TYB
NASA Astronomy Picture of the Day
December 20, 2024
The Long Night Moon
On the night of December 15, the Full Moon was bright. Known to some as the Cold Moon or the Long Night Moon, it was the closest Full Moon to the northern winter solstice and the last Full Moon of 2024. This Full Moon was also at a major lunar standstill. A major lunar standstill is an extreme in the monthly north-south range of moonrise and moonset caused by the precession of the Moon's orbit over an 18.6 year cycle. As a result, the full lunar phase was near the Moon's northernmost moonrise (and moonset) along the horizon. December's Full Moon is rising in this stacked image, a composite of exposures recording the range of brightness visible to the eye on the northern winter night. Along with a colorful lunar corona and aircraft contrail this Long Night Moon shines in a cold sky above the rugged, snowy peaks of the Italian Dolomites.
https://apod.nasa.gov/apod/astropix.html
And you as well
NASA Cameras to Capture Interaction Between Blue Ghost, Moon’s Surface
Dec 19, 2024
Say cheese again, Moon. We’re coming in for another close-up.
For the second time in less than a year, a NASA technology designed to collect data on the interaction between a Moon lander’s rocket plume and the lunar surface is set to make the long journey to Earth’s nearest celestial neighbor for the benefit of humanity.
Developed at NASA’s Langley Research Center in Hampton, Virginia, Stereo Cameras for Lunar Plume-Surface Studies (SCALPSS) is an array of cameras placed around the base of a lunar lander to collect imagery during and after descent and touchdown.
Using a technique called stereo photogrammetry, researchers at Langley will use the overlapping images from the version of SCALPSS on Firefly’s Blue Ghost — SCALPSS 1.1 — to produce a 3D view of the surface.
An earlier version, SCALPSS 1.0, was on Intuitive Machines’ Odysseus spacecraft that landed on the Moon last February.
Due to mission contingencies that arose during the landing, SCALPSS 1.0 was unable to collect imagery of the plume-surface interaction.
The team was, however, able to operate the payload in transit and on the lunar surface following landing, which gives them confidence in the hardware for 1.1.
The SCALPSS 1.1 payload has two additional cameras — six total, compared to the four on SCALPSS 1.0 — and will begin taking images at a higher altitude, prior to the expected onset of plume-surface interaction, to provide a more accurate before-and-after comparison.
These images of the Moon’s surface won’t just be a technological novelty.
As trips to the Moon increase and the number of payloads touching down in proximity to one another grows, scientists and engineers need to be able to accurately predict the effects of landings.
How much will the surface change? As a lander comes down, what happens to the lunar soil, or regolith, it ejects?
With limited data collected during descent and landing to date, SCALPSS will be the first dedicated instrument to measure the effects of plume-surface interaction on the Moon in real time and help to answer these questions.
“If we’re placing things – landers, habitats, etc. – near each other, we could be sand blasting what’s next to us, so that’s going to drive requirements on protecting those other assets on the surface, which could add mass, and that mass ripples through the architecture,” said Michelle Munk, principal investigator for SCALPSS and acting chief architect for NASA’s Space Technology Mission Directorate at NASA Headquarters in Washington.
“It’s all part of an integrated engineering problem.”
Under the Artemis campaign, the agency’s current lunar exploration approach, NASA is collaborating with commercial and international partners to establish the first long-term presence on the Moon.
On this CLPS (Commercial Lunar Payload Services) initiative delivery carrying over 200 pounds of NASA science experiments and technology demonstrations, SCALPSS 1.1 will begin capturing imagery from before the time the lander’s plume begins interacting with the surface until after the landing is complete.
The final images will be gathered on a small onboard data storage unit before being sent to the lander for downlink back to Earth.
The team will likely need at least a couple of months to process the images, verify the data, and generate the 3D digital elevation maps of the surface.
The expected lander-induced erosion they reveal probably won’t be very deep — not this time, anyway.
“Even if you look at the old Apollo images — and the Apollo crewed landers were larger than these new robotic landers — you have to look really closely to see where the erosion took place,” said Rob Maddock, SCALPSS project manager at Langley. “We’re anticipating something on the order of centimeters deep — maybe an inch. It really depends on the landing site and how deep the regolith is and where the bedrock is.”
