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Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

An Anticrepuscular Rainbow Fan

Explanation: This is an unusual rainbow. For one thing, the rainbow is not complete, appearing only in a sunlit fan — but that by itself is not very unusual. What is most unusual is the fake location of the Sun. The Sun appears to be toward the front, just below those hills — but it is not. That is not how rainbows work. Rainbows involve a backward reflection from falling rain, so that the Sun must really be behind you. In this case, gaps between clouds near the setting Sun allowed rays to cross the entire sky and appear to converge in front, an unusual phenomenon called anticrepuscular rays. The photo was taken with a phone last week at sunset in Presenzano, Italy. The seemingly reverse rainbow was noticed when hanging up laundry.

Tomorrow’s picture: open space

Date	October 20, 2026
Credit & Copyright	Aurelia Degli Esposti
Authors & editors:	Robert Nemiroff, Jerry Bonnell, Cecilia Chirenti, Keighley Rockcliffe
A service of:	ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U.

Source: science.nasa.gov

Humans are exerting increasing influence over how water moves through lakes, rivers, soil, and the subsurface, and a new NASA study shows where those effects are greatest. Using more than two decades of satellite measurements of subtle changes in Earth’s gravity, the researchers sharpened the picture of how—and why—terrestrial water storage has changed.

This map encapsulates their findings, depicting changes in terrestrial water storage from April 2002 to November 2025. Beyond the influence of climate variability, the scientists identified 40 regions where the changes also aligned with human activities such as irrigation, reservoir impoundment, and land-use change. These activities were significantly related to terrestrial water storage trends on every nonpolar continent except Australia.

In some areas, the effects of human activities were especially strong. “In four continental regions, an anthropogenic variable showed a stronger relationship with the storage trends than any climate variable did,” said Mary Michael O’Neill, a hydrologist at NASA’s Goddard Space Flight Center and lead author of the study.

They include well-known spots such as California’s Central Valley and northern India, where farmers’ heavy reliance on groundwater has drawn down storage—in India’s case, faster than earlier estimates suggested. Elsewhere, some types of farming and water management appear to have done the opposite.

Gravity as a Water Gauge

The data behind the map come from the GRACE (Gravity Recovery and Climate Experiment) and GRACE-FO (GRACE Follow-On) missions, each of which consists of two satellites that fly in tandem. As the lead satellite passes over an area with greater mass, the slight change in gravity tugs at it, and instruments aboard the satellites measure the change in distance between them. Since water and ice are heavy and shift around regularly, scientists can use GRACE data to infer gains and losses.

The satellites’ data are typically processed into monthly maps that show broad patterns of water storage. But over more than 20 years, the satellites have passed over most of the planet many times. By combining all of those passes, the researchers could map long-term water trends with five to 10 times more spatial detail than previous analyses. The tradeoff was a loss of temporal detail. They then applied statistical techniques to weigh the importance of various anthropogenic and climatic factors in the storage trends and to pinpoint where human activities may have contributed.

The improved spatial resolution uncovered some human impacts that had not been previously detected, said Matthew Rodell, deputy director of Earth Sciences for Hydrosphere, Biosphere, and Geophysics at Goddard and one of the study’s authors. The analysis also showed that some known trends were stronger than previously realized.

Where the Water Went

Across several continents, groundwater-irrigated farmland was strongly associated with declines in terrestrial water storage. In North America, these declines appeared in California’s Central Valley, the southern High Plains of the U.S., and Chihuahua, Mexico, where long-term droughts have increased farmers’ reliance on groundwater. Groundwater pumping also drove declines in northern India, where the refined analysis showed a steeper downward trend than previously realized. Consistent with previous findings, retreating Himalayan glaciers accounted for only 15 percent of the decline there.

Other types of agriculture had a different relationship with water storage trends. In parts of sub-Saharan Africa, for example, some increases occurred where rainfed cropland has expanded. There, swaths of native savanna were replaced by millet cultivation throughout the study period, and water tables rose despite below-average precipitation. A similar pattern emerged in northern Brazil’s Maranhão state, where soybean fields have replaced forests and shrublands. The resulting water storage trend might be explained in part by the efficient water use of cereal and legume plants and by Indigenous practices that help direct water into shallow aquifers, the researchers said.

