Sunday, May 20, 2018

Small Packages to Test Big Space Technology Advances

This weekend, when the next cargo resupply mission to the International Space Station lifts off from NASA Wallops Flight Facility in Virginia, it will be carrying among its supplies and experiments three cereal box-sized satellites that will be used to test and demonstrate the next generation of Earth-observing technology. NASA has been increasing its use of CubeSats - small satellites based on several configurations of approximately 4 x 4 x 4-inch cubes - to put new technologies in orbit where they can be tested in the harsh environment of space before being used as part of larger satellite missions or constellations of spacecraft. The three CubeSat missions launching on Orbital ATK's ninth commercial resupply mission represent a broad range of cutting-edge technologies housed in very small packages. RainCube - a Radar in a CubeSat - is just that: a miniaturized precipitation-studying radar instrument that weighs just over 26 pounds. RainCube is smaller, has fewer components, and uses less power than traditional radar instruments. NASA's Earth Science Technology Office (ESTO) In-Space Validation of Earth Science Technologies (InVEST) program selected the project to demonstrate that such a diminutive radar can be operated successfully on a CubeSat platform.

This mission marks the first time an active radar instrument has been flown on a CubeSat.

If successful, RainCube could open the door for lower-cost, quick-turnaround constellation missions, in which multiple CubeSats work together to provide more frequent observations than a single satellite.

"A constellation of RainCube radars would be able to observe the internal structure of weather systems as they evolve according to processes that need to be better characterized in weather and climate forecasting models," said RainCube Principal Investigator Eva Peral of NASA's Jet Propulsion Laboratory in Pasadena, California.

RainCube will use wavelengths in the high-frequency Ka-band of the electromagnetic spectrum. Ka wavelengths work with smaller antennas (RainCube's deployable antenna measures at just half a yard, or meter, across) and allow an exponential increase in data transfer over long distances - making RainCube a demonstration in improved communications as well. JPL developed the RainCube instrument, while Tyvak Inc. developed the spacecraft.

CubeSats can also be used to test new subsystems and techniques for improving data collection from space. Radio frequency interference (RFI) is a growing problem for space-based microwave radiometers, instruments important for studying soil moisture, meteorology, climate and other Earth properties. As the number of RFI-causing devices - including cell phones, radios, and televisions - increases, it will be even more difficult for NASA's satellite microwave radiometers to collect high-quality data.

To address this issue, NASA's InVEST program funded a team led by Joel Johnson of The Ohio State University to develop CubeRRT, the CubeSat Radiometer Radio Frequency Interference Technology Validation mission.

"Our technology," said Johnson, "will make it so that our Earth-observing radiometers can still continue to operate in the presence of this interference."

RFI already affects data collected by Earth-observing satellites. To mitigate this problem, measurements are transmitted to the ground where they are then processed to remove any RFI-corrupted data.

It is a complicated process and requires more data to be transmitted to Earth. With future satellites encountering even more RFI, more data could be corrupted and missions might not be able to meet their science goals.

Johnson collaborated with technologists at JPL and Goddard Space Flight Center, Greenbelt, Maryland, to develop the CubeRRT satellite to demonstrate the ability to detect RFI and filter out RFI-corrupted data in real time aboard the spacecraft. The spacecraft was developed by Blue Canyon Technologies, Boulder, Colorado.

One of the radiometer-collected weather measurements important to researchers involves cloud processes, specifically storm development and the identification of the time when rain begins to fall.

Currently, weather satellites pass over storms just once every three hours, not frequently enough to identify many of the changes in dynamic storm systems. But the development of a new, extremely-compact radiometer system could change that.

NASA's Earth System Science Pathfinder program selected Steven Reising of Colorado State University and partners at JPL to develop, build, and demonstrate a five-frequency radiometer based on newly available low-noise amplifier technologies developed with support from ESTO.

The TEMPEST-D (Temporal Experiment for Storms and Tropical Systems Demonstration) mission will validate the miniaturized radiometer technology and demonstrate the spacecraft's ability to perform drag maneuvers to control TEMPEST-D's low-Earth altitude and its position in orbit. The instrument fits into a Blue Canyon Technologies 6U CubeSat - the same size CubeSat as RainCube and CubeRRT.

"With a train-like constellation of TEMPEST-like CubeSats, we'd be able to take time samples every five to 10 minutes to see how a storm develops," said Reising. This would improve upon the three-hour satellite revisit time, especially when collecting data on tropical storms like hurricanes that can quickly intensify and change.

