DMSP F18 search elements

From: Ted Molczan (
Date: Fri Oct 16 2009 - 02:20:47 UTC

  • Next message: Russell Eberst: "2009OCT15-16.OBS"

    DMSP F18 is scheduled for launch on 2009 Oct 18, between 16:12 UTC and 16:22
    UTC, from Vandenberg AFB, aboard an Atlas 5-401 rocket.
    The launch vehicle's performance far exceeds mission requirements; so much so,
    that its Centaur stage will be disposed of in an unusual manner: a heliocentric
    orbit. That burn will be visible from parts of Europe about 3 h after launch,
    followed within minutes by the dump of any remaining propellant.
    Assuming launch at the start of the window, DMSP F18 will enter approximately
    the following orbit:
    DMSP F18                                                 838 X 853 km
    1 72900U          09291.72202813  .00000000  00000-0  00000-0 0    07
    2 72900  98.8000 325.8000 0010000 270.0000  90.0000 14.13250000    08
    On the first pass of Europe, beginning near 17:30 UTC, the Centaur is likely to
    lead the DMSP by several seconds in time.
    One rev later, at 19:10:07 UTC, while northbound over ~30 N, 6 E, the Centaur
    will begin a 220 s burn. At 170 s into the burn, it will reach escape velocity.
    By the end of the burn, it will have considerably exceeded escape velocity, by 1
    or 2 km/s, I estimate.
    My implementations of the SGP models begin to misbehave well short of escape
    velocity, so for the search elements, I settled for a ~500,000 km apogee:
    DMSP F18 r                                            925 X 508891 km
    1 72901U          09291.79869216  .00000000  00000-0  00000-0 0    01
    2 72901  98.8000 325.9000 9720500  29.8676 359.9900  0.06500000    02
    This elset seems to yield the most reasonable altitudes when used with SGP4 or
    the old SGP. SDP4 yields less accurate results.
    The blow down will begin at 19:17:14 UTC, and will last for more than 13 min.
    Spaceflight Now will cover the launch:
    The press kit is here:
    Ted Molczan
    Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive:

    This archive was generated by hypermail 2b29 : Fri Oct 16 2009 - 02:21:52 UTC