Swarm Communications and CubeSats: An Update on the Advantages and Challenges of Nanosatellites

Light, inexpensive and easy to launch and replace, nanosatellites are tiny space vehicles that are becoming ever more mainstream, presenting novel advancements and unique challenges.

Nanosatellites, or cube satellites, are tiny orbiting space vehicles, characterized not only by their diminutive size and weight but also by the fact that they are often built of cheap, off-the-shelf commercial grade components. Compared to typical satellites, which can dwarf cars and weigh tons, nano or microsatellites can be easier to manufacture—so much so that many of the first nanosatellites were originally used as educational tools.

NanoRacks CubeSats. Image used courtesy of NASA

Here's a look at the basics of nanosatellites, including examples of how they're used in the aerospace industry today.

The Benefits of Tiny Satellites

The basic unit size (one Unit, or 1U) of a typical nanosatellite is 10 centimeters in length, width, and height for a total volume of 1 liter. The approximate weight of such a device is 1.33 kg. They are most commonly deployed in configurations of 1U, 1.5U, 2U or 3U as depicted below.

Infographic excerpt used courtesy of Karl Tate, Infographics Artist, via Space.com

Space and weight restrictions are among the hallmark challenges that aerospace designers come up against. Though nanosatellites theoretically have much lower demands on the initial fuel costs, etc., a single CubeSat launch will still cost thousands of dollars. Because of this, nanosatellites often "hitch a ride" when larger space vehicles are launched into space, providing a low-cost opportunity for nanosats to make it into orbit. 

According to a nanosatellite database created by nanosatellite systems engineer Erik Kulu, over 2,000 satellites of these types have been launched as of August 2018. Part of this explosion of satellite launches is that there is now a strong private sector in the business of space, starting largely with CubeSats.

Because of the use of non-space-hardened components, nanosats often have limited lifespans. This may not, however, always be a disadvantage as these tiny, cheap vehicles are often used to test new types of space hardware concepts, such as novel antenna and communication modalities. Designing for longevity in space is a complex issue, as the Voyager project has been demonstrating for decades.

Nanosatellites for Improving Communication 

NASA and the US Air Force has awarded Simone D’Amico, an assistant professor at Stanford University grants to develop autonomous guidance navigation for “swarms” of nanosatellites.

Limited by the speed of radio waves, there is an unavoidable lag time in communications between control stations on Earth and CubeSats in space. The distances between members of the “swarm” will be small, so finer control will be affected as most decisions can be made locally with only occasional reference to Earth stations for command changes and reporting.

Aside from the communication benefits, distributing capabilities across many tiny satellites is in many ways a better bet than putting all your “eggs” in a multimillion-dollar basket—especially if you’re the military. Because of their tiny profiles, CubeSats are harder to track than their larger brethren and each one may be considered more disposable than a single large satellite.

The concept of swarm devices is not new to the military. In fact, it's worth wondering whether swarms of CubeSats inspired the use of swarm drones here on earth or whether it was the other way around. DARPA's Gremlins program involves unmanned air systems (UASs) that are released from larger aircraft. These smaller drone crafts are designed to cooperate as a network to accomplish objectives such as reconnaissance and defense saturation.

The analogy to CubeSats is obvious. Networking makes the loss of one drone unimportant, as others in the network can assume its function, just as in the example of CubeSats. 

A rendering of the Kestrel Eye microsatellite. Image used courtesy of the US Army

In June, Lt. General James Dickinson spoke at the US Army's 2018 Space and the Network Symposium about the role of small satellites in military operations, present and future. "We envision a potential constellation of microsatellites providing integrated situational awareness and mission command capability down to the soldier and squad level," Dickinson said at the event.

Individual nanosatellites are proving important, as well. August saw the launch of the Kestrel Eye, an electro-optical nanosatellite designed to improve planetside communications such as synchronized team movements. This may be part of a trend where even general-purpose satellites may be scaling down in future years.

Swarm Nanosatellites: Advantages and Regulation Headaches

It isn't just the military that's looking to take advantage of nanosatellites.
Swarm Technologies' mission is spelled out by its name, as its hope is to launch swarms of satellites for two main purposes. The first is to provide no-cost internet access to areas of the world that are unserved by any other means.

The second purpose is to serve as a conduit for the internet of things (IoT). As the company points out, it is expected that by 2020, there will be over 30 billion IoT devices. This will create an enormous demand for internet connectivity for these devices, many of which are located in remote, inaccessible areas. The company hopes to deploy a “constellation” of 100 satellites to provide low-cost, worldwide internet connectivity.

SpaceBees are even smaller than CubeSats. Image used courtesy of Swarm Technologies

 

Swarm Technologies also has, however, the dubious distinction of being the first company cited for a violation related to the pollution of the spaceways. The company planned on launching four tiny SpaceBEE’s, which are even smaller than CubeSats. The problem was that the vehicles were thought to be too small to be effectively tracked by the US Space Surveillance Network, a DOD entity charged with following all orbiting satellites.  

Thinking that some important modifications would eliminate the problem, the units were deployed from an Indian LEO (low Earth orbit) rocket along with many other satellites of various sizes.

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Do you have experience with nanosatellite design? Share your thoughts in the comments below.