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Category: satellites

2.8 days to disaster: Why we are running out of time in low earth orbit

A “House of Cards” is a wonderful English phrase that it seems is now primarily associated with a Netflix political drama. However, its original meaning is of a system that is fundamentally unstable. It’s also the term Sarah Thiele, originally a Ph.D. student at the University of British Columbia, and now at Princeton, and her co-authors used to describe our current satellite mega-constellation system in a new paper available in pre-print on arXiv.

They have plenty of justification for using that term. Calculations show that, across all low-Earth orbit mega-constellations, a “close approach,” defined as two satellites passing by each at less than 1km separation, occurs every 22 seconds. For Starlink alone, that number is once every 11 minutes. Another known metric of Starlink is that, on average, each of the thousands of satellites have to perform 41 maneuvers per year to avoid running into other objects in their orbit.

That might sound like an efficiently engineered system operating the way it should, but as any engineer will tell you, “edge cases”—the things that don’t happen in a typical environment, are the cause of most system failures. According to the paper, solar storms are one potential edge case for satellite mega-constellations. Typically, solar storms affect satellite operation in two ways.

A new five-year survey of the Magellanic Clouds will answer some questions about our neighbors

The Large and Small Magellanic Clouds are irregular dwarf galaxies and satellites of the Milky Way. The LMC is about 163,000 light-years away and the SMC is about 206,000 light-years away, and their close proximity makes them excellent laboratories for the study of galaxies in general. The Clouds are the focus of a new research group being formed at the Leibniz Institute for Astrophysics Potsdam (AIP).

Both clouds are home to numerous objects and regions that capture astronomers’ attention. The LMC hosts the Tarantula Nebula, an extremely active star-forming region that contains some of the largest stars known. The SMC hosts NGC 346, an open star cluster that contains numerous massive stars and is still forming many high-mass stars. The Clouds also contain variable stars that act as standard candles in the cosmic distance ladder. That’s just a sample from a long list of the clouds’ interesting features.

It can be easier to study things like star formation in galaxies other than the Milky Way, because we’re inside the Milky Way and can’t see all of it. The Large and Small Magellanic Clouds are excellent natural laboratories to study how galaxies evolve because astronomers can see them from a good vantage point.

An Old Jeweler’s Trick Could Unlock the Next Generation of Nuclear Clocks

Last year, a research team led by UCLA achieved a milestone scientists had pursued for half a century. They succeeded in making radioactive thorium nuclei interact with light by absorbing and emitting photons, similar to how electrons behave inside atoms. First envisioned by the group in 2008, the breakthrough is expected to transform precision timekeeping and could significantly improve navigation systems, while also opening the door to discoveries that challenge some of the most basic constants in physics.

The advance comes with a major limitation. The required isotope, thorium-229, exists only as a byproduct of weapons-grade uranium, making it extremely rare. Researchers estimate that just 40 grams of this material are currently available worldwide for use in nuclear clock research.

A new study now shows a way around this obstacle. An international collaboration led by UCLA physicist Eric Hudson has developed an approach that uses only a small fraction of the thorium needed in earlier experiments, while delivering the same results previously achieved with specialized crystals. Described in Nature, the technique is both straightforward and low cost, raising the possibility that nuclear clocks could one day be small and affordable enough to fit into everyday devices like phones or wristwatches. Beyond consumer electronics, the clocks could replace existing systems used in power grids, cell phone towers, and GPS satellites, and may even support navigation where GPS is unavailable, such as in deep space or underwater.

Chip-scale magnetometer uses light for high-precision magnetic sensing

Researchers have developed a precision magnetometer based on a special material that changes optical properties in response to a magnetic field. The device, which is integrated onto a chip, could benefit space missions, navigation and biomedical applications.

High-precision magnetometers are used to measure the strength and direction of magnetic fields for various applications. However, many of today’s magnetometers must operate at extremely low temperatures—close to 0 kelvin—or require relatively large and heavy apparatus, which significantly restricts their practicality.

“Our device operates at room temperature and can be fully integrated onto a chip,” said Paolo Pintus from the University of California, Santa Barbara (UCSB) and the University of Cagliari, Italy, co-principal investigator for the study. “The light weight and low power consumption of this magnetometer make it ideal for use on small satellites, where it could enable studies of the magnetic areas around planets or aid in characterizing foreign metallic objects in space.”

What Time Is It on Mars? Physicists Finally Have an Exact Answer

Summary: Time doesn’t flow uniformly across the solar system, and new research reveals just how differently it unfolds on Mars compared with Earth. By tracing subtle gravitational and orbital influences, scientists have uncovered variations in the pace of Martian time that could become crucial for future navigation and communication far from home.

NIST physicists have precisely calculated how Martian time subtly speeds up and slows down, revealing a daily drift that changes with the planet’s shifting orbit.

Ask someone on Earth for the time and you will get an exact answer, largely because our planet relies on a sophisticated network of atomic clocks, GPS satellites, and rapid communication systems.

