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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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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
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 NASA
On Jan. 9, 1990, space shuttle Columbia took off on its ninth flight, STS-32, from NASA’s Kennedy Space Center (KSC) in Florida. Its five-person crew of Commander Daniel Brandenstein, Pilot James Wetherbee, and Mission Specialists Bonnie Dunbar, Marsha Ivins, and David Low flew a then record-breaking 11-day mission to deploy the Syncom IV-F5 communications satellite for the U.S. Navy and retrieve the Long-Duration Exposure Facility (LDEF). Astronauts aboard a shuttle mission in 1984 deployed the LDEF and scientists eagerly awaited the return of their 57 experiments to study the effects of nearly six years exposure to the low Earth orbit environment. The crew also conducted several middeck experiments in biotechnology and materials processing and used an echocardiograph to study changes in their hearts.
The STS-32 crew of Mission Specialist Bonnie Dunbar, left, Commander Daniel Brandenstein, Pilot James Wetherbee, and Mission Specialists Marsha Ivins and David Low. The STS-32 crew patch. The Long Duration Exposure Facility during its deployment on the STS-41C mission in 1984. In November 1988, NASA announced Brandenstein, Wetherbee, Dunbar, Ivins, and Low as the STS-32 crew for the flight then planned for November 1989. Brandenstein, from the Class of 1978, had flown twice before, as pilot on STS-8 in August-September 1983 and commander of STS-51G in June 1985. Dunbar, selected in 1980, had flown once before on STS-61A in October-November 1985. For Wetherbee, Ivins, and Low, all selected in 1984, STS-32 marked their first spaceflight. During the second day of their planned 10-day mission, the astronauts would deploy the Syncom IV-F5, also known as Leasat-5, communications satellite for the U.S. Navy. The main focus of the flight involved the retrieval of LDEF, deployed by the STS-41C crew in April 1984. The original plan had LDEF, containing 57 science and technology experiments, retrieved by the STS-51D crew in February 1985. Delays in the shuttle program first pushed the retrieval to STS-61I in September 1986, and then the Challenger accident delayed it to STS-32. The facility ended up staying in orbit nearly six years instead of the originally intended 10 months. The crew rounded out the mission by conducting a series of middeck science and medical experiments.
Space shuttle Columbia rolls out to its launch pad on a foggy morning. NASA scientist John Charles, at rear, trains astronauts David Low, left, and Bonnie Dunbar, supine, in the operation of a cardiovascular experiment. The STS-32 crew exits crew quarters for the ride to Launch Pad 39A. Columbia returned to KSC on Aug. 21, 1989, following STS-28’s landing at Edwards Air Force Base (AFB) in California, and workers towed it to the Orbiter Processing Facility (OPF) the next day. They made 26 modifications to the orbiter, including the installation of the Remote Manipulator System (RMS), or robotic arm, and a fifth set of liquid hydrogen and liquid oxygen tanks to extend the vehicle’s duration in space. Rollover to the nearby Vehicle Assembly Building took place on Nov. 16, where Columbia joined its External Tank and twin Solid Rocket Boosters (SRB) on refurbished Mobile Launch Platform 3, last used in 1975. Rollout took place on Nov. 28 to Launch Pad 39A, newly refurbished since its previous launch in 1986.
On Dec. 1, engineers and the astronaut crew completed the Terminal Countdown Demonstration Test, a dress rehearsal for the planned Dec. 18 launch. Based on that date and the mission’s planned 10-day duration, the STS-32 crew would have spent Christmas in space, only the third American crew and the first space shuttle crew to do so. However, unfinished work on Pad 39A delayed the launch into January 1990. Trajectory specialists had estimated that due to orbital decay, LDEF would reenter the Earth’s atmosphere by March 1990, so a timely launch remained crucial for mission success. The countdown began on Jan. 4 for an expected Jan. 8 launch, with the crew arriving at KSC on Jan. 5.
