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Showing posts with label Space & Astrophysics. Show all posts
Showing posts with label Space & Astrophysics. Show all posts

Thursday, 6 January 2022

Matter and antimatter seem to respond equally to gravity


As part of an experiment to measure—to an extremely precise degree—the charge-to-mass ratios of protons and antiprotons, the RIKEN-led BASE collaboration at CERN, Geneva, Switzerland, has found that, within the uncertainty of the experiment, matter and antimatter respond to gravity in the same way.

Matter and antimatter create some of the most interesting problems in physics today. They are essentially equivalent, except that where a particle has a positive charge its antiparticle has a negative one. In other respects they seem equivalent. However, one of the great mysteries of physics today, known as "baryon asymmetry," is that, despite the fact that they seem equivalent, the universe seems made up entirely of matter, with very little antimatter. Naturally, scientists around the world are trying hard to find something different between the two, which could explain why we exist.

As part of this quest, scientists have explored whether matter and antimatter interact similarly with gravity, or whether antimatter would experience gravity in a different way than matter, which would violate Einstein's weak equivalence principle. Now, the BASE collaboration has shown, within strict boundaries, that antimatter does in fact respond to gravity in the same way as matter.

The finding, published in Nature, actually came from a different experiment, which was examining the charge-to-mass ratios of protons and antiprotons, one of the other important measurements that could determine the key difference between the two.

This work involved 18 months of work at CERN's antimatter factory. To make the measurements, the team confined antiprotons and negatively charged hydrogen ions, which they used as a proxy for protons, in a Penning trap. In this device, a particle follows a cyclical trajectory with a frequency, close to the cyclotron frequency, that scales with the trap's magnetic-field strength and the particle's charge-to-mass ratio. By feeding antiprotons and negatively charged hydrogen ions into the trap, one at a time, they were able to measure, under identical conditions, the cyclotron frequencies of the two particle types, comparing their charge-to-mass ratios. According to Stefan Ulmer, the leader of the project, "By doing this, we were able to obtain a result that they are essentially equivalent, to a degree four times more precise than previous measures. To this level of CPT invariance, causality and locality hold in the relativistic quantum field theories of the Standard Model."

Interestingly, the group used the measurements to test a fundamental physics law known as the weak equivalence principle. According to this principle, different bodies in the same gravitational field should undergo the same acceleration in the absence of frictional forces. Because the BASE experiment was placed on the surface of the Earth, the proton and antiproton cyclotron-frequency measurements were made in the gravitational field on the Earth's surface, and any difference between the gravitational interaction of protons and antiprotons would result in a difference between the cyclotron frequencies.

By sampling the gravitational field of the Earth as the planet orbited the Sun, the scientists found that matter and antimatter responded to gravity in the same way up to a degree of three parts in 100, which means that the gravitational acceleration of matter and antimatter are identical within 97% of the experienced acceleration.

Ulmer adds that these measurements could lead to new physics. He says, "The 3% accuracy of the gravitational interaction obtained in this study is comparable to the accuracy goal of the gravitational interaction between antimatter and matter that other research groups plan to measure using free-falling anti-hydrogen atoms. If the results of our study differ from those of the other groups, it could lead to the dawn of a completely new physics."

Reference: 

Stefan Ulmer, A 16-parts-per-trillion measurement of the antiproton-to-proton charge–mass ratio, Nature (2022). DOI: 10.1038/s41586-021-04203-w

Wednesday, 5 January 2022

Geomagnetic Storms Can Threaten Life on Earth – Swarm and Cluster Provide New Insights Into Space Weather


The notion of living in a bubble is usually associated with negative connotations, but all life on Earth is dependent on the safe bubble created by our magnetic field. Understanding how the field is generated, how it protects us, and how it sometimes gives way to charged particles from the solar wind is not just a matter of scientific interest, but also a matter of safety. Using information from ESA’s Cluster and Swarm missions along with measurements from the ground, scientists have, for the first time, been able to confirm that curiously named bursty bulk flows are directly connected to abrupt changes in the magnetic field near Earth’s surface, which can cause damage to pipelines and electrical power lines.

The magnetosphere is a teardrop-shaped region in space that begins some 65,000 km from Earth on the day side and extends to over 6,000,000 km on the night side. It is formed through interactions between Earth’s magnetic field and supersonic wind flowing from the Sun.

These interactions are extremely dynamic and comprise complicated magnetic field configurations and electric current systems. Certain solar conditions, known as space weather, can play havoc with the magnetosphere by driving highly energetic particles and currents around the system, sometimes disrupting space-based hardware, ground-based communication networks, and power systems.

In an elliptical orbit around Earth, up to 100,000 km away, ESA’s unique four-spacecraft Cluster mission has been revealing the secrets of our magnetic environment since 2000. Remarkably, the mission is still in excellent health and is still enabling new discoveries in the field of heliophysics – the science examining the relationship between the Sun and bodies in the Solar System, in this case, Earth.

Launched in 2013, ESA’s trio of Swarm satellites orbit much closer to Earth and are used largely to understand how our magnetic field is generated by measuring precisely the magnetic signals that stem from Earth’s core, mantle, crust, and oceans, as well as from the ionosphere and magnetosphere. However, Swarm is also leading to new insights into weather in space.

The complementarity of these two missions, forming part of the ESA Heliophysics Observatory, gives scientists a unique opportunity to dig deep into Earth’s magnetosphere and further understand the risks of space weather.

In a paper published in Geophysical Research Letters, scientists describe how they used data from both Cluster and Swarm along with measurements from ground-based instruments to examine the connection between solar storms, bursty bulk flows in the inner magnetosphere and perturbations in the ground level magnetic field which drive ‘geomagnetically induced currents’ on and below Earth’s surface.

The theory was that intense changes in the geomagnetic field driving geomagnetically induced currents are associated with currents flowing along the magnetic field direction, driven by bursty bulk flows, which are fast bursts of ions typically travelling at more than 150 km per second. These field-aligned currents link the ionosphere and magnetosphere and pass through the locations of both the Cluster and Swarm. Until now this theory had not been confirmed.

