Monday, September 30, 2024
NASA Analysis Shows Irreversible Sea Level Rise for Pacific Islands - EARTH
Pacific Island nations such as Kiribati — a low-lying
country in the southern Pacific Ocean — are preparing now for a future of
higher sea levels.
NASA Earth Observatory
Climate change is rapidly reshaping a region of the world that’s home to
millions of people.
In the next 30 years, Pacific
Island nations such as Tuvalu, Kiribati, and Fiji will experience at least 8
inches (15 centimeters) of sea level rise, according to an analysis by NASA’s
sea level change science team. This amount of rise will occur regardless of
whether greenhouse gas emissions change in the coming years.
The sea level change team undertook
the analysis of this region at the request of several Pacific Island nations,
including Tuvalu and Kiribati, and in close coordination with the U.S.
Department of State.
In addition to the overall
analysis, the agency’s sea level team produced high-resolution maps showing which areas of different Pacific Island nations will be
vulnerable to high-tide flooding — otherwise known as nuisance flooding or sunny day flooding — by the
2050s. Released on Sept. 23, the maps outline flooding potential in a range of
emissions scenarios, from best-case to business-as-usual to worst-case.
“Sea level will continue to rise
for centuries, causing more frequent flooding,” said Nadya Vinogradova Shiffer,
who directs ocean physics programs for NASA’s Earth Science Division. “NASA’s
new flood tool tells you what the potential increase in flooding frequency and
severity look like in the next decades for the coastal communities of the
Pacific Island nations.”
Team members, led by researchers at
the University of Hawaii and in collaboration with scientists at the University
of Colorado and Virginia Tech, started with flood maps of Kiribati, Tuvalu,
Fiji, Nauru, and Niue. They plan to build high-resolution maps for other
Pacific Island nations in the near future. The maps can assist Pacific Island
nations in deciding where to focus mitigation efforts.
“Science and data can help the
community of Tuvalu in relaying accurate sea level rise projections,” said
Grace Malie, a youth leader from Tuvalu who is involved with the Rising Nations
Initiative, a United Nations-supported program led by Pacific Island nations to
help preserve their statehood and protect the rights and heritage of
populations affected by climate change. “This will also help with early warning
systems, which is something that our country is focusing on at the moment.”
Future
Flooding
The analysis by the sea level change team also found that the number of high-tide flooding
days in an average year will increase by an order of magnitude for nearly all
Pacific Island nations by the 2050s. Portions of the NASA team’s analysis were
included in a sea level rise report published by the United Nations in August 2024.
Areas of Tuvalu that currently see
less than five high-tide flood days a year could average 25 flood days annually
by the 2050s. Regions of Kiribati that see fewer than five flood days a year
today will experience an average of 65 flood days annually by the 2050s.
“I am living the reality of climate
change,” said Malie. “Everyone (in Tuvalu) lives by the coast or along the
coastline, so everyone gets heavily affected by this.”
Flooding on island nations can come
from the ocean inundating land during storms or during exceptionally high
tides, called king tides. But it can also result when saltwater intrudes into
underground areas and pushes the water table to the surface. “There are points
on the island where we will see seawater bubbling from beneath the surface and
heavily flooding the area,” Malie added.
Matter of
Location
Sea level rise doesn’t occur
uniformly around the world. A combination of global and local conditions, such
as the topography of a coastline and how glacial meltwater is distributed in
the ocean, affects the amount of rise a particular region will experience.
“We’re always focused on the
differences in sea level rise from one region to another, but in the Pacific,
the numbers are surprisingly consistent,” said Ben Hamlington, a sea level
researcher at NASA’s Jet Propulsion Laboratory in Southern California and the
agency’s sea level change science team lead.
The impacts of 8 inches (15
centimeters) of sea level rise will vary from country to country. For instance,
some nations could experience nuisance flooding several times a year at their
airport, while others might face frequent neighborhood flooding equivalent to
being inundated for nearly half the year.
