Members Can Post Anonymously On This Site
-
Similar Topics
-
By NASA
Operational modal analysis (OMA) techniques have been used to identify the modal characteristics of the Artemis I launch vehicle during the Dynamic Rollout Test (DRT) and Wet Dress Rehearsal (WDR) configuration prior to launch. Forces induced during rollout and on the launch pad are not directly measurable, thus necessitating a unique approach.
NASA is developing the SLS to support lunar and deep space exploration. SLS is integrated inside the Vehicle Assembly Building (VAB) on the mobile launcher (ML), which supports the integrated SLS launch vehicle during transport to the pad through lift-off. The ML also provides the fuel, power, and data umbilicals running to the SLS and Orion Multi-Purpose Crew Vehicle (MPCV), as well as crew access to the MPCV crew module. The ML weighs ~10.6 million pounds and is over 380 feet tall. In the spring of 2022, the SLS was transported on the ML from the VAB to Launch Pad 39B (Figure 1) using the NASA crawler transporter (CT) to make this 4.2 mile trek, which takes ~8 hours. The CT alone weighs ~6.3 million pounds.
Figure 1. Artemis I Rollout to Launch Pad 39B. Although the rollout environment produces relatively small launch vehicle structural loads in comparison to launch and ascent loads for most structures, the induced loads are fully representative of all loading across the entire vehicle, which is not feasible to replicate using localized shakers as was done in the Integrated Modal Test. As mentioned, forces induced during rollout and on the launch pad are not directly measurable, and OMA techniques were used to identify the modal characteristics of Artemis I in the DRT and WDR configurations. WDR, which typically includes vehicle fueling and other operations to demonstrate launch readiness, included several days of on-pad operations. Data collected for the WDR configuration, with partially filled core fuel tanks and without the CT under the ML, provided engineers another model configuration to check (Figure 2).
Figure 2. Artemis I at Launch Pad 39B. Acquisition and processing the data from over 300 accelerometers located on Artemis I, ML, and CT was accomplished by a cross-program team of engineers and technicians from across the Agency, including from SLS, Exploration Ground Systems, and the NESC. Using analytical techniques developed from previous rollout tests combined with new data-processing methodologies, the team processed data from preselected CT speed increments during rollout and on-pad during WDR. By making the necessary modifications to the integrated models to match both the DRT and WDR configurations, the team was able to use those results to help make sense of what was being seen in the test data. This proved to be required for OMA testing on this structure, given the type of complex excitation that was being observed.
For information, contact Dexter Johnson dexter.johnson@nasa.gov and Teresa Kinney teresa.l.kinney@nasa.gov.
View the full article
-
By NASA
NASA/JPL-Caltech/University of Arizona On Jan. 16, 2020, the Mars Reconnaissance Orbiter (MRO) captured this image of two types of sand dunes on Mars: barchan and linear dunes.
The small dots are called barchan dunes, and from their shape we can tell that they are upwind. The downwind dunes are long and linear. These two types of dune each show the wind direction in different ways: the barchans have a steep slope and crescent-shaped “horns” that point downwind, while the linear dunes are stretched out along the primary wind direction. Linear dunes, however, typically indicate at least two different prevailing winds, which stretch out the sand along their average direction.
Barchan and linear dunes aren’t just a Martian phenomenon – we can also see them on Earth. Astronauts aboard the International Space Station have snapped photos of them occurring in Brazil and Saudi Arabia.
Image Credit: NASA/JPL-Caltech/University of Arizona
View the full article
-
By European Space Agency
ESA’s Mars Express has captured an intriguing view near Mars’s north pole, imaging where vast sand dunes meet the many layers of dusty ice covering the planet’s pole.
View the full article
-
By NASA
6 min read
NASA-ISRO Radar Mission to Provide Dynamic View of Forests, Wetlands
NISAR will use radar to study changes in ecosystems around the world, such as this forest in Tikal National Park in northern Guatemala, to understand how these areas are affected by climate change and human activity, and the role they play in the global carbon cycle.Credit: USAID NISAR will help researchers explore how changes in Earth’s forest and wetland ecosystems are affecting the global carbon cycle and influencing climate change.
Once it launches in early 2024, the NISAR radar satellite mission will offer detailed insights into two types of ecosystems – forests and wetlands – vital to naturally regulating the greenhouses gases in the atmosphere that are driving global climate change.
NISAR is a joint mission by NASA and ISRO (Indian Space Research Organisation), and when in orbit, its sophisticated radar systems will scan nearly all of Earth’s land and ice surfaces twice every 12 days. The data it collects will help researchers understand two key functions of both ecosystem types: the capture and the release of carbon.
Pictured in this artist’s concept, NISAR, short for NASA-ISRO Synthetic Aperture Radar, marks the first time the U.S. and Indian space agencies have cooperated on hardware development for an Earth-observing mission. Its two radar systems will monitor change in nearly all of Earth’s land and ice surfaces twice every 12 days.Credit: NASA/JPL-Caltech Forests hold carbon in the wood of their trees; wetlands store it in their layers of organic soil. Disruption of either system, whether gradual or sudden, can accelerate the release of carbon dioxide and methane into the atmosphere. Tracking these land-cover changes on a global scale will help researchers study the impacts on the carbon cycle – the processes by which carbon moves between the atmosphere, land, ocean, and living things.
“The radar technology on NISAR will allow us to get a sweeping perspective of the planet in space and time,” said Paul Rosen, the NISAR project scientist at NASA’s Jet Propulsion Laboratory in Southern California. “It can give us a really reliable view of exactly how Earth’s land and ice are changing.”