But this is a chance for researchers to see how well SCALPSS will work as the U.S. advances human landing systems as part of NASA’s plans to explore more of the lunar surface.
“Those are going to be much larger than even Apollo. Those are large engines, and they could conceivably dig some good-sized holes,” said Maddock.
“So that’s what we’re doing. We’re collecting data we can use to validate the models that are predicting what will happen.”
https://www.nasa.gov/general/nasa-cameras-to-capture-interaction-between-blue-ghost-moons-surface/
https://www.youtube.com/watch?v=n-iLjvhaKxc
Perseverance Blasts Past the Top of Jezero Crater Rim
Dec 19, 2024
I have always loved the mountains. Growing up on the flat plains of Midwestern USA, every summer I looked forward to spending a few days on alpine trails while on vacation.
Climbing upward from the trailhead, the views changed constantly. After climbing a short distance, the best views were often had by looking back down on where we had started.
As we climbed higher, views of the valleys below eventually became shrouded in haze.
Near the top we got our last views of the region behind us; then it disappeared from view as we hiked over the pass and started down the other side.
Approaching the summit held a special reward, as the regions beyond the pass slowly revealed themselves.
Frequent stops to catch our breath during our ascent were used to check the map to identify the new peaks and other features that came into view.
Sometimes the pass was an exciting gateway to a whole new area to explore.
This ever-changing landscape has been our constant companion over the last five months as Perseverance first climbed out of Neretva Vallis, then past “Dox Castle,” and “Pico Turquino.”
We stopped at “Faraway Rock” on Sol 1282 to get a panorama of the crater floor.
More recently, we could see many more peaks of the crater rim. As Perseverance crested the summit of “Lookout Hill,” half a mile (800 meters) above the traverse’s lowest point, we got our first views beyond the crater rim, out into the great unknown expanse of Mars’ Nili Planum, including the upper reaches of Neretva Vallis and the locations of two other candidate landing sites that were once considered for Perseverance.
As the rover crested the summit, Mastcam-Z took a large panoramic mosaic, and team members are excitedly poring over the images, looking at all the new features.
With Perseverance’s powerful cameras we can analyze small geological features such as boulders, fluvial bars, and dunes more than 5 miles (8 kilometers) distant, and major features like mountains up to 35 miles (60 kilometers) away.
One of our team members excitedly exclaimed, “This is an epic moment in Mars exploration!”
While Curiosity has been climbing “Mount Sharp” for 10 years, and Spirit and Opportunity explored several smaller craters, no extraterrestrial rover has driven out of such a huge crater as Jezero to see a whole new “continent” ahead.
We are particularly excited because it is potentially some of the most ancient surface on the Red Planet. Let’s go explore it!
Perseverance is now in Gros Morne quad, named for a beautiful Canadian national park in Newfoundland, and we will be naming our targets using locations and features in the national park.
For the drive ahead, described in a video in a recent press release, our next destination is on the lower western edge of the Jezero crater rim at a region named “Witch Hazel Hill.”
Perseverance made more than 250 meters of progress over the weekend (about 820 feet) and is already at the upper part of Witch Hazel Hill, a location called “South Arm.”
Much of the climb up the crater rim was on sandy material without many rocks to analyze.
Witch Hazel Hill appears to have much more exposed rock, and the science team is excited about the opportunity for better views and analyses of the geology directly beneath our wheels.
https://science.nasa.gov/blog/perseverance-blasts-past-the-top-of-jezero-crater-rim/
New Report Analyzes Long History of NASA Support for Commercial Space
Dec 19, 2024
NASA published a new report Thursday highlighting 17 agency mechanisms that have directly and indirectly supported the development and growth of the U.S. commercial space sector for the benefit of humanity.
The report, titled Enabling America on the Space Frontier: The Evolution of NASA’s Commercial Space Development Toolkit, is available on the agency’s website.
“This is the most extensive and comprehensive historical analysis produced by NASA on how it has contributed to commercial space development over the decades,” said Alex MacDonald, NASA chief economist.
“These efforts have given NASA regular access to space with companies, such as SpaceX and Rocket Lab, modernizing our communications infrastructure, and even led to the first private lunar lander thanks to Intuitive Machines.
