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New Research That Uses Gravitationally Lensed Quasars to Measure Universe is Good News, Bad News for Cosmologists
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By NASA
NASA’s Jet Propulsion Laboratory used radar data taken by ESA’s Sentinel-1A satellite before and after the 2015 eruption of the Calbuco volcano in Chile to create this inter-ferogram showing land deformation. The color bands west of the volcano indicate land sinking. NISAR will produce similar images.ESA/NASA/JPL-Caltech A SAR image — like ones NISAR will produce — shows land cover on Mount Okmok on Alaska’s Umnak Island . Created with data taken in August 2011 by NASA’s UAVSAR instrument, it is an example of polarimetry, which measures return waves’ orientation relative to that of transmitted signals.NASA/JPL-Caltech Data from NASA’s Magellan spacecraft, which launched in 1989, was used to create this image of Crater Isabella, a 108-mile-wide (175-kilometer-wide) impact crater on Venus’ surface. NISAR will use the same basic SAR principles to measure properties and characteristics of Earth’s solid surfaces.NASA/JPL-Caltech Set to launch within a few months, NISAR will use a technique called synthetic aperture radar to produce incredibly detailed maps of surface change on our planet.
When NASA and the Indian Space Research Organization’s (ISRO) new Earth satellite NISAR (NASA-ISRO Synthetic Aperture Radar) launches in coming months, it will capture images of Earth’s surface so detailed they will show how much small plots of land and ice are moving, down to fractions of an inch. Imaging nearly all of Earth’s solid surfaces twice every 12 days, it will see the flex of Earth’s crust before and after natural disasters such as earthquakes; it will monitor the motion of glaciers and ice sheets; and it will track ecosystem changes, including forest growth and deforestation.
The mission’s extraordinary capabilities come from the technique noted in its name: synthetic aperture radar, or SAR. Pioneered by NASA for use in space, SAR combines multiple measurements, taken as a radar flies overhead, to sharpen the scene below. It works like conventional radar, which uses microwaves to detect distant surfaces and objects, but steps up the data processing to reveal properties and characteristics at high resolution.
To get such detail without SAR, radar satellites would need antennas too enormous to launch, much less operate. At 39 feet (12 meters) wide when deployed, NISAR’s radar antenna reflector is as wide as a city bus is long. Yet it would have to be 12 miles (19 kilometers) in diameter for the mission’s L-band instrument, using traditional radar techniques, to image pixels of Earth down to 30 feet (10 meters) across.
Synthetic aperture radar “allows us to refine things very accurately,” said Charles Elachi, who led NASA spaceborne SAR missions before serving as director of NASA’s Jet Propulsion Laboratory in Southern California from 2001 to 2016. “The NISAR mission will open a whole new realm to learn about our planet as a dynamic system.”
Data from NASA’s Magellan spacecraft, which launched in 1989, was used to create this image of Crater Isabella, a 108-mile-wide (175-kilometer-wide) impact crater on Venus’ surface. NISAR will use the same basic SAR principles to measure properties and characteristics of Earth’s solid surfaces.NASA/JPL-Caltech How SAR Works
Elachi arrived at JPL in 1971 after graduating from Caltech, joining a group of engineers developing a radar to study Venus’ surface. Then, as now, radar’s allure was simple: It could collect measurements day and night and see through clouds. The team’s work led to the Magellan mission to Venus in 1989 and several NASA space shuttle radar missions.
An orbiting radar operates on the same principles as one tracking planes at an airport. The spaceborne antenna emits microwave pulses toward Earth. When the pulses hit something — a volcanic cone, for example — they scatter. The antenna receives those signals that echo back to the instrument, which measures their strength, change in frequency, how long they took to return, and if they bounced off of multiple surfaces, such as buildings.
This information can help detect the presence of an object or surface, its distance away, and its speed, but the resolution is too low to generate a clear picture. First conceived at Goodyear Aircraft Corp. in 1952, SAR addresses that issue.
