A quarter century of smallsat progress
by Jeff Foust
|“The early ’60s was a fabulous time” for smallsats, said Janson.|
However, as launch vehicles grew bigger, so did satellites, and the number of smallsats dropped off precipitously. For the 1970s and most of the 1980s, Janson noted, the smallsat realm was dominated by a class of Soviet microsatellites called Strela used for store-and-forward communications. (He used a common definition of microsatellite to refer to spacecraft weighing between 10 and 100 kilograms; “nanosatellite” refers to satellites weighing between 1 and 10 kilograms and “picosatellite” for satellites weighing between 0.1 and 1 kilograms.) A quarter-century ago, in 1986, 25 smallsats were launched: all but one (an amateur radio satellite) were Strela microsats.
Around that time, though, what Janson called the “small satellite doldrums” started to come to an end, thanks to two events. The first was the inception of the Utah State small satellite conference in 1987, which brought together a largely academic community to discuss smallsat development efforts. That conference has grown over the years to become the leading event in the global smallsat community, attracting hundreds of people from the commercial, government, and academic sectors for four days of presentations and networking. In recent years the conference grew so large it had to be moved from the campus’s conference center to the more spacious student center.
The other event that year that helped stimulate the smallsat field was a conference titled “Meeting on Lightweight Satellite Systems”, organized by the Defense Advanced Research Projects Agency (DARPA), which was pursuing a program called “Lightsat” to examine the potential applications of smallsats. That effort led to several military smallsats, he said, as well as development of the Pegasus small launch vehicle to launch them.
“Twenty-five years ago the small satellite world was kind of stagnant,” Janson said. Those two events, and the projects that sprang from them over the years, revitalized and diversified the field. Today, he said, “small satellite missions are more diverse, and launch rates are up.”
To demonstrate the diversity of the smallsat industry, Janson said that in 2010 there were 26 smallsats launched. While only one more than in 1986, the field is no longer dominated by a single class of satellites, as was the case with the Strela microsats a quarter century ago. Only 4 of the 26 smallsats launched in 2010 were classified as microsats, with 17 being smaller nanosats and the other 5 the yet-smaller picosats. The satellites launched in 2010 also served a wider range of applications than just communications, including technology development, scientific research, and even tracking of vessels in the ocean. Two of the picosatellites Janson included were camera platforms released from a Japanese solar sail experiment to monitor the sail’s deployment.
|“The CubeSat was like the PC of this industry, because it took the knowledge that had been concentrated in a handful of organizations and spread it out globally to all kinds of organizations,” said Bille.|
That diversity of spacecraft and missions has been enabled by a number of technological advancements that make it possible to put more capable payloads onto smaller satellites. Among the key technical advances Janson cited are improvements in microprocessors, solar cells, batteries, and microelectromechanical systems (MEMS) that give smallsats capabilities previously possible only with larger spacecraft. A less obvious innovation that has helped small satellite development has been the Internet, he said, allowing for improved collaboration on development efforts and even easier control of spacecraft through Internet-connected ground stations.
Another major innovation that has supported the growth of the smallsat field has been the CubeSat standard. Developed about a decade ago at California Polytechnic State University (Cal Poly) and Stanford University, a CubeSat is 10 centimeters on a side and weighs about 1 kilogram. CubeSats initially found interest among universities in part as a means to give students hand-on engineering experience with spacecraft for a tiny fraction of the cost of a larger spacecraft, particularly when coupled with secondary, or rideshare, payload launch opportunities.
The CubeSat form factor in recent years has attracted attention outside of academia, as both government agencies and companies have turned it into a de facto building block for nanosats and microsats. While a single CubeSat has limited utility, many organizations are putting multiple CubeSat units together into a single spacecraft. One common option is the “3U” CubeSat, where three CubeSats are put together into a spacecraft 10 by 10 by 30 centimeters long. Janson noted that 7 of the 17 nanosats launched in 2010 were 3U CubeSats, while 4 others were 1.5U CubeSats, half the size of a 3U satellite. And there are plans for 6U, 12U, and larger smallsats based on the CubeSat standard.
“The CubeSat was like the PC of this industry, because it took the knowledge that had been concentrated in a handful of organizations and spread it out globally to all kinds of organizations,” said Matt Bille of Booz Allen Hamilton in a separate presentation at the smallsat conference. “Microsatellites have passed their tipping point. They’re not a niche, they’re a global technology.”
One of the more unlikely organizations to express an interest in smallsats in recent years has been the National Reconnaissance Office (NRO). The NRO has typically been associated with so-called “exquisite” imagery and other satellite systems that are very big and capable, but also very expensive. In recent years, though, the NRO has funded some smallsat technology development work, using the CubeSat standard, through a program called Colony.
“Colony allows designers to focus on developing experiments and demonstrating concepts of operation,” said Bruce Carlson, director of the NRO, in a keynote address at the conference. “The NRO will continue to use small satellites to develop and demonstrate innovative technologies that solve our users’ most challenging problems, and to support university and industry outreach.”
