National Aeronautics and Space Administration
Volume 17
www.nasa.gov
Issue 4
Summer 2021
cuttingedge • goddard’s emerging technologies
Volume 17 • Issue 4 • Summer 2021
Goddard Tech will help NASA Explore Earth’s Mysterious Twin with DAVINCI Although Earth and Venus are similar in size and location, they are very different worlds today. While Earth has oceans of water and abundant life, Venus is dry and fiercely inhospitable. Somewhat closer to the Sun, Venus is much hotter, with surface temperatures high enough to melt lead. The scorched landscape is obscured by clouds of sulfuric acid and smothered by a thick atmosphere of mostly carbon dioxide. At more than 90 times Earth’s surface pressure, air near the surface behaves like a substance between a fluid and a gas. In spite of the extreme present-day conditions, scientists think that in an earlier time, Venus may have been an Earth-like habitable world. They hypothesize something caused a “runaway greenhouse” effect in Venus’ atmosphere, cranking up the temperature and vaporizing its possible oceans. NASA’s DAVINCI mission is set to explore Venus to determine if it was
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Summer 2021
habitable and understand how these similar worlds ended up with such different fates. The mission, Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging (DAVINCI), will consist of a carrier-relay spacecraft and an atmospheric descent probe. The carrierrelay spacecraft will track motions of the clouds and composition, as well as mapping regional surface composition by measuring heat emission from Venus’ surface that escapes to space through the massive atmosphere. The probe will sample the atmosphere’s chemistry, temperature, pressure, and winds as often as every 50-150 meters. The probe will also acquire the first high-resolution images of Alpha Regio, an ancient highland twice the size of Texas with rugged mountains, looking for evidence that past crustal water influenced the formation of its surface rocks.
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Goddard Tech will help NASA Explore Earth’s Mysterious Twin with DAVINCI
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Award-Winning Thermal Imager Captures Data for Agriculture and Wildfire Monitoring
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Early Career Innovator: Bethany Theiling Finds Adaptation is Key
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Laser Communications Realize Years of Innovation at Goddard
10 Goddard Scientist Looks to AI, Lensing to Find Masses of Free-Floating Planets 12 Small Mission to Shed New Light on Exoplanet Atmospheres 15 Adapted Computer Program Pushes Satellite Navigation Toward Autonomy 17 Scientist Looks for Specific Energy Emissions to Identify Sources of Cosmic Positrons
About the Cover NASA selected the Goddard-led Deep Atmosphere Venus Investigation of Noble-gases, Chemistry and Imaging mission to be the first probe to land on Venus since 1985. Where older missions settled on the plains, DAVINCI will bring 21st-century technologies to map and photograph the highlands of our world next door, investigating a mountainous region called Alpha Regio. A carrier-relay satellite will remain in orbit, mapping clouds and terrain and communicating with Earth. Goddard technology will power the atmospheric probe, seals, and parachute customization. (Photo Credit: NASA/Goddard Conceptual Image Lab/Michael Lentz)
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Image credits: NASA Goddard visualization and CI Labs Michael Lentz and colleagues
DAVINCI uses observations from both above and within the planetary atmosphere to answer major questions about how Venus was formed, has evolved, and possibly lost its habitability (and past surface oceans). Its “natural vertical mobility” extends from the top of the atmosphere, through the clouds, and then throughout the deep atmosphere to just above the surface, where imaging of mountain landscapes in 3D will be undertaken together with detailed chemistry.
Launch is targeted for late 2029 with two flybys of Venus prior to the probe’s descent through the atmosphere. The flybys are the initial phase of the remote-sensing mission phase designed to study the atmospheric circulation, composition, and map the surface of targeted highlands. Approximately two years later, the probe will be released to conduct its investigation of the atmosphere during a descent that will last about an hour before touching down at Alpha Regio.
probe will need cutting-edge technology to perform its necessary scientific duties. Goddard’s Internal Research and Development Program (IRAD) contributed to the development of DAVINCI’s parachute, window seal, atmosphere probe, and a new external antenna design.
The atmospheric probe enables scientists to investigate the connection between atmospheric evolution, the possible existence of global oceans, and surface-atmosphere chemistry interactions. “The next “Venus is ‘hard’ since every clue is hidden step in Venus exploration rebehind the curtain of a massive opaque atmoquires a capable instrument sphere with inhospitable conditions for surface payload that can employ exploration, so we have to be clever and bring modern capabilities to proour best ‘tools of science’ to Venus in innovative duce definitive datasets that transform our understanding ways with missions like DAVINCI. That is why of our planetary neighborwe named our mission ‘DAVINCI’ after Leonardo hood,” said Stephanie Getty, da Vinci’s inspired and visionary Renaissance deputy principal investigathinking that went beyond science to connect to tor for DAVINCI at NASA’s engineering, technology, and even art.” Goddard Space Flight Center.
