FEATURE

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Technologists Demonstrate End-to-End Internet-Based Communication System

Goddard technologists, who have long championed the use of basic computer networking protocols to communicate in space, have demonstrated a system using flight-compatible hardware in a space-flight environment.

In a series of recent demonstrations that participants described as moving “the state-of-the-art one step forward,” a team of Goddard technologists debuted radiation-hardened hardware critical for operating an onboard Ethernet network, said Jane Marquart, a technologist with Goddard’s Software Branch who participated in the demonstrations. In particular, the team demonstrated Goddard-developed Ethernet cards, which allow onboard computers to talk with a network, and switches, which transfer packets of data between computers onboard a spacecraft.

Goddard technologists developed and demonstrated radiation hardened hardware critical for operating an onboard ethernet network. From Left to right: Mike Lin, Greg Menke (Raytheon), Jane Marquart, and Freeman Johnson.

Goddard technologists, who have long championed the use of basic computer networking protocols to communicate in space, have demonstrated a system using flight-compatible hardware in a space-flight environment.

In a series of recent demonstrations that participants described asmoving “the state-of-the-art one step forward,” a team of Goddard technologists debuted radiation-hardened hardware critical for operating an onboard Ethernet network, said Jane Marquart, a technologist with Goddard’s Software Branch who participated in the demonstrations. In particular, the team demonstrated Goddard-developed Ethernet cards, which allow onboard computers to talk with a network, and switches, which transfer packets of data between computers onboard a spacecraft.

“What’s significant about our demonstration is the level of fidelity in the testbed. We used flight-compatible hardware in a flight development environment to prove the viability of an end-to-end Internet Protocol system — from a flight operations center on the ground to a receiving payload on a spacecraft — all communicating by way of Internet technologies,” Marquart said.

In addition to the Ethernet cards and switches, developed by Goddard’s Flight Data Systems and Radiation Effects Branch, Cisco Space Systems developed and tested a prototype for a radiation-hardened router. The company performed the work under a Space Act Agreement with the Goddard Space Flight Center. Routers allow messages to be sent between two or more networks.

“Now a mission has the hardware infrastructure for a fully compatible Internet Protocol network that will satisfy radiation requirements for any type of mission,” Marquart said. “There are no restrictions where this hardware can go.”

The demonstrations took place during the summer and represented the next step in NASA’s continuing efforts to extend Internet Protocol (IP) into space — a development that holds the promise of reducing mission costs as well as the time it takes to develop them.

Marquart said her team’s efforts were similar to what Goddard technologists demonstrated in 2003 when they flew the Communication and Navigation Demonstration on Shuttle (CANDOS) experiment aboard Space Shuttle Columbia. The equipment that flew on the Shuttle, however, was not space qualified to the degree necessary for a mission that lasted longer than a Space Shuttle mission.

In addition to demonstrating the radiation-hardened hardware, Marquart said the team made sure that they wouldn’t encounter hardware or software problems integrating standard commercial IP applications, including Voice-over IP and Mobile IP. In addition, they addressed security issues and overcame timing issues within the onboard network itself. Any one of these could have jeopardized their efforts to create a flight-ready, end-to-end system. “About the only thing we didn't tackle was the operations issues, which can be very mission dependent,” she said.

Although CANDOS demonstrated Mobile IP, it didn’t do so with flight-ready hardware. With mobile IP, a spacecraft equipped with a router or any other device with an IP address would be able to communicate with an IP-compatible ground station within range, reducing the level of set-up activity required to schedule and process satellite communication in advance.

The team also incorporated security protocols developed by the Internet Engineering Task Force to demonstrate how it would secure data and prevent hackers from tampering with the network. The protocol is currently used by e-commerce and the banking industry and is considered the safest for securing packets of information over the Internet. “This technology is proven in traditional terrestrial networks and its user-space can now span into flight mission environments here at NASA,” said Freemon Johnson, another Goddard technologist who participated in the demonstration.

“The point here is that we didn’t have to customize or invent any new technology. We simply took the commercial versions and integrated them onboard the spacecraft,” Marquart said.

To successfully demonstrate the flight-ready system, Goddard technologists also had to resolve timing and reliability issues associated with transporting data across the onboard network. The most commonly used technology is Transmission Control Protocol (TCP), which assures that data is reliably transmitted and received through a network by requiring that the sending computer receive a confirmation from the receiving computer once it receives a packet of information. In some instances, TCP acknowledgments would not be received within the strict time constraints of an onboard network.

Goddard technologists resolved the timing problem by using User Datagram Protocol (UDP), another transmission protocol that doesn’t require receipts after sending packets of information. Because UDP is unreliable, Marquart said the group added a layer of reliability into the Ethernet link by using another common protocol called Logical Link Control. She said the fix proved reliable, met the onboard timing requirements, and didn’t require any customized code.

“Our effort was demonstrated in a high-fidelity, mission-compatible environment,” Marquart said, describing the demonstrations. “Now we have radiation-hardened Ethernet hardware that can fly beyond low-Earth orbit. We believe this advances the state-of-the-art for Internet Protocols in space.”