Researchers would like to combine satellite data on ocean levels with ground-based measurements of sea levels at
specific points, as well as with better land elevation information. “But
there’s a real lack of on-the-ground data in these countries,” said Hamlington.
The combination of space-based and ground-based measurements can yield more
precise sea level rise projections and improved understanding of the impacts to
countries in the Pacific.
“The future of the young people of
Tuvalu is already at stake,” said Malie. “Climate change is more than an
environmental crisis. It is about justice, survival for nations like Tuvalu,
and global responsibility.”
To explore the high-tide flooding maps for Pacific Island nations, go to: https://sealevel.nasa.gov
By: Jet Propulsion
Laboratory
Source: NASA Analysis Shows Irreversible Sea Level Rise for Pacific Islands - NASA
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Saturday, September 28, 2024
In Odd Galaxy, NASA’s Webb Finds Potential Missing Link to First Stars - UNIVERSE
Looking deep into the early universe with NASA’s James Webb Space Telescope, astronomers have found something unprecedented: a galaxy with an odd light signature, which they attribute to its gas outshining its stars. Found approximately one billion years after the big bang, galaxy GS-NDG-9422 (9422) may be a missing-link phase of galactic evolution between the universe’s first stars and familiar, well-established galaxies.
Image A: Galaxy GS-NDG-9422 (NIRCam Image)
What appears as a faint dot in this James Webb Space
Telescope image may actually be a groundbreaking discovery. Detailed
information on galaxy GS-NDG-9422, captured by Webb’s NIRSpec (Near-Infrared
Spectrograph) instrument, indicates that the light we see in this image is
coming from the galaxy’s hot gas, rather than its stars. Astronomers think that
the galaxy’s stars are so extremely hot (more than 140,000 degrees Fahrenheit,
or 80,000 degrees Celsius) that they are heating up the nebular gas, allowing it
to shine even brighter than the stars themselves.
NASA, ESA, CSA, STScI, Alex
Cameron (Oxford)
“My first thought in looking at the
galaxy’s spectrum was, ‘that’s weird,’ which is exactly what the Webb telescope
was designed to reveal: totally new phenomena in the early universe that will
help us understand how the cosmic story began,” said lead researcher Alex
Cameron of the University of Oxford.
Cameron reached out to colleague
Harley Katz, a theorist, to discuss the strange data. Working together, their
team found that computer models of cosmic gas clouds heated by very hot,
massive stars, to an extent that the gas shone brighter than the stars, was
nearly a perfect match to Webb’s observations.
“It looks like these stars must be
much hotter and more massive than what we see in the local universe, which
makes sense because the early universe was a very different environment,” said
Katz, of Oxford and the University of Chicago.
In the local universe, typical hot,
massive stars have a temperature ranging between 70,000 to 90,000 degrees
Fahrenheit (40,000 to 50,000 degrees Celsius). According to the team, galaxy
9422 has stars hotter than 140,000 degrees Fahrenheit (80,000 degrees Celsius).
The research team suspects that the
galaxy is in the midst of a brief phase of intense star formation inside a
cloud of dense gas that is producing a large number of massive, hot stars. The
gas cloud is being hit with so many photons of light from the stars that it is
shining extremely brightly.
Image B: Galaxy GS-NDG-9422 Spectrum (NIRSpec)
This comparison of the data collected by the James
Webb Space Telescope with a computer model prediction highlights the same
sloping feature that first caught the eye of astronomer Alex Cameron, lead
researcher of a new study published in Monthly Notices of the Royal
Astronomical Society. The bottom graphic compares what astronomers would expect
to see in a "typical" galaxy, with its light coming predominantly
from stars (white line), with a theoretical model of light coming from hot
nebular gas, outshining stars (yellow line). The model comes from Cameron’s
collaborator, theoretical astronomer Harley Katz, and together they realized
the similarities between the model and Cameron's Webb observations of galaxy
GS-NDG-9422 (top). The unusual downturn of the galaxy's spectrum, leading to an
exaggerated spike in neutral hydrogen, is nearly a perfect match to Katz’s
model of a spectrum dominated by super-heated gas. While this is still only one
example, Cameron, Katz, and their fellow researchers think the conclusion that
galaxy GS-NDG-9422 is dominated by nebular light, rather than starlight, is
their strongest jumping-off point for future investigation. They are looking
for more galaxies around the same one-billion-year mark in the universe’s
history, hoping to find more examples of a new type of galaxy, a missing link
in the history of galactic evolution.
