TYB
NASA Astronomy Picture of the Day
July 25, 2023
The Eagle Nebula with X-ray Hot Stars
What do the famous Eagle Nebula star pillars look like in X-ray light? To find out, NASA's orbiting Chandra X-ray Observatory peered in and through these interstellar mountains of star formation. It was found that in M16 the dust pillars themselves do not emit many X-rays, but a lot of small-but-bright X-ray sources became evident. These sources are shown as bright dots on the featured image which is a composite of exposures from Chandra (X-rays), XMM (X-rays), JWST (infrared), Spitzer (infrared), Hubble (visible), and the VLT (visible). What stars produce these X-rays remains a topic of research, but some are hypothesized to be hot, recently-formed, low-mass stars, while others are thought to be hot, older, high-mass stars. These X-ray hot stars are scattered around the frame – the previously identified Evaporating Gaseous Globules (EGGS) seen in visible light are not currently hot enough to emit X-rays.
https://apod.nasa.gov/apod/astropix.html?
Advanced aircraft tracking will come live from space
July 25, 2023
Satellites will soon be used to keep an independent eye on airborne planes, under a deal agreed between ESA and Spire Global, a company that provides space-based data, analytics and space services.
Spire will design an advanced civilian aviation surveillance system that uses a constellation of satellites to monitor flights globally in real time, as well as building an in-orbit technology demonstrator for the system.
The system, called “Eurialo”, will determine the exact position of a plane by geolocating its radio frequency signals. This will provide an independent assessment of the plane’s location to complement today’s surveillance systems, which often rely on self-reported positions of aircraft derived from the Global Navigation Satellite System.
The project will not only provide reliable and resilient surveillance to complete the European communication, navigation and surveillance infrastructure, but also align with the European air traffic management master plan, which describes the need for resilient, space-based infrastructure to support safe, sustainable and efficient air travel.
The Eurialo system is expected to provide the most advanced and reliable system for civilian aircraft surveillance, with the ability to track a plane in real time anywhere in the world from take-off to landing.
Spire will develop the mission and preliminary system design for an operational satellite constellation, and then design, deploy and operate a demonstrator mission that proves the performance of the service and critical technologies.
The company will lead a consortium that includes the European Satellite Services Provider, which delivers communication, navigation and surveillance services for aviation.
Peter Platzer, Chief Executive Officer at Spire Global, said: “Space-based aircraft tracking and geolocation is the future of air traffic management to ensure safe, secure and sustainable air travel at a global scale. We are honoured to be selected by ESA to lead the development of this first-of-its-kind aviation surveillance system demonstrator, leveraging our more than 500 years of flight heritage operating satellites in space and expertise in radio frequency technology.
Javier Benedicto, acting director of Connectivity and Secure Communications at ESA, said: “ESA has a long track record of supporting companies that use satellites to improve aviation safety, security and sustainability, ensuring European autonomy and improving the lives of European citizens by creating jobs and prosperity. We are proud to partner with Spire Global with its strong heritage to develop a best-in-class satellite system design to demonstrate a system that will revolutionise air traffic management and surveillance for safer skies.”
The Eurialo project is mainly funded by the German Space Agency, DLR. Spire, through its newly established German subsidiary, plans to open an office in Munich that will expand the company’s global presence to nine offices in six countries.
https://www.esa.int/Applications/Connectivity_and_Secure_Communications/Advanced_aircraft_tracking_will_come_live_from_space
Chinese blockchain Sputnik’s maiden voyage
July 25, 2023
A Chinese satellite has become the first in the world to carry a blockchain imaging and screening system into orbit.
According to local news outlet Red Star News on July 22, the Tai’an Star Era 16 was successfully launched into orbit from the China Jiuquan Satellite Launch Center. Developed by NationStar Aerospace Technology Co., the satellite features a visual blockchain on-orbit certificate storage system dubbed ‘ADAChain’ (not related to Cardano) developed in-house by NationStar. Researchers wrote:
The [ADAChain] can realize functions such on-orbit visual blockchain multi-signature authentication, on-orbit video visual broadcasting, and on-orbit visual remote sensing data storage certificate confirmation.”
