Sometimes, Smaller is Better
As far as buzz words are concerned, “picosatellite” has certainly enjoyed a prolific run in recent years— both inside and outside of the aerospace industry. Small satellites are all the rage in a budget-constricted climate that has forced its brightest minds to innovate and find creative, cost-effective alternatives to the slow-moving, prohibitively expensive processes of the past.
From early on, Aerospace has been on the front lines of this minimalist movement, leaning on the remarkable work of its picosat lab to produce breakthroughs in the design and construction of small satellites. Over the years, Aerospace’s picosat lab has grown from a tiny operation comprised of a few engineers, to a more complex network of colleagues with its own ground control network, a burgeoning list of contracts, and a heightened public profile.
Picosatellites — for those still unfamiliar with the term— are small satellites that weigh anywhere from .1 to 1 kg. They were initially designed as simplistic research vessels for university students to test, build, and explore in a real-world setting. Over time, the technology evolved and scientists and engineers have rapidly improved the capabilities of the once-austere picosats. CubeSats are a cubic form of picosat or nanosatellite that conforms to the CubeSat Standard of California Polytechnic State University at San Luis Obispo and are launched from a Poly-Picosatellite Orbital Deployer (P-POD). The P-POD is the most widely used interface for American launch vehicles and its design is responsible for the CubeSats’ cubic shape. Aerospace’s particular line of CubeSats is known as the AeroCube.
Aerospace’s David Hinkley, senior projects leader, Mechanics Research Department, has been a driving force behind the picosat lab’s upward progression since its nascent days. Without infrastructure or suppliers for materials, Hinkley and a small group of colleagues began building picosatellites in the Aerospace offices. The aim was to make cheap, small satellites that could provide some measure of technological innovation, while securing available rides on rocket launches. With its first three CubeSat designs— AeroCubes 1, 2 and 3— Aerospace took a number of small, but essential steps in manufacturing a truly dynamic and versatile satellite. “The first ones [Aerocubes] were just simpler,” said Hinkley. “Each flight had a set of goals that, when achieved, was a milestone. In retrospect, you look at the technologies and you’re not impressed. But at that period of time, each was a big deal.”
AeroCube 1 was battery-powered and designed to last for a brief two weeks on orbit. Unfortunately, it was destroyed in a 2006 launch failure and never flew. AeroCube 2 introduced solar cells and photographic capabilities into the model, but failed almost immediately after its 2007 launch — though it was able to photograph another CubeSat during its brief period of activity in space. AeroCube 3 boasted a redesigned power system, an upper-stage tether, photographic capabilities and a host of new sensors to boot. It was successfully launched in 2009 and completed a number of experiments while on orbit. This pioneering trio of AeroCubes slowly built upon the innovations of its predecessors while ironing out technical flaws and efficiency issues. By the time AeroCube 3 successfully completed its space mission, the Aerospace picosat lab was preparing to fly AeroCube 4— which would prove to be its breakthrough development.
AeroCube 4— which is technically a constellation of three AeroCube 4s; AeroCube 4a, AeroCube 4b and AeroCube 4c— was launched in September of 2012 and will remain on orbit for a number of years. The AeroCube 4s all have three-axis attitude control with 1 degree pointing capability, deployable solar panels that also act as variable drag devices, and a custom transceiver. The AeroCube 4c maintains a launch vehicle environment data logger, which measures launch vibration in-situ, and contains a deorbit drag device that will be deployed at the end of its primary mission. Hinkley views AeroCube 4 as a breakthrough development, an archetype for all future AeroCubes and a proven design that has helped to generate demand for the next wave of AeroCubes.
Catherine Venturini, project engineer, Space and Ground, Development Planning and Architectures, works consistently with the picosat lab as a liaison between the scientists and SMCXR— the developmental planning directorate. Essentially, Venturini tries to keep the creatively minded picosat lab synched up with the more practically constrained vision of the customer. It can be a complex logistical process, but Venturini understands that in order for the AeroCube program to flourish, there must be a healthy blend of pragmatism and innovation. “Our goal is to push the envelope,” says Venturini. “And really try some innovative and exciting things where others in the community might not be willing to take that risk. The CubeSats might be a viable option for the military in the future, especially with tight budgets, and the work the picosat lab is doing is paving the way to show us that these CubeSats can actually do real missions and provide military utility.”
AeroCubes 5 and 6 and further models in development map out an ambitious agenda for the program’s future. Each of these CubeSats are in various phases of production and pre-production and they are the primary focus of the picosat lab. This new wave of CubeSats will tackle a host of different mission objectives and technological hurdles while incorporating many of the techniques and designs used to develop the previous models. With Aerocube 4, the picosat lab came of age and developed a fully mature realization of its initial goals. Now, the aim is to take things to new heights of innovation and functionality.
AeroCube 5 slightly modifies and upgrades the basic structural components of the AeroCube 4. Its primary mission will be to test its pointing and tracking capabilities while on orbit. Aerocube 6 will represent another major leap forward for the program as it incorporates a host of technical upgrades and a groundbreaking suite of micro dosimeters for measuring radiation in the space environment. Much like the redesigns that auto manufacturers introduce for specific car lines, AeroCube 6 represents the program’s first “model year” redesign since 2002.
“Since 2002 we haven’t changed our form factor and now we’re changing it and we’re fixing a whole bunch of stuff we’ve found in the past has been difficult to work with,” said Hinkley. In addition, the micro dosimeter will emphasize the functionality and versatility of miniaturized instruments as both an auxiliary and primary observational tool.
The most ambitious AeroCube to date, a NASA Edison selection, is set to introduce a breathtaking list of new features including a high-speed laser communications system, a low-cost automotive radar, and optical flow sensors. The laser communication system will exponentially increase the communicative capacity of the traditional CubeSat and add a truly innovative level of functionality to the typically minimal satellites.
Another Aerocube, a NASA invest selection, will demonstrate a cooled infrared avalanche photo diode that will be capable of conducting measurements within several important remote sensing wavelength detection bands from 0.9 to 4.0 microns while on orbit. The data it collects will be used in future remote sensing missions to develop a sharper understanding of the space environment and the Earth.
As a program, it is not simply the individual achievements of the AeroCubes that are so impressive, but the overall benefit of the accrued knowledge and technology that they create. After this new fleet of AeroCubes flies, the future models will undoubtedly incorporate many of the earlier technologies into a CubeSat that will be capable of functioning at an incredibly complex level. Perhaps someday in the not- so-distant future, the skyway will be populated with constellations of buzzing, humming CubeSats in addition to the monolithic satellites of today.