Malcolm Dunlop, from the Rutherford Appleton Laboratory in the UK, explained, “We used the example of a solar storm in 2015 for our research. Data from Cluster allowed us to examine bursty bulk flows – bursts of particles in the magnetotail – which contribute to large-scale convection of material towards Earth during geomagnetically active times, and which are associated with features in the northern lights known as auroral streamers. Data from Swarm showed corresponding large perturbations closer to Earth associated with connecting field-aligned currents from the outer regions containing the flows.

“Together with other measurements taken from Earth’s surface, we were able to confirm that intense magnetic field perturbations near Earth are connected to the arrival of bursty bulk flows further out in space.”

ESA’s Swarm mission manager, Anja Strømme, added, “It’s thanks to having both missions extended well beyond their planned lives, and hence are having both missions in orbit simultaneously, that allowed us to realize these findings.”

While this scientific discovery might appear somewhat academic, there are real benefits for society.

The Sun bathes our planet with the light and heat to sustain life, but it also bombards us with dangerous charged particles in the solar wind. These charged particles can damage communication networks and navigation systems such as GPS, and satellites – all of which we rely on for services and information in our daily lives.

As the paper discusses, these storms can affect Earth’s surface and subsurface, leading to power outages, such as the major blackout that Quebec in Canada suffered in 1989.

With a rapidly growing infrastructure, both on the ground and in space, that supports modern life, there is an increasing need to understand and monitor weather in space to adopt appropriate mitigation strategies.

Alexi Glover, from ESA’s Space Weather Office, said, “These new results help further our understanding of processes within the magnetosphere which may lead to potentially hazardous space weather conditions. Understanding these phenomena and their potential effects is essential to develop reliable services for end users operating potentially sensitive infrastructure.”

Reference: 

Intense dB/dt Variations Driven by Near-Earth Bursty Bulk Flows (BBFs): A Case Study by Dong Wei, Malcolm W. Dunlop, Junying Yang, Xiangcheng Dong, Yiqun Yu, Tieyan Wang, 20 January 2021, Geophysical Research Letters.

Tuesday, 4 January 2022

NASA estimates metrics of exploding meteor that shook ground


A meteor that caused an earthshaking boom over suburban Pittsburgh on New Year's Day exploded in the atmosphere with an energy blast equivalent to an estimated 30 tons (27,216 kilograms) of TNT, officials said.

NASA's Meteor Watch social media site said late Sunday a "reasonable assumption" of the speed of the meteor at about 45,000 mph (72,420 kph) would allow a "ballpark" estimate of its size as about a yard in diameter with a mass close to half a ton (454 kilograms).

If not for the cloudy weather, NASA said, it would have been easily visible in the daytime sky—maybe about 100 times the brightness of the full moon.

A nearby infrasound station registered the blast wave from the meteor as it broke apart, enabling the estimates.

National Weather Service meteorologist Shannon Hefferan told the Tribune-Review that satellite data recorded a flash over Washington County shortly before 11:30 a.m. Saturday and officials believed it was due to a meteor "falling through the atmosphere." Hefferan said a similar event occurred Sept. 17 in Hardy County, West Virginia.

Residents in South Hills and other areas reported hearing a loud noise and feeling their homes shaking and rattling. Allegheny County officials said they had confirmed that there was no seismic activity and no thunder and lightning.

Source: Link

NASA’s new space telescope ‘hunky-dory’ after problems fixed


NASA's new space telescope is on the verge of completing the riskiest part of its mission—unfolding and tightening a huge sunshade—after ground controllers fixed a pair of problems, officials said Monday.

The tennis court-size sunshield on the James Webb Space Telescope is now fully open and in the process of being stretched tight. The operation should be complete by Wednesday.

The $10 billion telescope—the largest and most powerful astronomical observatory ever launched—rocketed away Christmas Day from French Guiana. Its sunshield and primary mirror had to be folded to fit into the European Ariane rocket.

The sunshield is vital for keeping Webb's infrared-sensing instruments at subzero temperatures, as they scan the universe for the first stars and galaxies, and examine the atmospheres of alien worlds for possible signs of life.

Getting the sunshield extended last Friday "was really a huge achievement for us," said project manager Bill Ochs. All 107 release pins opened properly.

But there have been a few obstacles.

Flight controllers in Maryland had to reset Webb's solar panel to draw more power. The observatory—considered the successor to the aging Hubble Space Telescope—was never in any danger, with a constant power flow, said Amy Lo, a lead engineer for the telescope's prime contractor, Northrop Grumman.

They also repointed the telescope to limit sunlight on six overheating motors. The motors cooled enough to begin securing the sunshield, a three-day process that can be halted if the problem crops up again, officials said.

"Everything is hunky-dory and doing well now," Lo said.

Ochs expects the tightening of the sunshield to be drama-free.

"The best thing for operations is boring, and that's what we anticipate over the next three days, is to be boring," he told reporters in a teleconference.

If that holds true, the telescope's gold-plated mirror—more than 21 feet (6.5 meters) across—could unfold as soon as this weekend.

Webb should reach its destination 1 million miles (1.6 million kilometers) away by the end of January. As of Monday, the telescope was more than halfway there. The infrared telescope should begin observing the cosmos by the end of June, ultimately unveiling the first stars and galaxies formed in the universe 13.7 billion years ago. That's a mere 100 million years after the universe-creating Big Bang.

Launched in 1990, Hubble, which sees primarily visible light, has peered as far back as 13.4 billion years ago. Astronomers hope to close the gap with Webb, which is 100 times more powerful.

In another bit of good news Monday, officials said they expect Webb to last well beyond the originally anticipated 10 years based on its fuel efficiency.

Source: Link

Monday, 3 January 2022

China aims to complete space station in another huge year in space


China’s main space contractor will target more than 40 orbital launches this year, including completion of the Tiangong space station, following 48 successful launches in 2021.

