SCOOB: fit an experiment into a power budget

NTU’s Student Satellite Series gives students experience with the connected tasks of building and operating a small satellite. SCOOB-I launched on June 30, 2022 aboard PSLV-C53, while SCOOB-II followed in July 2023. Their archive cards use those same names. The sequence lets successive teams apply earlier experience while changing the payload and the design needed to support it.

SCOOB-I’s planned measurements included solar observations across multiple ultraviolet, visible and infrared bands. Measuring several bands can reveal differences that would disappear in a single total-brightness value. Two sources with the same summed signal can distribute their energy differently across the spectrum. A mission therefore needs an instrument suited to the scientific question, together with calibration — open definition that makes its band measurements interpretable.

SCOOB-II was designed to support a demanding electronics payload with deployable panels and improved pointing toward the Sun. Power describes the rate at which electrical energy is generated or used. Stored energy describes how much is available over time. A larger battery can extend an operating interval, but it does not automatically increase the rate at which solar panels recharge it.

For a fictional example, an eight-watt instrument running for half an hour consumes four watt-hours. A spacecraft must also supply its computer, radio and control system, so that four watt-hours is only the instrument’s share. Real operations allow for conversion losses, battery limits and periods in shadow. These constraints can require scheduling an experiment rather than operating everything continuously.

Budget energy across the mission

A solar panel facing the Sun generally receives more direct illumination than the same panel at an oblique angle, subject to its design and surrounding shadows. Pointing requirements can compete: a camera may need to look at Earth while panels would prefer another orientation. Deployable hardware adds useful area but also needs to unfold correctly and remain compatible with the rest of the vehicle.

Students encounter these trades as a connected engineering problem. A more capable payload may demand changes in power generation, heat rejection, communications and operating procedures. An attractive individual component does not establish a workable mission until those interfaces fit together. SCOOB’s educational contribution is therefore the practice of reasoning across a whole spacecraft, then using tests and flight observations to check whether its design decisions worked.