“Venus is a ‘Rosetta stone’ for reading the record books of climate change, the evolution of habitability, and what happens when a planet loses a long period of surface oceans,” said James Garvin, principal investigator for DAVINCI at Goddard. “But Venus is ‘hard’ since every clue is hidden behind the curtain of a massive opaque atmo– DAVINCI principal investigator sphere with inhospitable The science impact of James Garvin conditions for surface exDAVINCI will reach even beploration, so we have to be yond the solar system to Venus-like planets orbiting clever and bring our best ‘tools of science’ to Venus other stars, which represent important targets for in innovative ways with missions like DAVINCI. NASA’s upcoming James Webb Space Telescope. That is why we named our mission ‘DAVINCI’ after Leonardo da Vinci’s inspired and visionary Renais“Venus is the ‘exoplanet in our backyard’ that can sance thinking that went beyond science to connect help us understand these distant analog worlds to engineering, technology, and even art.” by providing ground truth to improve the computer With the harsh conditions on Venus, the DAVINCI www.nasa.gov/gsfctechnology
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models we will use to interpret exo-Venus planets,” said Giada Arney, deputy principal investigator for DAVINCI at Goddard. “DAVINCI’s investigation of the evolution of Venus may help us better understand how habitable worlds are distributed elsewhere in the universe, and how habitable planets evolve over time in a general sense.” NASA Goddard is the principal investigator institution and will perform project management for the mission, as well as project systems engineering to develop the probe flight system and instrument development of the Venus mass spectrometer. Major partners are Lockheed Martin, Denver, Colorado; the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland; NASA’s Jet Propulsion Laboratory, Pasadena, California; Malin Space Science Systems, San Diego, California; NASA’s Langley Research Center, Hampton, Virginia; NASA’s Ames Research Center at Moffett Federal Airfield in California’s Silicon Valley and KinetX, Inc., Tempe, Arizona. The University of Michigan is a key university partner associated with major instrumentation. v CONTACTS James.B.Garvin@nasa.gov or 301-286-5154 Giada.N.Arney@nasa.gov or 301-614-6627 Stephanie.A.Getty@nasa.gov or 301-614-5442
Image credits: NASA Goddard visualization and CI Labs Michael Lentz and colleagues
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DAVINCI will send a meter-diameter probe to brave the high temperatures and pressures near Venus’ surface and to explore the atmosphere from above the clouds to just above a mountainous landscape that may have been a past continent. During its final kilometers of free-fall descent (depicted here), the probe will capture spectacular images and chemistry measurements of the deepest atmosphere on Venus for the first time.
Award-Winning Thermal Imager Captures Data for Agriculture and Wildfire Monitoring Goddard’s newest compact infrared sensor is licensed for commercial CubeSats, and under consideration for NASA Earth science missions. It’s been an eventful few years for the Goddard-developed Compact Thermal Imager (CTI). In 2019, it received its first patent license, and in 2021, the CubeSat-compatible thermal imager was named co-winner of NASA’s Invention of the Year Award: honoring inventions that significantly contributed to NASA programs. NASA recognized inventors Murzy Jhabvala, Donald Jennings, and Compton Tucker for their patent “Compact, High Resolution Thermal Infrared Imager,” which was submitted in 2014 and issued in 2019. This patented concept served as the basis for the CTI instrument that flew with Robotic Refueling Mission 3 from late 2018 to 2019 aboard the International Space Station. Over the course of PAGE 4
several months, CTI captured more than 15 million infrared images of Earth in two spectral bands. “I’m thrilled to see CTI acknowledged in this way,” Jhabvala said of the NASA Invention of the Year recognition. “It’s very gratifying to me and the team that NASA recognizes and utilizes this technology, particularly given some of the challenges we overcame to get to this point.” The technology, conceived by Jhabvala at Goddard, is small enough to fit on miniaturized satellites, such as CubeSats, and represents the latest advances in infrared detectors. Funded by NASA’s Earth Science Technology Office (ESTO) and bolstered by technology developed through the Small Business Innovation Research (SBIR) program, CTI represents many years of collaboration and innovation. Continued on page 5
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Murzy Jhabvala and his team are developing a Compact Thermal Imager 2, incorporating optical filters directly attached to an innovative new sensor.
CTI’s emerging strained layer superlattice (SLS) infrared detector technology — developed in 2012 and 2013 using Goddard’s Internal Research and Development (IRAD) funds — possesses several advantages over other competing infrared technologies. SLS detectors share qualities with quantum well detectors, such as low cost, relative ease of fabrication, and stability; however they are 10 times more sensitive, can be spectrally tuned, and can operate at much warmer temperatures. This allows the technology to fly on smaller platforms, since it can work with lighter and less power-intensive cooling systems. Ultimately, CTI improves NASA’s ability to collect and analyze Earth images, gleaning science data that sheds light on topics related to climate change, wildfires, agriculture, and more. As a result of CTI’s successful 2019 mission, various SLS sensors are being considered for multiple NASA missions. “This instrument is very versatile,” said Compton Tucker, a senior Earth scientist at Goddard and co-investigator for CTI. “As a new technology, it has tremendous usage potential in biomass burning and crop surface temperature.” “CTI’s deployment on the space station was primarily a test of how well the hardware would perform in space. It was not initially designed as a science mission,” explained Doug Morton, chief of the Biospheric Sciences Laboratory at Goddard. “None-
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theless, CTI data proved scientifically useful as we monitored several high-profile fire outbreaks in the 2019 summer.” A Georgia-based company called Cybercorps LLC licensed CTI in 2019, and plans to offer real-time agricultural data for farmers, resource managers, first responders, and other interested user groups by flying CTI on a CubeSat. The small spacecraft will capture thermal images while pointed at Earth’s surface. Farmers and other interested customers can subscribe to Cybercorps’ service to access the thermal imaging data, which can be used to evaluate the health of agricultural and aquatic ecosystems. In combination with traditional techniques, this bundle of information could help farmers optimize fertilizer treatments and watering schedules. “Technologies like CTI were developed for research purposes, but they often have additional applications outside of pure science,” said Eric McGill, a senior technology manager with the Strategic Partnerships Office at Goddard. “In this case, infrared imaging can play an important role in monitoring crop health and helping members of the agricultural community yield better harvests.” In addition to CTI’s agricultural applications, Tucker said the technology can help detect wildfire activity by distinguishing between high combustion Continued on page 6
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Image courtesy: Murzy Jhabvala
Volume 17 • Issue 4 • Summer 2021
areas and less hot, smoldering sections of land. CTI’s observations of severe fires in Australia, the Amazon, India, and the U.S. detected the shape and location of fire fronts while also providing information on their distance from settled areas. For first responders, this data could influence life-saving evacuation plans. Furthermore, CTI made fire observations with 20 times more detail than NASA’s Visible Infrared Imaging Radiometer Suite (VIIRS) and with 190 times more detail than NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS). A fleet of CTI-like sensors could capture detailed measurements of wildfires several times a day, filling current gaps in coverage.