The China Aerospace Science and Technology Corp. (CASC) stated on social media that it is targeting more than 40 launches, including six missions to complete the construction of the country’s space station. 

The Tianzhou-4 cargo spacecraft will launch on a Long March 7 from Wenchang to dock with the orbiting Tianhe core module around March or April, following the end of the ongoing, six-month Shenzhou-13 crewed mission.

The station’s third crewed mission, Shenzhou-14, will follow Tianzhou-4. The mission’s three astronauts will be aboard Tianhe for the arrival of the 20-metric-ton-plus Wentian and Mengtian modules, expected to launch around June and August respectively. 

The module launches will complete the T-shaped orbital outpost. Tianzhou-5 will launch ahead of Shenzhou-15, both scheduled for late in the year. 

The module launches will be followed closely, partly due to the significance of the missions, but also because of the use of the Long March 5B, the two previous launches of which saw the large first stages make high-profile uncontrolled reentries which sparked acrimony.

The Tiangong space station is planned to operate in orbit for at least ten years. It will host a range of international experiments through collaboration with the United Nations Office of Outer Space Affairs, and potentially foreign astronauts and further modules in the coming years.

CASC will also launch the first Long March 6A, featuring a liquid core with solid boosters, from a new complex constructed at the Taiyuan spaceport. The Long March 8 will launch for the second time in February, but it is unknown if the mission will include tests related to plans for the eventual recovery and reuse of its first stage.

The group does not release a detailed manifest, meaning mission timing and payloads are often unknown until after launch. Airspace closure notices remain a main indicator of upcoming missions.

The workhorse Long March 3B will likely launch a number of communications and possibly replacement Beidou satellites in geosynchronous and medium Earth orbits. Weather, remote sensing, technology test and classified Shiyan and Shijian satellites can also be expected to be sent into orbit.

A number of sea launches of the Long March 11 are also expected from a new Eastern spaceport in Shandong province, established to facilitate maritime missions. A new vessel is being prepared to host the launches, which have previously been conducted in the Yellow Sea.

Possible space science launches include the Advanced Space-based Solar Observatory (ASO-S), which follows the October launch of the Chinese H-alpha Solar Explorer (CHASE), or Xihe. 

The Einstein Probe, an X-ray survey satellite featuring lobster-eye optics and dedicated to time-domain high-energy astrophysics, could also launch before the end of the year.

CASC will be continuing development of two new super heavy-lift launch vehicles, the Long March 9 and a new rocket for lunar crewed missions.

Overall China launched 55 times in 2021, with 48 Long March launches. 2022 could involve even more activity outside of CASC.

Commercial launch activity


In Addition to CASC activity a number of launches will be conducted by companies which are spinoffs from CASC and two other giant state-owned entities, the China Aerospace Science and Industry Corp. (CASIC), and the Chinese Academy of Sciences (CAS).

CASIC spinoff Expace had planned to launch at least 12 Xingyun satellites for CASIC’s narrowband Internet of Things constellation, as well as missions for commercial customers. However the Dec. 15 failure of its Kuaizhou-1A solid rocket could bring lengthy delays, just months after the rocket returned to action following being grounded for one year due to a 2020 failure. The larger Kuaizhou-11 has yet to fly following the loss of its first flight in 2020.

CAS spinoff Zhongke Aerospace, also known as CAS Space, is preparing to conduct its first launch in the first quarter of the year. The Lijian-1 (Zhongke-1A) solid rocket. Capable of lifting 1.5 tons to LEO, the ZK-1A could be China’s largest solid orbital rocket in terms of payload capacity at time of flight.

China Rocket, spun off from CASC, states it will launch the first Jielong-3 solid during 2022, providing yet more competition among three major groups. The firm says the rocket will be capable of lifting 1.5 tons into a 500-kilometer-altitude m Sun-synchronous orbit, and carry up to 20 satellites.

Private firm Galactic Energy will soon follow up its second successful launch of the Ceres-1 solid rocket with up to five further launches from Jiuquan, northwest China, during 2022. It could also debut the liquid Pallas-1 before the end of the year. 

Landspace is preparing to launch its methane-liquid oxygens Zhuque-2 rocket in the first quarter of the year, which could be the world’s first methalox orbital launch.

Private firms iSpace and Deep Blue Aerospace are planning hop tests as part of the development of reusable first stages for their respective methalox Hyperbola-2 and kerosene-liquid oxygen Nebula-1 rockets. 

Space Pioneer is meanwhile working on its Tianlong-1 commercial reusable launch vehicle. Linkspace could also be active following self-development of a new engine for its reusable rocket plans.

Source: Link

Sunday, 2 January 2022

why can’t we put a space station on the Moon?


A space station on the moon could be very useful. It would provide future space missions with a stopping point between leaving the Earth and reaching further into the solar system or even the Milky Way.

One reason we haven’t built a space station on the moon is that we don’t send people there very often. We have only managed to put astronauts on the moon six times so far. These moon landings took place in a three-year period between 1969 and 1972 and were part of a series of space missions called the Apollo missions.

The type of rocket used to get the astronauts to the moon was an extremely powerful one called a Saturn V, which is no longer produced. This means that, at the moment, we do not have a rocket powerful enough to get people to the moon – let alone build a space station there.

We are starting to build powerful rockets again. Space exploration company SpaceX is creating newer and bigger rockets which are capable of taking the weight of astronauts to the moon. NASA is also planning new missions to take astronauts to the moon.

However, there is a big difference between a short trip and building a space station on the moon, which is extremely difficult. One way to do it would be to build it in pieces on Earth, take the pieces to the moon and assemble them there. This would be like how the International Space Station was built: pieces were taken into space and then put together by astronauts aboard the space shuttle.

However, the International Space Station is only 250 miles (400 kilometers) from the surface of Earth. The moon is 230,000 miles (384,000 km). Each trip to the moon would take about three days and would require incredible amounts of fuel, potentially adding to climate problems on Earth.