Water storage and diversion projects also came into focus on the new map. Hundreds of large reservoirs were filled during the study period, the authors note, but the coarse spatial resolution of gravity measurements previously made them difficult to track. In the new analysis, the Boguchany Reservoir on Russia’s Angara River, the second-largest reservoir filled in the 21st century, produced the strongest water storage trend in nonpolar northern Asia.

The map also resolves smaller reservoirs and other hydrologic engineering projects. The Karakum Desert in Turkmenistan registered water storage gains stemming from the long, largely unlined Karakum Canal running through it. The canal diverts river water to support desert agriculture, but enough seeps into the ground during its journey to alter the water picture in the desert. The map’s finer resolution allows for better monitoring of such hydrologic changes in remote areas where other measurement options may be limited.

Moving forward, O’Neill wants to capture how dams, diversions, irrigation, and other controls on Earth’s water affect storage downstream, and to disentangle the influence of local and non-local activities. “I’d also like to recover more of the temporal picture,” she said. One way to do that is by combining the higher-resolution data with standard monthly products or by applying the recent technique over shorter timeframes. “This could help track how localized trends evolve in response to specific events like droughts or policy changes.”

NASA Earth Observatory map by Michala Garrison, using data from O’Neill, M.M., et al. (2026). Astronaut photograph ISS065-E-111045 was acquired on June 13, 2021, with a Nikon D5 digital camera using a focal length of 1,150 millimeters. It is provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit at NASA Johnson Space Center. The image was taken by a member of the Expedition 65 crew. The image has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Story by Lindsey Doermann.

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Terrestrial water storage trend map

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References & Resources

• NASA Earth Observatory (2018, May 23) Twin Satellites Map 14 Years of Freshwater Changes. Accessed October 19, 2026.
• O’Neill, M.M., et al. (2026) Spatially refined satellite gravimetry captures human signatures in global terrestrial water storage trends. Proceedings of the National Academy of Sciences, 123 (38) e2600775123.

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Written by Alex Innanen, Atmospheric Scientist at York University

Earth planning date: Friday, Oct. 9, 2026

Happy New Mars Year! We mark the start of a new year on Mars at the beginning of the northern hemisphere spring, or the vernal equinox. We then keep track of the seasons by counting degrees of solar longitude — each season is 90 degrees as Mars completes the whole 360 degrees of its orbit. The start of Mars year 39 at a solar longitude of 0 degrees (or L_s=0°, pronounced “ell-sub-ess-zero” if you want to sound like a Martian) came at the end of September on Earth. The new year also means it’s now autumn in Gale Crater, just south of the equator.

As Michelle talked about last week, we rang in the Martian new year with our drill campaign at “Basque Lakes.” This week was dedicated to wrapping up drill activities before we drive away on the weekend. After the team got a chance to see the results of last week’s lab activities, the SAM team decided on an additional GCMS (Gas Chromatograph/Mass Spectrometry) experiment. While GCMS tends to be an energy-intensive activity, we had four whole sols in Monday’s plan to play with, so we still had room for a slew of remote-sensing activities from Mastcam and ChemCam and contact science of the drill tailings — the bits of rock and minerals that are left over from our drill sample. This weekend’s plan gives us a couple more sols to wrap up drill activities at Basque Lakes and collect any last contact- or remote-science targets we want here before we begin a drive back toward the neat crystal forms we saw in the “Chiu Chiu” region.

While all this is happening, the atmosphere around us continues to go through its seasonal changes. Autumn means the return of high-altitude twilight clouds, which the low sun angle at sunset illuminates beautifully. While twilight cloud activity will pick up as the autumn progresses, our late afternoon cloud movies on Wednesday of this week already caught our first high-altitude clouds of the season, as you can see at the top of this post. Most of the clouds we tend to see at Gale Crater are suboptical, or too thin to be seen with either human eyes or with Curiosity’s robotic “eyes,” but these twilight clouds are bright enough that we can see them in the raw Navcam images. I’m looking forward to another Martian autumn of watching all these different clouds go by.

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Destined for Mars and beyond, NASA’s Space Reactor-1 (SR-1) Freedom will be humanity’s first fission-powered spacecraft to travel outside Earth’s orbit. Announced during NASA’s “Ignition” event, this mission will demonstrate nuclear electric propulsion in deep space, and progress is underway on its key element: the nuclear power module. To expedite development of the spacecraft, NASA and its partners have mutually agreed to key contract actions that will advance the SR‑1 Freedom mission. 

