Since SMAP began gathering soil-moisture measurements in the spring, the upgraded McMurdo TDRSS Relay System (MTRS) has transmitted terabytes of data via NASA’s Tracking and Data Relay Satellite System (TDRSS) at a whopping 200 megabits per second (Mbps).
SMAP measures the amount of water in the top two inches of soil everywhere on Earth’s surface, distinguishing between ground that is frozen or thawed. The mission is now producing its global measurements with just its radiometer instrument after it was found this summer that the SMAP radar could no longer return data. “The mission is downloading terabytes of data; hence the need for a faster link,” explained Philip Baldwin, a systems engineer at NASA Goddard, who led a six-member team that spent five years redesigning and building the system that allows for one of the fastest data transfers off the Antarctic continent.
“Not only do they have a lot of data to downlink, the mission’s data also is time-sensitive. We have only 30 minutes to deliver the data from one pass,” he said, adding that MTRS is actually capable of 300 Mbps data-transfer speeds.
As the polar-orbiting SMAP flies over Antarctica, it downlinks roughly 10 gigabytes of data during each pass to an X-band receiver located at the McMurdo Ground Station. A fiber-optic cable carries the data to the MTRS equipment housed 1.5 miles away inside a radome covering the MTRS 4.6-meter antenna dish and the system’s high-speed terminal consisting of two boxes or racks of electronic equipment. Every 12-hour period, the data are transferred to a TDRSS spacecraft that then downlinks the data to NASA’s Space Network ground station at the White Sands Complex, east of Los Cruces, NM, for ultimate delivery to SMAP scientists.
To create the capability, the team upgraded an existing system that Goddard initially developed 15 years ago to demonstrate data transfer from McMurdo to White Sands. The previous incarnation of the system was last used in 2005, and had remained dormant since. Among other issues, the existing equipment fell far short of SMAP’s operational readiness for data transfer and timing.
The team designed, upgraded, and refurbished every aspect of the system. It created the software, custom transceivers, and high-speed computers to produce the fastest data link off the world’s southern-most continent.
3D Printing for Electronics Packaging
For the past two years, the Internal Research and Development, or IRAD, program at NASA Goddard has awarded funding to a small number of researchers who are investigating how the agency might benefit from additive manufacturing or 3D printing. Said NASA Goddard Chief Technologist Peter Hughes, “We’re interested in finding out how this technology can enhance NASA’s ability to create one-of-a-kind instruments and components geared exclusively to studying and operating in space; in other words, improve what we already do well.”
One area that could potentially benefit from 3D manufacturing is electronics, particularly the techniques that technologists use to remove heat from heat-sensitive computer chips. Principal Investigator Jeffrey Didion, a researcher at NASA Goddard, is involved in a comprehensive, multi-year effort to advance electrohydrodynamic (EHD)-based thermal control for removing heat from spacecraft electronics.
Unlike traditional thermal-control technologies that rely on mechanical pumps and other moving parts, EHD uses electric fields to pump coolant through tiny ducts inside a thermal cold plate. From there, the waste heat is dumped onto a radiator and dispersed far from heat-sensitive circuitry that must operate within certain temperature ranges. The advantages are many. Without mechanical parts, the system is lighter and consumes less power and space. Perhaps more importantly, the system can be scaled to different sizes because mechanical hardware no longer drives the size or placement of the system within an electronics box.
Didion is continuing to investigate how he might use additive manufacturing to integrate EHD into the electronics board itself. “What we’d like to do is look at integrating thermal management into a functioning electronics board. In theory, we could do a better job of packaging devices and reducing mass, power consumption, and volume” — a notable endeavor given NASA’s push to reduce instrument size and fly a greater number of lessexpensive CubeSats and other smaller spacecraft.
To that end, Didion has joined forces with NASA Goddard Principal Investigator Beth Paquette, who received IRAD funding to advance a common customizable instrument electronics package called MinE Pack. The device would combine different functions inherent in all instruments — housekeeping, data processing, power, digitization, control and data handling, and amplification — all onto a single 3D chip or stack of chips.
“Our goal is to have all functions packaged into a component that could be plugged into a board or instrument,” Paquette said. “To help us get there, we plan to use additive manufacturing that could print conductors from chip to substrate.”