A much better idea would be to build as much of the base as possible from materials found on the moon. Lunar concrete is being tested on Earth as a possible building material.

On Earth you would make concrete from gravel or sand, cement and water. We have none of those things on the moon, but what we do have is lunar dust and sulphur. These can be melted and mixed together. Once this mixture cools, it produces a solid material that is stronger than many materials we use on Earth.

Food and power


We also need to think about what astronauts staying at the space station would need. The most important things would be a food supply and electricity to power equipment, food production and breathable air.

Scientists have been working on how to grow food in space. On board the International Space Station, astronauts are carrying out experiments to try to grow vegetables using soil pillows. Another option would be to grow plants using hydroponics, which means that the plants grow in water, not soil.

Getting power on the moon would be more complicated. The best way would be to use solar energy from the sun. However, the moon rotates every 28 days. This means that a space station in a fixed position on the moon would be in the sun for 14 days and then darkness for 14 days – and without light, solar-powered equipment wouldn’t work without a big improvement in battery storage.

One way to get round this problem would be to build the space station at either the north or south pole of the moon, and raise the solar panels above the surface. The panels would get constant sunlight as they can rotate and not be blocked by the planet at all.

Alternatively, we might not even need a base on the surface of the moon at all. Instead, NASA is planning to build a satellite to orbit the moon. Rockets launching from the lunar surface use more fuel to escape the moon’s gravity, but this would not be so difficult from a satellite. This means it would be even better than a base on the moon; a gateway for missions heading further into the solar system.

Japan’s billionaire Maezawa to release ‘No-Money World’ movie after trip to the Moon


Japanese billionaire Yusaku Maezawa said in an interview with TASS on board of the International Space Station (ISS) that he planned to make a movie about the ‘no-money world’ after his future trip to the Moon.

"I want to shoot movies about the no-money world. My explanation is not good so, people cannot understand what I imagine, so maybe I need a movie for understanding these things," he said.

"In 2023, I will go on the flight to the Moon…, go to space again, and maybe after that," Maezawa replied to a question about when his film should be expected to hit the screens. "In 2025 or 2026."

Maezawa said in an interview with Russian cosmonaut Alexander Misurkin that the movie would serve to convey an idea about getting rid of money.

"Certainly, money will disappear from our world. We can imagine that," Maezawa stated.

"I think, and you think maybe the world should be a better place and money is an enemy of the people, so money should disappear too," he continued. "And if money disappears, maybe every kind of war will also disappear and all crime [is] caused by money. So, money will disappear from this world, and every [type of] crime will also disappear. I think."

"I imagine [that in] a no-money world, people will work for people," the Japanese billionaire said. "Almost every person is working for money now, unfortunately, but in a no-money world people will work for people."

On the morning of December 20, a Soyuz MS-20 descent module carrying Roscosmos cosmonaut Alexander Misurkin, Maezawa and his business assistant Yozo Hirano successfully landed in Kazakhstan. Due to unfavorable weather conditions, helicopters remained grounded in the Kazakh city of Jezkazgan while rescue teams reached the landing site and the descent module on motor vehicles.

The evacuation effort involved special search and evacuation transport and later a helicopter flew to the site and airlifted the crewmembers to Jezkazgan where they boarded an An-26 plane to fly first to Karaganda and then to the Chkalovsky airfield near Moscow.

Misurkin, Maezawa, and Hirano had been on the ISS since December 8. On the same day, an epoch-making news office commenced its work aboard the ISS thanks to a memorandum of cooperation signed between the world-renowned TASS Russian News Agency and Roscosmos on November 17. Under the milestone agreement, Roscosmos cosmonaut, Hero of Russia Alexander Misurkin became the first TASS correspondent in space.

He reported on the space station’s daily routine and communicated with scientists responsible for scientific experiments aboard the orbital outpost. His latest information from space is available to the agency’s readership from TASS' news resources. In addition, his photo and video contributions can be seen on the agency’s website and official social media pages.

The full text of the interview is available at: https://tass.com/science/1382773.

Source: Link

NASA Announces Extension of International Space Station to 2030


NASA Administrator Bill Nelson announced today the Biden-Harris Administration’s commitment to extend International Space Station (ISS) operations through 2030, and to work with our international partners in Europe (ESA, European Space Agency), Japan (JAXA, Japan Aerospace Exploration Agency), Canada (CSA, Canadian Space Agency), and Russia (State Space Corporation Roscosmos) to enable continuation of the groundbreaking research being conducted in this unique orbiting laboratory through the rest of this decade.

“The International Space Station is a beacon of peaceful international scientific collaboration and for more than 20 years has returned enormous scientific, educational, and technological developments to benefit humanity. I’m pleased that the Biden-Harris Administration has committed to continuing station operations through 2030,” Nelson said. “The United States’ continued participation on the ISS will enhance innovation and competitiveness, as well as advance the research and technology necessary to send the first woman and first person of color to the Moon under NASA’s Artemis program and pave the way for sending the first humans to Mars. As more and more nations are active in space, it’s more important than ever that the United States continues to lead the world in growing international alliances and modeling rules and norms for the peaceful and responsible use of space.”

Over the past two decades, the United States has maintained a continuous human presence in orbit around the Earth to test technologies, conduct scientific research, and develop skills needed to explore farther than ever before. The unique microgravity laboratory has hosted more than 3,000 research investigations from over 4,200 researchers across the world and is returning enormous scientific, educational, and technological developments to benefit people on Earth. Nearly 110 countries and areas have participated in activities aboard the station, including more than 1,500,000 students per year in STEM activities.

Instruments aboard the ISS, used in concert with free-flying instruments in other orbits, help us measure the stresses of drought and the health of forests to enable improved understanding of the interaction of carbon and climate at different time scales. Operating these and other climate-related instruments through the end of the decade will greatly increase our understanding of the climate cycle.

