X-Ray for Space Communication

NavCube, the product of a merger between the Goddard-developed SpaceCube 2.0 and Navigator GPS technologies, could play a vital role helping to demonstrate X-ray communications in space. (Source: NASA / W. Hrybyk)

NavCube, the product of a merger between the Goddard-developed SpaceCube 2.0 and Navigator GPS technologies, could play a vital role helping to demonstrate X-ray communications in space. (Source: NASA / W. Hrybyk)

Two proven techno­logies have been combined to create a promising new techno­logy that could meet future navigational challenges in deep space. It also may help demonstrate for the first time X-ray communi­cations in space, a capability that would allow the trans­mission of gigabits per second throughout the solar system. The new tech­nology, called NavCube, combines NASA’s SpaceCube, a recon­figurable and fast flight computing platform, with the Navi­gator Global Posi­tioning System flight receiver. Navigator GPS uses the GPS signal to enable on-board auto­nomous posi­tioning, navi­gation, and timing even in weak-signal areas.

“NavCube is more flexible than previous Navigators because of its ample compu­tational resources. Also, because we added the ability to process moder­nized GPS signals, NavCube has the potential to signi­ficantly enhance performance at low, and espe­cially, high altitudes, potentially even to the area of space near the moon and lunar orbits,” said Luke Winter­nitz, Navigator’s chief architect. “This new product is a poster child for our research and deve­lopment efforts,” added Peter Hughes, the chief techno­logy officer at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, whose organi­zation funded the development. “Both SpaceCube and Navigator already proved their value to NASA. Now the combination of the two gives NASA another tool. Also, the possi­bility that it might help demonstrate X-ray communi­cations in space is parti­cularly exciting.”

This promising technology is slated to fly as one of several experiments on an external pallet to be deployed on the International Space Station in 2018. One NavCube unit will demonstrate its navigation and processing capabilities afforded by the merger of its technological parents, while the other could potentially provide precise timing data for an experiment demon­strating X-ray communi­cations, or XCOM. As part of the potential XCOM demon­stration, NavCube will drive the electronics for a device called the Modulated X-ray Source, or MXS, which generates rapid-fire X-ray pulses, turning on and off many times per second. These rapid-fire pulsations can be used to encode digital bits for trans­mitting data. It was developed as a testbed to validate NASA’s Neutron-star Interior Compo­sition Explorer, or NICER, which primarily will study neutron stars and their rapidly spinning next-of-kin, pulsars, when it launches as an attached space station payload in 2017.

XCOM is one of two techno­logy demon­strations that NICER Principal Inves­tigators Keith Gendreau and Zaven Arzou­manian want to demonstrate with NICER. To demonstrate one-way XCOM, the team will install MXS on the experiment pallet where it will transmit data via X-rays to NICER’s receivers positioned 166 feet away on the opposite side of the space station truss. NavCube’s job is to run MXS’s on-and-off switch, said Jason Mitchell, an engineer at Goddard who helped advance the MXS. Because NavCube combines SpaceCube’s high-speed computing with Navigator’s ability to track GPS signals, the team also wants to experiment with X-ray ranging, a technique for measuring distances between two objects.

Although most of the technology is ready, the team still is seeking additional funding to complete a space-ready MXS, including its housing and high-voltage power supply. “We have most of the hardware, but need a little more support to complete the XCOM package,” said Jenny Do­naldson, who is leading the development of the NavCube payload. “This is a great opportunity to demonstrate NavCube and, if all things go as planned, X-ray communications,” she said. NavCube traces its lineage to two already proven techno­logies: SpaceCube 2.0 and Navigator GPS. SpaceCube 2.0, one in a family of onboard processors, is 10 to 100 times faster than more tradi­tional flight processors. Having flown many times before, including on previous expe­riment pallets, SpaceCube now enjoys a growing list of customers, including future high-profile robotic-servicing missions.

The Navigator GPS Flight receiver was purposely designed to detect, acquire, and track faint GPS signals for NASA’s MMS mission. Navigator now is providing posi­tioning information to the four spacecraft that must fly in a particular, high-earth flight formation to gather scientific data. At the highest point of the MMS orbit, Navigator has tracked as many as twelve GPS satel­lites. The team ori­ginally expected to detect no more than two or three GPS satellites.

“We knew that proces­sing speed from SpaceCube and the tracking capa­bility of Navigator could be a powerful combi­nation,” said Barry Geldzahler, chief scientist and chief techno­logist for NASA’s Space Communi­cation and Navi­gation (SCaN) Program. “The next task was to figure out how to make it smaller and increase the sensitivity for more flexible mission appli­cations.”

“At the time, we needed a more robust, re-program­mable and extensible proces­sing platform,” added Monther Hasouneh, NavCube’s hardware lead. “SpaceCube was already there. Further­more, we figured that missions using SpaceCube 2.0 as a science data processor also could benefit from having a GPS receiver as a low-cost add-on,” he added. (Source: Nasa)

Links: NASA’s Goddard Space Flight Center in Greenbelt, Maryland, USA

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