With commercial space growth accelerating, this report can help agency leaders and stakeholders assess the numerous mechanisms that the agency uses to support this growth, both now and in the future.”
Throughout its history, NASA has supported the development of the commercial space sector, not only leading the way in areas such as satellite communications, launch, and remote sensing, but also developing new contract and operational models to encourage commercial participation and growth.
In the last three decades, NASA has seen the results of these efforts with commercial partners able to contribute more to missions across NASA domains, and increasingly innovative agency-led efforts to engage, nurture, and integrate these capabilities. These capabilities support the agency’s mission needs, and have seen a dramatic rise in importance, according to the report.
NASA has nurtured technology, companies, people, and ideas in the commercial space sector, contributing to the U.S. and global economies, across four distinct periods in the agency’s history:
1915–1960: NASA’s predecessor, the National Advisory Committee on Aeronautics (NACA), and NASA’s pre-Apollo years.
1961–1980: Apollo era.
1981–2010: Space shuttle era.
2011–present: Post-shuttle commercial era.
Each of these time periods are defined by dominant technologies, programs, or economic trends further detailed in the report.
Though some of these mechanisms are relatively recent, others have been used throughout the history of NASA and NACA, leading to some overlap.
The 17 mechanisms are as follows:
Contracts and Partnership Agreements
Research and Technology Development (R&TD)
Dissemination of Research and Scientific Data
Education and Workforce Development
Workforce External Engagement and Mobility
Technology Transfer
Technical Support
Enabling Infrastructure
Launch
Direct In-Space Support
Standards and Regulatory Framework Support
Public Engagement
Industry Engagement
Venture Capital Engagement
Market Stimulation Funding
Economic Analysis and Due Diligence Capabilities
Narrative Encouragement
NASA supports commercial space development in everything from spaceflight to supply chains.
Small satellite capabilities have inspired a new generation of space start-ups, while new, smaller rockets, as well as new programs are just starting.
Examples include CLPS (Commercial Lunar Payload Services), commercial low Earth orbit destinations, human landing systems, commercial development of NASA spacesuits, and lunar terrain vehicles.
The report also details many indirect ways the agency has contributed to the vibrance of commercial space, from economic analyses to student engagement.
The agency’s use of commercial capabilities has progressed from being the exception to the default method for many of its missions.
The current post-shuttle era of NASA-supported commercial space development has seen a level of technical development comparable to the Apollo era’s Space Race.
Deploying the 17 commercial space development mechanisms in the future are part of NASA’s mission to continue encouraging commercial space activities.
https://www.nasa.gov/organizations/otps/new-report-analyzes-long-history-of-nasa-support-for-commercial-space/
https://www.nasa.gov/wp-content/uploads/2024/12/nasa-enabling-america-on-the-space-frontier-december-16-final-tagged.pdf?emrc=676553f64da77
Amendment 86: E.12 Physical Sciences Research Studies Final Text and Due Dates
December 19, 2024
E.12 Physical Sciences Research Studies solicits proposals to investigate physical phenomena in the absence of gravity and fundamental laws that describe the universe, and applied research, which contributes to the basic understanding of processes underlying space exploration technologies.
The program is divided into two key goals: Foundations and Quantum Leaps. Foundations focuses on understanding the behavior of fluids, combustion, soft matter, and materials in the spaceflight environment.
Quantum Leaps aims to probe the very nature of the universe using exquisitely precise space-based quantum sensors to test the Einstein equivalence principle, dark sector physics, and the nature of fundamental physical constants.
This opportunity will include four different Project Types: Research Investigations, New NASA Investigators, Physical Sciences Informatics, and Fundamental Physics Investigations.
Specific requirements for each of these Project Types are described in detail in Section 2.2 of this program element. The Project Types have different platform opportunities described in Section 2.3
ROSES-2024 Amendment 86 releases final text and due dates for E.12 Physical Sciences Research Studies, that was previously released as draft. Step-1 proposals are due February 4, 2025, and Step-2 proposals are due May 6, 2025.
A pre-proposer’s townhall for applicants interested in submitting a proposal to this program element will be held virtually on January 22, 2025, at 3 pm Eastern Time connect information will appear on the NSPIRES page for this program element under "Other Documents."