Liftoff of space shuttle Columbia on STS-32. The deployment of the Syncom IV-F5 satellite. Syncom following deployment. Cloudy skies scrubbed the first launch attempt on Jan. 8. Liftoff took place the next day at 7:35 a.m. EST from Launch Pad 39A, with LDEF 1,500 miles ahead of Columbia. The powered ride to space took 8.5 minutes, placing Columbia into a 215-by-38-mile orbit. A burn of the two Orbiter Maneuvering System (OMS) engines 40 minutes later changed the orbit to the desired 222-by-180-mile altitude. The crew opened the shuttle’s payload bay doors and deployed its radiators. The major activities for the first day in space involved the checkout of the RMS and the first rendezvous maneuver in preparation for the LDEF grapple three days later. The astronauts also activated four of the middeck experiments. On the mission’s second day, Low deployed the 15,000-pound Syncom satellite, releasing it in a frisbee motion out of the payload bay. The satellite extended its antenna, stabilized itself, and 40 minutes after deployment, fired its engine for the first burn to send it to its geostationary orbit.
The Long Duration Exposure Facility (LDEF) during the rendezvous. STS-32 astronaut Bonnie Dunbar has grappled LDEF with the Remote Manipulator System. Dunbar lowers LDEF into the payload bay. Following the Syncom deploy, the crew turned its attention to the rendezvous with LDEF while also continuing the middeck experiments. On Flight Day 3, they completed three rendezvous burns as they steadily continued their approach to LDEF. Soon after awakening on Flight Day 4, the astronauts spotted LDEF appearing as a bright star. After the first of four rendezvous burns, Columbia’s radar locked onto the satellite. As they continued the approach, with three more burns carried out successfully, Dunbar activated the RMS in preparation for the upcoming grapple. Brandenstein took over manual control of Columbia for the final approach and parked the shuttle close enough to LDEF for Dunbar to reach out with the 50-foot arm and grapple the satellite. Brandenstein reported, “We have LDEF.”
For the next four hours, with Wetherbee flying the orbiter and Dunbar operating the arm, Ivins performed a comprehensive photo survey of LDEF, documenting the effects of nearly six years of space exposure on the various experiments. The survey completed, Dunbar slowly and carefully lowered LDEF into the payload bay, and five latches secured it in place for the ride back to Earth. With the two major goals of their mission completed, the astronauts settled down for the remainder of their 10-day mission conducting science experiments.
With astronaut David Low acting as an operator, astronaut Bonnie Dunbar serves as a subject for a cardiovascular experiment. Astronaut Marsha Ivins with several cameras testing the effects of spaceflight on different types of film. During the mission, the STS-32 crew conducted several middeck experiments. The Protein Crystal Growth experiment used vapor diffusion to grow 120 crystals of 24 different proteins, for study by scientists following their return to Earth. The Characterization of Neurospora Circadian Rhythm experiment studied whether spaceflight affected the daily cycles of pink bread mold. The Fluid Experiment Apparatus performed materials processing research in the microgravity environment. The astronauts used the American Flight Echocardiograph (AFE) to study changes in their hearts as a result of weightlessness. The crew used the large format IMAX camera to film scenes inside the cabin as well as through the windows, such as the capture of LDEF.
Astronaut Daniel Brandenstein holds an inflatable plastic cake given to him by his crew mates in honor of his birthday. The STS-32 crew poses in Columbia’s middeck. On Jan. 17, Brandenstein celebrated his 47th birthday, the fifth American astronaut to do so in space. His crew presented him with an inflatable plastic cake including candles while controllers in Mission Control passed on their birthday wishes as did his wife and teenage daughter. On the same day, NASA announced the selection of its 13th group of astronauts. Among them, engineer Ronald Sega, Dunbar’s husband, as well as the first female shuttle pilot, Eileen Collins, and the first Hispanic woman astronaut, Ellen Ochoa.
Columbia touches down at Edwards Air Force Base in California. At the welcome home ceremony at Ellington Field in Houston, director of NASA’s Johnson Space Center Aaron Cohen addresses the crowd as the STS-32 astronauts and their families listen. On Jan. 19, the astronauts awakened for their planned final day in space. However, due to fog at their landing site, Edwards AFB in California, Mission Control first informed them that they would have to spend an extra orbit in space, and finally decided to delay the landing by an entire day. With their experiments already packed, the crew spent a quiet day, looking at the Earth and using up what film still remained. As they slept that night, they passed the record for the longest space shuttle mission, set by STS-9 in 1983.
