2.1 Orbital Debris
SmallSat use is growing quickly: in 2019 alone, almost 250 satellites
with mass under 200 kg were launched, more than 5 times the number of
SmallSats launched during 2012 (Bryce Space, 2020). More than 1,100
CubeSats were launched during 2012–2019. While not all remain in orbit,
they add to the existing 900,000 pieces of orbital debris larger than a
marble, with 34,000 larger than a softball (i.e., about the size of a 1U
CubeSat), tracked by government agencies (ESA, 2020). As the number of
SmallSats in orbit increases, the concern is not just the growing number
of satellites occupying orbital space, but also that (depending on their
altitude) they will likely stay aloft as debris beyond their useful
life, presenting a collision hazard for human spaceflight and for other
satellites and robotic missions (Berger et al., 2020). The growing
number of small objects in orbit can also threaten the integrity of
ground-based astronomical observations (Witze, 2019).
Despite the scientific, economic, and other benefits of SmallSat launch
and use, these threats from the growing number of SmallSat
constellations represent a global problem. Going forward, assuming that
not all SmallSats can maneuver, international policies and restrictions
will be imperative to ensure that all SmallSats: (1) can be tracked,
either actively or passively; (2) cause no radio frequency interference
(see next section); and (3) abide by stricter guidelines to de-orbit
after they stop functioning. For example, the United Nations
Committee on the Peaceful Uses of Outer Space (UNCOPUOS, 2019; see Annex
II, Guideline B.8) has established policies for tracking and de-orbiting
of small satellites. However, international guidelines have not been
codified into law, and compliance rates remain low.