Extending operations through 2030 will continue another productive decade of research advancement and enable a seamless transition of capabilities in low-Earth orbit to one or more commercially owned and operated destinations in the late 2020s. The decision to extend operations and NASA’s recent awards to develop commercial space stations together ensure uninterrupted, continuous human presence and capabilities; both are critical facets of NASA’s International Space Station transition plan.

Source: Link

Saturday, 1 January 2022

With Webb’s Mid-Booms Extended, Sunshield Takes Shape


With the successful extension of Webb’s second sunshield mid-boom, the observatory has passed another critical deployment milestone. Webb’s sunshield now resembles its full, kite-shaped form in space.

Engineers began to deploy the second (starboard) mid-boom at 6:31 p.m. EST and completed the process at about 10:13 p.m. EST.

The completion of the sunshield cover and mid-boom deployments over the past two days marks a critical milestone for Webb: all 107 membrane release devices associated with the sunshield deployment — every single one of which had to work in order for the sunshield to deploy — have now successfully released. Webb has 178 of these ‘non-explosive actuators’ in all; 107 were used to keep the sunshield safe and folded prior to deployment.

As the mid-booms slowly pushed out horizontally from the spacecraft, each driven by a motor, they pulled the folded membranes of the sunshield with them. This extended the sunshield to its full 47-foot width all the way across the observatory.

“The mid-booms are the sunshield’s workhorse and do the heavy lifting to unfold and pull the membranes into that now-iconic shape,” said Keith Parrish, Webb observatory manager at NASA’s Goddard Space Flight Center.

While the deployments took longer than expected today, that was due to the operations team moving forward with caution and according to the protocols they laid out for dealing with unpredictable situations.

“Today is an example of why we continue to say that we don’t think our deployment schedule might change, but that we expect it to change,” Parrish said. “The team did what we had rehearsed for this kind of situation – stop, assess, and move forward methodically with a plan. We still have a long way to go with this whole deployment process.”

The two mid-boom arms are now locked in their final position. They will hold the sunshield membranes in their proper place, as the team turns to the final stage in the sunshield’s deployment: tensioning.

In the coming days, the team will separate and then individually tension each of the five sunshield layers, stretching them into their final, taut shape. This will create space between the membranes to allow heat to radiate out, making each successive layer of the sunshield cooler than the one below.

Webb’s engineers will begin with the bottom layer – the largest and flattest layer, which is closest to the Sun and will reach the highest temperatures. They will proceed sequentially to the fifth and smallest layer, closest to the primary mirror. Tensioning the layers involves sending commands to activate several motors to reel in a total of 90 cables through numerous pulleys and cable management devices. Sunshield tensioning will take at least two days but may take longer, due to the complexity of the process and the flexibility built into the timeline.

Source: Link

Thursday, 30 December 2021

Due to Precision Launch, NASA Says Webb Space Telescope’s Fuel Likely To Last Way More Than 10 Years


After a successful launch of NASA’s James Webb Space Telescope Dec. 25, and completion of two mid-course correction maneuvers, the Webb team has analyzed its initial trajectory and determined the observatory should have enough propellant to allow support of science operations in orbit for significantly more than a 10-year science lifetime.  (The minimum baseline for the mission is five years.)

The analysis shows that less propellant than originally planned for is needed to correct Webb’s  trajectory toward its final orbit around the second Lagrange point known as L2, a point of gravitational balance on the far side of Earth away from the Sun. Consequently, Webb will have much more than the baseline estimate of propellant – though many factors could ultimately affect Webb’s duration of operation.

Webb has rocket propellant onboard not only for midcourse correction and insertion into orbit around L2, but also for necessary functions during the life of the mission, including “station keeping” maneuvers – small thruster burns to adjust Webb’s orbit — as well as what’s known as momentum management, which maintains Webb’s orientation in space.

The extra propellant is largely due to the precision of the Arianespace Ariane 5 launch, which exceeded the requirements needed to put Webb on the right path, as well as the precision of the first mid-course correction maneuver – a relatively small, 65-minute burn after launch that added approximately 45 mph (20 meters/sec) to the observatory’s speed.  A second correction maneuver occurred on Dec. 27, adding around 6.3 mph (2.8 meters/sec) to the speed.

The accuracy of the launch trajectory had another result: the timing of the solar array deployment. That deployment was executed automatically after separation from the Ariane 5 based on a stored command to deploy either when Webb reached a certain attitude toward the Sun ideal for capturing sunlight to power the observatory – or automatically at 33 minutes after launch. Because Webb was already in the correct attitude after separation from the Ariane 5 second stage, the solar array was able to deploy about a minute and a half after separation, approximately 29 minutes after launch.

From here on, all deployments are human-controlled so deployment timing – or even their order — may change. Explore what’s planned here.

Source: Link

NASA Hires Theologians to Understand How World Will React to Discovery of Alien Life


Between heaven and Earth, where do aliens fit in?

That’s the question that NASA hopes theologians at the Center for Theological Inquiry (CTI) in Princeton, New Jersey, can answer, in a recent effort to understand how humans will react to news that intelligent life exists on other planets.

University of Cambridge religious scholar Rev. Dr. Andrew Davison, who also holds a doctorate in biochemistry from Oxford, is one of the 24 theologians enlisted to help with the project, the Times UK reported last week.

In a recent statement on the University of Cambridge’s Faculty of Divinity blog, Davison says his research so far has already seen “just how frequently theology-and-astrobiology has been topic in popular writing” during the previous 150 years.

Davison’s upcoming book, “Astrobiology and Christian Doctrine,” due out in 2022, according to the Times, will cover part of CTI and NASA’s joint spiritual exploration, in which his “most significant question” is how theologians would respond to the notion “of there having been many incarnations [of Christ]” in the universe, he added in the blog post.

This is the latest dispatch to come in a partnership between the US space agency and the religious institute. In 2014, NASA awarded CTI a $1.1 million grant to study worshippers’ interest in and openness to scientific inquiry called the Societal Implications of Astrobiology study.

