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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
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 USH
Quantum computing, a transformative field leveraging quantum mechanics, has the potential to solve complex problems far beyond the reach of classical computers. While it promises significant advancements, it also poses risks, such as breaking cryptographic codes, threatening global data security.
For example: At NASA's Quantum Artificial Intelligence Laboratory (QuAIL), experiments revealed unprecedented computational power and successfully solved the unsolvable problem. However, the quantum computer began generating independent and unconventional outputs, leading to speculation that it could think for itself or even connect with extraterrestrial intelligence. Concerned about the implications, NASA halted its quantum computing project in 2023, though some believe the research continued in secret.
Separately, researchers have hypothesized that advanced extraterrestrial civilizations might use black holes as quantum computers for computation and communication. highlighting the mysterious potential of these quantum systems to explore phenomena beyond Earthly understanding.
A fictional scenario (watch video below) illustrates the dangers of quantum technology spiraling out of control:
A mysterious data transfer lights up NSA monitors at 3 AM. Within hours, hospital records flash across Times Square billboards. Dating app messages spill onto every screen in the city.
Bank accounts vanish. Traffic lights freeze. Autonomous vehicles crash through shopping malls. Intelligence agencies scramble as decades of encrypted messages suddenly unlock. Someone or something has broken the unbreakable - the mathematical foundations that protect everything from banking passwords to nuclear launch codes.
The quantum apocalypse arrives years ahead of schedule. But as chaos spreads, patterns start to surface. The timing seems too perfect, the targets too precise.
Deep beneath the Pentagon, analysts notice something strange: some messages were decrypted months ago. The chaos isn't random - it's cover for something bigger.
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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
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of SUPREME-QG: Space-borne Ultra-Precise Measurement of the Equivalence Principle Signature of Quantum GravityNASA/Selim Shahriar Selim Shahriar
Northwestern University, Evanston
Progress in physics has largely been driven by the development and verification of new theories that unify different fundamental forces of nature. For example, Maxwell revolutionized physics with his unified theory of electricity and magnetism, and the Standard Model of particle physics provides a consistent description of all fundamental forces (electromagnetic, strong, and weak) except for gravity. The major barrier to completing the quest for unification is that General Relativity (GR), the current theory of gravity, cannot be reconciled with QM. Theories of Quantum Gravity (TQG), which are yet untested, prescribe modifications of both GR and QM in a manner that makes them consistent with each other. Tests of TQG represent arguably the greatest challenge facing our understanding of the Universe. The most promising way to test TQG is to search for violation of the Equivalence Principle (EP), a fundamental tenet of GR which states that all objects experience the same acceleration in a gravitational field. Violation of EP is characterized by a nonzero Eotvos parameter, Eta, defined as the ratio of the relative acceleration to the mean acceleration experienced by two objects with different inertial masses in a gravitational field. EP violations at the level of Eta < 10^(-18) arise in many versions of TQG (e.g., string theory). The most precise test of the EP to date has been carried out under the space-borne MICROSCOPE experiment employing classical accelerometers, constraining the value of Eta to <1.5×10^(-15). We propose to investigate the use of a radically new method that leverages quantum entanglement to test the EP with extreme precision, at the level of Eta ~ 10^(-20), using a space-borne platform. This method is described in a recent paper by us (PRD 108, 024011, ’23). It makes use of simultaneous Schroedinger Cat (SC) state atom interferometers (AIs) with two isotopes of Rb. Consisting of N=10^6 atoms, the SC state, which is a maximally entangled quantum state generated via spin-squeezing of cold atoms in an optical cavity, acts as a single particle, in a superposition of two collective states, enhancing the sensitivity by a factor of ~root(N)=10^3. Such large-N SC states are difficult to create and have not been observed yet, let alone leveraged for precision metrology. In another recent paper, we described a novel protocol, namely the generalized echo squeezing protocol (GESP), to overcome the challenges of creating such a state (PRA 107, 032610, ’23). We will demonstrate the functionality of this method in a testbed to enable a follow-on space-borne mission capable of testing the EP at the level of Eta ~ 10^(-20). If EP violation is observed, the version of TQG that agrees most closely with the result would form the foundation for a complete theory governing the universe, including its birth: the Big Bang. A null result would force physicists to conceive an entirely new approach to addressing the irreconcilability of GR and QM, fundamentally altering the course of theoretical physics. Either outcome would represent one of the greatest developments in our quest for understanding nature. The SC-state AI (SCAI), also holds the promise of revolutionary improvements in the precision of gravitational cartography and inertial navigation, when configured for simultaneous accelerometry and rotation sensing. The sensitivity of such a sensor, for one second averaging time, would be ~0.9 femto-g for accelerometry, and ~0.5 pico-degree/hour for rotation sensing. This would represent an improvement by a factor of ~10^5 over the best conventional accelerometer, and a factor of ~10^4 over the best conventional gyroscopes. As such, the SCAI would find widespread usage in defense as well as non-defense sectors, including deep-space exploration, for inertial navigation. A space-borne SCAI would be able to carry out gravitational cartography with a resolution far greater than that achieved using the GRACE-FO satellites.
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Last Updated Jan 10, 2025 EditorLoura Hall Related Terms
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