JWST.... data from "HORIZONS"

Code: Select all

*******************************************************************************
 Revised: Apr 05, 2018       James Webb Space Telescope / (E-S L2)         -170 

 Pre-launch planning trajectory for JWST.

 This is an update provided by STScI in April of 2018 that begins trajectory
 coverage in October of 2018.

 Trajectory files (from STScI)              Start (TDB)         End (TDB)
 --------------------------------------  -----------------  -----------------
 jwst-ephemeris (2018-Apr-03)            2018-Oct-01 13:18  2024-Dec-31 13:18
*******************************************************************************
 

 

*******************************************************************************
Ephemeris / WWW_USER Sun Jul  1 01:06:56 2018 Pasadena, USA      / Horizons   
*******************************************************************************
Target body name: James Webb Space Telescope (spacecraft) (-170) {source: jwst_2_out}
Center body name: Earth (399)                     {source: DE431mx}
Center-site name: BODY CENTER
*******************************************************************************
Start time      : A.D. 2020-Oct-01 00:00:00.0000 TDB
Stop  time      : A.D. 2020-Oct-02 00:00:00.0000 TDB
Step-size       : 1440 minutes
*******************************************************************************
Center geodetic : 0.00000000,0.00000000,0.0000000 {E-lon(deg),Lat(deg),Alt(km)}
Center cylindric: 0.00000000,0.00000000,0.0000000 {E-lon(deg),Dxy(km),Dz(km)}
Center radii    : 6378.1 x 6378.1 x 6356.8 km     {Equator, meridian, pole}   
Keplerian GM    : 2.9755363065130385E+15 km^3/d^2
Output units    : KM-D, deg, Julian Day Number (Tp)                           
Output type     : GEOMETRIC osculating elements
Output format   : 10
Reference frame : ICRF/J2000.0                                                 
Coordinate systm: Ecliptic and Mean Equinox of Reference Epoch                 
*******************************************************************************
JDTDB
   EC    QR   IN
   OM    W    Tp
   N     MA   TA
   A     AD   PR
*******************************************************************************
$$SOE
2459123.500000000 = A.D. 2020-Oct-01 00:00:00.0000 TDB
 EC= 9.633930211434892E-01 QR= 3.189527040387199E+04 IN= 2.450933296105284E+01
 OM= 1.776973002095750E+02 W = 2.509657820050173E+01 Tp=  2459077.920067532919
 N = 3.842922793176111E+00 MA= 1.751601613894220E+02 TA= 1.796633074664023E+02
 A = 8.712893388141282E+05 AD= 1.710683407224384E+06 PR= 9.367869701656589E+01
2459124.500000000 = A.D. 2020-Oct-02 00:00:00.0000 TDB
 EC= 9.658850606778864E-01 QR= 2.969849020292095E+04 IN= 2.228081597100178E+01
 OM= 1.749431178623462E+02 W = 2.779318856287871E+01 Tp=  2459078.658346822485
 N = 3.847871912717052E+00 MA= 1.763928096939285E+02 TA= 1.797582440708136E+02
 A = 8.705420790143510E+05 AD= 1.711385667825781E+06 PR= 9.355820780058073E+01
$$EOE
*******************************************************************************
Coordinate system description:

  Ecliptic and Mean Equinox of Reference Epoch

    Reference epoch: J2000.0
    XY-plane: plane of the Earth's orbit at the reference epoch
              Note: obliquity of 84381.448 arcseconds wrt ICRF equator (IAU76)
    X-axis  : out along ascending node of instantaneous plane of the Earth's
              orbit and the Earth's mean equator at the reference epoch
    Z-axis  : perpendicular to the xy-plane in the directional (+ or -) sense
              of Earth's north pole at the reference epoch.

  Symbol meaning [1 day=86400.0 s]:

    JDTDB    Julian Day Number, Barycentric Dynamical Time
      EC     Eccentricity, e                                                   
      QR     Periapsis distance, q (km)                                       
      IN     Inclination w.r.t XY-plane, i (degrees)                           
      OM     Longitude of Ascending Node, OMEGA, (degrees)                     
      W      Argument of Perifocus, w (degrees)                               
      Tp     Time of periapsis (Julian Day Number)                             
      N      Mean motion, n (degrees/day)                                     
      MA     Mean anomaly, M (degrees)                                         
      TA     True anomaly, nu (degrees)                                       
      A      Semi-major axis, a (km)                                           
      AD     Apoapsis distance (km)                                           
      PR     Sidereal orbit period (day)                                       

Geometric states/elements have no aberrations applied.

 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)
                  http://ssd.jpl.nasa.gov/?horizons
                  telnet ssd.jpl.nasa.gov 6775    (via command-line)
     Author     : Jon.D.Giorgini@jpl.nasa.gov
*******************************************************************************


SSC-file for JWST:

[toutatis]

Okay...

[jujuapapa]

Toutatis, are you sure about the speed of rotation of jwst in your ssc file ?

For me it's too fast !

[gironde]

I have detected an error in my ssc file for DSCOVR post viewtopic.php?p=139243#p139243


Period is

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Period         107.0140497825458 # Earth

and not

Code: Select all

Period         107140497825458 # Earth

Added after 34 minutes 18 seconds:
James Webb Space Telescope is not launched
the new date for launch is 30-03-2021

The ephemeris of Horizon change all the days

I have this (last ephemeris) :

Code: Select all

   EllipticalOrbit
   {
      Epoch            2459303.50  # 2021-03-30
      Period            93.10402806089452
      SemiMajorAxis      867722.4214289936
      Eccentricity      0.9695696127369036
      Inclination         21.40381720241684
      AscendingNode      350.9264893916750
      ArgOfPericenter      30.49012770837048
      MeanAnomaly         175.0276869444453


[toutatis]

:hi: Toutatis, are you sure about the speed of rotation of jwst in your ssc file ?

For me it's too fast !

It was just for test.... you can change it...