Office of the Secretary of Defense: 027_Satellite_Flaring_Paper

All-domain Anomaly Resolution Office (AARO)
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After the satellites have separated and traversed a specific distance from one another, they enter
the second phase known as orbital raise. During this phase, the satellites navigate from their initial
low orbit to their final orbital altitude, which is nominally 550km for the current generation of
Starlink satellites. During the ascent, drag arises due to skin friction along the satellites’ surfaces.
To reduce the effects of drag, the satellites orient into a streamlined profile by shifting their solar
panels parallel to the Earth, see Figure 6(a). It’s this phase that creates the satellite trains, as light
reflects off each solar panel of the ascending satellites. In the third phase, the satellites reach their
final position called their operational altitude. Here the satellites reorient to their operational
configuration with each satellite bus and its mirrored panels facing the ground and their solar
panels extended above to maximize capture of sunlight.
It is this operational orientation of the satellites, Figure 6(b), that leads to flares or glint when the
geometry of the Sun, satellite, and observer are properly aligned. These flares are orders of
magnitude brighter than starlight and appear in a small section of sky called the “flare window.” It
is possible to have simultaneous flares from multiple satellites moving in differing orbits. To an
observer on the ground, simultaneous flares might appear to be spinning lights, small glowing orbs
that disappear and reappear, or tracing out geometric shapes such as triangles, or other odd
morphologies that move quickly across this small section of the sky. To demonstrate how bright
satellites can appear from the ground, AARO personnel photographed Starlink flaring on March
11, 2024, near Sidney, Nebraska (NE). These photographs are shown in Figure 7 and Figure 8.
These images were taken using a 10 second exposure time which makes them appear as short
streaks in the images versus point sources.
Figure 6: (a) rendering of Starlink satellite in its configuration during orbital raise; and (b)
rendering of Starlink satellite in its final operational orbit. Adapted from [8].
Estimating When and Where to See Starlink Flares
The location and appearance of these flares is a function of the satellite’s location, the Sun’s
position, the time, the date, and the observer’s latitude. Many in the astronomy community are
concerned about the light pollution created by satellite flares from these mega-constellations and
their negative impact on scientific studies as well as the risks posed to the access and safety of
space [9] [10] [11] [12]. This has driven some groups to create software models that predict the
brightness of satellites based on their astronomical locations. Despite this, few publications exist027Page determined to be Unclassified
Reviewed by Chief of Staff, AARO
IAW FY24 NDAA, Section 1841(a)(1)(C)
Date: 2/14/2025