Did Russia Just Launch a Spacecraft to Stalk a US Spy Satellite?

 As reported by Space.com: A newly launched Russian spy satellite may be tasked with stalking one of its American counterparts.

The Russian satellite, known as Kosmos 2558(opens in new tab), was rumored to be an "inspector" craft even before it lifted off on Monday (Aug. 1), Netherlands-based satellite tracker Marco Langbroek noted in a blog post on Tuesday(opens in new tab) (Aug. 2). And those rumors are unlikely to die down anytime soon.

Kosmos 2558 launched into the same orbital plane as USA 326, an American spy satellite that rode a SpaceX Falcon 9 rocket to orbit this past February, Langbroek noted. The two satellites are close in altitude as well, and they're scheduled to have a relatively close encounter soon, provided neither one performs any significant maneuvers over the next day or so.

"With the current orbit, Kosmos 2558 will make a relatively close approach to USA [326] at August 4 near 14:47 UTC [10:47 a.m. EDT]," Langbroek wrote. "The approach distance is ~75 km [47 miles]; almost all of that (73 km [45 miles]) is in altitude."

To be fair, USA 326 does seem to be pretty interesting. The classified American satellite ejected something recently — either a subsatellite or a piece of debris — according to astrophysicist and satellite tracker Jonathan McDowell(opens in new tab), who's based at the Harvard-Smithsonian Center for Astrophysics.

It wouldn't be shocking if Kosmos 2558 were a spysat stalker. After all, two Russian satellites maneuvered within about 100 miles (160 km) of the United States' USA 245 spacecraft in early 2020, as Langbroek noted.

American officials weren't pleased with that apparent orbital inspection.

"We view this behavior as unusual and disturbing," Gen. John "Jay" Raymond, chief of space operations for the U.S Space Force, told Time magazine(opens in new tab) at the time. "It has the potential to create a dangerous situation in space."

Is Kosmos 2558 up to the same sorts of tricks? "It will be interesting to follow both satellites [in] the coming weeks, to see what happens," Langbroek wrote.

Unjammable GPS System Successfully Tested on DeltaQuad VTOL UAV

 As reported by sUAS News: With global tensions rising, the demand for aerial intelligence platforms has increased dramatically. Unfortunately, most commercial platforms are no match for the latest jamming technology, having their GPS and communication links jammed even before they are able to take off.

In the last few months, the R&D team at DeltaQuad has successfully integrated one of the most advanced anti-jamming GPS systems on the market today. The solution was put to the test using one of the most powerful military jamming systems, and the DeltaQuad came through with a perfect score.

The DeltaQuad equipped with the new anti-jamming GPS solution was flown in autonomous mode at close range to an active military jamming system.

Even while being hit directly by a military-grade GPS jamming platform, the system maintained a solid GPS lock and the vehicle managed to autonomously resume its mission without any interruption.

For testing purposes, the ruggedized GPS system was installed together with the standard GPS system. As the vehicle came in range of the GPS jamming system, the standard solution quickly lost all positional awareness while the ruggedized system maintained an impressive amount of satellite locks, even while flying directly over the jammer at close range.

In addition to the ruggedized GPS solution, the DeltaQuad UAV is equipped to maintain live aerial intelligence, even in the toughest environments. Therefore the transmission system on the DeltaQuad uses Frequency Hopping Spread Spectrum techniques (FHSS) to mitigate attempts to disrupt the communication links and also uses redundant video & communication links.

About the DeltaQuad

The DeltaQuad is an industrial-grade Vertical Takeoff and Landing Fixed-wing UAV that performs fully autonomous surveillance missions. The platform is extremely easy to deploy and control and offers a live video stream from a surveillance sensor for real-time reconnaissance missions. Organizations choose DeltaQuad because of its high endurance capabilities, extensive long-range connectivity options and the integration of smart technologies like object following.

China vs. Elon Musk: Scientists Develop Plan to Destroy Starlink Satellites

 

As reported by Newsweek: A team of Chinese researchers has reportedly published a study calling for anti-satellite capabilities that could disable Elon Musk's Starlink satellites if deemed necessary.

The study was led by Ren Yuanzhen, a researcher with the Beijing Institute of Tracking and Telecommunications, and co-authored by scientists within China's defense industry according to the South China Morning Post, which has seen the publication.