Image credit: NASA’s Earth Observatory
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CTI captured several images of the unusually severe fires in Australia that burned for four months in 2019-20. With its 80-meter (260 foot) per pixel resolution, CTI detected the shape and location of fire fronts and how far they were from settled areas — information critically important to first responders. Scientists have generally relied upon coarser resolution (375–1000 m) thermal data from the satellitebased Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) sensors to monitor fire activity from above.
CTI’s technology pathfinder mission leveraged the collaborative efforts of multiple Goddard directorates as well as miniature integrated detector cooler assembly development by New Hampshire-based QmagiQ LLC, funded through NASA’s SBIR program. ESTO supported and funded CTI instrument development under the Sustainable Land Imaging Technology program. ESTO has funded a follow-on instrument, CTI-
2, which is currently in development. CTI-2 will incorporate optical filters directly attached to an SLS detector that provides multi-spectral data. Two additional internal Goddard programs are supporting the development of detectors and instruments with different filters attached to the SLS detector assembly. v CONTACT Murzy.D.Jhabvala@nasa.gov or 301-286- 5232
Early Career Innovator: Bethany Theiling Finds Adaptation is Key Two years ago, Dr. Bethany Theiling arrived at Goddard with a horde of data, an open mind, and an inclination to make new connections. Only hours into her first day at Goddard, a chance meeting directed her path towards new lines of investigation. Theiling recalled her first moments at Goddard’s orientation, striking up a conversation with Brian Powell, who happened to be a machine learning expert. Theiling discussed a curiosity in machine learning for small laboratory data sets, and Powell took an interest in her work. “I will pretty much talk to anybody. You never know what’s going to happen, right? I mean, if it doesn’t work
out, it doesn’t work out, but it could be a great friendship or a partnership or anything,” Theiling said. An early career innovator, Theiling now leads two machine learning projects focused on the chemical analysis of ocean worlds. Theiling is currently using machine learning to determine the composition of an ocean world, using algorithms that target what she has termed “predictive features”, which are defining characteristics of data from a specific chemical system that makes the data look the way they do. Using the data brought with her from her professorship at the University of Tulsa, as well as a vast amount of data from the National Science Foundation, Theiling and Continued on page 7
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her team ‘teach’ the machine learning algorithms to identify these features. “These ocean worlds have the highest potential for life in the solar system, we think, so they’re really exciting targets,” Theiling said. Using IRAD funding, her team is also acquiring an isotope ratio mass spectrometer (IRMS) that includes two peripherals with the ability to analyze solids, liquids, and trace gases. This technology will be used to gather data and will continue to train the machine learning algorithms developed previously, making the system more precise. Not only will this new technology be able to make analyses easier and allow a greater understanding of the compositions of ocean worlds, but it is Theiling’s hope to be able to use the technology to contribute to the science of Earth’s climate as well.
Though her path ultimately led to research as a geochemist in Earth and planetary sciences, Theiling’s educational career started worlds away. “It’s been a very circuitous path,” she said. She began her college career as a fashion design major at Florida State, but almost immediately transitioned to anthropology. She completed her degree, then discovered geology was what most piqued her interest. In the first of many unexpected collaborations, Theiling found herself working for a geochemist in her graduate program after a professor initiated a conversation between the two. “She literally opened his door without any introduction, shoved me inside and said, ‘This is Bethany, she’s a go-getter’ and then closed the door behind me,” Theiling said. The meeting settled Theiling’s mind about what she was interested in, leading her to become a geochemist by accident. After receiving a masters in geology, as well as a doctorate in Earth and planetary sciences, Theiling began
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Photo credit: NASA/Rebecca Roth
“Recruiting Bethany was a really great win for Goddard,” said Goddard Chief Technologist Peter Hughes. “She brings a wealth of expertise and a vision for combining traditional mass spectrometry – an area where Goddard excels – with AI to enable smarter off-world missions, which will strategically position the center to contribute strongly to the exploration of these ocean worlds and other science frontiers.”
working as an assistant professor at the University of Tulsa but said she felt as if something were missing. “At that very moment, I kid you not, I got an email from somebody at Goddard,” Theiling said. The email transcribed a job description that seemed to be written for Theiling. She applied and received the position. Reflecting back on her experiences through academia and science, Theiling advocates collaboration and communication avidly. “One of the big lessons I’ve learned is that I can’t do everything by myself,” Theiling said. “I would love to! I’d love to be able to code and do lab work and create instruments, but I can’t. Ultimately, I need a great team to work with, either that I’m leading or I’m a part of, and to be perfectly honest, being at Goddard has been the best of that experience so far.” v CONTACT Bethany.P.Theiling@nasa.gov or 301-614-6909
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Laser Communications Realize Years of Innovation at Goddard Launching later this year, NASA’s Laser Communications Relay Demonstration (LCRD) mission will showcase the dynamic powers of laser communications technologies pioneered at Goddard. With NASA’s ever-increasing human and robotic presence in space, many missions can benefit from a new way of communicating with Earth, thanks in part to years of NASA and Goddard-funded research and development initiatives. Since the beginning of spaceflight in the 1950s, NASA missions have leveraged radio frequency communications to send data to and from space. Laser communications, also known as optical communications, will further empower missions with unprecedented data capabilities.