Studies have shown links between religiosity and belief in extraterrestrial intelligence. Research published in 2017 found that people with a strong desire to find meaning, but a low adherence to a particular religion, are more likely to believe aliens exist — indicating that faith in either theory may come from the same human impulse.

With NASA’s support, CTI’s director Will Storrar said they’d hoped to see “serious scholarship being published in books and journals” to come out on the subject, answering to the “profound wonder and mystery and implication of finding microbial life on another planet.”

According to the Times, Davison’s book notes that a “large number of people would turn to their religions traditions for guidance” if extraterrestrials were found, and what that means “for the standing and dignity of human life.”

“Detection [of alien life] might come in a decade or only in future centuries or perhaps never at all, but if or where it does, it will be useful to have thought through the implications in advance,” Davison writes.

Source: Link

Elon Musk's SpaceX satellites catch heat in China over close calls with space station


Elon Musk's rocky year in China is ending on another sour note.

The tech billionaire's SpaceX satellites are catching heat in the country after Beijing complained that two satellites launched by the American aerospace manufacturer endangered Chinese astronauts.

In a report sent earlier this month to the United Nations Office for Outer Space Affairs, China claimed that two SpaceX satellites flew too close to the country's space station this year, forcing the station to make evasive maneuvers to avoid collision.

The two encounters "constituted dangers to the life or health of astronauts aboard the China Space Station," according to the report, which said the incidents happened in July and October.

China filed its complaint to the UN early this month. But the episodes didn't gain widespread attention in the country until this week.

Chinese State media scrutinized the incidents, which involved satellites that are part of SpaceX's Starlink constellation — a project that promises to beam high-speed internet across the entire planet. The Global Times, a state-run tabloid, cited an expert Monday who speculated that SpaceX may have been "trying to test China's capability and response awareness in space."

The topic also attracted some 90 million views on Weibo, a Twitter-like social media service in China. Users criticized the "US Starlink satellites." One person decried the network as a "rogue project" and a "kind of monopoly in the space race." Another accused the United States of "provoking trouble."

Asked about the incident on Tuesday, a spokesperson for China's Ministry of Foreign Affairs called on the United States to "take immediate measures to prevent such incidents from happening again."

"It is a typical double standard for the US to proclaim the concept of 'responsible conduct in outer space' while ignoring its obligations under international treaties on outer space and posing a grave threat to the lives and safety of astronauts," Zhao Lijian told reporters.

SpaceX did not respond to a request from CNN Business for comment about the document that China filed with the UN, nor to questions about whether the company was able to communicate with Chinese authorities during the incidents.

The UN's Office for Outer Space Affairs did not immediately respond to a request from CNN Business for comment. In its report, China asked UN Secretary-General António Guterres to remind countries of the organization's treaty governing outer space activity.

The US military's Vandenberg Space Force Base, which monitors space traffic and attempts to track potential collisions, did not respond to a request for comment about the UNOOSA report.

A space traffic problem

People across the United States are already using the new Starlink network, and it's rapidly expanding across the globe as SpaceX launches more Starlink satellites and expands its service into new countries.

SpaceX's Starlink constellation already includes roughly 2,000 satellites, and it promises to far surpass that amount.

But that satellite constellation, other similar planned projects and increasing commercial and government activity in space has contributed to a growing problem: how to manage traffic in space.

Near-misses between objects in space happen all the time. And the apparent close calls documented in China's report to the UN may be symptoms of a larger problem plaguing space-faring nations: There is not a perfect, international solution for tracking and coordinating objects in space.

Concerns about potential collisions will likely keep growing, and activities in space will become more dangerous as humans launch more objects into orbit.

It should also be noted that Russia and China have conducted anti-satellite, or ASAT, military tests that have essentially blown up satellites in orbit and created massive plumes of debris in space. That debris whips uncontrollably through orbit, threatening any spacecraft, space station or satellite that might cross the debris field's path.

Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics, pointed out that the International Space Station has had to maneuver out of the way of debris created by China's 2007 ASAT test several times in recent years.

In other words: Every party involved shares a bit of the fault for how crowded Earth's orbit has become.

"This is another symptom that we're in a new era — a new space age that is both much busier much tenser," McDowell told CNN Business.

It's not clear whether the Starlink satellites mentioned in the UN report attempted to move out of the way of China's space station on their own. During October's close encounter, according to China, the satellite's "maneuver strategy was unknown and orbital errors were hard to be assessed," prompting the space station to evade the satellite and "avoid a potential collision."

The Starlink website, though, says that autonomous collision avoidance technology is embedded into its satellites, allowing them to automatically duck out of the way if they detect a potential crash with an oncoming piece of space junk, a space station or any other space-faring object.

McDowell told CNN Business that based on his data, the Starlink satellite that made a close approach to China's space station in July made a slight adjustment to its path that could indicate the autonomous system was working.

But he added that those systems are hardly effective if there's not more coordination.

"If I'm in China — even if I know that SpaceX has an autonomous system — I don't know that it's going to work this time," he said. "I don't know if it's switched on."

Musk's reputation in China

The controversy could hurt Musk's reputation in China.

Musk spent years winning over authorities and Chinese citizens alike as his electric carmaker Tesla made inroads where other foreign firms could not.

Tesla (TSLA) was the only foreign manufacturer without a local partner to win a big tax break for its cars in 2019, and Musk famously danced on stage during the debut of the Shanghai-made Model 3 early last year, which went viral on Weibo. Premier Li Keqiang once even said he would be happy to give Musk a "China green card" after the American entrepreneur said he "loves China very much."

But Musk's reception in the country has been damaged over the last year by a run of bad publicity, including a recall of virtually all of the Tesla cars that have been built in Shanghai. The company also faced protests by Telsa owners at this year's Shanghai auto show over poor car quality and various safety concerns flagged by Chinese regulators.