In preparation for reentry, the astronauts donned their orange spacesuits and closed the payload bay doors. A last-minute computer problem delayed reentry by one orbit, then Brandenstein and Wetherbee oriented Columbia into the deorbit attitude, with the OMS engines facing in the direction of travel. Over the Indian Ocean, they fired the two engines for 2 minutes 48 seconds to bring the spacecraft out of orbit. They reoriented the orbiter to fly with its heat shield exposed to the direction of flight as it encountered Earth’s atmosphere at 419,000 feet. The buildup of ionized gases caused by the heat of reentry prevented communications for about 15 minutes but provided the astronauts a great light show. After completing the Heading Alignment Circle turn, Brandenstein aligned Columbia with the runway, and Wetherbee lowered the landing gear. Columbia touched down and rolled to a stop, making the third night landing of the shuttle program and ending a 10-day 21-hour 1-minute flight, the longest shuttle flight up to that time, having completed 172 orbits of the Earth.
Other records set by the astronauts on this mission included Brandenstein as the new record holder for most time spent in space by a shuttle crew member – 24 days – and Dunbar accumulating the most time in space by a woman – 18 days – up to that time. Following eight hours of postflight medical testing, the astronauts boarded a jet bound for Houston’s Ellington Field, where they reunited with their families and took part in a welcome home ceremony led by Aaron Cohen, director of NASA’s Johnson Space Center.
Columbia returns to NASA’s Kennedy Space Center in Florida atop the Shuttle Carrier Aircraft. Workers lift the Long Duration Exposure Facility from Columbia’s payload bay. Following postlanding inspections, workers placed Columbia, with LDEF still cradled in its payload bay, atop a Shuttle Carrier Aircraft, a modified Boeing-747, and the combination left Edwards on Jan. 25. Following a refueling stop at Monthan Davis AFB in Tucson, an overnight stay at Kelly AFB in San Antonio, and another refueling stop at Eglin AFB in Fort Walton Beach, Florida, Columbia and LDEF arrived back at KSC on Jan. 26. The next day, workers towed Columbia to the OPF and on Jan. 30 lifted LDEF out of its payload bay, in preparation for the detailed study of the effects of nearly six years in space on the 57 experiments it carried. Meanwhile, workers began to prepare Columbia for its next flight, STS-35 in December 1990.
Enjoy the crew narrate a video of the STS-32 mission. Read Brandenstein‘s and Dunbar‘s recollections of the STS-32 mission in their oral histories with the JSC History Office. For an overview of the LDEF project, enjoy this video. For detailed information on the results of the LDEF experiments, follow this link.
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
An equal collaboration between NASA and the Indian Space Research Organisation, NISAR will offer unprecedented insights into Earth’s constantly changing land and ice surfaces using synthetic aperture radar technology. The spacecraft, depicted here in an artist’s concept, will launch from India.NASA/JPL-Caltech A Q&A with the lead U.S. scientist of the mission, which will track changes in everything from wetlands to ice sheets to infrastructure damaged by natural disasters.
The upcoming U.S.-India NISAR (NASA-ISRO Synthetic Aperture Radar) mission will observe Earth like no mission before, offering insights about our planet’s ever-changing surface.
The NISAR mission is a first-of-a-kind dual-band radar satellite that will measure land deformation from earthquakes, landslides, and volcanoes, producing data for science and disaster response. It will track how much glaciers and ice sheets are advancing or retreating and it will monitor growth and loss of forests and wetlands for insights on the global carbon cycle.
As diverse as NISAR’s impact will be, the mission’s winding path to launch — in a few months’ time — has also been remarkable. Paul Rosen, NISAR’s project scientist at NASA’s Jet Propulsion Laboratory in Southern California, has been there at every step. He recently discussed the mission and what sets it apart.
NISAR Project Scientist Paul Rosen of NASA’s Jet Propulsion Laboratory first traveled to India in late 2011 to discuss collaboration with ISRO scientists on an Earth-observing radar mission. NASA and ISRO signed an agreement in 2014 to develop NISAR. NASA/JPL-Caltech How will NISAR improve our understanding of Earth?