On or about December 19, 2024, this Amendment to the NASA Research Announcement "Research Opportunities in Space and Earth Sciences (ROSES) 2024" (NNH24ZDA001N) will be posted on the NASA research opportunity homepage at https://solicitation.nasaprs.com/ROSES2024
https://science.nasa.gov/researchers/solicitations/roses-2024/amendment-86-e-12-physical-sciences-research-studies-final-text-and-due-dates/
https://nspires.nasaprs.com/external/solicitations/summary.do?solId=%7B600EE5E5-E9D5-FF55-0CAD-764F6D4BEEA9%7D&path=&method=init
https://nspires.nasaprs.com/external/solicitations/summary.do?solId=%7b2CBDC34D-35C6-87C3-D73F-98C2111ECA07%7d&path=&method=init
ESA and NASA satellites deliver first joint picture of Greenland Ice Sheet melting
December 20, 2024
Academics from Northumbria University are part of an international research team which has used data from satellites to track changes in the thickness of the Greenland Ice Sheet.
Global warming is causing the Ice Sheet to melt and flow more rapidly, raising sea levels and disturbing weather patterns across our planet.
Because of this, precise measurements of its changing shape are of critical importance for tracking and adapting to the effects of climate warming.
Scientists have now delivered the first measurements of Greenland Ice Sheet thickness change using CryoSat-2 and ICESat-2—the ESA and NASA ice satellite missions.
Both satellites carry altimeters as their primary sensor, but they make use of different technologies to collect their measurements.
CryoSat-2 carries a radar system to determine the Earth's surface height, while ICESat-2 has a laser system for the same task.
Although radar signals can pass through clouds, they also penetrate into the ice sheet surface and have to be adjusted for this effect.
Laser signals, on the other hand, reflect from the actual surface, but they cannot operate when clouds are present.
The missions are therefore highly complementary, and combining their measurements has been a holy grail for polar science.
A study by scientists at the UK Center for Polar Observation and Modeling (CPOM), based at Northumbria University, and published in Geophysical Research Letters shows that CryoSat-2 and ICESat-2 measurements of Greenland Ice Sheet elevation change agree to within 3%.
This confirms that the satellites can be combined to produce a more reliable estimate of ice loss than either could achieve alone.
It also means that if one mission were to fail, the other could be relied upon to maintain our record of polar ice change.
Between 2010 and 2023, the Greenland Ice Sheet thinned by 1.2 meters on average. However, thinning across the ice sheet's margin (the ablation zone) was over five times larger, amounting to 6.4 meters on average.
The most extreme thinning occurred at the ice sheets outlet glaciers, many of which are speeding up.
At Sermeq Kujalleq in west central Greenland (also known as Jakobshavn Isbræ), peak thinning was 67 meters, and at Zachariae Isstrøm in the northeast peak thinning was 75 meters.
Altogether, the ice sheet shrank by 2,347 cubic kilometers across the 13-year survey period—enough to fill Africa's Lake Victoria.
The biggest changes occurred in 2012 and 2019 when summer temperatures were extremely hot and the ice sheet lost more than 400 cubic kilometers of its volume each year.
Greenland's ice melting also affects global ocean circulation and disturbs weather patterns. These changes have far-reaching impacts on ecosystems and communities worldwide.
The availability of accurate, up-to-date data on ice sheet changes will be critical in helping us to prepare for and adapt to the impacts of climate change.
Lead author and CPOM researcher Nitin Ravinder said, "We are very excited to have discovered that CryoSat-2 and ICESat-2 are in such close agreement.
"Their complementary nature provides a strong motivation to combine the data sets to produce improved estimates of ice sheet volume and mass changes.
"As ice sheet mass loss is a key contributor to global sea level rise, this is incredibly useful for the scientific community and policymakers."
The study made use of four years of measurements from both missions, including those collected during the Cryo2ice campaign, a pioneering ESA-NASA partnership initiated in 2020.
By adjusting CryoSat-2's orbit to synchronize with ICESat-2, ESA enabled the near-simultaneous collection of radar and laser data over the same regions.
This alignment allows scientists to measure snow depth from space, offering unprecedented accuracy in tracking sea and land ice thickness.
