Flexible Modem Interface is a Universal Translator for Satellites

The Flexible Modem Interface (FMI) was developed by the Department of Defense (DOD) as a hardware solution to act as a universal translator, able to understand and speak the proprietary "languages" used by commercial satellites.

“There is a lot of similarity between the growth of standards for cellular service and the commercial communications satellite market. The communications satellite industry discusses and adopts standard waveforms, but the current state of the industry doesn’t provide for roaming across networks.”

Eli Naffah, communications services project (CSP) manager at NASA’s Glenn Research Center.

With growing capabilities in the commercial satellite sector, NASA and other government agencies are transitioning to commercial satellite communications services. These services have taken great technological and capability steps forward in recent years, making them an appealing and cost-saving alternative to government-owned, near-Earth communications systems. Recent advancements in interoperability may also open up new capabilities allowing multiple space users to roam seamlessly between commercial services and networks, just like the cellphone networks of today, and creating a more robust commercial marketplace that provides users with a variety of diverse services at competitive prices.

“There is a lot of similarity between the growth of standards for cellular service and the commercial communications satellite market,” said Eli Naffah, communications services project (CSP) manager at NASA’s Glenn Research Center. “The communications satellite industry discusses and adopts standard waveforms, but the current state of the industry doesn’t provide for roaming across networks.”

Each commercial satellite provider has developed its own proprietary technology that uses specific “language,” including modulation, frequencies, etc. In other words, they can’t understand each other, which means they can’t communicate across more than one provider without using different equipment, creating the possibility of costly and dangerous delays. To limit risk, NASA and other users need flexibility to roam across various commercial systems and networks. This requires both technical solutions to interface between networks, as well as business solutions to collaborate with multiple partners without jeopardizing competitive advantages and proprietary technology.

In 2019, a version of the Flexible Modem Interface device was tested with space communication terminals for the first time at Glenn. In the test, a signal was sent from Glenn’s control center to the SCaN Testbed (pictured) aboard the International Space Station. The Testbed used a software-defined radio, which is a type of radio that leverages software instead of traditional hardware components, that was dynamically controlled using the FMI, allowing it to switch from one network to another.

The successful demonstration extends the DOD-developed capability to space, realizing the goal of creating a seamless interoperable commercial services ecosystem. A future version of this capability could increase mission autonomy by enabling a spacecraft to dynamically change its network configuration based on real-time sensing and positioning data.

NASA has been eager to engage with industry to leverage commercial investments in communications and is collaborating with industry to validate commercially provided services that can meet its mission needs and provide services to agency missions by 2030.

“The commercial satellite industry is mature for land, sea and air users, and is now looking to support spacecraft users,” said Naffah. “Most commercial satellite communications services have been designed for terrestrial uses, so supporting spacecraft moving at 17,000-plus mph poses new, fundamental challenges.”

The CSP team is in the initial planning stage for acquisition of commercial satellite communications services. Later this year, the agency will issue an announcement to establish public-private partnerships with commercial satellite communications companies to develop and demonstrate capabilities that can meet NASA’s needs.

The use of the Flexible Modem Interface and similar broadband multilingual terminals is the first step down the path to eventual creation of an interoperable communications and navigation ecosystem.

Currently, communicating with spacecraft is akin to the first telephone networks, where users would schedule a call with an operator who would then manually place it at the appointed time. Calls would have different prioritization—some being emergencies and others routine—and the human operator would decide when and how to connect them.

The situation using satellites is similar: at times, NASA and other agencies or companies need immediate access and high data rates to process sensor data, launch and maneuver a spacecraft, or conduct spacewalks. The current system can cost time, money and lives, whereas an automated system that is able to learn can increase efficiency and safety.

Current communications and processing technology easily supports interoperable capabilities. By expanding use of commercial services, NASA and other users can better integrate government and commercial capabilities, and eventual use of universal translators will facilitate more efficient switching between networks. The most pressing issues to implementation are business and operational policies as well as governance.

With full interoperability, a wide array of satellites and ground stations will be able to act as one, seamlessly transferring communications and location information within the system, which will in turn increase the safety and sustainability of all near-Earth space.

(Source: NASA. Image provided)