For now the NRO’s use of smallsats is limited to technology development, but Carlson hinted that the agency was studying ways to use them in more operational roles, perhaps by flying clusters of smallsats in formation to create large synthetic apertures for signals intelligence or radar imaging. “I’d like to be able to talk to you about the things we’re thinking about, but I can’t do that here,” he said.
This growing interest in smallsats doesn’t mean that the future is entirely rosy for such spacecraft. Smallsats still face a number of issues blocking their greater adoption. The biggest challenge, most acknowledge, is the long-running concern about finding frequent, affordable access to space, a problem being addressed today through a combination of rideshare opportunities on larger launch vehicles and the development of smaller vehicles intended exclusively to serve the smallsat market (see “New opportunities for smallsat launches”, The Space Review, August 22, 2011).
|“The real success in small satellite technology is in Earth imaging,” King said.|
Another major challenge for the smallsat field is finding sustainable market niches. To date smallsats have found limited success, at best, in two commercial markets: communications and remote sensing, according to Jan King, who has worked on small satellites for over 40 years. In communications, ORBCOMM found some success with its constellation of satellites providing data services, and is in the midst of developing a replacement system for launch in the next few years. A related market, ship tracking, is also showing potential, he said. Remote sensing has been a bigger success, with a number of small satellites developed for government and commercial customers.
“The real success in small satellite technology is in Earth imaging,” he said in his conference presentation. “I would say we had marginal success in telecommunications and pretty darn good success in remote sensing. In the rest of the area, I would say we have not produced to date.”
Smallsat developers also face some technical and policy issues that could slow down adoption of smallsats. At a side meeting of last year’s smallsat conference at Utah State, some developers expressed concern when a representative of the commercial remote sensing office at the National Oceanic and Atmospheric Administration (NOAA) informed attendees that even CubeSats with low-resolution cameras needed a remote sensing license from that office if they planned on taking any images of the Earth.
In a paper accompanying his presentation, King identified another issue: access to the radio spectrum to allow for communications. Many smallsats have relied on the use of free amateur frequencies for communications, but that approach isn’t viable for commercial ventures. “Small satellite proponents have yet to deal squarely with this issue but, as the goal here is to discuss commercial missions, this issue becomes paramount and expensive,” he wrote. “Commercial users, nowadays, should even be prepared to have to pay for the use of the radio spectrum once a particular commercial application has shown itself to be commercially viable,” a process that can be time consuming and expensive, he adds.
Heightened concern about orbital debris also raises an obstacle for smallsats, many of which have either limited propulsion systems or none at all. Orbital debris guidelines by the Inter-Agency Space Debris Coordination Committee (IADC) recommend that satellites in low Earth orbits be able to deorbit no more than 25 years after the end of their missions. Many smallsats, though, are in orbits that will last more than 25 years, with no means of lowering orbits on their own, noted Dan Oltrogge of Analytical Graphics, Inc., in a conference presentation. “We’re not using best practices,” he said. “It reflects poorly on CubeSats if we don’t, and it’s something we need to be concerned about.”
In the last few years some smallsat developers have sought to find solutions to the orbital debris problem by proposing innovative means to deorbit satellites with expensive, heavy propulsion systems. In one example, Andrews Space and Technology presented a concept at the conference for a deorbit system that could fit into a 1U CubeSat volume and potentially also have the means of safely returning spacecraft all the way back to the ground.
|“I think that the small space community is actually in a very good spot now,” said Klupar.|
Some also worry that the CubeSat standard could, over time, fracture into several incompatible forms, particularly as developers try to accommodate their spacecraft on a growing array of launch vehicles. “That’s not happening a lot yet, but it’s something that I am concerned about,” said Jordi Puig-Sauri of Cal Poly, one of the original developers of the CubeSat standard. “We need to move the standard forward. We can’t just leave it as it is and let things fracture.”
Even with those various technical, policy, and market concerns, the mood in the industry, at least at last month’s conference, was one of optimism for the future of smallsats. While no one believes that smallsats will completely overtake the market—there are many missions that require the physical size, power, and other attributes found only on large spacecraft—there is plenty of opportunity for continued growth of smallsat systems in a variety of applications.
“I think that the small space community is actually in a very good spot now,” said Pete Klupar, director of engineering at NASA Ames Research Center, which hosts much of NASA’s interest in smallsats. “I think we’re being very successful in our most recent missions and I think the future is also very bright.”
“We’re not saying that microsats can do everything,” Bille said. “When we say large versus small is over, we’re not saying that microsats won. We’re saying that microsats are established in everybody’s trade space. We’ve heard the age of microspacecraft predicted a few times before, but it’s on solid ground now. We’ve got the applications, the technology, and the mission experience to say that microsatellites have a secure presence and a brilliant future.”