Musk, who has long shown an affinity for Chinese culture, has in the meantime been on a monthslong charm offensive.

In July, he applauded the government on the 100th anniversary for the ruling Chinese Communist Party, tweeting: "The economic prosperity that China has achieved is truly amazing, especially in infrastructure! I encourage people to visit and see for themselves."

That came months after the world's richest man appeared for a rare interview with a Chinese state broadcaster, heaping praise on Beijing and saying that China would "become the biggest economy in the world." Musk has also predicted that the country will eventually become Tesla's most important market.

And his many utterances have often created buzz within the country. In November, Musk cryptically tweeted an ancient Chinese poem that is famous in the country, and which refers to a spat between brothers. It swiftly became a trending topic on Weibo.

Source: Link

Wednesday, 29 December 2021

Researchers capture high-frequency oscillations in the gigantic eruption of a neutron star


An international scientific group with outstanding Valencian participation has managed to measure for the first time oscillations in the brightness of a magnetar during its most violent moments. In just a 10th of a second, the magnetar released energy equivalent to that produced by the sun in 100,000 years. The observation was carried out without human intervention, thanks to an artificial intelligence system developed at the Image Processing Laboratory (IPL) of the University of Valencia.

Among neutron stars, objects that can contain a half-million times the mass of the Earth in a diameter of about 20 kilometers, are magnetars, a small group with the most intense magnetic fields known. These objects, of which only 30 are known, suffer violent eruptions that are still little known due to their unexpected nature and their duration of barely 10ths of a second. Detecting them is a challenge for science and technology.

Over the past 20 years, scientists have wondered if there are high frequency oscillations in the magnetars. The team recently published their study of the eruption of a magnetar in the journal Nature. They measured oscillations in the brightness of the magnetar during its most violent moments. These episodes are a crucial component in understanding giant magnetar eruptions. The work was conducted by six researchers from the University of Valencia and Spanish collaborators.

"Even in an inactive state, magnetars can be 100,000 times more luminous than our sun, but in the case of the flash that we have studied—GRB2001415—the energy that was released is equivalent to that which our sun radiates in 100,000 years," says lead researcher Alberto J. Castro-Tirado, from the IAA-CSIC.

"The explosion of the magnetar, which lasted approximately a 10th of a second, was discovered on April 15, 2020 in the midst of the pandemic," says Víctor Reglero, professor of Astronomy and Astrophysics at the UV, researcher at the Image Processing Laboratory (IPL), co-author of the article and one of the architects of ASIM, the instrument aboard the International Space Station that detected the eruption. "Since then we have developed very intense data analysis work, since it was a 10 ** 16 Gauss neutron star and located in another galaxy. A true cosmic monster," says Reglero.

Scientists think that eruptions in magnetars may be due to instabilities in their magnetospheres or to a kind of "earthquake" produced in their crust, a rigid and elastic layer about a kilometer thick. "Regardless of the trigger, a type of wave is created in the star's magnetosphere—the Alfvén—which are well known in the sun, and which interact with each other, dissipating energy," explains Alberto J. Castro-Tirado.

According to the study, the oscillations detected in the eruption are consistent with the emission produced by the interaction between Alfvén waves, whose energy is rapidly absorbed by the crust. Thus, in a few milliseconds, the magnetic reconnection process, and therefore also the pulses detected in GRB2001415, end, disappearing 3.5 milliseconds after the main burst. The analysis of the phenomenon has made it possible to estimate that the volume of the eruption was similar or even greater than that of the neutron star itself.

The eruption was detected by the ASIM instrument, which is on board the International Space Station (ISS). ASIM was the only one of the seven telescopes capable of registering the main phase of the eruption in its full energy range without suffering saturations. The scientific team was able to solve the temporal structure of the event, a truly complex task that involved more than a year of analysis for just two seconds during which the data was collected.

The Atmosphere Space Interactions Monitor (ASIM) is an ESA mission developed by Denmark, Norway and Spain, which has been operational in the ISS since 2018 under the supervision of researchers Torsten Neubert (Technical University of Denmark), Nikolai Ostgaard (University of Bergen, Norway) and Víctor Reglero (University of Valencia, Spain), who form the ASIM Facility Science Team.

ASIM's objective is to monitor violent phenomena in the Earth's atmosphere from optical to gamma wavelengths at 40 MeV, an activity that the telescope has been carrying out since June 2018. It has already detected 1,000 gamma-ray eruptions. "Given that these phenomena are unpredictable, ASIM decides completely autonomously when something has happened and sends the data to the different centers of the Science Data Centre in Copenhagen, Bergen and Valencia," explains Víctor Reglero.

The detection of quasi-periodic oscillations in GRB2001415 was quite a challenge from the point of view of signal analysis. "The difficulty lies in the brevity of the signal, whose amplitude rapidly decays and becomes embedded in background noise. And, as it is correlated noise, it is difficult to distinguish its signal," says Reglero. The artificial intelligence system, together with sophisticated data analysis techniques, allowed the researchers to detect this spectacular phenomenon.

Although these eruptions had already been detected in two of the 30 known magnetars in the galaxy and in other, nearby galaxies, GRB2001415 is the most distant magnetar eruption captured to date, located in the Sculptor group of galaxies about 13 million light years away. "Seen in perspective, it has been as if the magnetar wanted to indicate its existence to us from its cosmic solitude, singing in the kHz with the force of a Pavarotti of a billion suns," says Reglero.

According to the authors of the paper, the eruption provides a crucial component for understanding how magnetic stresses are produced in and around a neutron star. Continuous monitoring of magnetars in nearby galaxies will help to understand this phenomenon, and will also pave the way to a better understanding of fast radio bursts, currently among the most enigmatic phenomena in astronomy.