RainCube, CubeRRT and TEMPEST-D are currently integrated aboard Orbital ATK's Cygnus spacecraft and are awaiting launch on an Antares rocket. After the CubeSats have arrived at the station, they will be deployed into low-Earth orbit and will begin their missions to test these new technologies useful for predicting weather, ensuring data quality, and helping researchers better understand storms.

Wednesday, May 16, 2018

NASA's emerging microgap cooling to be tested aboard New Shepard

An emerging technology for removing excessive, potentially damaging heat from small, tightly packed instrument electronics and other spaceflight gear will be demonstrated for the first time during an upcoming suborbital flight aboard a reusable launch vehicle. Thermal engineer Franklin Robinson, who works at NASA's Goddard Space Flight Center in Greenbelt, Maryland, is scheduled to fly his experiment aboard the fully reusable Blue Origin New Shepard launch vehicle to prove that the microgap-cooling technology is immune from the effects of zero gravity. The demonstration, funded by NASA's Space Technology Mission Directorate's Flight Opportunities program, is an important step in validating the system, which engineers believe could be ideal for cooling tightly packed, high-power integrated circuits, power electronics, laser heads or other devices. The smaller the space between these electronics, the harder it is to remove the heat. Because these devices are vulnerable to overheating - just like any electronic device on Earth - the cooling technology must operate under all conditions, including the microgravity environment found in space.

"Frank [Robinson] is demonstrating the fundamental concept and we need the flight validation to gain confidence," said Goddard Senior Technologist for Strategic Integration Ted Swanson. "While theory predicts that the lack of gravity would have a negligible impact on the performance of microgap coolers, this needs to be demonstrated in a space-like environment. Otherwise, potential users are unlikely to commit to the technology."

Microchannel Conduits

With microgap cooling, heat generated by electronics and other devices is removed by flowing a coolant through embedded, rectangular-shaped channels within or between heat-generating devices. Robinson's flight experiment also features "flow boiling," where, as its name implies, the coolant boils as it flows through the tiny gaps. According to Robinson, the technique offers a higher rate of heat transfer, which keeps devices cooler and, therefore, less likely to fail due to overheating.

To remove heat in more traditional electronic devices, designers create a "floor plan." They keep the heat-generating circuits and other hardware as far apart as possible. The heat travels into the printed circuit board, where it is directed to a clamp in the sidewall of the electronics box, eventually making its way to a box-mounted radiator.

Traditional approaches, however, would not work well for emerging 3-D integrated circuitry - a highly promising technology that could satisfy users' thirst for more computing power.

With 3-D circuitry, computer chips literally are stacked atop one another and not spread over a circuit board, saving space in electronic devices and instruments. Interconnects link each level to its adjacent neighbors, much like how elevators connect one floor to the next in a skyscraper. With shorter wiring linking the chips, data moves both horizontally and vertically, improving bandwidth, computational speed and performance, all while consuming less power.

Because not all the chips are in contact with the printed circuit board, traditional cooling techniques wouldn't work well with 3-D circuitry, Robinson said, adding he began his research with NASA support to assure that the agency could take advantage of 3-D circuitry when it became available.

"However, we can remove the heat by flowing a coolant through these tiny embedded channels."

Testing Effectiveness in Microgravity

Although Robinson has tested his cooling technology at various orientations in a laboratory, the question is whether it would be equally effective in space. "What we need to determine is how small the channels must be to achieve gravity independence. Right now, we don't have a perfect understanding," he said.

Should the microgap technology succeed during the demonstration, the next step would be to find an actual application and demonstrate it in space, Swanson said.

Through the Flight Opportunities program, the Space Technology Mission Directorate (STMD) selects promising technologies from industry, academia and government for testing on commercial launch vehicles. The program is funded by STMD, and managed at NASA's Armstrong Flight Research Center in Edwards, California.

STMD is responsible for developing the crosscutting, pioneering, new technologies and capabilities needed by the agency to achieve its current and future missions.

Monday, May 14, 2018

RL10 engine to power ULA's new Vulcan Centaur Upper Stage

United Launch Alliance (ULA) has selected Aerojet Rocketdyne's RL10 rocket engine to power the upper stage that will fly atop ULA's new Vulcan Centaur launch vehicle. The selection came as part of a long-term agreement between the two companies that calls for Aerojet Rocketdyne to provide RL10 upper-stage rocket engines to support ULA's current and future launch vehicles."Having the RL10 selected to support Vulcan Centaur means ULA and Aerojet Rocketdyne will continue working together to extend our track record of mission success well into the future," said Aerojet Rocketdyne CEO and President Eileen Drake. "We look forward to working alongside the outstanding team at ULA to make the Vulcan Centaur rocket a reality in order to provide reliable and affordable access to space for our nation." "ULA and Aerojet Rocketdyne have a long and successful history together that began with the first flight of our Atlas and Delta rockets in the 1960s," said Tory Bruno, ULA president and CEO. "We could not be more pleased to have selected the proven and reliable RL10 to power our Vulcan Centaur upper stage."

