In the very near future, the Navy may be able to deploy scores of nanosatellites to meet its operational needs. The sea service is so interested in these tiny satellites that it set up a laboratory designed to quickly test and deploy new prototypes. Nanosatellites can be as small as a coffee mug, making them both lightweight and inexpensive. Another potential advantage is their versatility — a single launch can potentially put dozens of small spacecraft into low Earth orbit and as few as two or three launches could deploy entire constellations.
To better understand nanosatellite development and deployment, the Navy launched the Accelerated Capability for Integration and Testing of Nanosats laboratory, or ACTION, in 2016. Part of the service's Space and Naval Warfare Systems Command, or SPAWAR, ACTION's five-year mission is to match payloads made by small and large companies or government agencies with nanosatellite platforms and quickly integrate, test and launch them, explained Austin Mroczek, branch head for Space Systems and assistant program executive officer for science and technology at SPAWAR.
The laboratory operates much like a commercial software startup to speed innovation, Mroczek said. The laboratory has a small vacuum chamber and equipment to develop and test nanosatellites. But he noted that ACTION's main strength lies in its technically diverse development team and its ability to tap the expertise and test facilities of other SPAWAR departments and government agencies such as NASA.
"The idea is to build up the lab infrastructure, processes and team to be able to do this," he said.
Besides their small size, one of the major advantages of nanosats is low cost derived from using commercial components and software. This combination of off-the-shelf equipment in a small package allows for rapid testing and prototyping of spacecraft at a fraction of the cost of typical military communications or reconnaissance satellites. Mroczek said the technology demonstration spacecraft developed by ACTION average about $10 million each. Compared to a large satellite, which can cost in the hundreds of millions of dollars, nanosatellites are as costly (or inexpensive) as some missile systems, he explained.
CYBERSECURITY IN SPACE
The laboratory also tests nanosatellites’ resistance to cyberattacks. A challenge faced by satellites made of mostly commercial hardware and software is that they present a greater risk to hacking than strictly military systems. This is because opponents have greater opportunity to study and access the commercial supply chain, Mroczek said.
One of the laboratory’s goals is to build in cybersecurity from the beginning of the integration process.
"Within every step lifecycle of a satellite, from design to operations, we aim to blend cybersecurity objectives, tools and activities into other mission assurance activities," noted a recent ACTION paper.
Another risk factor is automation. Because nanosatellites can operate in large constellations, traditional ground station control would be prohibitively expensive without a large degree of software-based management and control.
"There’s more cyber surface area for us to deal with and more possible entry points. We’re looking at the whole system as we build it. Hopefully, from the beginning, from the concept phase. But also if we get hardware at the very end, we’ll be looking at various ways we can test the hardware to show it’s safe," Mroczek said.
POLAR NANOSATS
Roughly a year after its inception, ACTION already has several nanosatellite projects underway. One mature effort is the Integrated Communications Extension Capability, or ICE-Cap, that is testing the ability of nanosatellites to connect ground forces operating in the Arctic to the Mobile User Objective System, or MUOS, the Defense Department’s ultrahigh frequency, or UHF, communications satellite constellation.
The DoD’s current fleet of communications satellites are oriented to cover the equator and middle latitudes of the planet. Mroczek noted that these satellites do not provide effective coverage at latitudes above 65 to 70 degrees north. ICE-Cap is a way to get around this problem.
"A user will talk up to us from the North Pole area and then we will relay it through the UHF follow-on or the MUOS legacy payload back down to San Diego. Because we’re in low Earth orbit, we can see those [other] satellites. Whereas a user on the ground is basically looking straight through the Earth to try to see the satellite," he said.
As a technology demonstrator, ICE-Cap will determine if commercial hardware and software can fit in a nanosatellite bus (the term for a satellite’s case/frame into which hardware is installed) 10 centimeters (3.94 inches) high by 10 centimeters wide and 30 centimeters (11.8 inches) long. The entire satellite weighs 5.5 kilograms (12.12 pounds). This is a variant of a type of nano-satellite design known as a cubesat, because they are normally a 10-centimeter-by-10-centimeter cube. When it is launched, the satellite is expected to have a one-year lifespan.
ICE-Cap combines the technologies of four companies developed under a Small Business Innovation Research contract for the laboratory, Mroczek explained. One firm built the satellite’s radio, another provided cryptography software, a third built the satellite’s large retractable antenna while a fourth provided a smaller antenna. Putting these systems in one package for military missions and maturing the technology is one of ACTION’s objectives, he added.
Because ACTION uses off-the-shelf technology for ICE-Cap and its other satellite designs, the work is more evolutionary than cutting edge research, Mroczek said. The main challenge is an engineering one — being able to fit a variety of existing components into a nanosate/cubesat frame with as little modification as possible.
Another goal for ICE-Cap is to communicate with the MUOS satellites via wideband code division multiple access, or WCDMA, a new cellphone-like communications capability being installed on the MUOS constellation. However, the WCDMA capability won’t be ready for the first ICE-Cap test flight, which as of press time was scheduled for March. Mroczek hopes to fly the WCDMA capability on upcoming ICE-Cap tests. Another issue is that the WCDMA capability is still not operational on the MUOS satellites.
"They’re basically in testing mode," he explained. "They haven’t quite turned it over for operational use yet, but they’re testing with a number of radios and different configurations on the ground."
The key goal for ICE-Cap is to communicate with MUOS via a combined radio and cryptography system.
"If we build this package and demonstrate it with one satellite, then copies could be readily made and used for other satellites," Mroczek said. An additional advantage will be the proven ability to quickly swap out components using an existing nanosatellite design to make new configurations to meet changing mission needs.
ORBITAL LASER COMMUNICATIONS
Another project underway at ACTION is HALO-Net, or Hight-
bandwidth Anti-jam LPI/LPD Optical Network, which is testing a small, lightweight and low-power optical communications system consisting of a modulated retroreflector to reflect laser light beamed up from the Earth. According to SPAWAR, this creates a downlink and cross link optical communications capability that is secure, anti-jam and has a low probability of intercept/low probability of detection.
When the laser light is reflected, the satellite’s retroreflector acts like a shutter, sending the light back in a series of Morse code-like pulses. Stored satellite data is sent back down in these pulses, Mroczek explained.
"The idea is that for sensor satellites with lots of onboard data, it would be a very low-power way to get all that data down to the ground," he said.
The project’s goal is to test a secure communications capability able to work in a radio-frequency challenged environment — either due to bandwidth issues or active jamming. The retroreflector can also be used to determine a spacecraft’s precise orbit via laser ranging. This capability can be used for radar altimetry systems, he noted. In 2016, HALO-Net’s delicate optical systems underwent shock testing to ensure the equipment survives the jarring caused when the rocket upper stage housing the satellite separates from the lower stage.
