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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 European Space Agency
Image: This Copernicus Sentinel-2 image captures the borders between North and South Dakota and Minnesota blanketed with snow and ice. View the full article
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By NASA
Pandora, NASA’s newest exoplanet mission, is one step closer to launch with the completion of the spacecraft bus, which provides the structure, power, and other systems that will enable the mission to carry out its work.
Watch to learn more about NASA’s Pandora mission, which will revolutionize the study of exoplanet atmospheres.
NASA’s Goddard Space Flight Center “This is a huge milestone for us and keeps us on track for a launch in the fall,” said Elisa Quintana, Pandora’s principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The bus holds our instruments and handles navigation, data acquisition, and communication with Earth — it’s the brains of the spacecraft.”
Pandora, a small satellite, will provide in-depth study of at least 20 known planets orbiting distant stars in order to determine the composition of their atmospheres — especially the presence of hazes, clouds, and water. This data will establish a firm foundation for interpreting measurements by NASA’s James Webb Space Telescope and future missions that will search for habitable worlds.
Pandora’s spacecraft bus was photographed Jan. 10 within a thermal-vacuum testing chamber at Blue Canyon Technologies in Lafayette, Colorado. The bus provides the structure, power, and other systems that will enable the mission to help astronomers better separate stellar features from the spectra of transiting planets. NASA/Weston Maughan, BCT “We see the presence of water as a critical aspect of habitability because water is essential to life as we know it,” said Goddard’s Ben Hord, a NASA Postdoctoral Program Fellow who discussed the mission at the 245th meeting of the American Astronomical Society in National Harbor, Maryland. “The problem with confirming its presence in exoplanet atmospheres is that variations in light from the host star can mask or mimic the signal of water. Separating these sources is where Pandora will shine.”
Funded by NASA’s Astrophysics Pioneers program for small, ambitious missions, Pandora is a joint effort between Lawrence Livermore National Laboratory in California and NASA Goddard.
“Pandora’s near-infrared detector is actually a spare developed for the Webb telescope, which right now is the observatory most sensitive to exoplanet atmospheres,” Hord added. “In turn, our observations will improve Webb’s ability to separate the star’s signals from those of the planet’s atmosphere, enabling Webb to make more precise atmospheric measurements.”
Astronomers can sample an exoplanet’s atmosphere when it passes in front of its star as seen from our perspective, an event called a transit. Part of the star’s light skims the atmosphere before making its way to us. This interaction allows the light to interact with atmospheric substances, and their chemical fingerprints — dips in brightness at characteristic wavelengths — become imprinted in the light.
But our telescopes see light from the entire star as well, not just what’s grazing the planet. Stellar surfaces aren’t uniform. They sport hotter, unusually bright regions called faculae and cooler, darker regions similar to sunspots, both of which grow, shrink, and change position as the star rotates.
An artist’s concept of the Pandora mission, seen here without the thermal blanketing that will protect the spacecraft, observing a star and its transiting exoplanet. NASA’s Goddard Space Flight Center/Conceptual Image Lab Using a novel all-aluminum, 45-centimeter-wide (17 inches) telescope, jointly developed by Livermore and Corning Specialty Materials in Keene, New Hampshire, Pandora’s detectors will capture each star’s visible brightness and near-infrared spectrum at the same time, while also obtaining the transiting planet’s near-infrared spectrum. This combined data will enable the science team to determine the properties of stellar surfaces and cleanly separate star and planetary signals.
The observing strategy takes advantage of the mission’s ability to continuously observe its targets for extended periods, something flagship missions like Webb, which are in high demand, cannot regularly do.
Over the course of its year-long prime mission, Pandora will observe at least 20 exoplanets 10 times, with each stare lasting a total of 24 hours. Each observation will include a transit, which is when the mission will capture the planet’s spectrum.
Pandora is led by NASA’s Goddard Space Flight Center. Lawrence Livermore National Laboratory provides the mission’s project management and engineering. Pandora’s telescope was manufactured by Corning and developed collaboratively with Livermore, which also developed the imaging detector assemblies, the mission’s control electronics, and all supporting thermal and mechanical subsystems. The infrared sensor was provided by NASA Goddard. Blue Canyon Technologies provided the bus and is performing spacecraft assembly, integration, and environmental testing. NASA’s Ames Research Center in California’s Silicon Valley will perform the mission’s data processing. Pandora’s mission operations center is located at the University of Arizona, and a host of additional universities support the science team.
Download high-resolution video and images from NASA’s Scientific Visualization Studio
By Francis Reddy
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Media Contact:
Claire Andreoli
301-286-1940
claire.andreoli@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Jan 16, 2025 Related Terms
Astrophysics Astrophysics Division Exoplanet Atmosphere Exoplanet Exploration Program Exoplanet Science Exoplanet Transits Exoplanets Goddard Space Flight Center Studying Exoplanets The Universe View the full article
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By NASA
NASA On April 21, 1972, NASA astronaut John W. Young, commander of the Apollo 16 mission, took a far-ultraviolet photo of Earth with an ultraviolet camera. Young’s original black-and-white picture was printed on Agfacontour professional film three times, with each exposure recording only one light level. The three light levels were then colored blue (dimmest), green (next brightest), and red (brightest), resulting in the enhanced-color image seen here.
Dr. George Carruthers, a scientist at the Naval Research Laboratory, developed the ultraviolet camera – the first Moon-based observatory – for Apollo 16. Apollo 16 astronauts placed the observatory on the Moon in April 1972, where it sits today on the Moon’s Descartes highland region, in the shadow of the lunar module Orion.
Image credit: NASA
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By European Space Agency
On 8 January 2025, the ESA/JAXA BepiColombo mission flew past Mercury for the sixth time, successfully completing the final ‘gravity assist manoeuvre’ needed to steer it into orbit around the planet in late 2026. The spacecraft flew just a few hundred kilometres above the planet's north pole. Close-up images expose possibly icy craters whose floors are in permanent shadow, and the vast sunlit northern plains.
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