“These contract actions not only reduce technical risk and help us maintain momentum toward our 2028 launch, but they also strengthen collaboration across our partners,” said Steve Sinacore, SR-1 Freedom program director. “These actions keep SR‑1 Freedom on track and ensure we’re building the strongest possible foundation for NASA’s first fission‑powered voyage beyond Earth orbit while developing technology extensible to a vibrant space nuclear future.” 

Sierra Lobo Inc. will provide the nuclear power module’s closed Brayton cycle power conversion system, which converts thermal energy from its fission reactor into electrical power needed for SR-1 Freedom’s nuclear electric propulsion demonstration. The work will be conducted under the Space Flight Systems Development and Operations Contract III, awarded in 2024, to support spaceflight hardware design, development, testing, and operations at NASA’s Glenn Research Center in Cleveland.

The power conversion system will be integrated with the fission reactor, which is being designed and developed by the Department of Energy (DOE)’s Idaho National Laboratory to complete the nuclear power module. NASA and DOE incorporate thorough safety standards throughout the design and development of the SR-1 Freedom spacecraft, including interagency safety reviews, continuous oversight by a NASA chief safety officer, regulatory compliance, and a rigorous safety design process focusing on hazards, failure tolerance, and nuclear safety. In addition, the nuclear reactor portion of SR-1 Freedom will remain inactive until the spacecraft leaves Earth orbit.

Launching in late 2028, SR‑1 Freedom will deliver the SkyFall science mission, a team of three Mars helicopters evolved from the Ingenuity design, to collect scientific data, demonstrate exploration zones, and identify potential water sources. The mission will pave the way for deep space exploration and next‑generation fission-powered systems designed to keep NASA’s Moon Base operating through periods of darkness and in locations where solar power alone is not sufficient.

For information about SR-1 Freedom, visit:

https://www.nasa.gov/mission/space-reactor-1-freedom/

Source: www.nasa.gov

Ingenuity

roamx-0201

Ingenuityroamx-0201

Ingenuity

roamx-0201

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Image Details

Rotor blade cross-sections highlight the thinner profile of the roamx-0201 design (right) compared to the more traditional, rounded shape used by NASA’s Ingenuity Mars helicopter, which accomplished the first powered flight on Mars.

NASA researchers are developing the future of flight on Mars, laying the groundwork for helicopters with the ability to fly higher and farther while conducting science on the Red Planet. Using high-fidelity computer simulations and wind tunnel tests, engineers are reimagining the rotorcraft blades that could carry the next generation of Mars flyers.
 
NASA’s Ingenuity helicopter made history as the first powered aircraft to fly on another planet. The SkyFall mission, scheduled for launch in 2028, builds on that legacy with a trio of helicopters destined for Mars exploration. Both missions utilize a blade designed to operate in Mars’ thin atmosphere, with a curved edge reminiscent of but distinct from blades used on Earth.
 
Researchers are exploring unconventional blade designs that are thinner and sharper, aiming to enable future missions after Skyfall to expand their single-flight range across Mars. One team at NASA’s Ames Research Center in California’s Silicon Valley is working with Imperial College London, United Kingdom, and Nagoya University, Japan, to test a new blade cross-section, or airfoil, that promises to significantly boost aerodynamic performance on Mars.
 
Researchers designed the new airfoil, called roamx-0201, using advanced simulations and algorithms tuned to Mars conditions, pointing researchers toward a thinner, asymmetrical shape. Subsequent wind tunnel tests showed that the optimized design boosted performance and was better able to recover in risky flight conditions.
 
Researchers used high-fidelity simulation tools to analyze the performance of the roamx-0201 airfoil and compare it to Ingenuity’s capacity. They found that the redesigned blades could enable future Mars helicopters to expand the distances that can be covered in one uninterrupted flight from Ingenuity’s 0.7 kilometers to as much as 18.7 kilometers while carrying scientific instruments. The findings were announced in a paper published Sept. 22 in the journal of the American Institute of Aeronautics and Astronautics.
 
The roamx‑0201 blades performed well in part because they were able to operate longer at higher speeds before experiencing a phenomenon known as “drag divergence”, where performance drops suddenly when the rotors approach the speed of sound, which is lower on Mars than on Earth.
 