The purpose of the satellite’s voyage is to “obtain rich spectral information on the surface of the target area,” in the fields of “precision agriculture, water resources management, mineral resource investigation, environmental monitoring, and emergency safety.” Blockchain technology will also assist in achieving the goals of “high spatial resolution, high spectral resolution, and high temporal resolution” in such satellite imaging.
https://cointelegraph.com/magazine/chinas-blockchain-satellite-in-space-hong-kongs-mcnuggets-metaverse-asia-express/
https://baijiahao.baidu.com/s?id=1772136612439127385&
LEO, MEO or GEO? Diversifying orbits is not a one-size-fits-all mission (Part 1 of 3)
July 18, 2023
EL SEGUNDO, Calif. – All About Low Earth Orbit (LEO)
It may come as no surprise that most of the man-made objects in space can be found in Low Earth Orbit, also known as LEO. LEO is the orbital range closest to Earth, which also means it’s the easiest orbit to reach in terms of energy and rocket power. Satellites that orbit up to 1,200 miles above earth are in LEO. They include the International Space Station, the Hubble Telescope and some 4,000 Space X Starlink satellites, to name a few.
“LEO is used a lot for communications and imaging,” notes Kerstyn Auman, a space situational awareness analyst at the Aerospace Corporation. “One of the pros of this orbit is you have a really low latency (compared to other orbits) – how much time it takes to send out a signal and/or get one back. So when you’re thinking of things like voice communications or surfing the internet, you want it to be almost instantaneous.”
Because they’re so close to Earth, satellites in LEO also don’t need as much signal power to transmit and they can be much smaller in size, some as small as a Rubik’s cube (about 4” by 4” by 4”) and as light as three pounds. The trade-off is that you need a lot of them to sustain continuous coverage of a given area of earth. That’s because satellites in LEO don’t stay in one place for very long: they complete 16 orbits around the earth every 24 hours – about one orbit every 90 minutes. As a result, it can take hundreds or thousands of satellites in a LEO constellation to achieve continuous global coverage. But because the satellites are small, they are more cost efficient to produce and modern “ride shares” can launch multiple satellites on one rocket.
Once in LEO, satellites must travel at a rate of approximately 17,000 miles per hour to maintain the balance between momentum and gravity that is needed to keep it on course. If momentum lags, gravity can pull the satellite off-course.
Satellites in LEO are also subject to greater atmospheric drag. Like running against a strong wind, atmospheric drag can decrease satellite speed. As a result, satellites in LEO must burn fuel frequently versus other orbits to maintain their position or risk burning up as their orbit decays and they reenter Earth’s atmosphere.
“Drag is the biggest perturbing force that basically alters where you would expect your satellite to be,” Auman says. “It can be a lot more difficult to predict your future location in LEO because you have drag, and drag is affected by solar weather.”
Solar weather alters the composition of the earth’s atmosphere, which in turn alters the effects on a satellite in LEO.
“We have a general idea, but predicting that solar weather accurately is very difficult,” notes Auman. “Better measurements of a satellite position and velocity can improve the knowledge of where exactly a LEO satellite is, and thus where it is going. GPS satellites, with a vantage point from a higher orbit, can be used to track LEO satellites and improve location accuracy.”
Along with Medium Earth Orbit, LEO is the target destination for new missile warning, missile tracking and missile defense sensors currently under development at Space Systems Command. This is a significant departure from the current scheme, which utilizes very large satellites located 22,236 miles above the earth in Geostationary Orbit. In addition to spreading out risk by diversifying orbits, proliferated sensors operating closer to Earth will help to increase missile detection and tracking accuracy.
“By placing our sensors in varied orbits we gain multiple views of the same area and targets — enhancing our geometry with additional look angles and range,” says Col. Heather Bogstie, senior materiel leader for the Resilient Missile Warning, Tracking, and Defense Acquisition Delta at SSC.
The diversified orbital scheme for next generation missile warning, tracking and defense is based on a force design developed by the Space Warfighting and Analysis Center (SWAC) in direct response to emerging missile threats such as hypersonics which are more difficult to detect from GEO orbit.
