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Forest measuring satellite passes tests with flying colours
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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
Firefly Aerospace’s Blue Ghost lander getting encapsulated in SpaceX’s rocket fairing ahead of the planned liftoff for 1:11 a.m. EST Jan. 15 from Launch Complex 39A at NASA’s Kennedy Space Center in FloridaSpaceX As part of NASA’s CLPS (Commercial Lunar Payload Services) initiative and Artemis campaign, the agency is preparing to fly ten instruments aboard Firefly Aerospace’s first delivery to the Moon. These science payloads and technology demonstrations will help advance our understanding of the Moon and planetary processes, while paving the way for future crewed missions on the Moon and beyond, for the benefit of all.
Firefly’s lunar lander, named Blue Ghost, is scheduled to launch on a SpaceX Falcon 9 rocket Wednesday, Jan.15, from Launch Complex 39A at NASA’s Kennedy Space Center in Florida. After a 45-day cruise phase, Blue Ghost is targeted to land near a volcanic feature called Mons Latreille within Mare Crisium, a basin approximately 340 miles wide (550 kilometers) located in the northeast quadrant of the Moon’s near side.
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The ten NASA payloads aboard Firefly’s Blue Ghost lander include:
Lunar Instrumentation for Subsurface Thermal Exploration with Rapidity (LISTER) will measure heat flow from the Moon’s interior by measuring the thermal gradient, or changes in temperature at various depths, and thermal conductivity, or the subsurface material’s ability to let heat pass through it. LISTER will take several measurements up to 10 feet deep using pneumatic drilling technology with a custom heat flow needle instrument at its tip. Data from LISTER will help scientists retrace the Moon’s thermal history and understand how it formed and cooled. Lead organization: Texas Tech University
Lunar PlanetVac (LPV) is designed to collect regolith samples from the lunar surface using a burst of compressed gas to drive the regolith into a sample chamber (sieving) for collection and analysis by various instruments. Additional instrumentation will then transmit the results back to Earth. The LPV payload is designed to help increase the science return from planetary missions by testing low-cost technologies for collecting regolith samples in-situ. Lead organization: Honeybee Robotics
Next Generation Lunar Retroreflector (NGLR) serves as a target for lasers on Earth to precisely measure the distance between Earth and the Moon by reflecting very short laser pulses from Earth-based Lunar Laser Ranging Observatories. The laser pulse transit time to the Moon and back is used to determine the distance. Data from NGLR could improve the accuracy of our lunar coordinate system and contribute to our understanding of the inner structure of the Moon and fundamental physics questions. Lead organization: University of Maryland
Regolith Adherence Characterization (RAC) will determine how lunar regolith sticks to a range of materials exposed to the Moon’s environment throughout the lunar day. RAC will measure accumulation rates of lunar regolith on surfaces (for example, solar cells, optical systems, coatings, and sensors) through imaging to determine their ability to repel or shed lunar dust. The data captured will help test, improve, and protect spacecraft, spacesuits, and habitats from abrasive regolith. Lead organization: Aegis Aerospace
Radiation Tolerant Computer (RadPC) will demonstrate a computer that can recover from faults caused by ionizing radiation. Several RadPC prototypes have been tested aboard the International Space Station and Earth-orbiting satellites, but this flight will provide the biggest trial yet by demonstrating the computer’s ability to withstand space radiation as it passes through Earth’s radiation belts, while in transit to the Moon, and on the lunar surface. Lead organization: Montana State University
Electrodynamic Dust Shield (EDS) is an active dust mitigation technology that uses electric fields to move and prevent hazardous lunar dust accumulation on surfaces. EDS is designed to lift, transport, and remove particles from surfaces with no moving parts. Multiple tests will demonstrate the feasibility of the self-cleaning glasses and thermal radiator surfaces on the Moon. In the event the surfaces do not receive dust during landing, EDS has the capability to re-dust itself using the same technology. Lead organization: NASA’s Kennedy Space Center
Lunar Environment heliospheric X-ray Imager (LEXI) will capture a series of X-ray images to study the interaction of solar wind and Earth’s magnetic field that drives geomagnetic disturbances and storms. Deployed and operated on the lunar surface, this instrument will provide the first global images showing the edge of Earth’s magnetic field for critical insights into how space weather and other cosmic forces surrounding our planet impact Earth. Lead organizations: Boston University, NASA’s Goddard Space Flight Center, and Johns Hopkins University
Lunar Magnetotelluric Sounder (LMS) will characterize the structure and composition of the Moon’s mantle by measuring electric and magnetic fields. This investigation will help determine the Moon’s temperature structure and thermal evolution to understand how the Moon has cooled and chemically differentiated since it formed. Lead organization: Southwest Research Institute
Lunar GNSS Receiver Experiment (LuGRE) will demonstrate the possibility of acquiring and tracking signals from GNSS (Global Navigation Satellite System) constellations, specifically GPS and Galileo, during transit to the Moon, during lunar orbit, and on the lunar surface. If successful, LuGRE will be the first pathfinder for future lunar spacecraft to use existing Earth-based navigation constellations to autonomously and accurately estimate their position, velocity, and time. Lead organizations: NASA Goddard, Italian Space Agency
Stereo Camera for Lunar Plume-Surface Studies (SCALPSS) will use stereo imaging photogrammetry to capture the impact of the rocket exhaust plume on lunar regolith as the lander descends on the Moon’s surface. The high-resolution stereo images will aid in creating models to predict lunar regolith erosion, which is an important task as bigger, heavier spacecraft and hardware are delivered to the Moon in close proximity to each other. This instrument also flew on Intuitive Machines’ first CLPS delivery. Lead organization: NASA’s Langley Research Center
Through the CLPS initiative, NASA purchases lunar landing and surface operations services from American companies. The agency uses CLPS to send scientific instruments and technology demonstrations to advance capabilities for science, exploration, or commercial development of the Moon. By supporting a robust cadence of lunar deliveries, NASA will continue to enable a growing lunar economy while leveraging the entrepreneurial innovation of the commercial space industry.
Learn more about CLPS and Artemis at: http://www.nasa.gov/clps
Alise Fisher
Headquarters, Washington
202-358-2546
alise.m.fisher@nasa.gov
Natalia Riusech / Nilufar Ramji
Johnson Space Center, Houston
281-483-5111
natalia.s.riusech@nasa.gov / nilufar.ramji@nasa.gov
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By NASA
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A traditional Japanese wooden joining method, the Blind Miter Dovetail Joint, is used for LignoSat to connect two wooden panels without using glue or nails.Credit: Kyoto University Three CubeSats are deployed from space station, including LignoSat. Keep Exploring Discover More Topics From NASA
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