The new blade also differs from earlier designs in how it uses turbulence to create lift. As air flows over a rotorcraft blade, it forms a thin region called the “boundary layer.” The new airfoil intentionally disrupts the flow of that boundary layer at the front of the airfoil directly at the leading edge to create a disturbance that, counterintuitively, pulls the blade upward to help lift the rotorcraft more effectively than with earlier designs.
 
Another challenge for rotorcraft is “stall,” an aerodynamic condition in which performance drops sharply and flight becomes unstable following a change in the angle of airflow. Ingenuity’s blades experienced steep performance degradation at stall, but under the conditions studied, the roamx-0201 design showed significantly improved stall behavior. That means future helicopters could operate safely at a wider range of flight angles.
 
While the technology is not yet ready for Mars, tests are helping engineers understand and resolve discrepancies between computational predictions and real-world performance. Ongoing research across NASA aims to enable more efficient Mars helicopters that can fly farther, carry more payload, and unlock new science and discovery missions.

Source: www.nasa.gov

Army Col. Lloyd L. “Scooter” Burke served on active duty for 30 years and saw three wars. He received the Medal of Honor in 1952 for the courage and leadership he displayed as a young officer during the Korean War.

Source: www.war.gov

Rockets vibrate, shake, and flex intensely as they climb into space, and spacecraft packed with delicate scientific instruments must survive those forces. Before any rocket leaves the ground, NASA engineers work to predict how those stresses will affect every part of a spacecraft.

To do that, engineers in the Dynamic Environments Group with NASA’s Launch Services Program Office at the agency’s Kennedy Space Center in Florida have streamlined how they ensure spacecraft and rockets can withstand harsh vibration, shock, stress, or other physical forces, strengthening mission safety in the process.

Using a commercial digital software tool in a new way, the engineers developed a standardized modeling workflow for finite element modeling to strengthen shock and vibration analysis and ensure hardware is prepared for the extreme environments of launch and ascent.

“This computer-based method helps predict how rockets and spacecraft behave under extreme conditions before hardware is built and helps identify weak spots and potential failure risks early so the team can address the findings,” said Brian Beaver, chief of the Flight Analysis Division with the Launch Services Program Office at NASA Kennedy.

The team recently used the software for the first time while certifying a commercial launch provider’s rocket selected for a NASA mission. The commercial partner provided vibration testing but not shock testing. The Dynamic Environments Group determined shock testing was needed and used a template the group created to run what-if comparisons, visualize structural behavior, and answer complex questions that would have required extensive manual modeling in the past. The team verified the company’s testing results for flight environments, and the analysis provided new insights addressing shock during transport.

“We are using a tool that’s existed for decades, but it’s not normally used by the dynamic environments disciplines,” said Alex Hardt, aerospace engineer with the Launch Services Program Office at NASA Kennedy. “But we’re changing that. We’re using it in a relatively new area of dynamics.”

Although rockets and spacecraft are designed to absorb shocks and vibrations, those forces can cause wear and tear or potentially flight failures, especially during launch and ascent.

“We define how severe the random vibration levels and shock levels are, and then we verify that all the parts going on future rockets have been tested to those levels, maximizing their longevity,” Hardt said.

Software time saver

For decades, engineers have estimated shock and vibration environments using rules of thumb or by scaling previous data to estimate how each rocket component or spacecraft equipment would be impacted once assembled and flown. The approach worked, but relied heavily on engineering judgment and simple approximations drawn from past missions.

Because most dynamic environments engineers use finite element modeling tools infrequently, they often need to re-learn complex workflows. The software replaces older tools and provides a standard template that guides engineers more quickly and thoroughly through vibration profiles and shock conditions.

Finite element analysis is a powerful simulation technique that breaks a complex structure into smaller components so computers can accurately predict how a spacecraft or rocket could respond to specific forces or launch environments. This is important because issues can be addressed on the ground; once the rocket leaves the launch pad, most problems cannot be repaired or corrected, making early identification essential.

“We’ve used it to get really valuable insight very quickly into verifying a provider’s system,” Hardt said. “It’s already provided some really deep insight into something that normally takes a lot of effort.”

