Members Can Post Anonymously On This Site
-
Similar Topics
-
-
By NASA
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
A crane lowers the steel reflector framework for Deep Space Station 23 into position Dec. 18 on a 65-foot-high (20-meter) platform above the antenna’s pedestal that will steer the reflector. Panels will be affixed to the structure create a curved surface to collect radio frequency signals.NASA/JPL-Caltech After the steel framework of the Deep Space Station 23 reflector dish was lowered into place on Dec. 18, a crew installed the quadripod, a four-legged support structure that will direct radio frequency signals from deep space that bounce off the main reflector into the antenna’s receiver.NASA/JPL-Caltech Deep Space Station 23’s 133-ton reflector dish was recently installed, marking a key step in strengthening NASA’s Deep Space Network.
NASA’s Deep Space Network, an array of giant radio antennas, allows agency missions to track, send commands to, and receive scientific data from spacecraft venturing to the Moon and beyond. NASA is adding a new antenna, bringing the total to 15, to support increased demand for the world’s largest and most sensitive radio frequency telecommunication system.
Installation of the latest antenna took place on Dec. 18, when teams at NASA’s Goldstone Deep Space Communications Complex near Barstow, California, installed the metal reflector framework for Deep Space Station 23, a multifrequency beam-waveguide antenna. When operational in 2026, Deep Space Station 23 will receive transmissions from missions such as Perseverance, Psyche, Europa Clipper, Voyager 1, and a growing fleet of future human and robotic spacecraft in deep space.
“This addition to the Deep Space Network represents a crucial communication upgrade for the agency,” said Kevin Coggins, deputy associate administrator of NASA’s SCaN (Space Communications and Navigation) program. “The communications infrastructure has been in continuous operation since its creation in 1963, and with this upgrade we are ensuring NASA is ready to support the growing number of missions exploring the Moon, Mars, and beyond.”
This time-lapse video shows the entire day of construction activities for the Deep Space Station 23 antenna at the NASA Deep Space Network’s Goldstone Space Communications Complex near Barstow, California, on Dec. 18. NASA/JPL-Caltech Construction of the new antenna has been under way for more than four years, and during the installation, teams used a crawler crane to lower the 133-ton metal skeleton of the 112-foot-wide (34-meter-wide) parabolic reflector before it was bolted to a 65-foot-high (20-meter-high) alidade, a platform above the antenna’s pedestal that will steer the reflector during operations.
“One of the biggest challenges facing us during the lift was to ensure that 40 bolt-holes were perfectly aligned between the structure and alidade,” said Germaine Aziz, systems engineer, Deep Space Network Aperture Enhancement Program of NASA’s Jet Propulsion Laboratory in Southern California. “This required a meticulous emphasis on alignment prior to the lift to guarantee everything went smoothly on the day.”
Following the main lift, engineers carried out a lighter lift to place a quadripod, a four-legged support structure weighing 16 1/2 tons, onto the center of the upward-facing reflector. The quadripod features a curved subreflector that will direct radio frequency signals from deep space that bounce off the main reflector into the antenna’s pedestal, where the antenna’s receivers are housed.
In the early morning of Dec. 18, a crane looms over the 112-foot-wide (34-meter-wide) steel framework for Deep Space Station 23 reflector dish, which will soon be lowered into position on the antenna’s base structure.NASA/JPL-Caltech Engineers will now work to fit panels onto the steel skeleton to create a curved surface to reflect radio frequency signals. Once complete, Deep Space Station 23 will be the fifth of six new beam-waveguide antennas to join the network, following Deep Space Station 53, which was added at the Deep Space Network’s Madrid complex in 2022.
“With the Deep Space Network, we are able to explore the Martian landscape with our rovers, see the James Webb Space Telescope’s stunning cosmic observations, and so much more,” said Laurie Leshin, director of JPL. “The network enables over 40 deep space missions, including the farthest human-made objects in the universe, Voyager 1 and 2. With upgrades like these, the network will continue to support humanity’s exploration of our solar system and beyond, enabling groundbreaking science and discovery far into the future.”
NASA’s Deep Space Network is managed by JPL, with the oversight of NASA’s SCaN Program. More than 100 NASA and non-NASA missions rely on the Deep Space Network and Near Space Network, including supporting astronauts aboard the International Space Station and future Artemis missions, monitoring Earth’s weather and the effects of climate change, supporting lunar exploration, and uncovering the solar system and beyond.
