page_title: CubeSat
section_title: Power
hierarchical_section_title: CubeSat / Design / Power
caption_attribution_description: English: Winglet Pumpkin Solar Pannels for CubeSat to increase usable surface area.
context_page_description: A CubeSat is a type of miniaturized satellite for space research that is made up of multiples of 10 cm × 10 cm × 10 cm cubic units. CubeSats have a mass of no more than 1.33 kilograms per unit, and often use commercial off-the-shelf components for their electronics and structure. CubeSats are commonly put in orbit by deployers on the International Space Station, or launched as secondary payloads on a launch vehicle. More than 1200 CubeSats have been launched as of January 2020. More than 1100 have been successfully deployed in orbit and more than 80 have been destroyed in launch failures.
  In 1999, California Polytechnic State University and Stanford University developed the CubeSat specifications to promote and develop the skills necessary for the design, manufacture, and testing of small satellites intended for low Earth orbit that perform a number of scientific research functions and explore new space technologies. Academia accounted for the majority of CubeSat launches until 2013, when more than half of launches were for non-academic purposes, and by 2014 most newly deployed CubeSats were for commercial or amateur projects.
context_section_description: CubeSats use solar cells to convert solar light to electricity that is then stored in rechargeable lithium-ion batteries that provide power during eclipse as well as during peak load times. These satellites have a limited surface area on their external walls for solar cells assembly, and has to be effectively shared with other parts, such as antennas, optical sensors, camera lens, propulsion systems, and access ports. Lithium-ion batteries feature high energy-to-mass ratios, making them well suited to use on mass-restricted spacecraft. Battery charging and discharging is typically handled by a dedicated electrical power system (EPS). Batteries sometimes feature heaters to prevent the battery from reaching dangerously low temperatures which might cause battery and mission failure.
  The rate at which the batteries decay depends on the number of cycles for which they are charged and discharged, as well as the depth of each discharge: the greater the average depth of discharge, the faster a battery degrades. For LEO missions, the number of cycles of discharge can be expected to be on the order of several hundred.
  If it happens that the spacecraft is launched into a sun-synchronous orbit, the amount of eclipse time will dwindle, allowing fewer interruptions of continuous solar irradiation for the PV cells and thus reducing the battery capacity requirements. In LEO sun-synchronous orbits, however, the spacecraft will not always experience sunlight, and so depending on the time of year, the spacecraft may need to gain altitude to again be in the line of sight to the sun. Due to size and weight constraints, common CubeSats flying in LEO with body-mounted solar panels have generated less than 10 W. Missions with higher power requirements can make use of attitude control to ensure the solar panels remain in their most effective orientation toward the Sun, and further power needs can be met through the addition and orientation of deployed solar arrays. Recent innovations include additional spring-loaded solar arrays that deploy as soon as the satellite is released, as well as arrays that feature thermal knife mechanisms that would deploy the panels when commanded. CubeSats may not be powered between launch and deployment, and must feature a remove-before-flight pin which cuts all power to prevent operation during loading into the P-POD. Additionally, a deployment switch is actuated while the craft is loaded into a P-POD, cutting power to the spacecraft and is deactivated after exiting the P-POD.
caption: Winglet solar panels increase surface area for power generation
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