The study is said to call for "a combination of soft and hard kill methods" that could be used to stop some Starlink satellites from working.

Starlink is a satellite internet network developed by Musk's company SpaceX. It involves thousands of small satellites in low-Earth orbit that beam down an internet connection to paying customers.

One concern amongst the scientists was that the Starlink network could be used to vastly increase the data transmission speed of U.S. military vehicles like fighter jets.

It's not clear exactly what methods could be used, though the study notes that the approach should be "low-cost, high-efficiency" and that the whole network is a problem rather than individual satellites, South China Morning Post reported.

This could mean that a missile-based approach may be unlikely, considering Starlink is composed of thousands of small satellites, and using missiles to destroy them all would almost certainly not be low-cost or high-efficiency. Thus, lasers, microwave technology, or even smaller satellites could be used to defend Chinese interests.

US Air Force Successfully Tests Hypersonic Missile

 

As reported by Military.com: The Air Force announced Monday it has successfully tested a hypersonic missile off the California coast, marking the latest development in the U.S.' race to catch up to Russia and China in fielding its own weapon on the battlefield.

A B-52 Stratofortress bomber out of Edwards Air Force Base released an Air-launched Rapid Response Weapon -- otherwise known as an ARRW -- on Saturday, and the missile reached sound-shattering speed.

"Following separation from the aircraft, the ARRW's booster ignited and burned for expected duration, achieving hypersonic speeds five times greater than the speed of sound," Air Force spokeswoman Ann Stefanek said in a press release.

Hypersonic missiles' high speeds make them harder to track, trace and destroy before hitting a target, inspiring worry for years among U.S. officials and defense industry experts as some assess that adversaries like China and Russia have outpaced America in developing the weapons.

News of the Air Force's hypersonic missile test follows weeks of scrutiny by Washington lawmakers, who have raised the alarm amid Russia's continued use of the fast-moving projectiles during its invasion of Ukraine.

Prior to Saturday, the service had three unsuccessful hypersonic missile launches. Just one day before the most recent test, Air Force Secretary Frank Kendall stoked doubt about developing such a weapon.

"The program has not been successful in research and development so far," Kendall told the House Appropriations Subcommittee on Defense on May 13. "We want to see proof of success before we make the decision about commitment to production, so we're going to wait and see."

Jeffrey Lewis, a professor at the Middlebury Institute for International Studies who specializes in nonproliferation and arms control issues, told Military.com that research on this emerging technology is important but is likely motivated by political concerns from lawmakers worried about competition.

"The political pressure I think is real," Lewis said. "If China or Russia tests a capability, there's just enormous pressure in the United States to demonstrate the same capability even if it isn't applicable to what we want to do."

In March, Russia's defense ministry claimed its military used hypersonic missiles against an underground ammunition warehouse as well as a fuel depot during the country's fighting in Ukraine. It was the first time a country had used such a weapon in combat.

Military officials at the time downplayed the threat. Defense Secretary Lloyd Austin told CBS News' "Face the Nation" that reported use of a hypersonic missile by Russian President Vladimir Putin's military was likely a distraction tactic to grow fear in the international community.

"I would not see it as a game changer," Austin told CBS. "I think the reason he is resorting to using these types of weapons is because he is trying to reestablish some momentum. And again, we've seen him attack towns and cities and civilians outright, [and] we expect to see that continue."

Since then, a senior U.S. defense official told reporters that Russia has used about 10 to 12 hypersonic weapons thus far in its campaign in Ukraine.

More recently, Joint Chiefs of Staff Chairman Gen. Mark Milley told lawmakers during a House Appropriations defense subcommittee hearing May 11 that Russia's use of the weapons was not "really significant."

Last year, military officials confirmed China had a successful hypersonic launch that had circumnavigated the globe.

"It went around the world, dropped off a hypersonic glide vehicle that glided all the way back to China, that impacted a target in China," Air Force Gen. John Hyten, the outgoing vice chairman of the Joint Chiefs of Staff, told CBS News in November.

Saturday's launch in California makes history as the U.S.' first air-launched hypersonic weapon, according to the Air Force.

