Members Can Post Anonymously On This Site
-
Similar Topics
-
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
2025-006
Share
Details
Last Updated Jan 21, 2025 Related Terms
NISAR (NASA-ISRO Synthetic Aperture Radar) Earth Earth Science Earth Science Division Jet Propulsion Laboratory Explore More
4 min read NASA Scientists, Engineers Receive Presidential Early Career Awards
Article 4 days ago 6 min read NASA International Space Apps Challenge Announces 2024 Global Winners
Article 5 days ago 3 min read NASA Scientists Find New Human-Caused Shifts in Global Water Cycle
Article 5 days ago Keep Exploring Discover More Topics From NASA
Missions
Humans in Space
Climate Change
Solar System
View the full article
-
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
-
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
View the full article
-
By NASA
Hubble Space Telescope Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts News Hubble News Hubble News Archive Social Media Media Resources Multimedia Multimedia Images Videos Sonifications Podcasts e-Books Online Activities Lithographs Fact Sheets Glossary Posters Hubble on the NASA App More 35th Anniversary 4 Min Read NASA’s Hubble Tracks Down a ‘Blue Lurker’ Among Stars
Evolution of a “Blue Lurker” Star in a Triple System Credits:
NASA, ESA, Leah Hustak (STScI) The name “blue lurker” might sound like a villainous character from a superhero movie. But it is a rare class of star that NASA’s Hubble Space Telescope explored by looking deeply into the open star cluster M67, roughly 2,800 light-years away.
Forensics with Hubble data show that the star has had a tumultuous life, mixing with two other stars gravitationally bound together in a remarkable triple-star system. The star has a kinship to so-called “blue stragglers,” which are hotter, brighter, and bluer than expected because they are likely the result of mergers between stars.
Evolution of a “Blue Lurker” Star in a Triple System Panel 1: A triple star system containing three Sun-like stars. Two are very tightly orbiting. The third star has a much wider orbit. Panel 2: The close stellar pair spiral together and merge to form one more massive star. Panel 3: The merged star evolves into a giant star. As the huge photosphere expands, some of the material falls onto the outer companion, causing the companion to grow larger and its rotation rate to increase. Panels 4-5: The central merged star eventually burns out and forms a massive white dwarf, and the outer companion spirals in towards the white dwarf, leaving a binary star system with a tighter orbit. Panel 6: The surviving outer companion is much like our Sun but nicknamed a “blue lurker.” Although it is slightly brighter bluer than expected because of the earlier mass-transfer from the central star and is now rotating very rapidly, these features are subtle. The star could easily be mistaken for a normal Sun-like star despite its exotic evolutionary history. NASA, ESA, Leah Hustak (STScI) The blue lurker is spinning much faster than expected, an unusual behavior that led to its identification. Otherwise it looks like a normal Sun-like star. The term “blue” is a bit of a misnomer because the star’s color blends in with all the other solar-mass stars in the cluster. Hence it is sort of “lurking” among the common stellar population.
The spin rate is evidence that the lurker must have siphoned in material from a companion star, causing its rotation to speed up. The star’s high spin rate was discovered with NASA’s retired Kepler space telescope. While normal Sun-like stars typically take about 30 days to complete one rotation, the lurker takes only four days.
How the blue lurker got that way is a “super complicated evolutionary story,” said Emily Leiner of Illinois Institute of Technology in Chicago. “This star is really exciting because it’s an example of a star that has interacted in a triple-star system.” The blue lurker originally rotated more slowly and orbited a binary system consisting of two Sun-like stars.
Around 500 million years ago, the two stars in that binary merged, creating a single, much more massive star. This behemoth soon swelled into a giant star, dumping some of its own material onto the blue lurker and spinning it up in the process. Today, we observe that the blue lurker is orbiting a white dwarf star — the burned out remains of the massive merger.
“We know these multiple star systems are fairly common and are going to lead to really interesting outcomes,” Leiner explained. “We just don’t yet have a model that can reliably connect through all of those stages of evolution. Triple-star systems are about 10 percent of the Sun-like star population. But being able to put together this evolutionary history is challenging.”
Hubble observed the white dwarf companion star that the lurker orbits. Using ultraviolet spectroscopy, Hubble found the white dwarf is very hot (as high as 23,000 degrees Fahrenheit, or roughly three times the Sun’s surface temperature) and a heavyweight at 0.72 solar masses. According to theory, hot white dwarfs in M67 should be only about 0.5 solar masses. This is evidence that the white dwarf is the byproduct of the merger of two stars that once were part of a triple-star system.
“This is one of the only triple systems where we can tell a story this detailed about how it evolved,” said Leiner. “Triples are emerging as potentially very important to creating interesting, explosive end products. It’s really unusual to be able to put constraints on such a system as we are exploring.”
Leiner’s results are being presented at the 245th meeting of the American Astronomical Society in Washington, D.C.
The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Media Contact:
Claire Andreoli (claire.andreoli@nasa.gov)
NASA’s Goddard Space Flight Center, Greenbelt, MD
Ray Villard
Space Telescope Science Institute, Baltimore, MD
Science Contact:
Emily Leiner
Illinois Institute of Technology, Chicago, IL
Share
Details
Last Updated Jan 13, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
Astrophysics Astrophysics Division Goddard Space Flight Center Hubble Space Telescope Open Clusters Stars Keep Exploring Discover More Topics From Hubble
Hubble Space Telescope
Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
Hubble Science Highlights
Hubble’s Night Sky Challenge
Hubble Multimedia
View the full article
-
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
2025-001
Share
Details
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
27 min read Summary of the Third Annual AEOIP Workshop
Introduction The Applied Earth Observations Innovation Partnership (AEOIP) was established in 2018 to facilitate knowledge…
Article 3 days ago 5 min read NASA’s LEXI Will Provide X-Ray Vision of Earth’s Magnetosphere
A NASA X-ray imager is heading to the Moon as part of NASA’s Artemis campaign,…
Article 3 days ago 2 min read Science Done by Volunteers Highlighted at December’s American Geophysical Union Meeting
More than 30,000 scientists gathered in Washington, D.C. during the second week of December –…
Article 2 weeks ago Keep Exploring Discover Related Topics
Missions
Humans in Space
Climate Change
Solar System
View the full article
-
-
Check out these Videos
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.