JANUS FOV during Ganymede flyby

Example of representation of JANUS field of view during 2G2 Ganymede flyby.

import matplotlib.pyplot as plt

from planetary_coverage import GANYMEDE, TourConfig, read_events
from planetary_coverage.misc import wget

Download JUICE timeline from the SOC

URL = 'https://juicesoc.esac.esa.int/data/DATA/crema_5_0'
TIMELINE = 'mission_timeline_event_file_5_0.csv'

wget(f'{URL}/{TIMELINE}', TIMELINE, skip=True)

PosixPath('mission_timeline_event_file_5_0.csv')

Get the 2G2 flyby date from the timeline

timeline = read_events(TIMELINE)

flyby_2G2 = timeline['FLYBY_GANYMEDE']['2G2']

flyby_2G2

event name	FLYBY_GANYMEDE
event time [utc]	2032-02-13T23:04:50Z
Crema name	2G2
Time	13-FEB-2032_23:04:50
Altitude above ganymede [km]	400.05316
Sub-SC lon [deg]	233.9
Sub-SC lat [deg]	25.1
Sub-SC phase [deg]	74.5
Sub-SC loctime [hours]	16.8
Jup-Moon-Sc angle [deg]	120.4
Flight direction	1Y
Moon true anomalie	115.9
Ground track velocity [km/s]	5.5
Velocity wrt sub-sc point radial component [km/s]	-0.0
Velocity wrt sub-sc point tangential component [km/s]	5.5
Energy generated over +-12h around CA [Wh]	22974.8
Energy generated over +-1h around CA [Wh]	909.9
Energy for science over +-12h around CA [Wh]	8907.6
Energy for science over +-1h around CA [Wh]	-222.0
Relative energy amount for science compared to E1 +-12 h	0.985
Relative energy amount for science compared to E1 +-1 h	1.154
Optimum solar array orientation during pushbroom [deg]	-89.0
PEP-NIM FOV obstruction for optimum solar array [percent]	0.0
Energy for science over +-1h around CA [Wh] with zero NIM obstruction [Wh]	-1130.4
Maximum sc2sun direction angle to YZ plane during pushbroom	19.2
Malargue visibility	NO
Cebreros visibility	NO
Delta-time to closest perijove [h]	15.26

Load JUICE trajectory during 2G2

tour = TourConfig(mk='5.1 150lb', spacecraft='JUICE', instrument='JANUS',
                  target='Ganymede', version='v400')

janus_flyby = tour.flyby(flyby_2G2)

janus_flyby

<InstrumentFlyby> Observer: JUICE_JANUS | Target: GANYMEDE
 - Altitude at CA: 400.0 km
 - UTC at CA: 2032-02-13T23:03:55
 - Duration: 1 day, 0:00:00
 - Nb of pts: 2,041

Keep only the part of the trajectory below 100,000 km

mask_janus_flyby = janus_flyby.where(janus_flyby.alt < 100_000)

mask_janus_flyby

<MaskedInstrumentTrajectory> Observer: JUICE_JANUS | Target: GANYMEDE
 - First UTC start time: 2032-02-13T18:23:55.000
 - Last UTC stop time: 2032-02-14T03:43:55.000
 - Nb of pts: 1,953 (+88 masked)
 - Nb of segments: 1

Represent JANUS FOV on the map

fig = plt.figure(figsize=(12, 9))
ax = fig.add_subplot(projection=GANYMEDE)

ax.add_collection(mask_janus_flyby.fovs(facecolors='inc',
                                        vmin=0, vmax=90, sort='inc'))

ax.colorbar(vmin=0, vmax=90, label='inc', extend='max')

ax.set_title('JANUS footprints during 2G2 flyby (Feb. 13th 2032)')

plt.show()

Download

• janus_fov.ipynb

• janus_fov.py