Boiling oceans may lurk beneath the ice of solar system’s smallest moons

The outer planets of the solar system are swarmed by ice-wrapped moons. Some of these, such as Saturn’s moon Enceladus, are known to have oceans of liquid water between the ice shell and the rocky core and could be the best places in our solar system to look for extraterrestrial life. A new study published Nov. 24 in Nature Astronomy sheds light on what could be going on beneath the surface of these worlds and provides insights into how their diverse geologic features may have formed.

“Not all of these satellites are known to have oceans, but we know that some do,” said Max Rudolph, associate professor of earth and planetary sciences at the University of California, Davis and lead author on the paper. “We’re interested in the processes that shape their evolution over millions of years and this allows us to think about what the surface expression of an ocean world would be.”

How geology works on icy moons From mountains to earthquakes, Earth’s surface geology is powered by the movement and melting of rock deep inside the planet. On icy moons, geology is driven by the action of water and ice.

Space debris poses growing threat, but new study suggests cleanup is feasible

High up in Earth’s orbit, millions of human-made objects large and small are flying at speeds of over 15,000 miles per hour. The objects, which range from inactive satellites to fragments of equipment resulting from explosions or collisions of previously launched rockets, are space debris, colloquially referred to as space junk. Sometimes the objects collide with each other, breaking into even smaller pieces.

No matter the size, all of this debris poses a problem. Flying at high speeds caused by prior launches or explosions, they create danger for operational satellites and spacecraft, which are vital for the efficacy of modern technologies like GPS, digital communication and weather forecasting. At orbital speeds, even tiny fragments can cause significant damage to operational equipment, endangering future space missions and the people who would participate in them.

“Even if a tiny, five-millimeter object hits a solar panel or a solar array of a satellite, it could break it,” says Assistant Professor Hao Chen, whose research involves space systems design. “And we have over 100 million objects smaller than one centimeter in orbit. So if you want to avoid a collision, you have to maneuver your spacecraft, which takes up fuel and is costly. Additionally, we have humans on the International Space Station who sometimes must go outside the spacecraft where the space debris can hit them too. It’s really dangerous.”

Italian mission adds to growing IRIDE space fleet

The Italian programme IRIDE, which provides public sector services based on data from its fleet of Earth observation constellations, has added eight satellites to its second constellation, Eaglet II.

The Eaglet II satellites lifted off on board a Falcon 9 rocket at 19:44 CET (10:44 local time), 28 November, from Vandenberg Space Force Base in California, US. All satellites were placed into orbit about one hour after launch. Acquisition of signal for all satellites was confirmed several hours later by OHB’s Mission Control Centre in Rome.

The launch was a rideshare carrying numerous other satellites into orbit, including HydroGNSS (ESA’s first Scout mission under its FutureEO programme) and two ICEYE satellites for Greece.

The Cuckoo’s Egg: Tracking a Spy Through the Maze of Computer Espionage

Before the Internet became widely known as a global tool for terrorists, one perceptive U.S. citizen recognized its ominous potential. Armed with clear evidence of computer espionage, he began a highly personal quest to expose a hidden network of spies that threatened national security. But would the authorities back him up? Cliff Stoll’s dramatic firsthand account is “a computer-age detective story, instantly fascinating [and] astonishingly gripping” (Smithsonian).

Cliff Stoll was an astronomer turned systems manager at Lawrence Berkeley Lab when a 75-cent accounting error alerted him to the presence of an unauthorized user on his system. The hacker’s code name was “Hunter” — a mysterious invader who managed to break into U.S. computer systems and steal sensitive military and security information. Stoll began a one-man hunt of his spying on the spy. It was a dangerous game of deception, broken codes, satellites, and missile bases — a one-man sting operation that finally gained the attention of the CIA…and ultimately trapped an international spy ring fueled by cash, cocaine, and the KGB.

NASA, SpaceX launch US–European satellite to monitor Earth’s oceans

About the size of a full-size pickup truck, a newly launched satellite by NASA and its partners will provide ocean and atmospheric information to improve hurricane forecasts, help protect infrastructure, and benefit commercial activities, such as shipping.

The Sentinel-6B satellite lifted off aboard a SpaceX Falcon 9 rocket from Launch Complex 4 East at Vandenberg Space Force Base in central California at 9:21 p.m. PST on Nov. 16. Contact between the satellite and a ground station in northern Canada occurred about 1 hour and 30 minutes later at 10:54 p.m. All systems are functioning normally.

“Understanding tidal patterns down to the inch is critical in protecting how we use our oceans every day on Earth,” said Nicky Fox, associate administrator, Science Mission Directorate at NASA Headquarters in Washington. “Sentinal-6B will build upon the legacy of Sentinel-6 Michael Freilich by making sea level measurements that improve forecasts used by communities, businesses, and operations across the country. It also will support a safer reentry for our astronauts returning home, including crew from Artemis Moon missions.”

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