"This was a major accomplishment by the ARRW team, for the weapons enterprise, and our Air Force," Brig. Gen. Heath Collins, Air Force Program Executive Officer for Weapons, said in a press release. "We are ready to build on what we've learned and continue moving hypersonics forward."

But it's not clear from the Air Force's press release how successful the weapons test was. The ARRW, developed by Lockheed Martin, uses a rocket booster to glide the missile toward an area at breakneck speed before a glider separates to hit a target.

Hypersonic missiles -- some of which have nuclear-carrying capabilities and can be fired from very far distances at sound-shattering speed -- has nearly the same effect on a ground target as conventional bombs, making the use of the prohibitively expensive weapons surprising.

But that hasn't stopped the U.S. from prioritizing research and development into the new class of weapons. In 2022, lawmakers approved $509 million for hypersonics. That number has grown to $577 million in the 2023 budget proposal.

With a hefty price tag for creating, testing and eventually fielding those missiles, Lewis said they likely won't be used by the Air Force in battle anytime soon.

"This is a pretty exotic capability that's at the very beginning of development, which we may or may not ever find useful," Lewis said. "I suspect this will always be a niche capability, in part because it'll probably be pretty expensive."

Pentagon Impressed by Starlink's Fast Signal-Jamming Workaround in Ukraine

 As reported by PC Mag: SpaceX's Starlink satellite internet service is attracting some attention from the Pentagon for its ability to quickly foil signal-jamming attacks that likely came from Russia. 

"In kind of the way Starlink was able to upgrade when a threat showed up, we need to be able to have that agility," Dave Tremper, director of electronic warfare at the Office of the Secretary of Defense, said during the C4ISRNET military conference on Wednesday.

Few details have emerged about the signal-jamming attack Tremper referred to, or how it was stopped. But on March 4, SpaceX CEO Elon Musk tweeted about the incident, which affected Starlink dishes in Ukraine. Later, he added: "Some Starlink terminals near conflict areas were being jammed for several hours at a time. Our latest software update bypasses the jamming. Am curious to see what’s next." Three weeks later, he added: "Starlink, at least so far, has resisted all hacking and jamming attempts."

Tremper brought up the incident when he was asked during the C4ISRNET conference whether the war in Ukraine is highlighting any "gaps" in the US’s electronic warfare capabilities.

"It was eye-watering to see the news report that the Russians were trying to jam Starlink, and that almost the next day—I think it was in fact the next day—Starlink had slung a line of code and had fixed it. And suddenly that was not effective anymore," Tremper said. 

He was especially impressed with how quickly Starlink was able to adapt and stop the signal jamming. In contrast, the US military would have needed to go through several steps, involving a "significant timeline" if it faced a similar jamming incident to its equipment.

"There’s a really interesting case study to look at the agility that Starlink had in their ability to address that problem," he added. "And inevitably, what was the impact if they couldn’t address the problem?"

Since late February, SpaceX has been shipping Starlink dishes to Ukraine to help the country stay online in the face of the Russian invasion. Ukraine has already received over 10,000 Starlink dishes, which are being deployed in war-torn areas close to the fighting. 

“My personal experience is that the service has been great,” Alex Bornyakov, Ukraine’s deputy minister of digital transformation, told The Washington Post earlier this month.

Russia is Jamming GPS Satellite Signals in Ukraine, US Space Force Says

As reported by Space.com: Another piece of space infrastructure for Ukraine is under attack, according to an NBC report.

Jammers from Russian forces besieging the country are targeting global positioning system (GPS) satellites that are used for navigation, mapping and other purposes, the report said, quoting the U.S. Space Force.

"Ukraine may not be able to use GPS because there are jammers around that prevent them from receiving any usable signal," David Thompson, the Space Force's vice chief of space operations, told NBC Nightly News(opens in new tab) Monday (April 11).

"Certainly the Russians understand the value and importance of GPS and try to prevent others from using it," Thompson added. He noted that Russia has not directly attacked any satellites in orbit, but the Space Force is keeping an eye out for such possibilities.

Specifically, Russia is targeting the Navstar system of satellites used by the United States and made available openly to many countries around the world, Thompson said. (Russia has its own independent system, called GLONASS, while the Europeans have one called Galileo and China has one called Beidou.)

