MER-B and Delta Second stage predictions

From: Michael McCants (mmccants@jump.net)
Date: Fri Jun 27 2003 - 19:32:31 EDT

  • Next message: Ed Cannon: "Delta launch event art"

    Mars Exploration Rover-B is scheduled for launch late Saturday night
    or early Sunday morning from Cape Canaveral.
    
    See: http://spaceflightnow.com/mars/merb/status.html
    
    This status page will be updated as events happen.
    
    The launch opportunities Saturday night are June 29 03:56UT (azimuth 93)
    and 04:38UT (azimuth 99).
    
    Predictions for the payload and the Delta second stage can be obtained
    from the JPL Horizons system - see below.
    
    Separation from the Delta second stage and third stage ignition
    are about 72 minutes after launch.  These events are near Hawaii.
    
    After third stage cut-off and separation, the MER-B spacecraft and
    the third stage should be fairly close together.
    
    However, there is a "depletion burn" of the Delta second stage
    about 30 minutes after it separates from the payload.  This burn will
    take place about 05:36 UT (opp 1) or 06:18 UT (opp 2).  This burn
    should be visible from a lot of the south central and south eastern US.
    The height at the time of the burn will be about 1600 miles and
    the burn will take place over latitude 23 north, longitude 74 west
    for opportunity 1 and latitude 23, longitude 80 for opportunity 2.
    The duration of this depletion burn is about one minute.
    
    I have fit tles to the second stage:
    
    Opportunity 1 (launch azimuth 93):
    
    Del2 r Pre-depletion burn
    1 99991U          03180.21217174  .00000000  00000-0  00000+0 0    06
    2 99991  28.4791 158.9327 2815038  22.4813 350.4712 10.04070522    05
    
    Del2 r Post-depletion burn
    1 99992U          03180.31163007  .00000000  00000-0  00000+0 0    03
    2 99992  24.0787 180.8349 2873234   5.2759 341.2446  9.81329558    02
    
    Use the first tle until 05:36 and the second tle after 05:37 UT.
    
    Opportunity 2 (launch azimuth 99):
    
    Del2 r Pre-depletion burn
    1 99993U          03180.22908378  .00000000  00000-0  00000+0 0    02
    2 99993  29.3912 158.8717 2834800  23.1954 312.4513  9.97003331    07
    
    Del2 r Post-depletion burn
    1 99994U          03180.33718563  .00000000  00000-0  00000+0 0    00
    2 99994  23.7093 179.7107 2714465  13.0574 313.6313  9.20010545    03
    
    Use the first tle until 06:18 and the second tle after 06:19 UT.
    
    Predictions are available from the JPL Horizons system.  I have
    included some instructions below.  Note:  Apparently the JPL Horizons
    page will generate predictions for an object that is inside the Earth's
    penumbral shadow.
    
    After the third stage burn and separation, MER-B will be on an Earth
    escape orbit.  Thus the tle would be "hyperbolic" and such a tle
    cannot be handled by any normal satellite tracking program.
    
    If I try to fit a very high eccentricity, 10 day orbital period
    tle to the trajectory using fitelem/elcor and SGP4, I can get
    a reasonable fit for relatively short arcs.  But with such an
    elset, SGP4 and SDP4 are incompatible, so if I generate an SGP4
    elset, it cannot be used by a program that would automatically
    use SDP4 for such an elset.
    
    Use of JPL Horizons system:
    
    http://ssd.jpl.nasa.gov/horizons.html
    
    Select "WWW" for interactive predictions using your web browser.
    
    First specify the target body.
    
    If you enter "MER" into the "major body" (or spacecraft) window
    and hit "search", there are 5 choices.  The first is MER-B opportunity 1
    (launch azimuth 93) ephemeris -253.  The second is Delta second stage
    rocket for this first opportunity ephemeris -250.  The third is MER-B
    opportunity 2 (launch azimuth 99) ephemeris -252,  The fourth is
    the Delta second stage rocket for the second opportunity ephemeris -251.
    The fifth is the planet Mercury.  :-)
    
    You must specify your observer location (lat/long).
    
    You must specify a proper time span.  If you specify a time span
    that starts before the available data, you will get an error from
    the Horizons system.  I used the following time spans for Texas:
    
    MER-B opp 1: June 29 05:20 to 07:00 UT
    Del r opp 1: June 29 05:20 to 06:00 UT
    This object will be in the Earth's penumbral shadow from about
    05:28 to 05:33.  So it will be 1 or 2 magnitudes fainter during
    that time.
    
    MER-B opp 2: June 29 06:00 to 07:30 UT
    Del r opp 2: June 29 06:00 to 07:00 UT
    
    You should select the output quantities RA/Dec, Az/El, and Observer
    range and range-rate.
    
    Then hit "Generate Ephemeris".
    
    Mike McCants
    
    -----------------------------------------------------------------
    To unsubscribe from SeeSat-L, send a message with 'unsubscribe'
    in the SUBJECT to SeeSat-L-request@satobs.org
    List archived at http://www.satobs.org/seesat/seesatindex.html
    



    This archive was generated by hypermail 2b29 : Fri Jun 27 2003 - 19:36:36 EDT