Tracking Deforestation
Forestry and other land-use changes account for about 11% of net human-caused greenhouse gas emissions. NISAR’s data will improve our understanding of how the loss of forests around the world influences the carbon cycle and contributes to global warming.
“Globally, we do not understand well the carbon sources and sinks from terrestrial ecosystems, particularly from forests,” said Anup Das, an ecosystems scientist and co-lead of the ISRO NISAR science team. “So we expect that NISAR will greatly help address that, especially in less dense forests, which are more vulnerable to deforestation and degradation.”
To show the kind of imagery NISAR will produce, researchers pointed to this composite that uses data from two Japanese L-band SAR missions to reveal land-cover change in Brazil’s Xingu River basin between 1996 and 2007. Black shows forest areas converted to farmland before 1996, and red shows additional areas cleared by 2007.Credit: Woodwell Climate Research Center/Earth Big Data LLC. Data courtesy of METI and JAXA. The signal from NISAR’s L-band radar will penetrate the leaves and branches of forest canopies, bouncing off the tree trunks and the ground below. By analyzing the signal that reflects back, researchers will be able to estimate the density of forest cover in an area as small as a soccer field. With successive orbital passes, it will be able to track whether a section of forest has been thinned or cleared over time. The data – which will be collected in early morning and evening and in any weather – could also offer clues as to what caused the change, such as disease, human activity, or fire.
It’s an important set of capabilities for studying vast, often cloud-covered rainforests such as those in the Congo and Amazon basins, which lose millions of wooded acres every year. Fire releases carbon into the air directly, while the deterioration of forests reduces the absorption of atmospheric carbon dioxide.
The data could also help improve accounting of deforestation and forest degradation – as well as forest growth – as countries that rely on logging try to shift toward more sustainable practices, said Josef Kellndorfer, a member of the NISAR science team and founder of Earth Big Data LLC, a provider of large data sets and analytic tools for research and decisions support. “Reducing deforestation and degradation is low-hanging fruit to address a substantial part of the global carbon emission problem,” he added.
Monitoring Wetland Flooding
Wetlands present another carbon puzzle: Swamps, bogs, peatlands, inundated forests, marshes, and other wetlands hold 20 to 30% of the carbon in Earth’s soil, despite constituting only 5 to 8% of the land surface.
When wetlands flood, bacteria go to work digesting organic matter (mostly dead plants) in the soil. Through this natural process, wetlands are the planet’s largest natural source of the potent greenhouse gas methane, which bubbles to the water’s surface and travels into the atmosphere. Meanwhile, when wetlands dry out, the carbon they store is exposed to oxygen, releasing carbon dioxide.
NISAR will track wetland flooding to study how these carbon-rich ecosystems are reacting to climate change. It will generate images like this one from an airborne radar that flew over Peru in 2013. Black indicates water, gray is rainforest, green is low vegetation, and red and pink are flooded plants.Credit: NASA/JPL-Caltech “These are huge reservoirs of carbon that can be released in a relatively short time frame,” said Erika Podest, a NISAR science team member and a carbon cycle and ecosystems researcher at JPL.
Less well understood is how changing temperature and precipitation patterns due to climate change – along with human activities such as development and agriculture – are affecting the extent, frequency, and duration of flooding in wetlands. NISAR will be able to monitor flooding, and with repeated passes, researchers will be able to track seasonal and annual variations in wetlands inundation, as well as long-term trends.
By coupling NISAR’s wetlands observations with separate data on the release of greenhouse gases, researchers should gain insights that inform the management of wetland ecosystems, said Bruce Chapman, a NISAR science team member and JPL wetlands researcher. “We have to be careful to reduce our impact on wetland areas so that we don’t worsen the situation with the climate,” he added.
NISAR is set to launch in early 2024 from southern India. In addition to tracking ecosystem changes, it will collect information on the motion of the land, helping researchers understand the dynamics of earthquakes, volcanic eruptions, landslides, and subsidence and uplift (when the surface sinks and rises). It will also track the movements and melting of both glaciers and sea ice.
More About the Mission
NISAR 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. JPL, which is managed for NASA by Caltech in Pasadena, 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. ISRO’s U R Rao Satellite Centre in Bengaluru, which is leading the ISRO component of the mission, is providing the spacecraft bus, the S-band SAR electronics, the launch vehicle, and associated launch services and satellite mission operations.
To learn more about NISAR, visit:
https://nisar.jpl.nasa.gov/
See the NISAR spacecraft in 3D in NASA's interactive Eyes on the Earth 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
2023-151
Share
Details
Last Updated Oct 27, 2023 Related Terms
Earth Earth Science Earth Science Division Earth System Observatory (ESO) NISAR (NASA-ISRO Synthetic Aperture Radar) Explore More
5 min read NASA, Pacific Disaster Center Increase Landslide Hazard Awareness
Article 23 hours ago 5 min read AWE Launching to Space Station to Study Atmospheric Waves via Airglow
NASA’s Atmospheric Waves Experiment, or AWE, mission is scheduled to launch to the International Space…
Article 2 days ago 4 min read New Software Enables Atmospheric Modeling with Greater Resolution
Next-generation software is making it easier for researchers, policy makers, and citizen scientists to model…
Article 3 days ago Keep Exploring Discover Related Topics
Missions
Humans in Space
Climate Change
Solar System
View the full article
-
By NASA
NASA has selected a new mission to help humanity better understand Earth’s dynamic atmosphere – specifically, ice clouds that form at high altitudes throughout tropical and sub-tropical regions. The PolSIR instrument – short for Polarized Submillimeter Ice-cloud Radiometer – will study such ice clouds to determine how and why they change throughoutView 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.