Tommaso Parrinello, CryoSat Mission Manager at ESA, expressed optimism about the campaign's impact, "CryoSat has provided an invaluable platform for understanding our planet's ice coverage over the past 14 years, but by aligning our data with ICESat-2, we've opened new avenues for precision and insight.
"This collaboration represents an exciting step forward, not just in terms of technology but in how we can better serve scientists and policymakers who rely on our data to understand and mitigate climate impacts."
https://phys.org/news/2024-12-esa-nasa-satellites-joint-picture.html
https://www.youtube.com/watch?v=1clUGqYZEpg
https://www.psu.edu/news/eberly-college-science/story/penn-state-extraterrestrial-intelligence-center-awarded-nasa-grant
https://www.pseti.psu.edu/
Penn State Extraterrestrial Intelligence Center awarded NASA grant
December 19, 2024
Researchers at the Penn State Extraterrestrial Intelligence (PSETI) Center have been awarded a three-year, $480,000 grant under the NASA Exoplanets Research Program to search for radio and laser signals from alien civilizations.
The project is led by Pinchen Fan, a doctoral student in astronomy, astrophysics and astrobiology, under the supervision of her adviser, Jason Wright, professor of astronomy and astrophysics and director of the PSETI Center.
“This NASA grant marks a significant milestone for both Penn State and the broader field of the search for extraterrestrial intelligence (SETI),” Wright said.
“This area of research has been historically underfunded by NASA but is now seeing a resurgence in attention and support.
The PSETI Center is uniquely positioned to lead this exploration, thanks to Penn State’s support, NASA’s support and the dedication of researchers like Pinchen, who will be driving much of this project forward.”
In 2018, Wright organized a workshop in Houston on behalf of NASA to inform the agency how it might better participate in the search for technological life elsewhere in the universe.
The new grant represents a continuation of the momentum started with that workshop, as well as a signal that NASA is increasingly open to supporting innovative approaches to the search for life elsewhere in the universe, according to Wright.
"The renewed interest from NASA is a game-changer for SETI research," Fan said.
"It provides us with the resources and support needed to push the boundaries of our understanding and explore uncharted territories in the search for extraterrestrial intelligence."
Technosignatures are defined as any detectable sign that would indicate the presence of intelligent civilizations elsewhere in the universe.
This new project aims to develop novel laser and radio technosignature detection techniques that will push the boundaries of how researchers can detect technosignatures from planets outside the solar system.
“We will analyze the patterns of humanity’s most powerful deep-space radio transmissions as a baseline for understanding the patterns of a civilization’s transmissions to its own interplanetary probes,” Fan said.
“We will use these patterns as a guide to how we might eavesdrop on radio transmissions from other spacefaring civilizations that are not specifically intended for Earth.”
Fan will also use the tens of thousands of infrared spectroscopic measurements taken by the Habitable Zone Planet Finder (HPF) built at Penn State to detect planets orbiting other stars to see if there are any communicative laser transmissions coming from them.
“Humanity has been moving towards laser communications for interplanetary communications for a while now,” Fan said.
“It makes sense that other species might do the same, so we are excited to use the HPF for this novel search.”
The HPF is an astronomical spectrograph installed on the 10-meter Hobby-Eberly Telescope at the McDonald Observatory in Texas.
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“There is a long tradition of SETI searches piggybacking on surveys at the radio wavelengths” said Suvrath Mahadevan, Verne M. Willaman Professor of Astronomy and Astrophysics and the principal investigator of the HPF spectrometer.
“It is great to see this approach now used in the near-infrared with HPF to search for laser transmissions.”
This funding underscores Penn State's prominent role in a field that is gaining traction within the scientific community, Wright said.
The 2018 workshop, along with a series of SETI Symposia hosted by the PSETI Center on Penn State’s University Park campus, played a pivotal role in renewing NASA’s focus on SETI research.
“NASA’s support for our technosignature research reflects both the growing scientific credibility and public interest in SETI,” Fan said.
“I’m excited to contribute to Penn State’s leadership in this field and to develop new techniques that could bring us closer to finding extraterrestrial life.”
The PSETI Center was founded in 2020 to establish Penn State as an academic leader in technosignature research.