Image Cedit: NASA
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Measuring Light and Shadow Illustration of the U.S. Department of Defense’s Space Test Program Satellite-6 (STPSat-6) with the Laser Com-
As science instruments munications Relay Demonstration (LCRD) payload communicating data over infrared links. evolve to capture highdefinition data like 4K video, when designing and developing mission concepts. missions will need expedited ways to transmit “LCRD will demonstrate all of the advantages of information to Earth. With laser communications, using laser systems and allow us to learn how to NASA can significantly accelerate the data transfer use them best operationally,” said Principal Investiprocess and empower more discoveries. gator David Israel at NASA’s Goddard Space Flight Laser communications will enable 10 to 100 times Center in Greenbelt, Maryland. “With this capabilmore data transmitted back to Earth than current ity further proven, we can start to implement laser radio frequency systems. It would take roughly nine communications on more missions, making it a weeks to transmit a complete map of Mars back to standardized way to send and receive data.” Earth with current radio frequency systems. With How it Works lasers, it would take about nine days. Additionally, laser communications systems are ideal for missions because they need less volume, weight, and power. Less mass means more room for science instruments, and less power means less of a drain of spacecraft power systems. These are all critically important considerations for NASA
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Both radio waves and infrared light are electromagnetic radiation with wavelengths at different points on the electromagnetic spectrum. Like radio waves, infrared light is invisible to the human eye, but we encounter it every day with things like television remotes and heat lamps. Continued on page 9
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Missions modulate their data onto the electromagnetic signals to traverse the distances between spacecraft and ground stations on Earth. As the communication travels, the waves spread out. The infrared light used for laser communications differs from radio waves because the infrared light packs the data into significantly tighter waves, meaning ground stations can receive more data at once. While laser communications aren’t necessarily faster, more data can be transmitted in a single downlink. Laser communications terminals in space use narrower beam widths than radio frequency systems, providing smaller “footprints” that can minimize interference or improve security by drastically reducing the geographic area where someone could intercept a communications link. However, a laser communications telescope pointing to a ground station must be exact when broadcasting from thousands or millions of miles away. A deviation of even a fraction of a degree can result in the laser missing its target entirely. Like a quarterback throwing a football to a receiver, the quarterback needs to know where to send the football, i.e. the signal, so that the receiver can catch the ball in stride. NASA’s laser communications engineers have intricately designed laser missions to ensure this connection can happen.
Laser Communications Relay Demonstration Located in geosynchronous orbit, about 22,000 miles above Earth, LCRD will be able to support missions in the near-Earth region. LCRD will spend its first two years testing laser communications capabilities with numerous experiments to refine laser technologies further, increasing our knowledge about potential future applications. LCRD’s initial experiment phase will leverage the mission’s ground stations in California and Hawaii, Optical Ground Station 1 and 2, as simulated users. This will allow NASA to evaluate atmospheric disturbances on lasers and practice switching support from one user to the next. After the experiment phase, LCRD will transition to supporting space missions, sending and receiving data to and from satellites over infrared lasers to demonstrate the benefits of a laser communications relay system. The first in-space user of LCRD will be NASA’s Integrated LCRD Low-Earth Orbit User Modem and Amplifier Terminal (ILLUMA-T), which is set to launch to the International Space Station in 2022. The terminal will receive high-quality science data
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from experiments and instruments onboard the space station and then transfer this data to LCRD at 1.2 gigabits per second. LCRD will then transmit it to ground stations at the same rate. LCRD and ILLUMA-T follow the groundbreaking 2013 Lunar Laser Communications Demonstration (LLCD), which downlinked data over a laser signal at 622 megabits-per-second, proving the capabilities of laser systems at the Moon. “Goddard has had quite the hand in the conception and subsequent development of LCRD,” said Goddard optical physicist Guan Yang. Once ILLUMA-T is on the space station, it will complete an end-to-end laser communications system with LCRD. Prior to these missions, laser communications was relatively unheralded. MIT Lincoln Laboratory contributed significantly to LLCD, LCRD and ILLUMA-T. In addition to these missions, Yang developed a technology that was able to match the speed of the LLCD and provide highly precise distance and speed measurements all from the same package. “Our LCRD/ILLUMA-T optical communications-based high-precision ranging and range rate measurement (Optimetrics Experiment) was initially funded by NASA Goddard’s Internal Research and Development (IRAD) program under the Communications and Navigation Line of Business. The IRAD funding enabled us to conduct the research on two different optimetrics measurements in the lab,” Yang said. A data clock phase-based measurement achieves precision ranging and range rate measurements by encoding a time signature in the optical data. And an optical carrier phase-based measurement achieved the same goals by measuring the optical carrier phase of the signal. These lab measurement methods achieved incredible precision, he said, and the success of the experiment in combination with the orbit determination simulation software will significantly advance orbit determination precisions. Once LCRD and ILLUMA-T are in orbit, NASA will verify these results in space. NASA has many other laser communications missions currently in different stages of development. Each of these missions will increase our knowledge about the benefits and challenges of laser communications. v CONTACT Guangning.Yang-1@nasa.gov or 301-614-6806
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Goddard Scientist Looks to AI, Lensing to Find Masses of Free-Floating Planets Image credit: NASA/JPL-Caltech
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This illustration shows a Jupiter-like planet alone in the dark of space, floating freely without a parent star. The planet survey, Microlensing Observations in Astrophysics, scanned the central bulge of our Milky Way galaxy using the microlensing technique CUμLUS seeks to employ.
