Re: Simulated Launches - directional, a local view (fwd)
Josh R. Williams (jrwsat@gatecoms.gatecom.com)
Fri, 29 Mar 1996 15:19:25 -0500 (EST)
Seesat,
This is the response from Dave Ransom about the Shuttle launch prediction
program in STSPlus...
-*-*-
Josh R. Williams ** JRW Satellite Page **
E-Mail: jrwsat@gatecoms.gatecom.com URL: http://www.gatecom.com/~jrwsat/
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-==-=-=-=-=-=-=-=-=
SeeSat-L and HearSat-L member located at:
Latitude: 41 deg 59' 29" N -- Longitude: 83 deg 27' 41" W
---------- Forwarded message ----------
Date: Thu, 28 Mar 1996 17:12:17 -0600 (CST)
From: David H. Ransom <rans7500@spacelink.msfc.nasa.gov>
To: "Josh R. Williams" <jrwsat@gatecoms.gatecom.com>
Cc: Stephen Thompson <SThompson@gatecoms.gatecom.com>,
SeeSat-L <seesat-l@gatecoms.gatecom.com>
Subject: Re: Simulated Launches - directional, a local view
Josh et al,
The ascent simulation in STSPLUS starts with a model ascent profile
derived from several prior launches. The model is adjusted for the
planned orbital altitude and inclination by simple interpolation.
Matching 2-line elements (NORAD 2-line format) must also be available.
STSPLUS starts by relying entirely on the adjusted model. After about ten
minutes, the data from the adjusted model are merged with the 2-line data
until at T+40 minutes the data are derived entirely from the 2-line data.
(The 2-line data are processed with the SGP4 model, by the way, like all
satellites in STSPLUS.)
As must be obvious from this description, the ascent simulation is
specific to space shuttle launches. The ascent simulation is only a rough
approximation for a variety of reasons. The actual launch profile is
mission specific and is a function of vehicle mass, payload, intended
altitude and inclination. Since the 2-line data takes over at T+40
minutes, and since several tests during actual launches have shown that
the ascent model I've developed is "reasonably accurate", I don't think
it necessary to refine the process with a more elaborate and accurate
model.
Hope that answers some of the questions ...
DAVE
On Thu, 28 Mar 1996, Josh R. Williams wrote:
> Stephen,
>
> I have used this program and have simulated a few launches, I too have
> wondered how this particular part of the program works (Documentation is
> a little vague in this area), therefore I have forwarded a copy of the message
> to Dave Ransom and maybe we will get some answers..
>
> -*-*-
> Josh R. Williams ** JRW Satellite Page **
> E-Mail: jrwsat@gatecoms.gatecom.com URL: http://www.gatecom.com/~jrwsat/
> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-==-=-=-=-=-=-=-=-=
> SeeSat-L and HearSat-L member located at:
> Latitude: 41 deg 59' 29" N -- Longitude: 83 deg 27' 41" W
>
> On Thu, 28 Mar 1996, Stephen Thompson wrote:
>
> >
> > No, I cannot explain how to use TLE's to determine rocket position during
> > launch phase. What I can do is run STS-PLUS Version 9517 which has a
> > Shuttle launch simulator (see STSPLUS Doc p 59). Dave Ransom makes it very
> > clear that this model is only good for the Shuttle launched from the Cape
> > and that the prelaunch TLE's and launch time must match.
> >
> > It would be interesting to know more about how his model works. Maybe fancy
> > polynomial substitution for the physics?
> >
> > Stephen
> >
> > SThompson@esiusa.com
> >
> > ----------
> > From: seesat-l-request
> > To: seesat-L
> > Subject: Re: Launches - directional, a local view
> > Date: Thursday, March 28, 1996 1:19AM
> >
> > On Wed, 27 Mar 1996, Stephen Thompson wrote:
> >
> > > When STS-76 left for Mir the other morning, the 'launch simulation" in
> > > STS-PLUS was spot-on for rise and set times as well as altitude, I
> > recommend
> > > that anyone interested in seeing launches from a great distance use
> > STS-PLUS
> > > to see if a particular launch will be visible from their location.
> >
> > Can you explain how to use TLEs to determine rocket position during
> > launch phase?
> > --
> >
> > JRespler@InJersey.com or Jay.Respler@bytewise.org
> > Satellite Tracker * Early Typewriter Collector
> > Freehold, New Jersey
> >
> >
> >
> >
> >
>
----------
David H. Ransom, Jr. Email:rans7500@spacelink.msfc.nasa.gov