Navstar uses 24 main satellites that each orbit the Earth every 12 hours. The system works by sending synchronized signals to users on Earth. Because the satellites move in different directions, the user receives their signals at slightly different times. When four satellites are available, GPS receivers can use their signals to calculate the user's position, often to within just a few feet.

Ukraine is also suffering from a lack of Internet connectivity as a result of the Russian attacks, which began Feb. 24 and are ongoing. SpaceX, at Ukraine's request, has shipped thousands of Starlink terminals to the country to provide an independent set of infrastructure. 

In early March, SpaceX CEO Elon Musk noted that Starlink signals have also been jammed, although his company is adapting. "Some Starlink terminals near conflict areas were being jammed for several hours at a time," Musk wrote via Twitter(opens in new tab) on March 1. "Our latest software update bypasses the jamming."

Delivery Robots Begin to Look Real

On university and business campuses, getting lunch and dinner is becoming a lot easier as robot delivery units hit the pathways.

 As reported by GPS World: If you were a student or faculty member at the University of Wisconsin – Madison campus (UW) during the 2020 COVID lockdown, you might have experienced a novel way to reduce contact with others when ordering a meal. People on campus could avoid a trip to the store and interaction with a delivery person. They could place an order on a special app, and a Starship Technologies robot would pick up and deliver their food.

Of course, for a student, technology that saves a trip to the store, especially anytime of the day or night, would be popular.

From demo to full production

At first, the meal-delivery robots at UW and other campuses were a demonstration to showcase how useful the small bots could be.

But after I soaked up robot-tech news from all over, I learned these little guys have found their way into towns, cities and campuses around the world: specifically, the United States, United Kingdom,  Estonia, Germany and Denmark.

With 1,500 bots working every day, the demonstration phase is long over, and Starship robots are full production. Starship, based in San Francisco, has been in operation since 2014. Its robots now make more than 1,000 deliveries each day. They have made more than 2.5 million deliveries to date, and make 100,000 road-crossings each day.

In the United States alone, 16 states have approved delivery robots, including Virginia, Idaho, Wisconsin, Florida, Ohio, Utah, Arizona, Washington and Texas. At UW, three Starship employees manage maintenance and recover units if they get stuck (while autonomous, the bots need help every now and then).

To have a robot come to visit, UW users download the Starship Food Delivery app, select from a local store menu, pay and then indicate on a map exactly where the bot should deliver the order. The robot collects a minimal $2 delivery charge, which goes toward the $2,000 to $3,000 cost of the vehicle and its operation. (According to Starship, each unit costs the equivalent of a high-end laptop.)

The unit uses GNSS and computer vision to navigate detailed, stored maps. The on-site employees take the robots out on particular routes for their first test runs, and the bot learns each route. The on-board system also uses 12 cameras, ultrasonic sensors, radars and neural networks to form a collision-avoidance net around the vehicle. In this way, pedestrians, dogs and road vehicles (when the robots cross a road) can all be avoided.

When waiting to cross a road, the robot’s safety systems might prevent it from moving. In this case, the device will “phone home” for a support person come out and fix the issue.

What could go wrong?

So far, the robots have been welcomed on the university and industry campuses where they operate. People walk round them as they go about their business. Even better, students and other users have pulled the units out of snow mounds and other hang-ups, returning them to the sidewalk or making other small adjustments to send the bots on their way.

And no one has stolen a unit. That could be because a loud siren erupts if they are picked up.  Presumably the units are programmed to remain within the bounds of their rigorously mapped environments. In any event, the food compartment remains locked until the order is removed by the customer.

Disrupting Doordash

Will robots disrupt today’s car-based delivery services, such as UberEats, Grubhub or DoorDash? Only for the last-mile section of a delivery. In a pinch, Starship robots can travel as far as three miles from their base. As the bots take on more territory, the auto-based delivery companies may be pushed toward the longer routes.

Deliveries such as time-sensitive medical materials could benefit from robotic short-distance, small-package carriers. Other robot delivery services, including Amazon Scout and Roxo, the FedEX SameDay Bot, are also making waves as testing progresses toward last-mile delivery automation from warehouse hubs to customer homes.

Federal, state and local laws may need to be enhanced to allow these autonomous delivery robots to progress toward widespread deployment.

