COMMUNICATIONS / NETWORKS
NASA plans improved ‘Internet in space’
NASA’s Deep Space Network is on the way toward becoming a true Internet in space, thanks to the agency’s research and investment in software-defined radios (SDRs). Also, the agency is preparing an SDR test module for the International Space Station that will be capable of connecting the station with an uplink of 100 megabits per second.
Pat Elben, the chairman of NASA’s software defined radio architecture and technology team (SAT) at NASA’s Space Communications and Navigation directorate, told attendees at the IDGA’s Software Radio Summit that the agency is setting up a new test platform. The platform, named the Communication Navigation and Networking Reconfigurable Testbed (CoNNeCT) will help NASA test waveforms based on the agency's Space Telecommunications Radio System (STRS), NASA's own standard for space-rated software-defined radio systems.
CoNNeCT will be added to the International Space Station in 2011, and demonstrate communications between the space station and the Tracking and Data Relay Satellite constellation that makes up the backbone of NASA’s network with three radio systems -- the Electra radio that flew aboard MRO, the General Dynamics Starlight radio, and the Orion radio -- the system being designed for NASA's follow-on to the space shuttle.
NASA developed its own standard because of the demanding requirements of space, where reprogramming a radio often has to be done remotely while the radio is on a spacecraft traveiing through the solar system.
That was the case, Elben said, when the Mars Reconnaissance Orbiter (MRO) was launched. Technicians discovered the Electra radio aboard MRO, a software-defined radio that was to act as the communications link to the two Mars rovers on the surface, was getting interfered with by something else on the spacecraft just before launch. NASA was able to launch the MRO and create a software patch and upload it to the Electra radios aboard it while the spacecraft was en route to Mars, he said.
Some observers have expressed concerns that suppliers might be reluctant to write software to yet another SDR architecture — the Defense Department’s Joint Tactical Radio System uses the Software Communications Architecture, which has been adopted by the Software Defined Radio Forum along with its own SW Radio standard. Elben said NASA plans on buying more than 1,000 STRS-based radios between now and 2025, but the price of these radios — between $1 million and $5 million — makes STRS radios a potentially $1 billion market for radio developers.
Although NASA has deployed software-defined radios for years, starting with the “Blackjack” global positioning system receiver on spacecraft in 2000, STRS will be part of the basis of an ambitious revamp of the agency’s Deep Space Network. The re-engineering will be based on SDRs and on high-bandwidth optical links, Elben said. It will also entail the use of software-defined systems and a move to less-expensive arrays of dish antennas instead of the old larger dishes. The new approaches are expected to make the network more automated and less expensive.
In the 1960s when NASA first created what became its Deep Space Network, “there was no grand vision,” Elben said. “NASA’s goal for 2024 is a highly integrated, IP-based disruption resistant network.”
Last November, NASA successfully tested Disruption Tolerant Networking (DTN), an Internet Protocol-based network using store-and-forward technology to ensure that packets of data would not be lost when being passed through the Deep Space Network. The agency will begin testing DTN aboard the International Space Station this summer.