While some terms of the agreement remain confidential, it includes a long-term commitment by ULA to use RL10 engines on the company's current Centaur and next-generation Centaur upper stages for future ULA procurements, as well as a joint commitment to invest in next-generation engine development.

"The agreement also defines a path forward that will enable us to develop the next generation of RL10 engines that will incorporate additive manufacturing and other advanced technologies to make the engine more affordable while retaining its proven performance and reliability," continued Drake.

Last year, Aerojet Rocketdyne successfully hot-fire tested a full-scale, additively manufactured thrust chamber assembly for the RL10 that was built from a copper alloy using a 3-D printing technique known as selective laser melting or SLM. Since then, the company has been working to develop and qualify a variety of components that take advantage of SLM technology.

"With nearly 500 engines flown in space over the last five decades, the RL10 has earned an unmatched reputation in the industry," said Drake. "We will continue to build this proud legacy by supporting ULA's new Vulcan Centaur rocket for many years to come."

Sunday, May 13, 2018

Testing maintenance-free engines that power science in deep space

There are no gas stations or mechanics in deep space. So, if you want the power to perform science in the deep, dark frontiers of our solar system, you must have an engine that is reliable for the long haul. At NASA Glenn Research Center, engineers have recently set a record of operating a free-piston Stirling engine at full power, for over 110,000 hours of cumulative operation. That's over 12 years, and it's still running without issue. This length of time is important because traveling to outer planets and operating scientific experiments in space takes many years. How does it work? A radioisotope element provides heat energy and the Stirling engine converts it to electricity. Free floating pistons inside the engine move continuously at high frequency, but there is no contact with other parts. Engineers have virtually eliminated the mechanisms of wear and tear. Small and lightweight, these engines can operate on small spacecraft that need electrical power to run optics, sensors, recording devices and communications systems to get data back to scientists on Earth.

"We are demonstrating that it is possible to build an engine that does not wear out on the scale of the lifetime of a space mission," says Sal Oriti, project engineer. "Our goal is to improve state-of-the-art technology to enable the next generation of science missions in deep space."

Wednesday, May 9, 2018

Satellite row tests UK's post-Brexit security plans

Britain outlined its proposals Wednesday for close security cooperation with the EU after Brexit, but these risk being undermined by the bloc's refusal to share sensitive data on the Galileo satellite project. Prime Minister Theresa May has called for a deep trade and security relationship with Brussels after Britain leaves the European Union in March 2019, and hopes to have a deal agreed in principle by October. A document presented to the European Commission last week and published on Wednesday outline plans for a treaty on internal security and models of cooperation on foreign policy and in defence operations. But officials have been taken aback by Brussels' decision to deny London access to encrypted signals from the EU's Galileo satellite navigation system, citing legal issues about sharing sensitive information with a non-member state. Britain played a major role in developing the Pounds 9 billion (10 billion euros, $12 billion) project, an alternative to the US' GPS which is expected to be fully operational in 2026. Being frozen out due to security concerns could have implications for the rest of the partnership, the government document warns. "The arrangements for any UK cooperation on Galileo are an important test of the depth of operational cooperation and information-sharing envisaged under the security partnership," it said.

It demands continued British access to the secure signal and a right to compete for contracts.

Britain is looking into developing its own, separate system if the EU maintains its position, and has also raised the question of Galileo's use of Britain's overseas territories as monitoring bases.

The Times newspaper meanwhile reported Wednesday that the government is looking at ways to ban British-based technology companies from transferring sensitive information overseas.

Elsewhere, the document set out plans for a new treaty allowing Britain to continue using EU internal security measures such as the European Arrest Warrant, participate in agencies such as Europol, and continue the swift and secure exchange of data and criminal records.

Britain also wants to agree ways to allow it to contribute to EU defence missions on a case-by-case basis, as well as defence research projects and defence planning.

It points to the common threats faced by all European countries, from terrorism to illegal immigration, cyber threats and aggression, which has been blamed for a March chemical weapons attack in the English city of Salisbury.