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Table 1 Objectives and requirements for visibility calculations

From: Visibility analysis of Phobos to support a science and exploration platform

Objective Requirement Justification Data
Remote sensing of the Mars atmosphere and surface Visibility of Mars > 0 min Visibility of Mars dayside and nightside No map required due to Phobos’ tidal lock and equatorial orbit. All Mars local times are covered equally. Dayside and nightside are both observed ~ 3 h 50 min per orbit
Visibility from Deimos during Mars occultation If stations are located on both Phobos and Deimos, attenuation of a signal transmitted between the two captures information about Mars’ atmosphere and ionosphere Map of Phobos quantifying the number of occultation events showing locations where the line of sight to Deimos intersects Mars’ surface
Radio/ranging science: Geodesy, dynamics, gravity, fundamental physics Visibility from Deimos: ≥ 2 h per day Both cases are mostly covered by the GPS requirement Boolean map of Phobos true where visibility from Deimos is ≥ 2 h per day
Visibility (laser ranging) from Earth ≥ 2 h per day Boolean map of Phobos true where visibility from Earth is ≥ 2 h per day
Phobos in-situ science No requirements All locations on Phobos have science potential -
Mars space environment monitoring Visibility from Sun (solar wind) 2 h per day Solar wind monitoring Boolean map of Phobos true where solar visibility ≥ 2 h per day
Data relay Visibility from Earth ≥ 6 h per day, except during solar superior conjunction 6 h is considered a basic requirement (including consideration of eclipses) for ESA planetary missions Boolean map of Phobos true where Earth to Phobos visibility ≥ 6 h/day
Visibility from Mars > 0 min
Minimum elevation angle (above horizon) = 10°
Link to surface rover for data downlink or telecommanding. As an example, we use the NASA Mars Science Laboratory landing site at Gale crater: 5.4°S, 137.8°E Boolean map of Phobos true where a rover landing site to Phobos visibility > 0 min/day (accounting for a buffer in elevation of + 10° above horizon)
Visibility from Jupiter: at least 3 h per day, during solar superior conjunction (Earth-Jupiter) 3 h per day is estimated to provide sufficient data volume for downlink of housekeeping data and uplink of telecommands from and to the JUICE spacecraft Boolean map of Phobos true where Jupiter to Phobos visibility ≥ 3 h, there is a solar superior conjunction
Global Mars positioning system Visibility from Deimos ≥ 2 h per day For positioning, laser ranging, radio tracking Boolean map of Phobos true where Deimos to Phobos visibility ≥ 2 h per day
Visibility to Phobos from Mars and Deimos simultaneously Concurrent visibility of Phobos and Deimos from the surface of Mars allows better positioning Map of Mars showing hours per day where Phobos and Deimos are concurrently visible
Power (assuming solar power system) Solar illumination should be ≥ 4.5 h per day This time duration is estimated based on previous studies (ESA Concurrent Design Facility Study Report: Phobos Sample Return 2014) Boolean map of Phobos true where visibility from Sun is ≥ 4.5 h per day
Public outreach Visibility from Mars: once per day on the dayside of Mars Public outreach ‘Phobos-webcam’ Visualisation to demonstrate outreach potential