“It’s a technique to create high-resolution images from a low-resolution system,” said Paul Rosen, NISAR’s project scientist at JPL.
As the radar travels, its antenna continuously transmits microwaves and receives echoes from the surface. Because the instrument is moving relative to Earth, there are slight changes in frequency in the return signals. Called the Doppler shift, it’s the same effect that causes a siren’s pitch to rise as a fire engine approaches then fall as it departs.
Computer processing of those signals is like a camera lens redirecting and focusing light to produce a sharp photograph. With SAR, the spacecraft’s path forms the “lens,” and the processing adjusts for the Doppler shifts, allowing the echoes to be aggregated into a single, focused image.
Using SAR
One type of SAR-based visualization is an interferogram, a composite of two images taken at separate times that reveals the differences by measuring the change in the delay of echoes. Though they may look like modern art to the untrained eye, the multicolor concentric bands of interferograms show how far land surfaces have moved: The closer the bands, the greater the motion. Seismologists use these visualizations to measure land deformation from earthquakes.
Another type of SAR analysis, called polarimetry, measures the vertical or horizontal orientation of return waves relative to that of transmitted signals. Waves bouncing off linear structures like buildings tend to return in the same orientation, while those bouncing off irregular features, like tree canopies, return in another orientation. By mapping the differences and the strength of the return signals, researchers can identify an area’s land cover, which is useful for studying deforestation and flooding.
Such analyses are examples of ways NISAR will help researchers better understand processes that affect billions of lives.
“This mission packs in a wide range of science toward a common goal of studying our changing planet and the impacts of natural hazards,” said Deepak Putrevu, co-lead of the ISRO science team at the Space Applications Centre in Ahmedabad, India.
Learn more about NISAR at:
https://nisar.jpl.nasa.gov
News Media Contacts
Andrew Wang / Jane J. Lee
Jet Propulsion Laboratory, Pasadena, Calif.
626-379-6874 / 818-354-0307
andrew.wang@jpl.nasa.gov / jane.j.lee@jpl.nasa.gov
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Last Updated Jan 21, 2025 Related Terms
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By NASA
Insights into metal alloy solidification
Researchers report details of phase and structure in the solidification of metal alloys on the International Space Station, including formation of microstructures. Because these microstructures determine a material’s mechanical properties, this work could support improvements in techniques for producing coatings and additive manufacturing or 3D printing processes.
METCOMP, an ESA (European Space Agency) investigation, studied solidification in microgravity using transparent organic mixtures as stand-ins for metal alloys. Conducting the research in microgravity removed the influence of convection and other effects of gravity. Results help scientists better understand and validate models of solidification mechanisms, enabling better forecasting of microstructures and improving manufacturing processes.
Image from the METCOMP investigation of how a metal alloy could look like as it solidifies. E-USOC Measuring the height of upper-atmospheric electrical discharges
Researchers determined the height of a blue discharge from a thundercloud using ground-based electric field measurements and space-based optical measurements from Atmosphere-Space Interactions Monitor (ASIM). This finding helps scientists better understand how these high-altitude lightning-related events affect atmospheric chemistry and could help improve atmospheric models and climate and weather predictions.
ESA’s ASIM is an Earth observation facility that studies severe thunderstorms and upper-atmospheric lighting events and their role in the Earth’s atmosphere and climate. Upper-atmospheric lightning, also known as transient luminous events, occurs well above the altitudes of normal lightning and storm clouds. The data collected by ASIM could support research on the statistical properties of many upper atmosphere lightning events, such as comparison of peak intensities of blue and red pulses with reports from lightning detection networks.
An artist’s impression of a blue jet as observed from the International Space Station.Mount Visual/University of Bergen/DTU Modeling a complex neutron star
Scientists report that they can use modeling of neutron star PSRJ1231−1411’s X-ray pulses to infer its mass and radius and narrow the possible behaviors of the dense matter at its core. This finding provides a better understanding of the composition and structure of these celestial objects, improving models that help answer questions about conditions in the universe.