Through initiatives like this NASA-funded project, the center provides a platform for researchers to explore sophisticated technosignature detection methods and more.
“This grant from NASA highlights a pivotal moment in the advancement of SETI as a scientific discipline and the pioneering work being done at Penn State,” Wright said.
“With renewed support, innovative ideas, and a team of dedicated researchers, Penn State is well positioned to lead in the quest to uncover evidence of intelligent life beyond Earth.”
Members of the PSETI Center are also building an interdisciplinary academic SETI community, developing a SETI curriculum at the undergraduate and graduate levels, and training new SETI researchers.
"I'm eager to see where this journey takes us," Fan said. "Every step we take brings us closer to potentially answering the age-old question: ‘Are we alone?’"
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Roscosmos Spacewalkers Finish External Science Work
December 19, 2024
Roscosmos cosmonauts Alexey Ovchinin and Ivan Vagner concluded their spacewalk Dec. 19 at 5:53 p.m. EST after seven hours and 17 minutes.
Ovchinin and Vagner completed all of their major objectives, which included installing an experiment package designed to monitor celestial x-ray sources and new electrical connector patch panels and removing several experiments for disposal.
The two cosmonauts were unable to complete their non-critical final objective due to time constraints, which was to relocate a control panel for the European robotic arm, which is attached to the Nauka multipurpose laboratory module.
This was the second spacewalk in Ovinchin’s career, and the first for Vagner. It is the 272nd spacewalk for space station assembly, maintenance, and upgrades.
Learn more about station activities by following the space station blog, @space_station and @ISS_Research on X, as well as the ISS Facebook and ISS Instagram accounts.
https://blogs.nasa.gov/spacestation/2024/12/19/roscosmos-spacewalkers-finish-external-science-work/
https://blogs.nasa.gov/spacestation/tag/japan-aerospace-exploration-agency/
ESA 2025: A fifty-years legacy of building the future
20/12/2024
In 1975, 10 European countries came together with a vision to collaborate on key space activities: science and astronomy, launch capabilities and space applications: the European Space Agency, ESA, was born.
In 2025, we mark half a century of joint European achievement – filled with firsts and breakthroughs in science, exploration and technology, and the space infrastructure and economy that power Europe today.
During the past five decades ESA has grown, developing ever bolder and bigger projects and adding more Member States, with Slovenia joining as the latest full Member State in January.
We’ll also celebrate the 50th anniversary of ESA’s Estrack network, 30 years of satellite navigation in Europe and 20 years since ESA launched the first demonstration satellite Giove-A which laid the foundation for the EU’s own satnav constellation Galileo.
Other notable celebrations are the 20th anniversary of ESA’s Business Incubation Centres, or BICs, and the 30th year in space for SOHO, the joint ESA and NASA Solar and Heliospheric Observatory.
Sadly though, 2025 will mean end of science operations for Integral and Gaia. Integral, ESA's gamma-ray observatory has exotic objects in space since 2002 and Gaia concludes a decade of mapping the stars.
But as some space telescopes retire, another one provides its first full data release. Launched in 2023, we expect Euclid’s data release early in the new year.
Launch-wise, we’re looking forward to Copernicus Sentinel-4 and -5 (Sentinel-4 will fly on an MTG-sounder satellite and Sentinel-5 on the MetOp-SG-A1 satellite), Copernicus Sentinel-1D, Sentinel-6B and Biomass.
We’ll also launch the SMILE mission, or Solar wind Magnetosphere Ionosphere Link Explorer, a joint mission with the Chinese academy of science.
The most powerful version of Europe’s new heavy-lift rocket, Ariane 6, is set to fly operationally for the first time in 2025.
With several European commercial launcher companies planning to conduct their first orbital launches in 2025 too, ESA is kicking off the European Launcher Challenge to support the further development of European space transportation industry.
In human spaceflight, Polish ESA project astronaut Sławosz Uznański will fly to the ISS on the commercial Axiom-4 mission.
Artemis II will be launched with the second European Service Module, on the first crewed mission around the Moon since 1972.
The year that ESA looks back on a half century of European achievement will also be one of key decisions on our future.