Exoplanet hunters have found thousands of planets orbiting close to their host stars, but relatively few of these alien worlds follow more distant orbits – and even fewer float freely through the galaxy, not bound to any star. NASA’s Roman Space Telescope will discover many more planets by observing dense star fields to maximize the chances of detecting an intervening planet as it passes precisely in front of a distant star. These chance alignments cause background stars to brighten briefly. The planet’s gravity acts as a lens that magnifies light from the background star’s light. One drawback of this technique, called gravitational microlensing, is that the distance to the lensing planet is poorly known. Goddard scientist Dr. Richard K. Barry is working to exploit parallax effects to pin down these distances. PAGE 10
Parallax is the apparent shift in the position of a foreground object as seen by observers in slightly different locations. Our brains exploit the slightly different views of our eyes so we can see in 3D. Astronomers in the 19th century first measured distances to nearby stars using the same effect, measuring how their positions shifted relative to background stars in photographs taken when Earth was on opposite sides of its orbit. It works a little differently with microlensing. In this case, two well-separated observers, each equipped with a precise clock, may observe the same microlensing event. The time delay between the two detections allows scientists to determine the distance to the lensing object. Barry is developing a concept called the CUbesat Continued on page 11
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Image credit: NASA’s Goddard Space Flight Center Conceptual Image Lab
This illustration shows the concept of gravitational microlensing. When one star in the sky passes nearly in front of another, it can lens light from the background source star. If the nearer star hosts a planetary system, the planets can also act as lenses, each producing a short deviation in the brightness of the source.
MicroLensing Uniform Surveyor (CUμLUS, read: cumulus). It’s designed to make independent observations of some of the Roman lensing events by observing the same star fields. His goal is to develop a concept compatible with the new NASA Astrophysics Pioneers program, which aims to develop small low-cost missions) to gather information about these free-floating worlds and investigate their origins. CUμLUS will rely on gravitational microlensing, an effect first described by Albert Einstein in the 1930s and now used as a technique to detect planets or other objects that emit little or no light, such as black holes or neutron stars. Microlensing works because the warped spacetime around a massive object moving between a distant star and an observer magnifies the source’s light. As the precise alignment between source and lens changes due to the object’s motion in space, so does the brightness of the source. How the event plays out provides information about the lensing object. But if only one observer views the lens’ passage, it is exceedingly difficult to determine its mass because its distance is unknown. If two observers view from different angles, however, they will see the event occur at slightly different times. Determining the amount of time that elapses between each detection makes it possible to determine the distance between the lens and the observer, yielding a more precise mass estimate of the lens. This technique is called microlensing parallax. The CUμLUS project would support the Roman Space Telescope and PRime-focus Infrared Microlensing Experiment (PRIME), a terrestrial telescope currently in development using four detectors loaned by the Roman mission. While Roman and PRIME will detect many hundreds of microlensing planets, mass estimates for these objects will be www.nasa.gov/gsfctechnology
significantly improved using simultaneous parallax observations provided by CUμLUS. “CUμLUS would be at a great distance from the principal observatory, either Roman or a terrestrial telescope,” Barry said. “The parallax signal should then permit us to calculate quite precise masses for these objects, thereby increasing scientific return.” CUμLUS would hitch a ride on a Mars-bound mission in four or five years and boost off past Mars around the Sun, where it could orbit at a sufficient distance from Earth to effectively measure the microlensing parallax signal and fill in this missing information. Additionally, Barry said, if they are fortunate enough to detect a free-floating planet, the only way to confidently determine its mass, without resorting to galactic models to estimate a probable distance to the lens, will be through microlensing parallax. Stela Ishitani Silva, research assistant at Goddard and Ph.D. student at the Catholic University of America in Washington, DC, said understanding these free-floating planets will help fill in some of the gaps in our knowledge of how planets form. Some hypotheses predict there are many freefloating planets, while others predict only a few, she said. A survey in 2006 to 2007 found ten such planets through a microlensing technique from Mount John University Observatory in New Zealand. “So we really need to know how many free-floating planets are there,” Ishitani Silva said. “Can we get a statistical analysis of it? Because it’s not just about finding one planet — we want to find multiple free-floating planets and try to obtain information about their masses, so we can understand what is common or not common at all.” Continued on page 12
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The project is currently receiving Internal Research and Development (IRAD) funding to accomplish the necessary preliminary work on orbit, optics, artificial intelligence and science arguments as well as operating a Mission Planning Lab run at NASA’s Wallops Flight Facility, in Chincoteague, Virginia.
or deny what it is seeing in the light curve. The AI starts out by searching for random patterns, and then small adjustments are made to the patterns to get it closer to the right answer. Then, the researcher gives the AI another example and the process starts over.
“I’m really grateful for the IRAD support, because these very necessary steps simply wouldn’t be possible without it,” Barry said.
“And then you repeat this process many, many times,” Olmschenk said. “And this gets you progressively closer to a generalized answer that works well for any case. This itself is the training algorithm then — it’s a repetitive process where you’re giving the AI an example, asking what its prediction is, updating all the pieces of the AI, and then repeating.”
