[Ground-station] Ground-Station Digest, Vol 34, Issue 21

[Michelle Thompson]

Of course - it's here:

https://github.com/phase4ground/documents/tree/master/Engineering/Link_Budget

The link budget spreadsheet, and the propa.dll, are both there.

-Michelle W5NYV




On Fri, Feb 5, 2021 at 8:03 AM anshul makkar via Ground-Station
<ground-station at lists.openresearch.institute> wrote:

> Hi Michelle,
>
> Please can you share the Jan's spreadsheet or any script that he might
> have written. I can use it to compare the GMAT script that I have and
> include any additional factors into my deltaV calculations for GEO to
> Graveyard orbit.
>
> Thanks
> Anshul Makkar
>
> On Sun, Jan 31, 2021 at 7:54 AM anshul makkar <anshulmakkar at gmail.com>
> wrote:
> >
> > Hi,
> >
> > Not expert in this area and still learning, I found a help page :
> > http://gmat.sourceforge.net/docs/R2018a/help.html which talks about
> > configuring atmospheric models.
> >
> > Also, a brief web research showed that people have used the GMAT
> > atmospheric model to configure their mission.
> >
> > For my script "GEO to graveyard orbit", I am only using the Gravity
> > Field Force Model.
> >
> > I can (based on your post I believe I need to ) introduce Atmospheric
> > model related coefficients and provide the deltaV comparative results.
> >
> > Thanks
> > Anshul Makkar
> >
> > On Sat, Jan 30, 2021 at 9:51 PM Thomas Parry via Ground-Station
> > <ground-station at lists.openresearch.institute> wrote:
> > >
> > > This is not my area of expertise at all. But I have heard people that
> do know what they're talking about say its very hard to analytically
> predict re-entry at low altitudes with real satellite geometries.
> > >
> > > With a spherical satellite everything is well behaved but with
> different drag coefficients at different angles from square-ish satellites
> the behaviour becomes chaotic and the window of possible solutions widens
> dramatically.
> > >
> > > Not really a useful answer but maybe a interesting thing to think
> about.
> > >
> > > Cheers,
> > > Thomas
> > >
> > >
> > > On Sat, 30 Jan 2021, 22:03 ,
> <ground-station-request at lists.openresearch.institute> wrote:
> > >>
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> > >> Today's Topics:
> > >>
> > >>    1. GMAT vs. STK/HPOP - call for help (Michelle Thompson)
> > >>
> > >>
> > >> ----------------------------------------------------------------------
> > >>
> > >> Message: 1
> > >> Date: Fri, 29 Jan 2021 17:28:20 -0800
> > >> From: Michelle Thompson <mountain.michelle at gmail.com>
> > >> To: Michelle Thompson via Ground-Station
> > >>         <ground-station at lists.openresearch.institute>
> > >> Subject: [Ground-station] GMAT vs. STK/HPOP - call for help
> > >> Message-ID:
> > >>         <CACvjz2UOeHpUmGgtvqTS=Y4WQ4_XDLyQRu_7=
> qw13bY_hzevFg at mail.gmail.com>
> > >> Content-Type: text/plain; charset="utf-8"
> > >>
> > >> For the Debris Mitigation presentation to the FCC, we want to give
> answers
> > >> (and show our work) about how much delta-v we need for some of the
> proposed
> > >> orbits for minimum viable amateur spacecraft in the Amateur Radio
> Satellite
> > >> Service.
> > >>
> > >> There's a question that Jan King and I have about a critical altitude
> and
> > >> low surface_area:mass ratio spacecraft. It occurred to us that we
> really
> > >> might want to compare results across two or more software packages to
> build
> > >> some confidence.
> > >>
> > >> Jan has a set of results from a spreadsheet from SMAD.
> > >>
> > >> https://smad.com/
> > >>
> > >> The calculation under review is around 165km with a relatively
> lightweight
> > >> 6U spacecraft. It's acting like it wants to do some strange things.
> Is this
> > >> physics, or at a limit of the model?
> > >>
> > >> We have a couple of people who are good or are getting good at GMAT.
> > >>
> > >> https://software.nasa.gov/software/GSC-17177-1
> > >>
> > >> Question: Are the atmospheric models in GMAT good enough for this
> > >> calculation?
> > >>
> > >> Does anyone have access to STK/HPOP to run this calculation, for
> > >> comparison?
> > >>
> > >> https://www.agi.com/products/stk
> > >>
> > >> https://help.agi.com/stk/11.0.1/Content/hpop/hpop.htm
> > >>
> > >> Thank you,
> > >> -Michelle W5NYV
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> > >> ------------------------------
> > >>
> > >> End of Ground-Station Digest, Vol 34, Issue 21
> > >> **********************************************
> > >>
>
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