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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
NISAR (NASA-ISRO Synthetic Aperture Radar) Earth Earth Science Earth Science Division Jet Propulsion Laboratory Explore More
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A capacity increase by almost 80%! In late July 2024, the Malargüe deep-space communication station completed an important upgrade of its antenna feed that will allow missions to send much more data back to Earth.
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By European Space Agency
The first IRIDE satellite – the Pathfinder Hawk – is now in orbit around Earth after lifting off on a SpaceX Falcon 9 rocket from the Vandenberg Space Force Base in California on 14 January.
As its ‘Pathfinder’ name suggests, this new microsatellite is a prototype for one of the six IRIDE constellations, which are tailored to provide information for a wide range of environmental, emergency and security services for Italy.
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By NASA
Internal view of LignoSat’s structure shows the relationship among wooden panels, aluminum frames, and stainless-steel shafts.Credit: Kyoto University In December 2024, five CubeSats deployed into Earth’s orbit from the International Space Station. Among them was LignoSat, a wooden satellite from JAXA (Japanese Aerospace Exploration Agency) that investigates the use of wood in space. Findings could offer a more sustainable alternative to conventional satellites.
A previous experiment aboard station exposed three species of wood to the space environment to help researchers determine the best option for LignoSat. The final design used 10 cm long honoki magnolia wood panels assembled with a Japanese wood-joinery method.
Researchers will use sensors to evaluate strain on the wood and measure its responses to temperature and radiation in space. Geomagnetic levels will also be monitored to determine whether the geomagnetic field can penetrate the body of the wooden satellite and interfere with its technological capabilities. Investigating uses for wood in space could lead to innovative solutions in the future.
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Danah Tommalieh, commercial pilot and engineer at Reliable Robotics, inputs a flight plan at the control center in Mountain View, California, ahead of remotely operating a Cessna 208 aircraft at Hollister municipal airport in Hollister, California.NASA/Don Richey NASA recently began a series of flight tests with partners to answer an important aviation question: What will it take to integrate remotely piloted or autonomous planes carrying large packages and cargo safely into the U.S. airspace? Researchers tested new technologies in Hollister, California, that are helping to investigate what tools and capabilities are needed to make these kinds of flights routine.
The commercial industry continues to make advancements in autonomous aircraft systems aimed at making it possible for remotely operated aircraft to fly over communities – transforming the way we will transport people and goods. As the Federal Aviation Administration (FAA) develops standards for this new type of air transportation, NASA is working to ensure these uncrewed flights are safe by creating the required technological tools and infrastructure. These solutions could be scaled to support many different remotely piloted aircraft – including air taxis and package delivery drones – in a shared airspace with traditional crewed aircraft.
“Remotely piloted aircraft systems could eventually deliver cargo and people to rural areas with limited access to commercial transportation and delivery services,” said Shivanjli Sharma, aerospace engineer at NASA’s Ames Research Center in California’s Silicon Valley. “We’re aiming to create a healthy ecosystem of many different kinds of remotely piloted operations. They will fly in a shared airspace to provide communities with better access to goods and services, like medical supply deliveries and more efficient transportation.”
During a flight test in November, Reliable Robotics, a company developing an autonomous flight system, remotely flew its Cessna 208 Caravan aircraft through pre-approved flight paths in Hollister, California.
Although a safety pilot was aboard, a Reliable Robotics remote pilot directed the flight from their control center in Mountain View, more than 50 miles away.
Cockpit of Reliable Robotics’ Cessna 208 aircraft outfitted with autonomous technology for remotely-piloted operations.NASA/Brandon Torres Navarrete Congressional staffers from the United States House and Senate’s California delegation joined NASA Deputy Associate Administrator for Aeronautics Research Mission Directorate, Carol Caroll, Ames Aeronautics Director, Huy Tran, and other Ames leadership at Reliable Robotics Headquarters to view the live remote flight.
Researchers evaluated a Collins Aerospace ground-based surveillance system’s ability to detect nearby air traffic and provide the remote pilot with information in order to stay safely separated from other aircraft in the future.
Initial analysis shows the ground-based radar actively surveilled the airspace during the aircraft’s taxi, takeoff, and landing. The data was transmitted from the radar system to the remote pilot at Reliable Robotics. In the future, this capability could help ensure aircraft remain safely separated across all phases of fight.
A Reliable Robotics’ modified Cessna 208 aircraft flies near Hollister Airport. A Reliable Robotics pilot operated the aircraft remotely from the control center in Mountain View.NASA/Brandon Torres Naverrete While current FAA operating rules require pilots to physically see and avoid other aircraft from inside the cockpit, routine remotely piloted aircraft will require a suite of integrated technologies to avoid hazards and coordinate with other aircraft in the airspace.
A radar system for ground-based surveillance offers one method for detecting other traffic in the airspace and at the airport, providing one part of the capability to ensure pilots can avoid collision and accomplish their desired missions. Data analysis from this testing will help researchers understand if ground-based surveillance radar can be used to satisfy FAA safety rules for remotely piloted flights.
NASA will provide analysis and reports of this flight test to the FAA and standards bodies.
“This is an exciting time for the remotely piloted aviation community,” Sharma said. “Among other benefits, remote operations could provide better access to healthcare, bolster natural disaster response efforts, and offer more sustainable and effective transportation to both rural and urban communities. We’re thrilled to provide valuable data to the industry and the FAA to help make remote operations a reality in the near future.”
Over the next year, NASA will work with additional aviation partners on test flights and simulations to test weather services, communications systems, and other autonomous capabilities for remotely piloted flights. NASA researchers will analyze data from these tests to provide a comprehensive report to the FAA and the community on what minimum technologies and capabilities are needed to enable and scale remotely piloted operations.
This flight test data analysis is led out of NASA Ames under the agency’s Air Traffic Management Exploration project. This effort supports the agency’s Advanced Air Mobility mission research, ensuring the United States stays at the forefront of aviation innovation.
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Last Updated Jan 07, 2025 Related Terms
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