Hardt says having the ability to visualize non-intuitive dynamics problems using finite element models also highlights the software’s valuable impact on learning, efficiency, and alignment with NASA’s people focused culture. The workflow can help the engineers share knowledge, refine assessments with additional flight data, and increase proficiency with modeling tools. This capability already has saved months by allowing the team to run analysis independently without having to request and wait for analysis reports or data, and by helping them identify risks that weren’t previously considered.

NASA’s Launch Services Program Office is responsible for launching rockets delivering spacecraft that observe the Earth, visit other planets and explore the universe, from weather satellites to space telescopes to Mars rovers. The team is constantly adopting new tools like this to give the agency the highest practical chance of success for each mission.

Source: www.nasa.gov

Research teams at NASA’s Glenn Research Center are involved in developing theory and software to predict the noise from aircraft engines. This software helps engineers to design and analyze new and improved aircraft propulsion systems. Copies of our software can be requested from NASA’s Software Catalog.

JeNo

Development of jet noise prediction codes is multifaceted. Since JeNo predicts jet noise using Lilley’s Acoustic Analogy and the mean flow solutions from a Reynolds-Averaged Navier-Stokes (RANS) code, accurate acoustic predictions hinge on accurate aerodynamic predictions. This is why acoustic source modeling and turbulence modeling, together with the development of advanced measurement systems, are the leading areas of research in jet noise prediction at NASA Glenn. RANS-based jet noise prediction schemes based on Lilley’s Acoustic Analogy offer relatively quick answers compared to those from alternative methods like Large-Eddy Simulations (LES) or Direct Numerical Simulation (DNS).

The JeNo jet noise prediction code calculates the far-field sound spectral density produced by axisymmetric jets at a user-specified observer location and frequency range. Currently, JeNo has been validated for subsonic and low supersonic, unheated axisymmetric jets. Copies of the JeNo code can be requested from NASA’s Software Catalog.

MGBK

Development of the MGBK code preceeded JeNo. Researchers at NASA GRC have used MGBK to predict trends in jet noise for complicated aircraft engine exhaust nozzles. MGBK was used to analyze the noise reduction benefits of chevrons–serrations on teh edge of turbofan nozzles–which are a familiar site on many commercial aircraft engines today. Copies of the MGBK codes can be requested from NASA’s Software Catalog.

V072

Predicated on simplistic models of the fan flow and geometry, V072 has been proven useful in studying rotor/stator interaction tone noise. When you need to design a low-noise fan stage, tone noise level predictions from V072 can help you make smart choices for such important design parameters as blade and vane counts, rotor-stator spacing, and stator vane sweep and lean. When you’re after quick noise estimates early in the design cycle, V072 may be your tool of choice. Copies of V072 can be requested from NASA’s Software Catalog.

TFaNS

Taking rotor/stator interaction noise prediction to the next level, not only can TFaNS calculate the tone noise levels generated by rotor/stator interaction it can also account for the blade row acoustic coupling effects such transmission and reflection and can propagate those tones to the far field. Like V072, TFaNS runs quickly and can be used in early design stages for studying trends. Copies of TFaNS can be requested from NASA’s Software Catalog

Linflux

When simple models are too simple, an analysis with Linflux gives you the power to study realistic, 3-D flows and blade geometries. Compared with V072 and TFaNS, Linflux requires significantly more computational resources since it models much more of the physics involved. Linflux predicts rotor/stator tone noise and, like all the software developed by the NASA Glenn Acoustics Branch, has been rigorously validated against experimental data. Copies of Linflux can be requested from NASA’s Software Catalog.

BFANS

Using estimates of turbulence intensity and characteristic length scale as input, BFANS can be used to calculate the broadband noise generated by turbulence impinging on the leading edges of the rotor blades and stator vanes. Calculations with BFANS, combined with experimental data from tests at facilities like NASA Glenn’s 9’x 15’ Low Speed Wind Tunnel, can be used to hunt down the noisiest components in a fan stage. Copies of BFANS can be requested from NASA’s Software Catalog.

RSI

RSI is a computer code for calculating the spectrum of broadband noise produced as a result of the interaction of the fan rotor wake turbulence with the fan exit guide vanes. The software computes the spectra of acoustic power upstream and downstream of the stator on a mode-by-mode basis at each frequency of interest given information about the incident turbulence characteristics. The target frequencies are arbitary and need not be harmonics of the blade passing frequency of the fan. Copies of RSI can be requested from NASA’s Software Catalog.

