Cubesats to pocketqubes

Abstract

In the last two
decades, CubeSats have changed the perception of satellite missions aided by
standardization and usage of commercial-off-the-shelf components. CubeSats have
also proven the feasibility of low cost and short development time space
missions. The PocketQube with a form factor of 5x5x5 cm has been proposed as
the next class of spacecraft to benefit from miniaturization. This paper
presents a comparison between the two standards and analyzes the impact of
miniaturization on spacecraft design and performance. At satellite level, the
reduction of volume has a tremendous impact on the available power and makes
energy management and efficiency critical. Thermal issues become important due
to the reduced thermal capacitance, leading to higher thermal swings and larger
temperature variations than CubeSats. The other important impact on the
satellite bus is the reduced communication capacity due to several reasons: the
reduced volume limits the available antenna size and also the available power
available. At mission level, other factors have a substantial impact: de-orbit
time becomes a major criterion in the launch selection process to comply with
orbital debris policy. The volume reduction also affects the radar
cross-section making the satellite more difficult to detected for space
surveillance radars. Despite these challenges, PocketQubes are an attractive
standard currently for academic and research groups as a way to reduce the cost
and development time considerably. Payload capabilities also can force a
paradigm shift from single to multiple satellites more than it was already
happening with CubeSats: PocketQubes could better fit certain niches where high
spatial or temporal resolutions are required instead of full resolution.
Distributed space weather monitoring could be an interesting application where
specific phenomena could benefit from multi-point sensing. All these strong
points can also be coupled with a bigger satellite to complement and enhance
its capabilities. Delfi-PQ is a PocketQube currently being developed at TU
Delft using an agile approach, contrary to the typical V-model design. Shorter
life cycle development benefits students, allowing them to get more involved in
every iteration. The reduction in cost and development cycle increases the
launch frequency. Incremental engineering becomes fundamental, also providing
benefits on the reliability side because flight experience becomes more frequent
than when following traditional development strategies. End-to-end development
motivates students and provides them with a better insight into real-world
engineering opportunities and training experiences. With this strategy,
technical and educational objectives are more aligned, and the integration of
such a project in the curriculum is facilitated.