One selling point: Fast robot deliveries lead to fewer delivery trucks, reducing traffic congestion and lowering exhaust pollution. We might have to wait awhile to realize these benefits.

Russia-Ukraine Conflict Prompted U.S. to Develop Autonomous Drone Swarms, 1,000-Mile Cannon

 

As reported by Scientific American: When Russia annexed Crimea and meddled in Ukraine’s Donets Basin, or Donbas, region in 2014, its military revealed new technology, organization and tactics—and upended much of the U.S. military’s thinking about modern warfare. Now, as Moscow keeps U.S. and European leaders guessing about whether it will invade Ukraine again, the Pentagon is pushing forward with projects that reflect priorities set after the onset of the ongoing Russia-Ukraine conflict.

Technologies currently in development include futuristic-sounding projects such as swarms of autonomous drones and a supercannon that can fire a projectile to a distance of 1,000 miles. And perhaps the most staggeringly ambitious campaign aims to combine existing radar and communications with state-of-the-art cloud computing and artificial intelligence in order to create an automated system that coordinates operations across multiple combat areas.

Technologies currently in development include futuristic-sounding projects such as swarms of autonomous drones and a supercannon that can fire a projectile to a distance of 1,000 miles. And perhaps the most staggeringly ambitious campaign aims to combine existing radar and communications with state-of-the-art cloud computing and artificial intelligence in order to create an automated system that coordinates operations across multiple combat areas.

“We are at an inflection point, and we have strategic competitors that are out there that have large militaries,” says General James McConville, chief of staff of the U.S. Army. He notes that the U.S. military has focused on counterterror operations in Afghanistan and Iraq. But a potential fight against Russia—or China, which the Pentagon now regards as the U.S. military’s preeminent threat—would require it to shift focus to a different set of technologies. “In order to deter strategic competitors,” McConville says, “we need to be able to do large-scale combat operations.”

MULTIDOMAIN OPERATIONS

“We are at an inflection point, and we have strategic competitors that are out there that have large militaries,” says General James McConville, chief of staff of the U.S. Army. He notes that the U.S. military has focused on counterterror operations in Afghanistan and Iraq. But a potential fight against Russia—or China, which the Pentagon now regards as the U.S. military’s preeminent threat—would require it to shift focus to a different set of technologies. “In order to deter strategic competitors,” McConville says, “we need to be able to do large-scale combat operations.”

This technology project would quickly coordinate combat across multiple fronts. Much like the way a ride-sharing app combines data on location, distance and travel time to determine the best match for a specific driver and passenger, JADC2 aims to pool all U.S. military intelligence, surveillance and reconnaissance in a data cloud and to use artificial intelligence and algorithms to match the best weapon against a given target. This coordination would ideally integrate the Army, Navy, Air Force and Marines into a single fighting force, within which any sensor could connect with any shooter. For instance, if the radar equipment on an F-16 fighter jet spotted an enemy target, and JADC2 determined that a submarine was best positioned to take the shot with a land-attack cruise missile, then that calculus—which might currently take hours or days to coordinate across the air and maritime domains—could be executed in near real time.

“This spring’s prospect of a major Russian attack on Ukraine may give us a case study of what high-end, multidomain attack looks like,” says Melanie Marlowe, a nonresident senior fellow at the Center for Strategic and International Studies. “The combination of [uncrewed aerial vehicles], missiles, electronic attack and various ground forces will be a huge challenge.” The idea is that a capability such as JADC2 could tackle that challenge by helping U.S. forces and their allies simultaneously stage attacks across multiple domains, including land, maritime, air, space, cyberspace and electronic warfare. This would hopefully present a closely matched adversary, such as Russia or China, with new dilemmas at a pace it cannot match. “What we look for is speed, range and convergence in our systems so we will have overmatch,” McConville says, using a Pentagon term for dominance. “We are looking for an edge, looking for an advantage, and we’re doing it working together ... as a combined force with allies and partners.”

SWARMING DRONES

Earlier this month the Pentagon unveiled new priorities that aim to drive innovation in 14 “critical technology” areas. Among the key fields are artificial intelligence and autonomy because science and research in such categories are needed to support weapon systems for fighting over well-defended territory: swarms of drones.

