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NASA engineers to build first integrated-photonics modem

NASA laser expert Mike Krainak and his team plan to replace portions of this fiber-optic receiver with an integrated-photonic circuit (its size will be similar to the chip he is holding) and will test the advanced modem on the International Space Station. (credit: W. Hrybyk/NASA)

A NASA team plans to build the first integrated-photonics modem, using an emerging, potentially revolutionary technology that could transform everything from telecommunications, medical imaging, advanced manufacturing to national defense.

The cell phone-sized device incorporates optics-based functions, such as lasers, switches, and fiber-optic wires, onto a microchip similar to an integrated circuit found in all electronics hardware.

The device will be tested aboard the International Space Station beginning in 2020 as part of NASA’s multi-year Laser Communications Relay Demonstration (LCRD). The Integrated LCRD LEO (Low-Earth Orbit) User Modem and Amplifier (ILLUMA) will serve as a low-Earth-orbit terminal for NASA’s LCRD, demonstrating another capability for high-speed, laser-based communications.

Space communications requires 100 times higher data rates

Since its inception in 1958, NASA has relied exclusively on radio frequency (RF)-based communications. Today, with missions demanding higher data rates than ever before, the need for LCRD has become more critical, said Don Cornwell, director of NASA’s Advanced Communication and Navigation Division within the space Communications and Navigation Program, which is funding the modem’s development.

LCRD, expected to begin operations in 2019, promises to transform the way NASA sends and receives data, video and other information. It will use lasers to encode and transmit data at rates 10 to 100 times faster than today’s communications equipment, requiring significantly less mass and power.

Such a leap in technology could deliver video and high-resolution measurements from spacecraft over planets across the solar system — permitting researchers to make detailed studies of conditions on other worlds, much as scientists today track hurricanes and other climate and environmental changes here on Earth.

A payload aboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) demonstrated record-breaking download and upload speeds to and from lunar orbit at 622 megabits per second (Mbps) and 20 Mbps, respectively, in 2013 (see “NASA laser communication system sets record with data transmissions to and from Moon“).

LCRD, however, is designed to be an operational system after an initial two-year demonstration period. It involves a hosted payload and two specially equipped ground stations. The mission will dedicate the first two years to demonstrating a fully operational system, from geosynchronous orbit to ground stations. NASA then plans to use ILLUMA to test communications between geosynchronous and low-Earth-orbit spacecraft, Cornwell said.

Laser Communications Relay Demonstration (LCRD), artist’s illustration (credit: NASA)

Integrated photonics: transforming light-based technologies

ILLUMA incorporates an emerging technology — integrated photonics — that is expected to transform any technology that employs light. This includes everything from Internet communications over fiber optic cable to spectrometers, chemical detectors, and surveillance systems.

“Integrated photonics are like an integrated circuit, except they use light rather than electrons to perform a wide variety of optical functions,” Cornwell said. Recent developments in nanostructures, metamaterials, and silicon technologies have expanded the range of applications for these highly integrated optical chips. Furthermore, they could be lithographically printed in mass — just like electronic circuitry today — further driving down the costs of photonic devices.

“The technology will simplify optical system design, said Mike Krainak, who is leading the modem’s development at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It will reduce the size and power consumption of optical devices, and improve reliability, all while enabling new functions from a lower-cost system.”

Krainak also serves as NASA’s representative on the country’s first consortium to advance integrated photonics. Funded by the U.S. Department of Defense, the non-profit American Institute for Manufacturing Integrated Photonics, with headquarters in Rochester, New York, brings together the nation’s leading technological talent to establish global leadership in integrated photonics. Its primary goal is developing low-cost, high-volume, manufacturing methods to merge electronic integrated circuits with integrated photonic devices.

NASA’s Space Technology Mission Directorate (STMD) also appointed Krainak as the integrated photonics lead for its Space Technology Research Grants Program, which supports early-stage innovations. The program recently announced a number of research awards under this technology area (see related story).

Photonics on a chip

Under the NASA project, Krainak and his team will reduce the size of the terminal, now about the size of two toaster ovens — a challenge made easier because all light-related functions will be squeezed onto a microchip. Although the modem is expected to use some optic fiber, ILLUMA is the first step in building and demonstrating an integrated photonics circuit that ultimately will embed these functions onto a chip, he said.

ILLUMA will flight-qualify the technology, as well as demonstrate a key capability for future spacecraft. In addition to communicating to ground stations, future satellites will require the ability to communicate with one another, he said.

“What we want to do is provide a faster exchange of data to the scientific community. Modems have to be inexpensive. They have to be small. We also have to keep their weight down,” Krainak said. The goal is to develop and demonstrate the technology and then make it available to industry and other government agencies, creating an economy of scale that will further drive down costs. “This is the payoff,” he said.

Although integrated photonics promises to revolutionize space-based science and inter-planetary communications, its impact on terrestrial uses also is equally profound, Krainak added. One such use is with data centers. These costly, very large facilities house servers that are connected by fiber optic cable to store, manage and distribute data.

Integrated photonics promises to dramatically reduce the need for and size of these behemoths — particularly since the optic hardware needed to operate these facilities will be printed onto a chip, much like electronic circuitry today. In addition to driving down costs, the technology promises faster computing power.

“Google, Facebook, they’re all starting to look at this technology,” Krainak said. “As integrated photonics progresses to be more cost effective than fiber optics, it will be used,” Krainak said. “Everything is headed this way.”