“This design is based on improved sensor technology paired with an abundance of commercial space vehicles to give us affordable options to place more sensors closer to the targets we need to detect and track,” says Bogstie.
From LEO to GEO and orbits in between, Space systems Command is taking advantage of every lane in space to deliver more resilient space capabilities to combatant commands.
https://www.ssc.spaceforce.mil/Newsroom/Article-Display/Article/3462074/leo-meo-or-geo-diversifying-orbits-is-not-a-one-size-fits-all-mission-part-1-of
LEO, MEO or GEO? Diversifying orbits is not a one-size-fits-all mission (Part 2 of 3)
July 20, 2023
Sandwiched between Low Earth Orbit (LEO) and Geosynchronous Orbit (GEO) lies Medium Earth Orbit, also known as MEO. Less costly to reach compared to GEO and less fuel intensive to operate in compared to LEO, Medium Earth Orbit offers a blend of benefits not found in other orbital planes. It also presents unique challenges.
At 1,243 miles to 22,236 miles above earth, satellites in MEO require significantly less momentum to stay on course compared to their counterparts in LEO. Traveling at approximately 7,000 mph, satellites in MEO circle the globe once every 12 hours, or roughly twice per day. LEO, by comparison, requires satellite speeds of up to 17,500 mph to resist Earth’s gravity and stay in orbit.
It also takes less energy to keep satellites on course in MEO because there’s minimal gravitational pull from the Earth as well as less atmospheric drag.
“Station-keeping is easier in MEO versus LEO and requires less fuel,” notes Gregory Henning, a project leader who specializes in space debris simulations with the Aerospace Corporation.
In addition to lower fuel consumption, one of the main advantages of MEO is that satellites have a higher vantage point compared to LEO and this means it takes fewer satellites to provide full coverage of the Earth. This makes MEO ideal for navigation satellites. It is home to the U.S.’s Global Positioning Satellite System, as well as Galileo, GLONASS and BeiDou, the European, Russian and Chinese versions of GPS.
“If you were to try to do the GPS mission in LEO, the number of satellites you would need would be enormous,” says Henning. Compared to the thousands of satellites in LEO, MEO contains under 200 satellites.
“The trade-off is, the further away from Earth that you go, the stronger your transmit power beam needs to be; thus, the larger your equipment and the bigger your satellite, so it (generally) costs more to launch (satellites into MEO compared to LEO),” notes Kerstyn Auman, a space situational awareness (SSA) analyst at the Aerospace Corporation.
Another trade-off that’s wholly unique to MEO involves the two zones of energy charged particles above the equator known as the Van Allen radiation belts. Satellites passing through these belts must have special shielding to avoid damage to their electronic systems.
Along with LEO, MEO is the target destination for a new missile warning, missile tracking and missile defense program under development at Space Systems Command. It will supplement the existing SBIRS (Space-Based Infrared) satellites in geosynchronous orbit and provide an overlapping layer of resiliency to the nation’s space sensing capabilities.
Col. Daniel T. Walter, senior materiel leader, Strategic Missile Warning Acquisition Delta at Space Systems Command, points out that space-sensing satellites in MEO offer a number of advantages not found in GEO or LEO.
For one, greater proximity to Earth reduces the size and complexity of the satellites and sensors needed to perform the new missile warning and tracking mission when compared to their counterparts in GEO.
For another, sensors orbiting in MEO have longer target area pass times and wider fields of view than LEO. As a result, “MEO sensors can maintain custody of missile tracks for longer periods of time (compared to LEO) because the higher altitude allows for a larger field of view,” says Walter.
“As we continue to innovate and enhance what systems are placed in each orbit and then create connections between orbits, we open up warfighting opportunities we have never seen before,” says Col. Heather Bogstie, senior materiel leader for the Resilient Missile Warning, Tracking, and Defense Acquisition Delta at SSC. “Couple this with rapid commercial technical innovation and future allied systems, and we have emerging a truly robust sensing network.”
