[Paper Review] The Brightness of OneWeb Satellites

Anthony Mallama|arXiv (Cornell University)|Dec 9, 2020

Space Satellite Systems and Control9 references4 citations

TL;DR

This paper measures the visual brightness of OneWeb satellites using observational data, finding a mean magnitude of 7.18 at 1,000 km, which adjusts to 7.58 at their nominal 1,200 km orbit. The study shows OneWeb satellites are fainter than initial Starlink satellites but still brighter than the newer, dimmer VisorSat design at their respective altitudes.

ABSTRACT

The mean visual magnitude of OneWeb satellites at the standard satellite distance of 1,000 km is 7.18 +/-0.03 . When this value is adjusted to the nominal 1,200 km altitude of a OneWeb satellite in orbit it corresponds to magnitude 7.58 which is an indication of the mean brightness at zenith. The OneWeb satellites are fainter than the original Starlink satellites at a common distance. Preliminary data on the new and dimmer VisorSat design for Starlink suggests that they are still brighter than OneWeb at the satellites' respective operational altitudes.

Motivation & Objective

• To quantify the visual brightness of OneWeb satellites under standard observational conditions.
• To compare the brightness of OneWeb satellites with that of initial Starlink satellites at equivalent distances.
• To assess the relative brightness of the newer VisorSat design for Starlink in comparison to OneWeb satellites at their operational altitudes.
• To provide accurate magnitude measurements for use in astronomical impact assessments and satellite tracking.
• To support mitigation strategies for satellite constellations by informing their visibility and potential interference with ground-based astronomy.

Proposed method

• Conducted visual magnitude measurements of OneWeb satellites using ground-based observations.
• Calculated the mean visual magnitude at a standard distance of 1,000 km based on observed data.
• Applied geometric and atmospheric correction factors to adjust the magnitude to the nominal 1,200 km orbital altitude.
• Used standard astrophysical magnitude scaling laws to convert brightness at 1,000 km to brightness at 1,200 km.
• Compared results with published data on Starlink satellites and the VisorSat design to assess relative brightness.
• Reported uncertainties in magnitude measurements using error propagation from observational data.

Experimental results

Research questions

• RQ1 What is the mean visual magnitude of OneWeb satellites at 1,000 km distance?
• RQ2 How does the brightness of OneWeb satellites compare to that of the initial Starlink satellite design at the same distance?
• RQ3 What is the adjusted visual magnitude of OneWeb satellites at their nominal 1,200 km orbital altitude?
• RQ4 How does the brightness of the newer VisorSat design for Starlink compare to OneWeb satellites at their respective operational altitudes?
• RQ5 To what extent do OneWeb satellites contribute to sky brightness and potential interference in ground-based astronomical observations?

Key findings

• The mean visual magnitude of OneWeb satellites at 1,000 km is 7.18 ± 0.03.
• After correction to the nominal 1,200 km orbital altitude, the mean magnitude is 7.58, representing the brightness at zenith.
• OneWeb satellites are fainter than the original Starlink satellite design at a common distance of 1,000 km.
• Preliminary data indicate that the newer VisorSat design for Starlink remains brighter than OneWeb satellites at their respective operational altitudes.
• The brightness measurements provide a quantitative basis for assessing the impact of satellite constellations on astronomical observations.
• The results support ongoing efforts to model and mitigate the effects of constellations on ground-based optical astronomy.