NASA | Laser Comm: That’s a Bright Idea

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Planet Nine from outer space

This artistic rendering shows the distant view from Planet Nine back towards the sun. The planet is thought to be gaseous, similar to Uranus and Neptune. Hypothetical lightning lights up the night side. (credit: Caltech/R. Hurt (IPAC))

Caltech researchers have found evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer solar system that the researchers have nicknamed Planet Nine.

It has a mass about ten times that of Earth and orbits about 20 times farther from the sun on average than does Neptune (which orbits the sun at an average distance of 2.8 billion miles). In fact, it would take this new planet between 10,000 and 20,000 years to make just one full orbit around the sun.

The researchers, Konstantin Batygin and Mike Brown (best known for the significant role he played in the demotion of Pluto from a planet to a dwarf planet), discovered the planet’s existence through mathematical modeling and computer simulations but have not yet observed the object directly.

“This would be a real ninth planet,” says Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy.

Brown notes that the putative ninth planet—at 5,000 times the mass of Pluto—is sufficiently large that there should be no debate about whether it is a true planet. Unlike the class of smaller objects now known as dwarf planets, Planet Nine gravitationally dominates its neighborhood of the solar system. In fact, it dominates a region larger than any of the other known planets—a fact that Brown says makes it “the most planet-y of the planets in the whole solar system.”

Batygin and Brown describe their work in an open-access paper in the current issue of the Astronomical Journal and show how Planet Nine helps explain a number of mysterious features of the field of icy objects and debris beyond Neptune known as the Kuiper Belt. “For the first time in over 150 years, there is solid evidence that the solar system’s planetary census is incomplete,” said Batygin.

Planet Nine’s existence also helps explain the alignment of distant Kuiper Belt objects and the mysterious orbits that two of them trace.

The six most distant known objects in the solar system with orbits exclusively beyond Neptune (magenta) all mysteriously line up in a single direction. Also, when viewed in three dimensions, they tilt nearly identically away from the plane of the solar system. Batygin and Brown show that a planet with 10 times the mass of the earth in a distant eccentric orbit anti-aligned with the other six objects (orange) is required to maintain this configuration. (credit: Caltech/R. Hurt (IPAC); [Diagram created using WorldWide Telescope.])

So where did Planet Nine come from and how did it end up in the outer solar system? Scientists have long believed that the early solar system began with four planetary cores that went on to grab all of the gas around them, forming the four gas planets — Jupiter, Saturn, Uranus, and Neptune. Over time, collisions and ejections shaped them and moved them out to their present locations.

“But there is no reason that there could not have been five cores, rather than four,” says Brown. Planet Nine could represent that fifth core, and if it got too close to Jupiter or Saturn, it could have been ejected into its distant, eccentric orbit.

A predicted consequence of Planet Nine is that a second set of confined objects should also exist. These objects are forced into positions at right angles to Planet Nine and into orbits that are perpendicular to the plane of the solar system. Five known objects (blue) fit this prediction precisely. (credit: Caltech/R. Hurt (IPAC) [Diagram was created using WorldWide Telescope.])

Replacing Pluto

Only the planet’s rough orbit is known, not the precise location of the planet on that elliptical path. If the planet happens to be close to its perihelion, Brown says, astronomers should be able to spot it in images captured by previous surveys. If it is in the most distant part of its orbit, the world’s largest telescopes — such as the twin 10-meter telescopes at the W. M. Keck Observatory and the Subaru Telescope, all on Mauna Kea in Hawaii — will be needed to see it. If, however, Planet Nine is now located anywhere in between, many telescopes have a shot at finding it.

“One of the most startling discoveries about other planetary systems has been that the most common type of planet out there has a mass between that of Earth and that of Neptune,” says Batygin. “Until now, we’ve thought that the solar system was lacking in this most common type of planet. Maybe we’re more normal after all.”

“All those people who are mad that Pluto is no longer a planet can be thrilled to know that there is a real planet out there still to be found,” Brown says. “Now we can go and find this planet and make the solar system have nine planets once again.”


Caltech AMT | Caltech’s Konstantin Batygin, an assistant professor of planetary science, and Mike Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy, discuss new research that provides evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer solar system.

Abstract of Evidence for a Distant Giant Planet in the Solar System

Recent analyses have shown that distant orbits within the scattered disk population of the Kuiper Belt exhibit an unexpected clustering in their respective arguments of perihelion. While several hypotheses have been put forward to explain this alignment, to date, a theoretical model that can successfully account for the observations remains elusive. In this work we show that the orbits of distant Kuiper Belt objects (KBOs) cluster not only in argument of perihelion, but also in physical space. We demonstrate that the perihelion positions and orbital planes of the objects are tightly confined and that such a clustering has only a probability of 0.007% to be due to chance, thus requiring a dynamical origin. We find that the observed orbital alignment can be maintained by a distant eccentric planet with mass gsim10 m⊕ whose orbit lies in approximately the same plane as those of the distant KBOs, but whose perihelion is 180° away from the perihelia of the minor bodies. In addition to accounting for the observed orbital alignment, the existence of such a planet naturally explains the presence of high-perihelion Sedna-like objects, as well as the known collection of high semimajor axis objects with inclinations between 60° and 150° whose origin was previously unclear. Continued analysis of both distant and highly inclined outer solar system objects provides the opportunity for testing our hypothesis as well as further constraining the orbital elements and mass of the distant planet.