23 August 2017
Alta Devices’ GaAs solar cells being used by Twiggs Space Lab, Nearspace Launch and Virginia Space
At the 31st Annual AIAA/USU Conference on Small Satellites (SmallSat) in Logan, Utah (5-10 August), satellites powered by solar cells made by Alta Devices of Sunnyvale, CA, USA (a subsidiary of solar-cell specialist Hanergy Thin Film Power) were displayed by Twiggs Space Lab LLC (TSL), NearSpace Launch Inc (NSL) of Upland, IN, USA and Virginia Commercial Space Flight Authority (VCSFA), which are pioneering new models of satellites that are smaller, simpler and more affordable. Their focus is to broaden access to space for educational and commercial participants. Alta Devices says that its gallium arsenide (GaAs) solar technology was chosen due to its unique modular, lightweight and high-efficiency characteristics.
“Our goal is to inspire future generations of engineers and scientists through innovation in the field of space,” says TSL founder Bob Twiggs (a former consulting professor at Stanford University Department of Aeronautics and Astronautics, where he established the Space Systems Development Laboratory). “Alta Devices technology is easy to integrate, and its modular form factor is well suited to the standardized dimensions of CubeSats [which he co-developed in 1999].”
CubeSats (built around a 10cm x 10cm x 10cm building block) were originally developed for university students to participate in space research. The standard has now been adopted worldwide and has helped to ignite a small satellite revolution. Typically placed into low-earth orbits, they often have standardized or off-the-shelf components and have facilitated more affordable and easier access to space. CubeSats are driving new industries via the explosion of big data accessible from space.
All small satellites need solar cells to generate electrical power. Alta Devices says that, until now, no commercial solar technologies could match the improvement in cost, weight and ease of use that other components of small-satellite technology have achieved: solar cells are traditionally expensive, fragile, rigid, and difficult to encapsulate and robustly attach to spacecraft.
Alta Devices says that its solar cells overcome these challenges because they are flexible, easy to encapsulate and mount, and provide high power conversion efficiencies, providing mechanical and design flexibility for the small-satellite industry (e.g. they can be mounted to low-mass deployable structures including coiled carbon-fiber booms, flat-packed, polymer-based accordioned arrays, and even inflatable structures, allowing creative design approaches to maximizing onboard solar power).
“Innovation in solar is essential to the continued evolution of small-satellite technology,” says CEO Jian Ding. “Our thin-film GaAs solar technology uniquely meets the challenge of limited surface area; it can be wrapped around curved surfaces yet is highly robust. Our small cell size enables high packing density,” he adds.
Oregon’s first satellite Oresat using Alta Devices solar technology
“Highly integrated electronics, novel sensor technologies, and micro-propulsion systems are enabling small satellites such as CubeSats to expand into missions that traditionally have been possible only with large satellites,” notes Portland State University professor Andrew Greenberg, the faculty advisor behind Oregon’s first satellite OreSat, which is using Alta Devices’ solar cell technology.
“These new capabilities always require more electrical power, which need larger solar arrays, necessitating the use of a flexible, powerful and easy-to-integrate solar cell,” says Greenberg. “These cells can be easily handled by students, don’t require traditionally painstaking encapsulation techniques, and are surprisingly affordable. And they provide excellent power output compared to other alternatives.”
Part of the 2017 NASA CubeSat Launch Initiative, Oregon’s first satellite OreSat is a vehicle for collaborative, interdisciplinary aerospace engineering education for the state of Oregon. It will perform atmospheric science research and serve as a testbed for long-range WiFi, solar cell and satellite bus technologies, while providing STEM-based outreach to the state of Oregon and beyond.
Often weighing less than 15kg and typically placed into low-earth orbits a few hundred kilometers in altitude, CubeSats have standardized dimensions and often use commercial off-the-shelf technologies, resulting in satellites with much lower costs that are much easier to launch. CubeSats are thus in a strong position to serve the burgeoning demand for space-based assets, such as real-time remote sensing for Earth observation, precision agriculture and on-demand satellite data communications. These new opportunities have sparked a rapidly growng class of CubeSat-based businesses, resulting in rapid growth in the small satellite industry. CubeSats are beginning to create new kinds of products, services and markets that are only possible with increased access to space.