<div dir="ltr">Of course - it's here:<br><br><a href="https://github.com/phase4ground/documents/tree/master/Engineering/Link_Budget">https://github.com/phase4ground/documents/tree/master/Engineering/Link_Budget</a><br><br>The link budget spreadsheet, and the propa.dll, are both there. <br><br clear="all"><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div dir="ltr">-Michelle W5NYV<br><br><div dir="ltr"><br></div></div></div></div></div></div></div></div></div><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Feb 5, 2021 at 8:03 AM anshul makkar via Ground-Station <ground-station@lists.openresearch.institute> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi Michelle,<br>
<br>
Please can you share the Jan's spreadsheet or any script that he might<br>
have written. I can use it to compare the GMAT script that I have and<br>
include any additional factors into my deltaV calculations for GEO to<br>
Graveyard orbit.<br>
<br>
Thanks<br>
Anshul Makkar<br>
<br>
On Sun, Jan 31, 2021 at 7:54 AM anshul makkar <<a href="mailto:anshulmakkar@gmail.com" target="_blank">anshulmakkar@gmail.com</a>> wrote:<br>
><br>
> Hi,<br>
><br>
> Not expert in this area and still learning, I found a help page :<br>
> <a href="http://gmat.sourceforge.net/docs/R2018a/help.html" rel="noreferrer" target="_blank">http://gmat.sourceforge.net/docs/R2018a/help.html</a> which talks about<br>
> configuring atmospheric models.<br>
><br>
> Also, a brief web research showed that people have used the GMAT<br>
> atmospheric model to configure their mission.<br>
><br>
> For my script "GEO to graveyard orbit", I am only using the Gravity<br>
> Field Force Model.<br>
><br>
> I can (based on your post I believe I need to ) introduce Atmospheric<br>
> model related coefficients and provide the deltaV comparative results.<br>
><br>
> Thanks<br>
> Anshul Makkar<br>
><br>
> On Sat, Jan 30, 2021 at 9:51 PM Thomas Parry via Ground-Station<br>
> <ground-station@lists.openresearch.institute> wrote:<br>
> ><br>
> > 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.<br>
> ><br>
> > 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.<br>
> ><br>
> > Not really a useful answer but maybe a interesting thing to think about.<br>
> ><br>
> > Cheers,<br>
> > Thomas<br>
> ><br>
> ><br>
> > On Sat, 30 Jan 2021, 22:03 , <ground-station-request@lists.openresearch.institute> wrote:<br>
> >><br>
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> >> Today's Topics:<br>
> >><br>
> >> 1. GMAT vs. STK/HPOP - call for help (Michelle Thompson)<br>
> >><br>
> >><br>
> >> ----------------------------------------------------------------------<br>
> >><br>
> >> Message: 1<br>
> >> Date: Fri, 29 Jan 2021 17:28:20 -0800<br>
> >> From: Michelle Thompson <<a href="mailto:mountain.michelle@gmail.com" target="_blank">mountain.michelle@gmail.com</a>><br>
> >> To: Michelle Thompson via Ground-Station<br>
> >> <ground-station@lists.openresearch.institute><br>
> >> Subject: [Ground-station] GMAT vs. STK/HPOP - call for help<br>
> >> Message-ID:<br>
> >> <CACvjz2UOeHpUmGgtvqTS=Y4WQ4_XDLyQRu_7=<a href="mailto:qw13bY_hzevFg@mail.gmail.com" target="_blank">qw13bY_hzevFg@mail.gmail.com</a>><br>
> >> Content-Type: text/plain; charset="utf-8"<br>
> >><br>
> >> For the Debris Mitigation presentation to the FCC, we want to give answers<br>
> >> (and show our work) about how much delta-v we need for some of the proposed<br>
> >> orbits for minimum viable amateur spacecraft in the Amateur Radio Satellite<br>
> >> Service.<br>
> >><br>
> >> There's a question that Jan King and I have about a critical altitude and<br>
> >> low surface_area:mass ratio spacecraft. It occurred to us that we really<br>
> >> might want to compare results across two or more software packages to build<br>
> >> some confidence.<br>
> >><br>
> >> Jan has a set of results from a spreadsheet from SMAD.<br>
> >><br>
> >> <a href="https://smad.com/" rel="noreferrer" target="_blank">https://smad.com/</a><br>
> >><br>
> >> The calculation under review is around 165km with a relatively lightweight<br>
> >> 6U spacecraft. It's acting like it wants to do some strange things. Is this<br>
> >> physics, or at a limit of the model?<br>
> >><br>
> >> We have a couple of people who are good or are getting good at GMAT.<br>
> >><br>
> >> <a href="https://software.nasa.gov/software/GSC-17177-1" rel="noreferrer" target="_blank">https://software.nasa.gov/software/GSC-17177-1</a><br>
> >><br>
> >> Question: Are the atmospheric models in GMAT good enough for this<br>
> >> calculation?<br>
> >><br>
> >> Does anyone have access to STK/HPOP to run this calculation, for<br>
> >> comparison?<br>
> >><br>
> >> <a href="https://www.agi.com/products/stk" rel="noreferrer" target="_blank">https://www.agi.com/products/stk</a><br>
> >><br>
> >> <a href="https://help.agi.com/stk/11.0.1/Content/hpop/hpop.htm" rel="noreferrer" target="_blank">https://help.agi.com/stk/11.0.1/Content/hpop/hpop.htm</a><br>
> >><br>
> >> Thank you,<br>
> >> -Michelle W5NYV<br>
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> >> ------------------------------<br>
> >><br>
> >> End of Ground-Station Digest, Vol 34, Issue 21<br>
> >> **********************************************<br>
> >><br>
</blockquote></div>