For more information about the Deep Space Network, visit:
https://www.nasa.gov/communicating-with-missions/dsn
News Media Contact
Ian J. O’Neill
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-2649
ian.j.oneill@jpl.nasa.gov
2024-179
Share
Details
Last Updated Dec 20, 2024 Related Terms
Deep Space Network Jet Propulsion Laboratory Space Communications & Navigation Program Space Operations Mission Directorate Explore More
4 min read Lab Work Digs Into Gullies Seen on Giant Asteroid Vesta by NASA’s Dawn
Article 8 hours ago 5 min read Avalanches, Icy Explosions, and Dunes: NASA Is Tracking New Year on Mars
Article 9 hours ago 8 min read NASA’s Kennedy Space Center Looks to Thrive in 2025
Article 2 days ago Keep Exploring Discover Related Topics
Missions
Humans in Space
Climate Change
Solar System
View the full article
-
By NASA
NASA’s Dawn spacecraft captured this image of Vesta as it left the giant asteroid’s orbit in 2012. The framing camera was looking down at the north pole, which is in the middle of the image.NASA/JPL-Caltech/UCLA/MPS/DLR/IDA Known as flow formations, these channels could be etched on bodies that would seem inhospitable to liquid because they are exposed to the extreme vacuum conditions of space.
Pocked with craters, the surfaces of many celestial bodies in our solar system provide clear evidence of a 4.6-billion-year battering by meteoroids and other space debris. But on some worlds, including the giant asteroid Vesta that NASA’s Dawn mission explored, the surfaces also contain deep channels, or gullies, whose origins are not fully understood.
A prime hypothesis holds that they formed from dry debris flows driven by geophysical processes, such as meteoroid impacts, and changes in temperature due to Sun exposure. A recent NASA-funded study, however, provides some evidence that impacts on Vesta may have triggered a less-obvious geologic process: sudden and brief flows of water that carved gullies and deposited fans of sediment. By using lab equipment to mimic conditions on Vesta, the study, which appeared in Planetary Science Journal, detailed for the first time what the liquid could be made of and how long it would flow before freezing.
Although the existence of frozen brine deposits on Vesta is unconfirmed, scientists have previously hypothesized that meteoroid impacts could have exposed and melted ice that lay under the surface of worlds like Vesta. In that scenario, flows resulting from this process could have etched gullies and other surface features that resemble those on Earth.
To explore potential explanations for deep channels, or gullies, seen on Vesta, scientists used JPL’s Dirty Under-vacuum Simulation Testbed for Icy Environments, or DUSTIE, to simulate conditions on the giant asteroid that would occur after meteoroids strike the surface.NASA/JPL-Caltech But how could airless worlds — celestial bodies without atmospheres and exposed to the intense vacuum of space — host liquids on the surface long enough for them to flow? Such a process would run contrary to the understanding that liquids quickly destabilize in a vacuum, changing to a gas when the pressure drops.
“Not only do impacts trigger a flow of liquid on the surface, the liquids are active long enough to create specific surface features,” said project leader and planetary scientist Jennifer Scully of NASA’s Jet Propulsion Laboratory in Southern California, where the experiments were conducted. “But for how long? Most liquids become unstable quickly on these airless bodies, where the vacuum of space is unyielding.”
The critical component turns out to be sodium chloride — table salt. The experiments found that in conditions like those on Vesta, pure water froze almost instantly, while briny liquids stayed fluid for at least an hour. “That’s long enough to form the flow-associated features identified on Vesta, which were estimated to require up to a half-hour,” said lead author Michael J. Poston of the Southwest Research Institute in San Antonio.
Launched in 2007, the Dawn spacecraft traveled to the main asteroid belt between Mars and Jupiter to orbit Vesta for 14 months and Ceres for almost four years. Before ending in 2018, the mission uncovered evidence that Ceres had been home to a subsurface reservoir of brine and may still be transferring brines from its interior to the surface. The recent research offers insights into processes on Ceres but focuses on Vesta, where ice and salts may produce briny liquid when heated by an impact, scientists said.
Re-creating Vesta
To re-create Vesta-like conditions that would occur after a meteoroid impact, the scientists relied on a test chamber at JPL called the Dirty Under-vacuum Simulation Testbed for Icy Environments, or DUSTIE. By rapidly reducing the air pressure surrounding samples of liquid, they mimicked the environment around fluid that comes to the surface. Exposed to vacuum conditions, pure water froze instantly. But salty fluids hung around longer, continuing to flow before freezing.
The brines they experimented with were a little over an inch (a few centimeters) deep; scientists concluded the flows on Vesta that are yards to tens of yards deep would take even longer to refreeze.
The researchers were also able to re-create the “lids” of frozen material thought to form on brines. Essentially a frozen top layer, the lids stabilize the liquid beneath them, protecting it from being exposed to the vacuum of space — or, in this case the vacuum of the DUSTIE chamber — and helping the liquid flow longer before freezing again.