In order to efficiently find these planets, CUμLUS will use artificial intelligence. Dr. Greg Olmschenk, a postdoctoral researcher working with Barry at Goddard, has developed an AI, called RApid Machine learnEd Triage (RAMjET), for the mission. “I work with certain kinds of artificial intelligence called neural networks,” Olmschenk said. “It’s a type of artificial intelligence that will learn through examples. So, you give it a bunch of examples of the thing you want to find, and the thing you want it to filter out, and then it will learn how to recognize patterns in that data to try to find the things that you want to keep and the things you want to throw away.” Prior to beginning its mission, the AI is trained to know what to look for. This process typically begins by showing the AI, for example, a light curve — a graph that shows the brightness of an object over a particular period of time — and asking it to confirm
Eventually, the AI learns what it needs to identify and will only send back important information. In filtering this information, RAMjET will help save power and memory and keep costs down. “CUμLUS will permit us to estimate many highprecision masses for new planets detected by Roman and PRIME,” Barry said. “And it may allow us to capture or estimate the actual mass of a freefloating planet for the first time — which has never been done before. So cool, and so exciting. Really, it’s a new golden age for astronomy right now, and I’m just very excited about it.” v CONTACT Richard.K.Barry@nasa.gov or 301-286-0664
Small Mission to Shed New Light on Exoplanet Atmospheres A SmallSat mission called Pandora seeks new uses for well-known spectroscopy tools to doublecheck the compositions of exoplanet atmospheres that may have previously been misidentified due to fluctuations in the light of their host stars. “Pandora would be about a meter high and about half a meter wide, and it has two primary ways of measuring,” said Thomas Barclay, a research scientist at the University of Maryland Baltimore County and Goddard. “Light received by the telescope goes behind the mirror and is split into a visible light channel, which will be primarily used for measuring the brightness of the star over time, and an infrared channel, which we primarily use for understanding exoplanet atmospheres.” Most of the 4,400 planets found outside our solar system were discovered because they periodically PAGE 12
block light from their host stars – an event called a transit –as seen from our perspective on Earth. In order to obtain accurate measurements of the star’s brightness before and during the planet’s transit, the analysis methods assume the star’s disk is uniformly bright. However, this is not the case. One way starlight fluctuates is the presence of bright or dark spots rotating into and out of view. These features increase and decrease during the star’s activity cycle. Goddard research scientists Elisa Quintana and Barclay are working on a technology that takes that fluctuation into account. Different chemicals absorb light at different colors, which is true for the gases in exoplanet atmospheres too. Using a spectrometer, astronomers can study which wavelengths are absorbed, which Continued on page 13
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reveals the gases that make up a planet’s atmosphere. “The beauty of Pandora is that none of the individual things we are trying to do are new, but packaging them together in a small spacecraft is innovative,” Barclay said. Pandora’s infrared sensor was designed originally for the James Webb Space Telescope, and the mirror technology has also been used in previous missions. The mission would be the first satellite to undertake long-duration study of exoplanets using both visible infrared detectors at the same time, Quintana said. These instruments have never been included on an Astrophysics SmallSat before, which adds complications to the design. The limited size associated with a SmallSat, analogous to a small washing machine, presented an important challenge for the Pandora team. The infrared camera in particular must operate at very low temperatures, requiring a cryocooler. This, along with the necessary electronics to allow the spectrometers to work, complicates the design, as specific components of the satellite must remain www.nasa.gov/gsfctechnology
stable or cannot interact with sunlight. The technology and research being completed in relation to Pandora can benefit future missions as well. “Having simultaneous multi-wavelength observations is really how we are going to learn the most about complex phenomena like stellar activity and how it impacts planets,” Quintana explained, “so I think it’s something that people are going to want to duplicate.” For research focused on finding Earth-sized planets around cool M dwarf stars, or studies on how the proximity of “active” stars, with numerous and powerful stellar flares, affects the habitability of nearby planets, satellites similar to Pandora will be extremely useful. Beyond that, Pandora can become a model for other low-budget, high-impact projects. “As we have done with previous missions, future scientists can apply what we have learned about creating complex projects in a small volume and relatively constrained cost cap to their own missions.” Barclay said. Continued on page 14
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Image credit: NASA’s Goddard Space Flight Center/Francis Reddy
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Pandora is a middle-sized mission under a new program called Pioneers, which has a $20 million cost cap. This opens the door to missions between Explorer size and research and development programs. Pandora fits within this range and was selected along with three other concepts to be studied for six months. After a review process, Pandora may be selected to continue through the Pioneer program. If so, construction of the spacecraft and telescope can begin in partnership with the Lawrence Livermore National Lab. The Pioneer program allows missions like Pandora, which provide opportunities for scientists to explore ideas that can be accomplished through lowerbudget missions. “SmallSats enable early career scientists, and that enables us to have a diverse team,” Quintana said.