The Neutron star Interior Composition Explorer provides high-precision measurements of pulses of X-ray radiation from neutron stars. This particular neutron star presented challenges in finding a fit between models and data, possibly due to fundamental issues with its pulse profile. The authors recommend a program of simulations using synthetic data to determine whether there are fundamental issues with this type of pulse profile that could prevent efforts to obtain tighter and more robust constraints.
Concentrators on the Neutron star Interior Composition Explorer instrument.NASAView the full article
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By NASA
Freelancer NASA’s Sustainable Business Model Challenge is looking for entrepreneurs, startups, and researchers to leverage the agency’s publicly available Earth system science data to develop commercial solutions for climate challenges.
This opportunity, with a submission deadline of June 13, bridges the gap between vast climate data and actionable solutions by inviting solvers to transform data into sustainable business models that support climate resilience and decision-making.
“Creative, outcome-driven entrepreneurs are the lifeblood of our country’s economy, and we’re excited to see the sustainable climate solutions they’re able to come up with when working closely with NASA’s vast resources and data,” said Jason L. Kessler, program executive for the NASA Small Business Innovation Research / Small Business Technology Transfer (SBIR/STTR) program, which is sponsoring the challenge.
Through the Sustainable Business Model Challenge, NASA aims to foster a new set of sustainable enterprises capable of turning climate insights into tangible market-ready services, ultimately contributing to a more resilient future for vulnerable communities, businesses, and ecosystems. NASA is committed to broadening participation in its solicitations and fostering technology advancements.
By engaging new entrepreneurs, the challenge serves as a pathway to NASA’s SBIR/STTR program, helping scale solutions to advance the global response to climate change and encourage a more sustainable future. From its vantage point in space, NASA holds a wealth of data that can inform new approaches to climate adaptation and mitigation.
Participants will submit a 10-page business concept paper that includes details on how they will incorporate NASA climate or Earth system data to deliver a product or service. Up to ten winning teams will receive $10,000 each, along with admission to a 10-week capability development training designed to strengthen any future proposals for potential NASA funding.
NASA’s SBIR/STTR program, managed by the agency’s Space Technology Mission Directorate, is part of America’s Seed Fund, the nation’s largest source of early-stage funding for innovative technologies. Through this program, entrepreneurs, startups, and small businesses with less than 500 employees can receive funding and non-monetary support to build, mature, and commercialize their technologies, advancing NASA missions and advancing the nations aerospace economy.
Ensemble is hosting the challenge on behalf of NASA. The NASA Tournament Lab, part of the Prizes, Challenges, and Crowdsourcing program in the Space Technology Mission Directorate, manages the challenge. The program supports global public competitions and crowdsourcing as tools to advance NASA research and development and other mission needs.
The deadline to participate in NASA’s Sustainable Business Model Challenge is June 13, 2025.
For more information about the challenge, visit: https://nasabusinesschallenge.org/
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By Space Force
Space Launch Delta 45 supported the maiden flight for Blue Origin’s New Glenn from Space Launch Complex 36 at Cape Canaveral Space Force Station.
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By NASA
NASA Elton W. Miller, chief of aerodynamics at what is now NASA’s Langley Research Center in Hampton, Virginia, stands in the entrance cone of the Propeller Research Tunnel in this Sept. 9, 1926, photo. In front of the entrance is the Sperry M-1 Messenger, the first full-scale airplane tested in the tunnel.
The Propeller Research Tunnel, or PRT as it came to be known, was only the National Advisory Committee for Aeronautics’ third wind tunnel and the largest one built. The PRT was in fact the largest tunnel built at that time anywhere in the world. Designed to accommodate a full-scale propeller, the throat of the PRT was 20 feet in diameter.
Learn more about the PRT from the report originally published in December 1928.
Image credit: NASA
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