This phenomenon is similar to how on Earth lava flows farther in lava tubes than when exposed to cool surface temperatures. It also matches up with modeling research conducted around potential mud volcanoes on Mars and volcanoes that may have spewed icy material from volcanoes on Jupiter’s moon Europa.
“Our results contribute to a growing body of work that uses lab experiments to understand how long liquids last on a variety of worlds,” Scully said.
Find more information about NASA’s Dawn mission here:
https://science.nasa.gov/mission/dawn/
News Media Contacts
Gretchen McCartney
Jet Propulsion Laboratory, Pasadena, Calif.
818-287-4115
gretchen.p.mccartney@jpl.nasa.gov
Karen Fox / Molly Wasser
NASA Headquarters, Washington
202-358-1600
karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov
2024-178
Share
Details
Last Updated Dec 20, 2024 Related Terms
Dawn Asteroids Ceres Jet Propulsion Laboratory Vesta Explore More
5 min read Avalanches, Icy Explosions, and Dunes: NASA Is Tracking New Year on Mars
Article 1 hour ago 5 min read Cutting-Edge Satellite Tracks Lake Water Levels in Ohio River Basin
Article 3 days ago 5 min read NASA Mars Orbiter Spots Retired InSight Lander to Study Dust Movement
Article 4 days ago Keep Exploring Discover More Topics From NASA
Missions
Humans in Space
Climate Change
Solar System
View the full article
-
By European Space Agency
Global warming is driving the rapid melting of the Greenland Ice Sheet, contributing to global sea level rise and disrupting weather patterns worldwide. Because of this, precise measurements of its changing shape are of critical importance for adapting to climate change.
Now, scientists have delivered the first measurements of the Greenland Ice Sheet’s changing shape using data from ESA's CryoSat and NASA's ICESat-2 ice missions.
View the full article
-
By NASA
Download PDF: Statistical Analysis Using Random Forest Algorithm Provides Key Insights into Parachute Energy Modulator System
Energy modulators (EM), also known as energy absorbers, are safety-critical components that are used to control shocks and impulses in a load path. EMs are textile devices typically manufactured out of nylon, Kevlar® and other materials, and control loads by breaking rows of stitches that bind a strong base webbing together as shown in Figure 1. A familiar EM application is a fall-protection harness used by workers to prevent injury from shock loads when the harness arrests a fall. EMs are also widely used in parachute systems to control shock loads experienced during the various stages of parachute system deployment.
Random forest is an innovative algorithm for data classification used in statistics and machine learning. It is an easy to use and highly flexible ensemble learning method. The random forest algorithm is capable of modeling both categorical and continuous data and can handle large datasets, making it applicable in many situations. It also makes it easy to evaluate the relative importance of variables and maintains accuracy even when a dataset has missing values.
Random forests model the relationship between a response variable and a set of predictor or independent variables by creating a collection of decision trees. Each decision tree is built from a random sample of the data. The individual trees are then combined through methods such as averaging or voting to determine the final prediction (Figure 2). A decision tree is a non-parametric supervised learning algorithm that partitions the data using a series of branching binary decisions. Decision trees inherently identify key features of the data and provide a ranking of the contribution of each feature based on when it becomes relevant. This capability can be used to determine the relative importance of the input variables (Figure 3). Decision trees are useful for exploring relationships but can have poor accuracy unless they are combined into random forests or other tree-based models.
The performance of a random forest can be evaluated using out-of-bag error and cross-validation techniques. Random forests often use random sampling with replacement from the original dataset to create each decision tree. This is also known as bootstrap sampling and forms a bootstrap forest. The data included in the bootstrap sample are referred to as in-the-bag, while the data not selected are out-of-bag. Since the out-of-bag data were not used to generate the decision tree, they can be used as an internal measure of the accuracy of the model. Cross-validation can be used to assess how well the results of a random forest model will generalize to an independent dataset. In this approach, the data are split into a training dataset used to generate the decision trees and build the model and a validation dataset used to evaluate the model’s performance. Evaluating the model on the independent validation dataset provides an estimate of how accurately the model will perform in practice and helps avoid problems such as overfitting or sampling bias. A good model performs well on
both the training data and the validation data.
The complex nature of the EM system made it difficult for the team to identify how various parameters influenced EM behavior. A bootstrap forest analysis was applied to the test dataset and was able to identify five key variables associated with higher probability of damage and/or anomalous behavior. The identified key variables provided a basis for further testing and redesign of the EM system. These results also provided essential insight to the investigation and aided in development of flight rationale for future use cases.
For information, contact Dr. Sara R. Wilson. sara.r.wilson@nasa.gov
View 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.