In order to penetrate highly defended and contested environments, such as those the U.S. military would face if fighting China or Russia, Washington, D.C., would need a specific set of technologies, says Heidi Shyu, U.S. undersecretary of defense for research and engineering. Shyu says that when Secretary of Defense Lloyd Austin asked her, in an initial meeting last year, what those technologies would be, she responded, “Make sure that we penetrate with attritable, low-cost unmanned systems.” (Attritable systems are designed to have a limited life: these drone swarms would be deployed with the assumption that they would not return.) “To be able to do that, I believe that we need trusted AI and trusted autonomy to be able to operate without GPS,” Shyu explains. She says she wants to combine artificial intelligence and engineering in order to automate fleets of robotic aircraft, ground vehicles, and both surface and underwater marine vessels. If all these can perform tasks with limited human intervention, even in an environment where satellite navigation tools no longer work, then they can carry out missions such as intelligence, surveillance and reconnaissance, and target attack.

Shyu’s new efforts will build on existing commercial and U.S. military work in this area. For instance, the Pentagon has already demonstrated the ability to deploy 3-D-printed swarming micro drones from planes. This would help fighter pilots avoid taking the risk of loitering over hostile territory.

DEEP STRIKE

In early January the U.S. Army disclosed plans to test-fire a prototype supercannon as soon as 2024. This “long-range cannon” is envisioned to be able to strike targets 1,000 miles away, a range that would utterly dwarf the 25-mile reach of today’s artillery.

One of the key lessons from Russia’s 2014 invasion of Ukraine was a need for the U.S. Army to extend its long-range strike systems. Now the Army is on track to field a number of new long-range missiles by 2023. The long-range cannon is not yet part of the weapons roster. It is what senior leaders call a “big bet” in their science and technology plan because it shows promise but still must prove its maturity before it is built for real-world missions. The idea is that this weapon would be used in tandem with the Army’s new Long-Range Hypersonic Weapon, a truck-launched system that fires missiles at hypersonic speeds. This combination could punch through dense, sophisticated enemy air defenses and create an opening for U.S. military forces to break through. Even on its own, the cannon would be a much cheaper alternative to the estimated $106-million-per-shot tab of the Long-Range Hypersonic Weapon.

In 2020 Congress, curious about the practicality of what lawmakers have called an “imaginative concept,” directed the National Academies of Sciences, Engineering, and Medicine to conduct an independent review of the cannon project and report on its feasibility. That study’s findings have not yet been published, but the panel has briefed Army leaders—and key service officials say they are optimistic. “The expert bodies that we’ve had look at it come away saying, ‘Yeah, you can do this,’” says Brigadier General John Rafferty, Army Futures Command’s director of developing new long-range missiles and cannons. “There are certainly challenges associated with it.... But it’s about the only investment that’s looking at doing anything like this mission in a more affordable way.”

A rocket launcher shoots missiles during tactical and special exercises with scouts of the Guards Tank Army of the Western Military District at the Golovenki training ground in the Moscow region, Russia, on January 28, 2022.

SpaceX Loses up to 40 Satellites to Geomagnetic Storm after Starlink Launch

 SpaceX had to ditch most of its latest batch of Starlink satellites because they were disrupted by a geomagnetic storm after being launched from the Falcon 9 rocket. Up to 40 of the 49 satellites will re-enter the atmosphere or have already done so because they were unable to reach their intended orbits.

In an update posted yesterday, SpaceX said that on February 3, the Falcon 9's second stage deployed 49 "satellites into their intended orbit, with a perigee of approximately 210 kilometers above Earth, and each satellite achieved controlled flight." SpaceX initially deploys satellites into lower altitudes than they ultimately orbit in "so that in the very rare case any satellite does not pass initial system checkouts, it will quickly be deorbited by atmospheric drag," the company said. SpaceX has licenses for altitudes of 540 km to 570 km and 335 km to 346 km.