Pandora’s telescope has a 0.45 meter diameter aperture that will collect light for a visible channel, and will use a prism to split the light for an infrared channel. (Image credit: Lawrence Livermore National Lab and NASA’s Goddard Space Flight Center)
Quintana focused on allowing a diverse group of early career scientists to lead the mission’s science, engineering and management. By opening the doors for newer scientists to gain experience in leadership and focus on a unique science case, she said, the next generation of spaceflight leaders matures. Barclay also noted the importance of this aspect of Pandora, highlighting how a high number of the leadership are women and Hispanic scientists. “That makes Pandora stand out as doing things differently, and I think doing things better than we have done in the past,” Barclay said. The investments in the updated usage of spectroscopy technology as well as the future generations of diverse scientists create a noteworthy project out of Pandora. “We are a small mission,” Barclay said, “but we can do groundbreaking science.” v CONTACTS
Pandora will use transmission spectroscopy, a proven technique to identify the makeup of a planet’s atmosphere as it transits its host star. (Image credit: Lawrence Livermore National Lab and NASA’s Goddard Space Flight Center)
Elisa.Quintana@nasa.gov or 301-286-0851 Thomas.Barclay@nasa.gov or 301-286-5079
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Image credits: NASA/Goddard/University of Arizona/Lockheed Martin
Adapted Computer Program Pushes Satellite Navigation Toward Autonomy
This view of asteroid Bennu ejecting particles from its surface on January 19, 2019 was created by combining two images taken on board NASA’s OSIRIS-REx spacecraft. The Optical Navigation team on OSIRIS-REx used images of Bennu, like this one, to help navigate the spacecraft with unprecedented accuracy, proving the technology.
As Goddard engineers continue to push the boundaries of navigation technology, one team is working to make navigation easier for smaller satellites with less processing power and bandwidth. Optical navigation technology, adapted from NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRISREx) mission, would place navigation capabilities onboard satellites rather than on the ground like other, similar technologies. The new technology serves three purposes, said aerospace engineer and team lead Andrew Liounis: building a 3-D global model of the object the satellite is approaching — called a global shape model, modeling small patches of the same object in higher resolution, and estimating the relative brightness of spots on the surface. www.nasa.gov/gsfctechnology
With this new technology, satellites would not only be able to navigate better, but scientists and engineers would also get a better sense of the target objects, such as their geographical features and gravity fields. The team previously worked on navigation for OSIRIS-REx, helping create the high-resolution model of the asteroid Bennu. That mission had ample access to the Deep Space Network, which helps communicate data back to Earth, along with more ground workers to process the images once they arrived. Images were communicated back to Earth and compiled into a model in a long, handson process, using resources that might not be available for smaller missions. Continued on page 16
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“With small satellites, you run into a number of limitations, the largest being an issue with downlink bandwidth,” Liounis said. “On OSIRIS-REx we had on the order of 40,000 images. But on a smaller mission downlinking just hundreds of images could be prohibitively expensive.”
Image credit: Josh Lyzhoft
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This year, Liounis’s team received Internal Research and Development (IRAD) funding to support additional development. The team is developing the project as part of onboard This is a shape model built from an early prototype of the flight software, using images of Vesta taken by the Dawn mission. tool cGIANT — based on the Goddard Image “With these small projects, we won’t necessarily Analysis and Navigation Tool, GIANT which was have the same bandwidth,” Lyzhoft said. “We won’t improved in FY19 and FY20 by IRAD and other have the funds to do all the shape modeling on the funding (See CuttingEdge Spring 2019, Page 10). ground; we won’t have the humans to do all this cGIANT is a part of the automatic Navigation Guidprocessing. But we’re reducing these costs by startance and Control, or autoNGC, suite of autonoing to make this autonomous, and it’ll be easier to mous tools. This funding allowed the team to denavigate these small bodies in the future to do more velop a way to break up the algorithm’s processing space exploration.” steps, allowing for regions of a shape model to be developed separately then added together, rather Right now, the team has a functioning software than processing the entire model at once. Splitting prototype of this new optical navigation technology. the steps enables them to run the algorithms even They’re using it to look for bottlenecks, or places on small satellites with limited computational power. where the code slows down. The team can then send it to specialized software engineers to turn the Onboard shape modeling has been both a great technology into flight code and continue to test and challenge and great success, said team member validate the system. Finally, the team will work with Joshua Lyzhoft. The team knew that by decreasing other projects to incorporate this technology into a the initial amount of the images used to make the satellite and fly it in space. models and providing updates with newly obtained images, they could cut costs while maintaining the The key focus of this optical navigation technology efficacy of the program. To do so onboard a small is automation. In the future, only one person might satellite, they needed to develop new methods be needed to make sure the system is functionof creating models that are more robust and less ing properly, Lyzhoft said, rather than the team of computationally expensive. people required to process this data currently. These adaptations bring autonomous visual “We’re trying to automate a lot of things to not navigation within reach of small-satellite missions, require as much human involvement in the system,” who’s limitations arise from a number of factors, he said. “When it comes to navigating small bodies, particularly radiation-hardened technology. In it would be really good to have this automation to space, satellites no longer have radiation protechelp reduce mission costs and improve computation from earth’s atmosphere, which can cause tional requirements.” v electronics to behave unpredictably. Scientists and engineers must harden their technologies against CONTACT space radiation. This process protects the technoloAndrew.J.Liounis@nasa.gov or 301-286-2856 gies onboard, but decreases processing power and costs more.
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Scientist Looks for Specific Energy Emissions to Identify Sources of Cosmic Positrons The universe contains far more than what can be seen with even the most advanced telescopes currently functioning. Even the Milky Way galaxy contains secrets scientists are still trying to pry out of the darkness. One of these mysteries lies in the center of the galaxy, where electrons and positrons collide and annihilate, transforming into gamma rays of a characteristic energy. Scientists discovered the radiation — called the positron annihilation line, measured at 511 kiloelectron volts (keV) — decades ago, but the sources of the positrons remain unknown. Goddard astrophysicist Dr. Carolyn Kierans is developing a telescope concept that would provide the necessary resolution to identify where the positrons – the antimatter counterpart of electrons – are coming from. “There are regions in the galaxy that we know should be emitting 511 keV because massive stars emit positrons as they evolve,” Kierans said. “If we point a high-angular-resolution telescope at one of these sources, we could confirm for the first time that we see a positron source.”