Reference: 

A. J. Castro-Tirado et al, Very-high-frequency oscillations in the main peak of a magnetar giant flare, Nature (2021). DOI: 10.1038/s41586-021-04101-1

Tuesday, 28 December 2021

Drunken solution to the chaotic three-body problem


The three-body problem is one of the oldest problems in physics: It concerns the motions of systems of three bodies—like the sun, Earth, and the moon—and how their orbits change and evolve due to their mutual gravity. The three-body problem has been a focus of scientific inquiry ever since Newton.

When one massive object comes close to another, their relative motion follows a trajectory dictated by their mutual gravitational attraction, but as they move along and change their positions along their trajectories, the forces between them, which depend on their mutual positions, also change, which, in turn, affects their trajectory. For two bodies (e.g., the Earth moving around the sun without the influence of other bodies), the orbit of the Earth would continue to follow a specific curve (an ellipse), which can be accurately described mathematically. However, under the influence of a third object, the complex interactions lead to the three-body problem—the system becomes chaotic and unpredictable, and the system's evolution over long time scales cannot be predicted. Indeed, while this phenomenon has been known for over 400 years, ever since Newton and Kepler, a neat mathematical description for the three-body problem is still lacking.

In the past, physicists—including Newton himself—have tried to solve the three-body problem; in 1889, King Oscar II of Sweden even offered a prize, in commemoration of his 60th birthday, to anybody who could provide a general solution. In the end, it was the French mathematician Henri Poincaré who won the competition. He ruined any hope for a full solution by proving that such interactions are chaotic, in the sense that the final outcome is essentially random; in fact, his finding opened a new scientific field of research, termed chaos theory.

The absence of a solution to the three-body problem means that scientists cannot predict what happens during a close interaction between a binary system (formed of two stars that orbit each other like Earth and the sun) and a third star, except by simulating it on a computer and following the evolution step-by-step. These simulations show that when such an interaction occurs, it proceeds in two phases: First, a chaotic phase during which all three bodies pull on each other violently until one star is ejected far from the other two, which then settle down to an ellipse. If the third star is on a bound orbit, it eventually comes back down toward the binary, whereupon the first phase ensues once again. This triple dance ends when, in the second phase, one of the stars escapes on an un-bound orbit, never to return.

In a paper accepted for publication in Physical Review X this month, Ph.D. student Yonadav Barry Ginat and Professor Hagai Perets of the Technion-Israel Institute of Technology used this randomness to provide a statistical solution to the entire two-phase process. Instead of predicting the actual outcome, they calculated the probability of any given outcome of each phase-1 interaction. While chaos implies that a complete solution is impossible, its random nature allows calculation of the probability that a triple interaction ends in one particular way rather than another. Then, the entire series of close approaches could be modeled by using a the theory of random walks, sometimes called "drunkard's walk." The term got its name from mathematicians thinking about how a drunk would walk, regarding it as a random process—with each step, the drunk doesn't realize where they are and takes the next step in some random direction.

The triple system behaves, essentially, in the same way. After each close encounter, one of the stars is ejected randomly (but with the three stars collectively still conserving the overall energy and momentum of the system). This series of close encounters could be regarded as a drunkard's walk. Like a drunk's step, a star is ejected randomly, comes back, and another (or the same star) is ejected to a likely different random direction (similar to another step taken by the drunk) and comes back, and so forth, until a star is completely ejected and never returns (akin to a drunk falling into a ditch).

Another way of thinking about this is to notice the similarities with describing the weather, which also exhibits the same phenomenon of chaos that Poincaré discovered; this is why the weather is so hard to predict. Meteorologists therefore have to recourse to probabilistic predictions (think about that time when a 70 percent chance of rain ended up as glorious sunshine in reality). Moreover, to predict the weather a week from now, meteorologists have to account for the probabilities of all possible types of weather in the intervening days, and only by composing them together can they get a proper long-term forecast.

What Ginat and Perets showed in their research was how this could be done for the three-body problem: They computed the probability of each phase-2 binary-single configuration (the probability of finding different energies, for example), and then composed all of the individual phases using the theory of random walks to find the final probability of any possible outcome, much like calculating long-term weather forecasts.

"We came up with the random walk model in 2017, when I was an undergraduate student," said Mr. Ginat, "I took a course that Prof. Perets taught, and there I had to write an essay on the three-body problem. We didn't publish it at the time, but when I started a Ph.D., we decided to expand the essay and publish it."

The three-body problem was studied independently by research groups in recent years, including Nicholas Stone of the Hebrew University in Jerusalem, collaborating with Nathan Leigh, then at the American Museum of Natural History, and Barak Kol, also of the Hebrew University. Now, with the current study by Ginat and Perets, the entire, multi-stage, three-body interaction is fully solved statistically.

"This has important implications for our understanding of gravitational systems, and in particular, cases where many encounters between three stars occur, like in dense clusters of stars," said Prof. Perets. "In such regions, many exotic systems form through three-body encounters, leading to collisions between stars and compact objects like black holes, neutron stars and white dwarves, which also produce gravitational waves that have been directly detected only in the last few years. The statistical solution could serve as an important step in modeling and predicting the formation of such systems."

The random walk model can also do more: So far, studies of the three-body problem treat the individual stars as idealized point particles. In reality, of course, they are not, and their internal structure might affect their motion, for example, in tides. Tides on Earth are caused by the moon and change the planet's shape slightly. Friction between the water and the rest of the planet dissipates some of the tidal energy as heat. Energy is conserved, however, so this heat must come from the moon's energy in its motion about the Earth. Similarly for the three-body problem, tides can draw orbital energy out of the three-bodies' motion.

"The random walk model accounts for such phenomena naturally," said Mr. Ginat. "All you have to do is to remove the tidal heat from the total energy in each step, and then compose all the steps. We found that we were able to compute the outcome probabilities in this case, too." As it turns out, a drunkard's walk can sometime shed light on some of the most fundamental questions in physics.

Reference: 

Yonadav Barry Ginat et al, Analytical, Statistical Approximate Solution of Dissipative and Nondissipative Binary-Single Stellar Encounters, Physical Review X (2021). DOI: 10.1103/PhysRevX.11.031020