WOBBLE

Propeller noise can be strongly affected by any inflow that leads to unsteady blade loading. The WOBBLE code computes the tone noise associated with propellers with varying inflow angle and predicts the axial and circumferential directivity. Inflow angle is specified in terms of yaw, pitch, and roll angles of the aircraft. The acoustic model is exact and accounts for all unsteady sources such as thickness and loading effects from the blades. Copies of WOBBLE can be requested from NASA’s Software Catalog.

MPT

Multiple pure tone noise (aka “buzz saw” noise), created by rotor locked shocks present when the fan blade tip speed is supersonic, can be estimated with the MPT code. The MPT codes also use flow predictions from a Computational Fluid Dynamics (CFD) code as input. This tool can be used by engineers to study the real-world effects of blade-to-blade difference caused during fabrication (manufacturing variations) or during hot-running operation (blade setting angle and untwist variations). Copies of the MPT code can be requested from NASA’s Software Catalog.

ADPAC

Developed by the Allison Engine Company under contracts with Glenn Research Center, ADPAC solves tightly coupled internal/external flows through future-concept short-duct turbofan engines. ADPAC is one of our flexible validated CFD tools. Characteristics of the problems that can be modeled with ADPAC include: 2D/axisymmetric/3D/mixed, steady/unsteady, inviscid/viscous, rotating/non-rotating/mixed components, with bleeds, leakages, and injection. ADPAC was developed specifically for propulsion system aerodynamic analysis Copies of the ADPAC code can be requested from NASA’s Software Catalog.

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Research teams at the NASA Glenn Research Center perform experiments in world-class facilities such as the 9- by 15-Foot Low-Speed Wind Tunnel (9 x15 LSWT), the Aero-Acoustic Propulsion Laboratory (AAPL), the Small Hot Jet Acoustic Rig (SHJAR), the Nozzle Acoustic Test Rig (NATR), the DGEN AeroPropulsion Research Turbofan (DART), and the Acoustical Testing Laboratory (ATL).

9×15 Low-Speed Wind Tunnel (9×15 LSWT)

The 9- by 15-Foot Low Speed Wind Tunnel is specially designed to give researchers a controlled environment to study aircraft engine aerodynamics and acoustics at takeoff and landing conditions. This helps us to reduce noise in communities near airports. Major modifications were completed in 2019 to improve the flow and lower the background noise of the tunnel. A new 5-sensor traversing microphone rake helps measure sound produced by scale experimental propulsors. Read more about the capabilities of the 9 x 15 LSWT on our facilities page.

Aero-Acoustic Propulsion Laboratory (AAPL)

The Aero-Acoustic Propulsion Laboratory (AAPL) is a dual-purpose 65-foot radius geodesic dome used to reduce community noise and perform aeroacoustic tests of aircraft engines and engine components. The test area inside the dome can be configured as a hemi-anechoic or anechoic chamber. There are no echoes in the dome during tests because 17,000 custom-designed 2-ft thick fiberglass wedges are mounted to the inside surface of the dome walls and placed on the floor and around test rigs to absorb sound and prevent sound reflections. When AAPL was constructed in 1993, it was the first known free-standing geodesic dome to include materials to reduce transmission of sound through the walls and absorb sound within it. AAPL currently houses the Nozzle Acoustic Test Rig (NATR), Small Hot Jet Acoustic Rig (SHJAR), and the DGEN 380 Aeropropulsion Research Turbofan (DART). Read more about the capabilities of the AAPL on our facilities page.

Small Hot Jet Acoustic Rig (SHJAR)

SHJAR is one of three rigs installed inside the anechoic dome of the Aeroacoustic Propulsion Lab. It can be used to test single stream nozzles up to 5 cm in diameter, Mach 2.0 and 800 K. SHJAR is a key tool in connecting the dots between nozzle geometry, jet flow, and noise. Creative nozzle designs are inexpensively created for this rig, and their impact on flow and noise is measured with world-leading measurement techniques. Researchers at NASA Glenn have been using SHJAR to develop advanced flow measurement techniques like Rayleigh Scattering, Raman Scattering, digital Schleiren, and real-time Particle Image Velocimetry. Three-dimensional microphone arrays have been deployed to map the sources of the noise. These techniques hold the promise of unlocking some of the mysteries of how the turbulence caused by the nozzle creates noise. The data from this rig is used to validate the computer codes that are being developed to calculate jet noise. Better noise prediction codes will help engineers design quieter nozzles.