NASA, ESA, CSA, Leah Hustak
(STScI)
In addition to its novelty, nebular gas
outshining stars is intriguing because it is something predicted in the
environments of the universe’s first generation of stars, which astronomers
classify as Population III stars.
“We know that this galaxy does not have Population III stars, because
the Webb data shows too much chemical
complexity. However, its stars are different than
what we are familiar with – the exotic stars in this galaxy could be a guide
for understanding how galaxies transitioned from primordial stars to the types
of galaxies we already know,” said Katz.
At this point, galaxy 9422 is one example of this phase of galaxy
development, so there are still many questions to be answered. Are these
conditions common in galaxies at this time period, or a rare occurrence? What
more can they tell us about even earlier phases of galaxy evolution? Cameron,
Katz, and their research colleagues are actively identifying more galaxies to
add to this population to better understand what was happening in the universe
within the first billion years after the big bang.
“It’s a very exciting time, to be able to use the Webb telescope to
explore this time in the universe that was once inaccessible,” Cameron said.
“We are just at the beginning of new discoveries and understanding.”
The research paper is published in Monthly Notices of the Royal
Astronomical Society.
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
By: NASA Webb Mission Team, Goddard Space Flight Center
Source: In Odd Galaxy, NASA’s Webb Finds Potential Missing Link to First Stars - NASA ScienceLiDAR-based system allows unmanned aerial vehicle team to rapidly reconstruct environments
(a) Illustration of the proposed
framework’s execution process. (b) 3D reconstruction result of the above scene
produced by the proposed framework. Credit: arXiv (2024). DOI: 10.48550/arxiv.2409.02738
Unmanned
aerial vehicles (UAVs), commonly known as drones, have proved to be highly
effective systems for monitoring and exploring environments. These autonomous
flying robots could also be used to create detailed maps and three-dimensional
(3D) visualizations of real-world environments.
Researchers at Sun Yat-Sen University
and the Hong Kong University of Science and Technology recently introduced
SOAR, a system that allows a team of UAVs to rapidly and autonomously
reconstruct environments by simultaneously exploring and photographing them.
This system, introduced in a paper published on the arXiv preprint
server and set to be presented at the IEEE/RSJ International Conference on Intelligent Robots and Systems
(IROS) 2024, could
have numerous applications, ranging from the urban planning to the design of
videogame environments.
"Our paper stemmed from the
increasing need for efficient and high-quality 3D reconstruction using
UAVs," Mingjie Zhang, co-author of the paper, told Tech Xplore.
"We observed that existing methods often fell into two categories: model-based approaches, which can be time-consuming and expensive due to their reliance on prior information, and model-free methods, which explore and reconstruct simultaneously but might be limited by local planning constraints. Our goal was to bridge this gap by developing a system that could leverage the strengths of both approaches."
Credit: Zhang et al.
The primary objective of the recent
study by Zhang and his colleagues was to create a heterogeneous multi-UAV
system that could simultaneously explore environments and collect photographs,
collecting data that could be used to reconstruct environments. To do this,
they first set out to develop a technique for incremental viewpoint generation
that adapts to scene information that is acquired over time.
In addition, the team planned to
develop a task assignment strategy that would optimize the efficiency of the
multi-UAV team, ensuring that it consistently collected the data necessary to
reconstruct environments. Finally, the team ran a series of simulations to
assess the effectiveness of their proposed system.
"SOAR is a LiDAR-Visual heterogeneous multi-UAV system designed for rapid autonomous 3D reconstruction," explained Zhang. "It employs a team of UAVs: one explorer equipped with LiDAR for fast scene exploration and multiple photographers with cameras for capturing detailed images."