In this composite image of Cygnus OB2, X-rays from Chandra (red diffuse emission and blue point sources) are shown with optical data from the Isaac Newton Telescope (diffuse emission in light blue) and infrared data from the Spitzer Space Telescope (orange). (Image credit: X-ray: NASA/CXC/SAO/J. Drake et al;
H-alpha: Univ. of Hertfordshire/INT/IPHAS; Infrared: NASA/JPL-Caltech/Spitzer) While the technology is a few years away, Kierans said, they want to start done before. While Chandra collects photons in a development now in anticipation of results from similar way, and is very effective within the 1 to 10 other proposed mission concepts, such as the keV band, it is unable to focus photons at higher Compton Spectrometer and Imager (COSI) and the energies. All-sky Medium Energy Gamma-ray Observatory Explorer (AMEGO-X), now under study. Once 511Kierans said if the technology was used in a large keV hot spots have been identified in the galaxy, telescope, it would amount to bringing unprecKierans’ instrument can perform more detailed edented NuSTAR-like capabilities to the gamma-ray observations. range. NuSTAR is the current record-holder for
In order to accomplish this, Kierans requires optics that can focus and image gamma rays.
high-energy focusing capabilities; it is sensitive to X-rays from 3 to 79 keV.
Dr. Danielle Gurgew, a NASA postdoctoral fellow at Goddard, said the technology concept is exciting because it would provide an advantage for several realms in gamma-ray astrophysics. Both Gurgew and Kierans emphasized that imaging in the sense of focusing gamma rays has never been
Gurgew is working to develop grazing incident reflectors for so-called hard X-rays. Hard X-rays have energies greater than 10 keV, she said. At still higher energies, such as 511 keV, the radiation takes the form of gamma rays.
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“Grazing incidence X-ray optics optimized for high energies could focus gamma-ray photons to a much smaller point on the telescope detectors than previous gamma-ray instruments operating at 511 keV,” Gurgew said. This both increases the telescope’s sensitivity to gamma-ray light, and allows for much higher-resolution imaging of these sources, Gurgew said. Gurgew is working on going beyond what X-ray missions such as Chandra or XMM-Newton have done in focusing photons. She anticipates extending the energy band for focusing optics up to several hundred keV, into the gamma ray band. “So instead of just a single thin film of highly reflective materials, like the iridium Chandra uses, we use a more complex structure — a multilayer coating,” Gurgew said. Such a coating boosts reflectivity, allowing for imaging at higher energies, Gurgew said. This technology will ideally be able to image anywhere from 2 to 200 keV, she said. However, Kierans’ project demands imaging at an even higher energy — so the goal is to build on this work to investigate a multilayer coating capable of imaging at 511 keV.
Looking Forward The technology is still in the very early stages of development. Kierans said the next step involves proposing for an Astrophysics Research and Analysis Program (APRA) technology and development grant to process small samples of a few different multilayer coatings and test them in the lab. For a 511 keV telescope, the optics would require hundreds of individual layers with a thickness measured in dozens of angstroms. Each layer could be only about 10 atoms thick. This is particularly challenging since the individual layers also need to be very smooth. Understanding how different combinations of materials interact with one another during multilayer processing is crucial. Kierans said performing tests of small mirror substrates would be the first step in this development. It is still unclear whether the current state-of-the-art
predictions of multilayer coating performance are valid at gamma-ray energies, and comparing the results of laboratory measurements with models will be a big step in our understanding of how we can extend this technology to the 511 keV goal, Kierans said. If there is ever a desire to reach energy levels higher than 511 keV, Gurgew said they may run into issues while working at such a small scale. Essentially, the higher the energy, the thinner the layer becomes, and you run into a point where you can’t physically deposit thin or smooth enough layers to achieve that energy. One other technological challenge is that a 511 keV focusing telescope needs to have a large focal length, at 50 to 100 meters, with really small grazing angles, between 0.01 and 0.04 degrees. This will require precision formation flying using two satellites: one for the mirror and one for the telescope detector. The 511 keV focusing telescope without a doubt has its challenges, said Gurgew, but if proven successful over time, could revolutionize gammaray astrophysics as we know it. “Proposing to get something like this launched would be obviously a wonderful next step,” Kierans said. “But being realistic, expanding the energy range would be the next most feasible step in terms of advancing the technology in other science directions as well. Because if we can image a large band of energy, then others are going to be interested in using it for wider gamma-ray energies, not just 511 keV.” Gurgew said demonstrating the optics capability at 511 keV is likely the best way to move forward with the project. As far as the current guesses are for what they hope to find when searching for the source of positrons with this technology some people think the answer could be related to dark matter or something beyond the standard model of physics. “Once we do understand the sources of positrons,” Kierans said, “the 511 keV emission can be used as a tool to better understand their galactic environments.” v CONTACT Carolyn.A.Kierans@nasa.gov or 301-286-7628
CuttingEdge is published quarterly by the Office of the Chief Technologist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. The publication describes the emerging, potentially transformative technologies that Goddard is pursuing to help NASA achieve its missions. For more information about Goddard technology, visit the website listed below or contact Chief Technologist Peter Hughes, Peter.M.Hughes@nasa.gov. If you wish to be placed on the publication’s distribution list, contact Editor Karl Hille, Karl.B.Hille@nasa.gov. Contributors to this issue include: Emma Edmund, Julie Freijat, Erica McNamee, Katherine Shauer, Amy Klarup and Daniel Baird. Publication Number: NP-2021-6-677-GSFC
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