At the Ministerial Council towards the end of 2025, our Member States will convene to ensure that Europe's crucial needs, ambitions and the dreams that unite us in space become reality.
So, in 2025, we’ll celebrate the legacy of those who came before but also help establish a foundation for the next 50 years.
Join us as we look forward to a year that honours ESA’s legacy and promises new milestones in space.
https://www.esa.int/ESA_Multimedia/Videos/2024/12/ESA_2025_A_fifty-years_legacy_of_building_the_future
https://www.youtube.com/watch?v=va8191PHyk0
Earth from Space: Star cities
20/12/2024
With the festive season approaching, even Earth-observing satellites are getting into the spirit, capturing a stunning compilation of European cities that resemble stars.
Star-shaped cities are scattered across Europe, their geometric designs most appreciated when viewed from above.
The concept of building star-shaped fortresses originated in Italy during the Renaissance, as medieval walls proved ineffective against advances in warfare, particularly gunpowder and cannons.
Wide moats and protruding bastions made it harder for enemies to exploit blind spots or breach fortifications.
Four examples of such cities can be seen here, arranged clockwise from the top left: Bourtange in the Netherlands, Palmanova in Italy, Almeida in Portugal, and Neuf-Brisach in France.
The green and red hues evoke a Christmas vibe, achieved through different band combinations during image processing to generate true-colour (green) and false-colour (red) visuals.
Bourtange, Netherlands
Located in northeast Netherlands, near the German border, Fort Bourtange was built in 1593 as a military fortification to guard the only road connecting Germany and the city of Groningen.
Converted into a village in 1851, it retains its iconic pentagonal shape and geometric street pattern. Today, the entire site serves as a museum, preserving its historical and architectural significance.
Palmanova, Italy
Palmanova, which lies in the Friuli-Venezia Giulia region in northeast Italy, is listed as a UNESCO World Heritage site.
Built by the Venetians to defend the Republic’s northeast border, it is a quintessential example of a Renaissance star fortress and is one of the largest and best preserved geometric towns.
Palmanova’s radial design extends from a central hexagonal square, the ‘Piazza del Duomo’, with concentric rings crossed by straight avenues. This internal area is surrounded by a star-shaped double perimeter of fortifications.
Almeida, Portugal
Situated on a high plain in northeast Portugal, close to the Spanish border, lies the fortress of Almeida.
It played a crucial role in defending Portugal’s border during its early years of independence.
As seen in the image, its old town is surrounded by striking star-shaped ramparts.
Neuf-Brisach, France
Located in the Alsace region of France near the German border, Neuf-Brisach was built in 1697 on the French side of the Rhine, after the loss of Breisach on the opposite bank.
The town’s name ‘Neuf’, meaning new in French, reflects its origins. Designed for both civilian and military use, Neuf-Brisach has a central octagonal layout with streets arranged in a square grid.
It is part of the UNESCO listed network of fortifications created by Louis XIV’s famed engineer, Sébastien Le Prestre de Vauban.
https://www.esa.int/ESA_Multimedia/Images/2024/12/Earth_from_Space_Star_cities
https://earth.esa.int/eogateway/missions/third-party-missions
Need to accurately measure time in space? Use a COMPASSO
December 19, 2024
Telling time in space is difficult, but it is absolutely critical for applications ranging from testing relativity to navigating down the road.
Atomic clocks, such as those used on the Global Navigation Satellite System network, are accurate, but only up to a point.
Moving to even more precise navigation tools would require even more accurate clocks.
There are several solutions at various stages of technical development, and one from Germany's DLR, COMPASSO, plans to prove quantum optical clocks in space as a potential successor.
There are several problems with existing atomic clocks—one has to do with their accuracy, and one has to do with their size, weight, and power (SWaP) requirements.
Current atomic clocks used in the GNSS are relatively compact, coming in at around .5 kg and 125 x 100 x 40 mm, but they lack accuracy.
In the highly accurate clock world terminology, they have a "stability" of 10e-9 over 10,000 seconds. That sounds absurdly accurate, but it is not good enough for a more precise GNSS.
Alternatives, such as atomic lattice clocks, are more accurate, down to 10e-18 stability for 10,000. However, they can measure .5 x .5 x .5m and weigh hundreds of kilograms.