The system overview of the proposed
LiDAR-Visual heterogeneous multi-UAV system for fast aerial reconstruction.
Credit: arXiv (2024). DOI: 10.48550/arxiv.2409.02738
To
create 3D reconstructions, the team's proposed system completes various steps.
Firstly, a UAV that they refer to as the "explorer" efficiently
navigates and maps an environment employing a surface frontier-based strategy.
As this UAV gradually maps the
environment, the team's system incrementally generates viewpoints that would
collectively enable the full coverage of surfaces in the delineated
environment. Other UAVs, referred to as photographers, will then visit these sites
and collect visual data there.
"The viewpoints are clustered and
assigned to photographers using the Consistent-MDMTSP method, balancing
workload and maintaining task consistency," said Zhang. "Each
photographer plans an optimal path to capture images from the assigned viewpoints.
The collected images and their corresponding poses are then used to generate a
textured 3D model."
A unique feature of SOAR is that it enables data collection by both LiDAR and visual sensors. This ensures the efficient exploration of environments and the production of high-quality reconstructions.
Trajectories generated and
reconstruction results by our method, SSearchers, and Multi-EE in two scenes.
Except for the explorer (the black trajectory) in our method, which does not
participate in image capture, all other UAVs are involved in image acquisition
tasks. Credit: arXiv (2024). DOI: 10.48550/arxiv.2409.02738
"Our
system adapts to the dynamically changing scene information, ensuring optimal
coverage with minimal viewpoints," said Zhang. "By consistently
assigning tasks to UAVs, it also improves scanning efficiency and reduces
unnecessary detours for photographers."
Zhang and his colleagues evaluated their
proposed system in a series of simulations. Their findings were highly
promising, as SOAR was found to outperform other state-of-the-art methods for
environment reconstruction.
"A key achievement of our study is
the introduction of a novel framework for fast autonomous aerial
reconstruction," said Zhang. "Central to this framework is the
development of several key algorithms that employ an incremental design, striking
a crucial balance between real-time planning capabilities and overall
efficiency, which is essential for online and dynamic reconstruction
tasks."
In the future, SOAR could be used to
tackle a wide range of real-world problems that require the fast and accurate
reconstruction of 3D environments. For instance, it could be used to create
detailed 3D models of cities and infrastructure or help historians preserve a
country's cultural heritage, helping them reconstruct historic sites and
artifacts.
"SOAR could also be used for
disaster response and assessment," said Zhang. "Specifically, it
could allow responders to rapidly assess damage after natural disasters and
plan rescue and recovery efforts."
The team's system could additionally
contribute to the inspection of infrastructure and construction sites, allowing
workers to map these locations clearly. Finally, it could be used to create 3D
models of video game environments inspired by real cities and natural
landscapes.
"We are enthusiastic about the
potential for future research in this area," said Zhang. "Our plans
include bridging the Sim-to-Real Gap: We aim to tackle the challenges
associated with transitioning SOAR from simulation to real-world environments.
This will involve addressing issues like localization errors and communication
disruptions that can occur in real-world deployments."
As part of their next studies, the
researchers plan to develop new task allocation strategies that could further
improve the coordination between different UAVs and the speed at which they map
environments. Finally, they plan to add scene prediction and information
processing modules to their system, as this could allow it to anticipate the
structure of a given environment, further speeding up the reconstruction
process.
"We will also explore the
implementation of active reconstruction techniques, where the system receives real-time feedback during the reconstruction
process," added Zhang.
"This will allow SOAR to adapt its planning on-the-fly and achieve even better results. Moreover, we will investigate incorporating factors like camera angle and image quality directly into the planning process, which will ensure that the captured images are optimized for generating high-quality 3D reconstructions. These research directions represent exciting opportunities to advance the capabilities of SOAR and push the boundaries of autonomous 3D reconstruction using UAVs."
by Ingrid Fadelli , Tech Xplore
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