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Microgravity on demand with Earth return through ESA’s Boost!
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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 NASA
Science in Space January 2025
At the start of a new year, many people think about making positive changes in their lives, such as improving physical fitness or learning a particular skill. Astronauts on the International Space Station work all year to maintain a high level of performance while adapting to changes in their physical fitness, cognitive ability, sensory perception, and other functions during spaceflight.
Research on the space station looks at how these qualities change in space, the ways those changes affect daily performance, and countermeasures to keep astronauts at their peak.
CSA astronaut David Saint-Jacques wears the Bio-Monitor health sensor shirt and headband.NASA A current CSA (Canadian Space Agency) investigation, Space Health, assesses the effects of spaceflight on cardiovascular deconditioning. The investigation uses Bio-Monitor, wearable sensors that collect data such as pulse rate, blood pressure, breathing rate, skin temperature, and physical activity levels. Results could support development of an autonomous system to monitor cardiovascular health on future space missions. Similar technology could be used to monitor heart health in people on Earth.
Maintaining muscle fitness
NASA astronaut Serena Auñón-Chancellor tests ESA astronaut Alexander Gerst’s muscle tone.ESA During spaceflight, astronauts lose muscle mass and stiffness, an indication of strength. Astronauts exercise daily to counteract these effects, but monitoring the effectiveness of exercise had been limited to before and after flight due to the lack of technologies appropriate for use in space. The ESA (European Space Agency) Myotones investigation demonstrated that a small, non-invasive device accurately measured muscle stiffness and showed that current countermeasures seem to be effective for most muscle groups. Accurate inflight assessment could help scientists target certain muscles to optimize the effectiveness of exercise programs on future missions. The measuring device also could benefit patients in places on Earth without other means for monitoring.
Keeping a sharp mind
Research suggests that the effects of spaceflight on cognitive performance likely are due to the influence of stressors such as radiation and sleep disruption. Longer missions that increase the exposure to these hazards may change how they affect individuals.
Test subject Lance Dean performs a manual control task in the Johnson Space Center Neurosciences Laboratory’s Motion Simulator.NASA Manual Control used a battery of tests to examine how spaceflight affects cognitive, sensory, and motor function right after landing. The day they return from spaceflight, astronauts demonstrate significant impairments in fine motor control and ability to multitask in simulated flying and driving challenges. Researchers attribute this to subtle physiological changes during spaceflight. Performance recovered once individuals were exposed to a task, suggesting that having crew members conduct simulated tasks right before actual ones could be beneficial. This work helps scientists ensure that crew members can safely land and conduct early operations on the Moon and Mars.
Standard Measures collects a set of physical and mental measurements related to human spaceflight risks, including a cognition test battery, from astronauts before, during, and after missions. Using these data, researchers found that astronauts on 6-month missions demonstrated generally stable cognitive performance with mild changes in certain areas, including processing speed, working memory, attention, and willingness to take risks. The finding provides baseline data that could help identify cognitive changes on future missions and support development of appropriate countermeasures. This research includes the largest sample of professional astronauts published to date.
Evaluating perception
CSA astronaut David Saint-Jacques conducts a session for VECTION.NASA Another function that can be affected by spaceflight is sensory perception, such as the ability to interpret motion, orientation, and distance. We use our visual perception of the height and width of objects around us, for example, to complete tasks such as reaching for an object and deciding whether we can fit through an opening. VECTION, a CSA investigation, found that microgravity had no immediate effect on the ability to perceive the height of an object, indicating that astronauts can safely perform tasks that rely on this judgment soon after they arrive in space. Researchers concluded there is no need for countermeasures but did suggest that space travelers be made aware of late-emerging and potentially long-lasting changes in the ability to perceive object height.
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International Space Station Research Communications Team
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By European Space Agency
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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 USH
During a live Fox News broadcast covering the intense Palisades wildfire in California, an unusual event captured viewers' attention. A camera aimed at the blazing inferno recorded a mysterious spherical object emerging suddenly from the middle of the flames. This object moved at a remarkable speed before vanishing over the treetops, leaving many wondering about its origin and purpose.
The object does not appear to be debris carried aloft by the fire’s updraft. Its trajectory and speed seem too controlled and deliberate to be a random effect of the wildfire. Additionally, the object shows no signs of explosion or disintegration, characteristics that might be expected if it were merely a piece of material affected by the intense heat.
Observers have ruled out common explanations such as birds, planes, or helicopters. The object’s rapid movement and apparent change in direction suggest advanced maneuverability, sparking comparisons to UFOs/UAPs.
With the growing number of reported sightings involving drones, orbs, and UFOs, the appearance of this potential UFO or drone in such an environment is especially intriguing. Could this object represent evidence of advanced technology monitoring Earth's natural disasters? Or is it an entirely natural but poorly understood phenomenon?
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