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Monitoring LEO Assets with a MEO Relay Network

By | August 23, 2017
      The architecture of Audacy's three satellite network. Photo: Audacy.

      The architecture of Audacy’s three satellite network. Photo: Audacy.

      The Center for the Advancement of Science in Space (CASIS) recently awarded Audacy a grant that will allow the two-year-old startup to demonstrate the Software-Defined Radio (SDR) that will power its space-based communications network. According to James Spicer, Audacy co-founder and chief engineer, the company will use a combination of relay satellites, ground stations and client-side SDRs to significantly cut the costs and wait time of transmitting data from orbit.

      In an interview with Via Satellite, Spicer compared the network’s architecture to NASA’s Tracking and Data Relay Satellite System (TDRSS), which offers a continuous telecommunications link for tracking, telemetry, command and high-bandwidth data return services. NASA uses TDRSS to communicate with assets like the International Space Station (ISS), but also for any relevant launches or missions. According to Spicer, the idea behind Audacy emerged during fellow co-founder Ralph Ewig’s tenure as a mission operator for SpaceX, when the company first flew the Dragon capsule to the ISS. During those missions, TDRSS enabled continuous access to the spacecraft from launch all the way through to its ISS rendezvous. The difference between launching with TDRSS support and without it during non-NASA missions was stark — once the spacecraft crossed the horizon, you were essentially blind to what it was doing, Spicer said. Consequently, the Audacy team has developed their own version of the TDRSS to provide similar real-time communications services to commercial operators at a fraction of the cost.

      Initially, the Audacy network will comprise three relay satellites in Medium Earth Orbit (MEO) connected to three ground stations in Singapore, Luxembourg, and the San Francisco Bay Area in California.

      James Spicer, chief engineer and co-founder of Audacy. Photo: Audacy.

      James Spicer, chief engineer and co-founder of Audacy. Photo: Audacy.

      “Our main value proposition is that we provide 100 percent line of sight coverage wherever you are in LEO,” Spicer said. “For that, the lowest orbit at which you can provide 100 percent line of sight is in MEO at roughly 14,000km. At that point, between our three relays … we can serve even the largest constellations.”

      As the Federal Communications Commission (FCC) parses through a score of varying LEO constellation proposals, Spicer sees opportunity in providing these companies with an “always-on, 100 percent coverage” means of monitoring their assets — some of which number in the thousands. “Most of these companies … don’t want us to provide high data rate payload. They just want to use us as a monitoring system, so that if a satellite seems to be acting odd they can get that line of sight within seconds and receive telemetry,” Spicer said.

      The network’s real-time capability can also add value to verticals such as Earth observation. The EO industry is currently restrained by the extended wait time to task a satellite and download the data once it passes over a ground station, particularly those companies that only operate a small handful of satellites. “[Audacy] can shorten that whole cycle down to a few seconds, enabling the imagery company to deliver that information to their customer in an order of magnitude reduced time frame,” Spicer said.

      Additionally, like TDRSS, Spicer said the Audacy network can be used to track orbital and suborbital launch vehicles from its MEO birds’ eye view. This is particularly ideal for human spaceflight missions, he noted, where maintaining a continuous link with the spacecraft is a critical safety measure.

      To allay any cybersecurity concerns, Spicer said Audacy will layer its data streams with a baseline AES-256 encryption on top of any encryption the customer already uses. He also pointed out that the network doesn’t look at the data, minimizing the opportunity for breaches much like a cellphone network. “They don’t read the data, they just pass it from point-to-point. We’re doing a similar thing in space,” he said. “We don’t care what the ones and zeroes are — it could be pictures, command information, telemetry, video — we don’t care. We just pass it from operator out to the satellite or vice versa.”

      As proof of concept, Audacy will put the CASIS grant toward a demonstration mission of its customer terminal using the ISS’ NanoRacks External Payload Platform late next year. The company also recently announced a partnership with Clyde Space for a separate demonstration mission next year, for which Clyde Space will manufacture a CubeSat bus carrying an Audacy high-speed K-band SDR and antenna.

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