Among the many firsts in turbulent jet research produced on SHJAR, time-resolved measurements of turbulent temperature were recently made using Raman-based optical methods, achieving high-frequency measurements of thermodynamic temperature fluctuations needed to complete turbulence models used in heat transfer as well as jet noise. In 2006, researchers had used the first time-resolved particle image velocimetry to measured space-time correlations of turbulent velocities in hot jets, a flow statistic key to the production of noise. Time-resolved velocimetry was also used to map convection speeds of turbulence, another flow metric required by jet noise theory but previously unavailable in hot jets.

The SHJAR is not only a good place to develop advanced diagnostic techniques, it has been a good testbed for exploring canonical problems in jet noise such as how the installation of the jet on an aircraft changes the noise produced by the jet. Jet-surface interaction, where the plume of the jet interacts with the wings, flaps, and tail of an aircraft, was identified as a fundamentally different noise mechanism in SHJAR tests.

Most of these ground-breaking measurement techniques and practical noise insights first developed on the relatively simple SHJAR have been deployed on the high-fidelity Nozzle Acoustic Test Rig (NATR), co-located in the Aero-Acoustic Propulsion Lab. Read more about the capabilities of the SHJAR on our facilities page.

Nozzle Acoustic Test Rig (NATR)

The Nozzle Acoustic Test Rig (NATR), a free-jet wind tunnel, plays a key role in evaluating jet noise reduction concepts so that only the most promising concepts are selected for full-scale engine tests. Scale models of nozzles from both military and commercial aircraft engines can be tested in the NATR, which is one of three test rigs housed in the NASA Glenn Aero-Acoustic Propulsion Lab. The NATR can simulate take-off and landing flight conditions up to Mach 0.35. A jet engine simulator with up to three streams of air at a variety of pressures and temperatures simulate the flow of a turbofan engine to evaluate advanced nozzle concepts. The arc of microphones overhead simultaneously measures the far-field noise at all angles, allowing accurate translation of measurements to those of an actual aircraft flying overhead. The NATR enables engineers to evaluate a number of nozzle noise reduction concepts at a fraction of the cost and time required for a full-scale engine test.

Over its 30-year history, NATR has been the origin of many important jet noise breakthroughs. First built to support jet noise testing for the High-Speed Research program on commercial supersonic airliners, the facility has hosted many test programs led by NASA and industry. The chevron nozzles seen flying on today’s aircraft were first ‘discovered’ during a NASA-led test campaign in 1997. Over the years industry has used the rig to develop noise prediction methods for near-term designs. NASA has explored low-noise concepts for engines that are not yet available, such as engines with dual-fan systems. Recent tests have measured the noise likely to be heard from supersonic airliners, reducing the risk that these unique aircraft will not be allowed to fly from current airports. The tests also point to technologies to reduce their noise, allowing the aircraft designers to make the aircraft more efficient and environmentally acceptable.

The ability to test nozzle with flight is critical, as this has a strong impact on the noise produced by the relative velocity of the jet and the surrounding air, and it is a key feature allowing noise measurements to be directly transformed to what would be heard from a real airplane flying overhead. The large size of the anechoic space around the NATR is also critical to measuring the true acoustic far-field of the jet nozzle. The NATR in the Aero-Acoustic Propulsion Lab is one of the very few facilities in the world where these measurements are possible, and the only facility where both flow diagnostics and acoustics can be made on the same rig, a key capability in understanding the relationship between jet flow and noise. Read more about the capabilities of the NATR on our facilities page.

DGEN AeroPropulsion Research Turbofan (DART)

DGEN 380 is the primary component integrated into the NASA Glenn Research Center’s DGEN Aero-propulsion Research Turbofan (DART). It serves as a flexible, relevant, experimental aeroacoustic and aero-performance test bed, providing valuable information throughout NASA’s technology maturation process for a variety of multidisciplinary research that includes turbofan noise, engine controls, installation effects, and measurement technologies.