The planet’s surfaces never stop changing — in some ways small and subtle, and in other ways monumental and sudden. With NISAR, we’ll measure that change roughly every week, with each pixel capturing an area about half the size of a tennis court. Taking imagery of nearly all Earth’s land and ice surfaces this frequently and at such a small scale — down to the centimeter — will help us put the pieces together into one coherent picture to create a story about the planet as a living system.
What sets NISAR apart from other Earth missions?
NISAR will be the first Earth-observing satellite with two kinds of radar — an L-band system with a 10-inch (25-centimeter) wavelength and an S-band system with a 4-inch (10-centimeter) wavelength.
Whether microwaves reflect or penetrate an object depends on their wavelength. Shorter wavelengths are more sensitive to smaller objects such as leaves and rough surfaces, whereas longer wavelengths are more reactive with larger structures like boulders and tree trunks.
So NISAR’s two radar signals will react differently to some features on Earth’s surface. By taking advantage of what each signal is or isn’t sensitive to, researchers can study a broader range of features than they could with either radar on its own, observing the same features with different wavelengths.
Is this new technology?
The concept of a spaceborne synthetic aperture radar, or SAR, studying Earth’s processes dates to the 1970s, when NASA launched Seasat. Though the mission lasted only a few months, it produced first-of-a-kind images that changed the remote-sensing landscape for decades to come.
It also drew me to JPL in 1981 as a college student: I spent two summers analyzing data from the mission. Seasat led to NASA’s Shuttle Imaging Radar program and later to the Shuttle Radar Topography Mission.
What will happen to the data from the mission?
Our data products will fit the needs of users across the mission’s science focus areas — ecosystems, cryosphere, and solid Earth — plus have many uses beyond basic research like soil-moisture and water resources monitoring.
We’ll make the data easily accessible. Given the volume of the data, NASA decided that it would be processed and stored in the cloud, where it’ll be free to access.
How did the ISRO partnership come about?
We proposed DESDynI (Deformation, Ecosystem Structure, and Dynamics of Ice), an L-band satellite, following the 2007 Decadal Survey by the National Academy of Sciences. At the time, ISRO was exploring launching an S-band satellite. The two science teams proposed a dual-band mission, and in 2014 NASA and ISRO agreed to partner on NISAR.
Since then, the agencies have been collaborating across more than 9,000 miles (14,500 kilometers) and 13 time zones. Hardware was built on different continents before being assembled in India to complete the satellite. It’s been a long journey — literally.
More About NISAR
The NISAR mission is an equal collaboration between NASA and ISRO and marks the first time the two agencies have cooperated on hardware development for an Earth-observing mission. Managed for the agency by Caltech, JPL leads the U.S. component of the project and is providing the mission’s L-band SAR. NASA is also providing the radar reflector antenna, the deployable boom, a high-rate communication subsystem for science data, GPS receivers, a solid-state recorder, and payload data subsystem.
Space Applications Centre Ahmedabad, ISRO’s lead center for payload development, is providing the mission’s S-band SAR instrument and is responsible for its calibration, data processing, and development of science algorithms to address the scientific goals of the mission. U R Rao Satellite Centre in Bengaluru, which leads the ISRO components of the mission, is providing the spacecraft bus. The launch vehicle is from ISRO’s Vikram Sarabhai Space Centre, launch services are through ISRO’s Satish Dhawan Space Centre, and satellite mission operations are by ISRO Telemetry Tracking and Command Network. National Remote Sensing Centre in Hyderabad is primarily responsible for S-band data reception, operational products generation, and dissemination.
To learn more about NISAR, visit:
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 06, 2025 Related Terms
NISAR (NASA-ISRO Synthetic Aperture Radar) Climate Change Earth Earth Science Earth Science Division Ice & Glaciers Jet Propulsion Laboratory Seasat Shuttle Radar Topography Mission (SRTM) SIR-C/X-SAR (Shuttle Imaging Radar-C / X-Band Synthetic Aperture Radar) Explore More
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