To learn more about SSC’s pivot to MEO for missile warning, tracking and defense, view this video. And stay tuned for All About Orbits: Part Three, which delves into the realm of Geostationary orbits.
https://www.ssc.spaceforce.mil/Newsroom/Article-Display/Article/3465697/leo-meo-or-geo-diversifying-orbits-is-not-a-one-size-fits-all-mission-part-2-of
LEO, MEO or GEO? Diversifying orbits is not a one-size-fits-all mission (Part 3 of 3)
July 21, 2023
If you watch weather reports on the nightly news or any program on cable tv, you are most likely reaping the benefits of satellites in Geosynchronous Orbit, also known as GEO.
Satellites in GEO are 22,236 miles above the earth's equator and move in sync with the Earth's daily rotation, completing one revolution every 24 hours. Sensors in GEO provide a wider field of view compared to Low Earth and Medium Earth orbits. They also provide 24/7 coverage of a given region. That makes GEO ideal for weather monitoring systems, such as the National Oceanic and Atmospheric Administration GOES system.
The magic of a GEO orbit is if you're sitting on the ground you know where that satellite is. It's not streaking across the sky - it just sits right there, says Gregory Henning, a project leader who specializes in space debris simulations with the Aerospace Corporation.
Satellite transmissions from GEO are also easier to capture from ground radars because the sensors are always in the same position relative to Earth
Television has used that orbit quite a bit - satellite TV will have a dish on the roof pointed at that one spot in the sky, Henning notes.
GEO is also a powerful platform for national defense and surveillance capabilities. It currently hosts many of the SBIRS satellites that provide the nations unblinking eye, enabling 24/7 missile warning and tracking capabilities.
If you can plant a satellite that can essentially stare (at one spot) and it doesn't have to worry about flying over and gimballing its sensor or its camera to capture an image - it can capture an image of a region at any time of day from GEO any time it wants, as long as it's sitting above that point on Earth, Henning explains.
However, much like MEO orbits, it costs more to put a satellite into GEO. It also takes longer for a signal to make its way down from GEO, which can introduce lag times in applications such as satellite internet. The extremely high altitude also requires the use of very large, complex and expensive instruments to capture and deliver clear images.
Satellites in GEO and HEO (High Earth Orbit) provide a wide field of view, notes Col. Heather Bogstie, senior materiel leader for the Resilient Missile Warning, Tracking, and Defense Acquisition Delta at Space Systems Command. But as the threat and ballistic missile technology has changed, particularly with regard to hypersonic missiles and hypersonic glide vehicles, the need to detect and track dim and fast moving targets drives us to a different architecture (and different orbits).
To address these emerging threats, SSC is planning to deploy missile warning, tracking and defense sensors in LEO and MEO orbits to augment the existing constellation in GEO.
This is the first mission area to receive a force design from the Space Warfighting and Analysis Center (SWAC), Bogstie says. The design calls for Overhead, Persistent, Infrared, (OPIR) sensors in various orbits, including LEO and MEO, to deliver a robust set of OPIR capabilities to deter and defeat the emerging threat.
Sensors in LEO and MEO are closer to the Earth, so they can capture more detailed views compared to sensors in GEO. The downside is that you need more of them to achieve the same field of view of the Earth that you get with a single satellite in GEO. But with enough assets, they can work as a family of sensors to achieve the same effect. And because satellites bound for LEO and MEO are generally smaller, they are more cost-efficient to build and less energy-intensive to launch.
This (multi-orbit) design is based on improved sensor technology paired with an abundance of commercial space vehicles to give us affordable options to place more sensors closer to the targets we need to detect and track, says Bogstie. addition, by placing our sensors in varied orbits we gain multiple views of the same area and targets - enhancing our geometry with additional look angles and range. Overall, we gain increased detection and tracking accuracy.
Whether it's in LEO, MEO or GEO, developing sensors to take advantage of diversified orbits is one important way that Space Systems Command is delivering resiliency in space.
https://www.ssc.spaceforce.mil/Newsroom/Article-Display/Article/3465828/leo-meo-or-geo-diversifying-orbits-is-not-a-one-size-fits-all-mission-part-3-of