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115 lines
2.8 KiB
Plaintext
115 lines
2.8 KiB
Plaintext
---
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title: "ISS Eclipse Determination"
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description: |
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Determining how much sunlight a body is receiving.
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draft: false
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author:
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- name: Anson Biggs
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url: https://ansonbiggs.com
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repository_url: https://gitlab.com/lander-team/air-prop-simulation
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date: 04-01-2021
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fig_width: 6
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fig_align: "center"
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output:
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distill::distill_article:
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self_contained: false
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categories:
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- Julia
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- Astrodynamics
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#bibliography: ../../citations.bib
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creative_commons: CC BY
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preview: preview.png
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---
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Determining the eclipses a satellite will encounter is a major driving factor when designing a mission in space. Thermal and power budgets have to be made with the fact that a satellite will periodically be in the complete darkness of space with no solar radiation to power the solar panels and keep the spacecraft from freezing.
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```{r setup, include=FALSE}
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knitr::opts_chunk$set(echo = TRUE, results = 'hide')
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library(JuliaCall)
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#julia_setup(JULIA_HOME = "/opt/julia-1.6.1/bin/")
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julia_setup(installJulia = TRUE)
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```
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## What is an Eclipse
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## The Code
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```{julia, code_folding=TRUE}
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using Unitful
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using LinearAlgebra
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using SatelliteToolbox
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using Plots
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using Colors
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theme(:ggplot2)
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```
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```{julia}
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ISS = tle"""
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ISS (ZARYA)
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1 25544U 98067A 21103.84943184 .00000176 00000-0 11381-4 0 9990
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2 25544 51.6434 300.9481 0002858 223.8443 263.8789 15.48881793278621
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"""
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```
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```{julia}
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orbit = init_orbit_propagator(Val(:twobody), ISS[1]);
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time = 0:0.1:((24 / ISS[1].n) .* 60 * 60);
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o, r, v = propagate!(orbit, time);
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```
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```{julia}
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function sunlight(Rbody, r_sun_body, r_body_sc)
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Rsun = 695_700u"km"
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hu = Rbody * norm(r_sun_body) / (Rsun - Rbody)
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θe = acos((r_sun_body ⋅ r_body_sc) / (norm(r_sun_body) * norm(r_body_sc)))
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θu = atan(Rbody / hu)
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du = hu * sin(θu) / sin(θe + θu)
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θp = π - atan(norm(r_sun_body) / (Rsun + Rbody))
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dp = Rbody * sin(θp) / cos(θe - θp)
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S = 1
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if (θe < π / 2) && (norm(r_body_sc) < du)
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S = 0
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end
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if (θe < π / 2) && ((du < norm(r_body_sc)) && (norm(r_body_sc) < dp))
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S = (norm(r_body_sc .|> u"km") - du) / (dp - du) |> ustrip
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end
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return S
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end
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```
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```{julia}
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S = r .|> R -> sunlight(6371u"km", [0.5370, 1.2606, 0.5466] .* 1e8u"km", R .* u"m")
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```
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## Plotting the Results
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```{julia, code_folding=TRUE, results='show',layout="l-body-outset",fig.cap= "Rocket Motor Data: [@thrustcurve]", preview=TRUE }
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light_range = range(colorant"black", stop = colorant"yellow", length = 101);
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light_colors = [light_range[unique(round(Int, 1 + s * 100))][1] for s in S];
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plot(
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LinRange(0, 24, length(S)),
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S .* 100,
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linewidth = 5,
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legend = false,
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color = light_colors,
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);
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xlabel!("Time (hr)");
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ylabel!("Sunlight (%)");
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title!("ISS Sunlight Over a Day")
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``` |