Last week's geomagnetic storm hit a day after launch, SpaceX explained:

Unfortunately, the satellites deployed on Thursday were significantly impacted by a geomagnetic storm on Friday. These storms cause the atmosphere to warm and atmospheric density at our low deployment altitudes to increase. In fact, onboard GPS suggests the escalation speed and severity of the storm caused atmospheric drag to increase up to 50 percent higher than during previous launches. The Starlink team commanded the satellites into a safe-mode where they would fly edge-on (like a sheet of paper) to minimize drag—to effectively "take cover from the storm"—and continued to work closely with the Space Force's 18th Space Control Squadron and LeoLabs to provide updates on the satellites based on ground radars.

Preliminary analysis shows the increased drag at the low altitudes prevented the satellites from leaving safe-mode to begin orbit-raising maneuvers, and up to 40 of the satellites will re-enter or already have re-entered the Earth's atmosphere. The deorbiting satellites pose zero collision risk with other satellites and by design demise upon atmospheric re-entry—meaning no orbital debris is created and no satellite parts hit the ground.

SpaceX touted its systems for minimizing space debris, saying last week's "unique situation demonstrates the great lengths [to which] the Starlink team has gone to ensure the system is on the leading edge of on-orbit debris mitigation."

SpaceX has about 1,900 Starlink satellites in orbit. SpaceX has Federal Communications Commission permission to launch nearly 12,000 satellites and is seeking a license to launch an additional 30,000.

In a First, an ‘Atomic Fountain’ Has Measured the Curvature of Spacetime - Could provide an alternative to GPS in the future

 

As reported by Scientific American: In 1797, English scientist Henry Cavendish measured the strength of gravity with a contraption made of lead spheres, wooden rods and wire. In the 21st century, scientists are doing something very similar with rather more sophisticated tools: atoms.

Gravity might be an early subject in introductory physics classes, but that doesn’t mean scientists aren’t still trying to measure it with ever-increasing precision. Now, a group of physicists has done it using the effects of time dilation—the slowing of time caused by increased velocity or gravitational force—on atoms. In a paper published online today (Jan. 13) in the journal Science, the researchers announce that they’ve been able to measure the curvature of space-time.

The experiment is part of an area of science called atom interferometry. It takes advantage of a principle of quantum mechanics: just as a light wave can be represented as a particle, a particle (such as an atom) can be represented as a “wave packet.” And just as light waves can overlap and create interference, so too can matter wave packets.

In particular, if an atom’s wave packet is split in two, allowed to do something, and then recombined, the waves might not line up anymore—in other words, their phases have changed.

“One tries to extract useful information from this phase shift,” Albert Roura, a physicist at the Institute of Quantum Technologies in Ulm, Germany, who was not involved in the new study, told Space.com. Roura wrote a “Perspectives” piece about the new research, which was published online in the same issue of Science today.

Gravitational wave detectors work via a similar principle. By studying particles in this way, scientists can fine-tune the numbers behind some of the key workings of the universe, such as how electrons behave and how strong gravity really is—and how it subtly changes over even relatively small distances.

It’s that last effect that Chris Overstreet of Stanford University and his colleagues measured in the new study. To do this, they created an “atomic fountain,” consisting of a vacuum tube 33 feet (10 meters) tall ornamented with a ring around the very top.

The researchers controlled the atomic fountain by shooting laser pulses through it. With one pulse, they launched two atoms up from the bottom. The two atoms reached different heights before a second pulse shot them back down. A third pulse caught the atoms at the bottom, recombining the atoms’ wave packets.

The researchers found that the two wave packets were out of phase—a sign that the gravitational field in the atomic fountain wasn’t completely uniform.

“That … in general relativity, can be understood, actually, as the effect of space-time curvature,” Roura told Space.com, referring to one of Albert Einstein’s most famous theories.

Since the atom that went higher was closer to the ring, it experienced more acceleration thanks to the ring’s gravity. In a perfectly uniform gravitational field, such effects would cancel out. That isn’t what happened here; the atoms’ wave packets were out of phase instead, and thanks to the effects of time dilation, the atom that experienced more acceleration was ever so slightly out of time with its counterpart.

The result is a minuscule change, but atom interferometry is sensitive enough to pick it up. And since the scientists can control the placement and the mass of the ring, Roura told Space.com, “they are able to measure and study these effects.”

Although the technology behind this discovery—atom interferometry—might seem arcane, atom interferometry may one day be used to detect gravitational waves and help us navigate better than GPS, researchers have said.