Satellites over time

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Tags: #celestrak #opendata #satelltes
Author: Dumorya​
We analyze the number of satellites in the space from the first launch to now, and the part of them which became inactive. These data come from http://www.celestrak.com/. It provides free data as CSV files easily accessible. The CSV file we got contains many data as the name of the satellite, its owner, launch site, id, apogee and many others. What interested us the most were the status code, the launch date and the decay date, in order to create a graph with years in X axis and number of satellites in Y axis.
Input
Import librairies
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import pandas as pd
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import plotly.express as px
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import plotly.graph_objects as go
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import numpy as np
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Variables
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URL = 'http://www.celestrak.com/pub/satcat.csv'
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Model
Recovery and processing of CSV data
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df = pd.read_csv(URL)
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df = df[['OPS_STATUS_CODE', 'LAUNCH_DATE', 'DECAY_DATE']]
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df['DECAY_DATE'] = df['DECAY_DATE'].mask(df['DECAY_DATE'].isnull(), '9999')
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df['LAUNCH_DATE'] = df['LAUNCH_DATE'].str[:4].astype(int)
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df['DECAY_DATE'] = df['DECAY_DATE'].str[:4].astype(int)
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years = df['LAUNCH_DATE'].unique()
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inactive = list()
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active = list()
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​
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for year in years:
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    active.append(len(df[
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        ((df['OPS_STATUS_CODE'].isin(['+', 'P', 'B', 'S', 'X'])) & (df['LAUNCH_DATE'] <= year))
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        | ((df['DECAY_DATE'] > year) & (df['OPS_STATUS_CODE'] == 'D') & (df['LAUNCH_DATE'] <= year))
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    ].index))
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    inactive.append(len(df[
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        ((df['OPS_STATUS_CODE'] == 'D') & (df['DECAY_DATE'] <= year))
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        | ((df['OPS_STATUS_CODE'] == '-') & (df['LAUNCH_DATE'] <= year) )
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    ].index))
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Output
Display plot of the number of satellites in space over time
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fig = go.Figure(data=[
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    go.Bar(name='Inactive satellites', x=years, y=inactive),
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    go.Bar(name='Active satellites', x=years, y=active)
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])
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# Change the bar mode
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fig.update_layout(
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    title="Number of satellites in space over time",
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    xaxis_title="Years",
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    yaxis_title="Number of satellites",
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    barmode='stack'
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)
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fig.show()
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Source: http://www.celestrak.com/pub/satcat.csv
Display the percentage of inactive VS active satellites from 1957 to now
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labels = years
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widths = [100/len(years) for year in years]
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​
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active_percentage = list()
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inactive_percentage = list()
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​
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for index, _ in np.ndenumerate(active):
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    total = active[index[0]] + inactive[index[0]]
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    active_percentage.append(active[index[0]]/total*100)
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    inactive_percentage.append(inactive[index[0]]/total*100)
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​
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data = {
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    "Inactive": inactive_percentage,
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    "Active": active_percentage
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}
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​
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fig = go.Figure()
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for key in data:
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    fig.add_trace(go.Bar(
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        name=key,
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        y=data[key],
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        x=years,
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        offset=0
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    ))
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​
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fig.update_xaxes(range=[years[0],years[-1]])
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fig.update_yaxes(range=[0,100])
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​
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fig.update_layout(
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    title_text="Percentage of inactive VS active satellites from 1957 to now",
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    barmode="stack",
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    uniformtext=dict(mode="hide", minsize=10),
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)
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Celestrak

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Contents

Input

Model

Output