Recent tests were completed August 2019 to develop a better understanding of propulsion-noise sources to enable improved turbofan noise-prediction methods and noise-mitigation techniques. Simultaneous acoustic measurements were obtained using a circumferential infinite-tube-probe array at the core-nozzle exit in conjunction with sideline and farfield microphone arrays. The extensive data set will allow for the application of advanced source-separation and phased-array methods to elucidate not only the core-noise structure, but also the propagation characteristics of other propulsion noise sources. Read more about the capabilities of the DART on our facilities page.

Acoustical Testing Laboratory

The Acoustical Testing Laboratory at NASA GRC is used to support NASA’s human space exploration and aeronautics research missions. The ATL is a versatile test chamber that can be configured as an anechoic or hemi-anechoic chamber. Dense rubber material in the walls and ceiling of the ATL absorb or reflect sound from the outside. 34-inch deep fiberglass wedges that line the walls and floor are designed to absorb 99% of incident sound above 100 Hz which helps create an ideal environment for making acoustic measurements. A separate control room is attached for any noisy equipment or persons needed to perform the measurements.

The ATL has been used to quantify the noise emissions of experiments performed on the International Space Station, to measure noise sources and levels from electric motors, to calibrate microphone equipment, to measure the effectiveness of acoustic liners for aircraft engine models and to evaluate the over-the-wing engine placement for reducing takeoff and landing noise. Recent tests in the ATL have also included a scale model of a supersonic aircraft engine inlet and a spacecraft cabin ventilation fan.

To get a copies of NASA technical reports related to research in the Acoustical Testing Laboratory, please visit the NASA Technical Reports Server (NTRS).

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The four crew members in NASA’s simulated Mars mission have spent the past year living and working in isolation in a confined habitat at NASA’s Johnson Space Center in Houston. For the past 365 days, the Crew Health and Performance Exploration Analog (CHAPEA) Mission 2 crew members have operated as though they were on the Red Planet, growing crops, managing limited resources, navigating communication delays, and conducting suited extravehicular activities on a simulated Martian surface.

Crew members include Ross Elder, mission commander; Ellen Ellis, medical officer; Matthew Montgomery, science officer; and James Spicer, flight engineer. They entered their 1,700 square foot 3D-printed habitat Oct. 19, 2025. Leading up to the one-year mark of their 378‑day mission, science teams at NASA prepared to process health and performance data collected on the crew. This critical data can help NASA balance priorities and develop methods that counter spaceflight risks during future long-duration missions on Mars.

“We are extremely proud of the crew for their commitment and achievements over the last year on such a fast-paced, highly demanding mission,” said Grace Douglas, CHAPEA principal investigator. “The entire CHAPEA team is excited to congratulate the crew in person.” 

The crew will exit their habitat on Saturday, Oct. 31, to conclude their mission. They will have a chance to reconnect with their families, who they’ve only spoken with via email over the course of their mission with a Mars-like communication delay. The crew will then begin two weeks of post-mission evaluations and debriefs with NASA scientists.

These debriefs and evaluations will help scientists learn what it takes for crews to adapt to the routines and demands of daily life on long-duration missions, giving NASA insight into what future explorers may need to stay healthy, productive, and connected during missions far from Earth.

For example, data could shed light on how limited food and exercise systems will influence NASA’s ability to achieve mission objectives, including spacewalks on the surface of Mars. Some data also could help NASA foster autonomy and build decision-making support systems that best aid crew with communication delays lasting up to 45 minutes each way.

“This mission has been incredibly valuable in starting to teach us how to understand requirements for year-long missions, including medical and psychological care, via communication delays,” said Michael Stenger, chief scientist for NASA’s Human Research Program. “When combining this Mars-realistic mission analog with a suite of physiological, psychological, and performance measures in a rigorously controlled environment, we’ll be able to translate the knowledge from these experiences to Moon Base and beyond.”

To watch the CHAPEA Mission 2 egress ceremony on Oct. 31, visit:

https://www.youtube.com/live/2MONMgAmXNU

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NASA’s Human Research Program 

NASA’s Human Research Program pursues methods and technologies to support safe, productive human space travel. Through science conducted in laboratories, ground-based analogs, commercial missions, the International Space Station and Artemis missions, the program scrutinizes how spaceflight affects human bodies and behaviors. Such research drives the program’s quest to innovate ways that keep astronauts healthy and mission ready as human space exploration expands to the Moon, Mars, and beyond. 

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