Given satellite space and weight constraints, those are way too large to be adopted as a basis for satellite timekeeping.
To find a middle ground, ESA has developed a technology development roadmap focusing on improving clock stability while keeping it small enough to fit on a satellite.
One such example of a technology on the roadmap is a cesium-based clock cooled by lasers and combined with a hydrogen-based maser, a microwave laser.
NASA is not missing out on the fun either, with its work on a mercury ion clock that has already been orbitally tested for a year.
COMPASSO hopes to surpass them all. Three key technologies enable the mission: two iodine frequency references, a "frequency comb," and a "laser communication and ranging terminal."
Ideally, the mission will be launched to the ISS, where it will sit in space for two years, constantly keeping time. The accuracy of those measurements will be compared to alternatives over that time frame.
Lasers are the key to the whole system.
The iodine frequency references display the very distinct absorption lines of molecular iodine, which can be used as a frequency reference for the frequency comb, a specialized laser whose output spectrum looks like it has comb teeth at specific frequencies.
Those frequencies can be tuned to the frequency of the iodine reference, allowing for the correction of any drift in the comb.
The comb then provides a method for phase locking for a microwave oscillator, a key part of a standard atomic clock.
Overall, this means that the stability of the iodine frequency reference is transferred to the frequency comb, which is then again transferred to the microwave oscillator and, therefore, the atomic clock.
In COMPASSO's case, the laser communication terminal is used to transmit frequency and timing information back to a ground station while it is active.
COMPASSO was initially begun in 2021, and a paper describing its details and some breadboarding prototypes were released this year.
It will hop on a ride to the ISS in 2025 to start its mission to make the world a more accurately timed place—and maybe improve our navigation abilities as well.
https://phys.org/news/2024-12-accurately-space-compasso.html
https://link.springer.com/article/10.1007/s10291-023-01551-0
The Ursid meteor shower peaks this weekend. Here's what to expect from the final 'shooting stars' of 2024
December 20, 2024
Missed the Geminid meteor shower earlier this month? Don't worry. We're in for a little pre-Christmas stargazing treat.
The Ursid meteor shower — the final one of the year — is predicted to peak in the early morning hours of Sunday (Dec. 22).
As far as meteor showers go, the Ursids aren't known to be particularly active. If viewing conditions are perfect, you might see upwards of 10 meteors per hour, according to In-the-Sky.org. But this year, the last quarter moon will interfere with the show, so it's best to keep expectations low — say, maybe five meteors per hour.
Still, you never know what might happen. Per EarthSky, the Ursids unexpectedly produced around 100 meteors per hour in 1945 and 1968 and some 30 meteors per hour in 1973.
The Ursids are named for their radiant, or the point from which they appear to emanate: the constellation Ursa Minor, also known as the Little Dipper.
But they actually come from the comet 8P/Tuttle, or more specifically, the trail of debris it leaves behind on its orbit of the sun.
As Earth moves into that trail, the debris burns up in our atmosphere, creating shooting stars.
If you're hoping to catch a glimpse of the show, here's what you need to know about the Ursids in 2024.
The Ursids run from Dec. 17 to Dec. 26, with the peak occurring in the early morning of Dec. 22.
While you can see them any time during the period, the best view will likely occur in the predawn hours of Dec. 22. That's when the radiant will be highest in the sky.
What are the viewing conditions for the Ursid meteor shower this year?
Unfortunately, the moon will be quite bright during the Ursid peak this year.
It'll be approaching its last quarter phase at 54% illumination, meaning it'll be fairly bright in the night sky. The moon's light will likely drown out dimmer meteors.
How to look for the Ursids
All you have to do is bundle up and get out someplace dark with a wide view of the night sky. Let your eyes adjust to the darkness, then look up.
You won't need to look directly at the radiant — in fact, it's better to look in a slightly different direction, as the meteors will be moving away from it.
When is the next meteor shower?
After the Ursids, the next meteor shower is the Quadrantids, which will peak the night of Jan. 2 into the morning of Jan. 3, 2025.
https://www.space.com/stargazing/the-ursid-meteor-shower-peaks-this-weekend-heres-how-to-see-it
Is it the Hour of the Time?