Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: space – Page 81

Originally published on Towards AI.

ABSTRACT: The fundamental problem of causal inference defines the impossibility of associating a causal link to a correlation, in other words: correlation does not prove causality. This problem can be understood from two points of view: experimental and statistical. The experimental approach tells us that this problem arises from the impossibility of simultaneously observing an event both in the presence and absence of a hypothesis. The statistical approach, on the other hand, suggests that this problem stems from the error of treating tested hypotheses as independent of each other. Modern statistics tends to place greater emphasis on the statistical approach because, compared to the experimental point of view, it also shows us a way to solve the problem. Indeed, when testing many hypotheses, a composite hypothesis is constructed that tends to cover the entire solution space. Consequently, the composite hypothesis can be fitted to any data set by generating a random correlation. Furthermore, the probability that the correlation is random is equal to the probability of obtaining the same result by generating an equivalent number of random hypotheses.

Read more | >

Asteroids are remnants of the formation of our solar system, and while many can be found within the asteroid belt between the orbits of Mars and Jupiter, some cannot. One such object is asteroid (162173) Ryugu, a 1 km-wide near-Earth asteroid believed to have originated in the asteroid belt. However, it has since moved to cross Earth’s orbit, located 300 million km from our planet.

The asteroid is constantly bombarded by debris in space and new research, published in The Astrophysical Journal, has suggested that even can have damaging effects.

Japan’s Aerospace Exploration Agency (JAXA) launched the Hayabusa2 spacecraft to conduct and sample collection on the asteroid in 2018 and 2019. Laboratory work on these samples identified a distinct pattern of dehydration of phyllosilicates (sheet-like silicate minerals, such as magnesium-rich serpentine and saponite), whereby the bonds between the included oxygen and hydrogen atoms are broken.

Read more | >

Free-space optical communication links promise better security and increase bandwidths but can suffer from noise in daylight. This is particularly detrimental in quantum communications where current mitigation techniques, such as spectral, temporal, and spatial filtering, are not yet sufficient to make daylight tolerable for satellite quantum key distribution (SatQKD). As all current SatQKD systems are polarization-encoded, polarization filtering has not been investigated. However, by using time-and phase-encoded SatQKD, it is possible to filter in polarization in addition to existing domains. Scattered daylight can be more than 90% polarized in the visible band, yielding a reduction in detected daylight between 3 dB and 13 dB, such that polarization filtering can reduce the brightness of 780 nm daylight to below the unfiltered equivalent at 1,550 nm. Simulations indicate that polarization filtering increases the secure key rate and allows for SatQKD to be performed at dawn and dusk. This could open the way for daylight SatQKD utilizing shorter near-infrared wavelengths and retaining their benefits.

Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Read more | >

The Space Force’s 45th Weather Squadron pegs the odds of “go for launch” weather at 85%. Chief meteorological risks include thick cloud layers and liftoff winds, coupled with a low-to-moderate risk of upper-level wind shear.

Check back for live FLORIDA TODAY Space Team launch coverage updates on this page, starting about 90 minutes before the launch window opens. When SpaceX’s live webcast kicks off about five minutes before liftoff, look for it posted below the countdown clock.

Read more | >

Ocean currents spin off huge gyres, whose kinetic energy is transferred to ever-smaller turbulent structures until viscosity has erased velocity gradients and water molecules jiggle with thermal randomness. A similar cascade plays out in space when the solar wind slams into the magnetopause, the outer boundary of Earth’s magnetic field. The encounter launches large-scale magnetic, or Alfvén, waves whose energy ends up heating the plasma inside the magnetosphere. Here, however, the plasma is too thin for viscosity to mediate the cascade. Since 1971 researchers have progressively developed their understanding of how Alfvén waves in space plasmas generate heat. These studies later culminated in a specific hypothesis: Alfvén waves accelerate ion beams, which create small-scale acoustic waves, which generate heat. Now Xin An of UCLA and his collaborators have found direct evidence of that proposed mechanism [1]. What’s more, the mechanism is likely at work in the solar wind and other space plasmas.

Laboratory-scale experiments struggle to capture the dynamics of rotating plasmas, and real-world observations are even more scarce. The observations that An and his collaborators analyzed were made in 2015 by the four-spacecraft Magnetospheric Multiscale (MMS) mission. Launched that year, the MMS was designed to study magnetic reconnection, a process in which the topology of magnetic-field lines is violently transformed. The field rearrangements wrought by reconnection can be large, on the scale of the huge loops that sprout from the Sun’s photosphere. But the events that initiate reconnection take place in a much smaller region where neighboring field lines meet, the X-line. The four spacecraft of MMS can fly in a configuration in which all of them witness the large-scale topological transformation while one of them could happen to fly through the X-line—a place where no spacecraft had deliberately been sent before.

On September 8, 2015, the orbits of the MMS spacecraft took them through the magnetopause on the dusk side of Earth. They were far enough apart that together they could detect the passage of a large-scale Alfvén wave, while each of them could individually detect the motion of ions in the surrounding plasma. An and his collaborators later realized that these observations could be used to test the theory that ion beams and the acoustic waves that they generate mediate the conversion of Alfvén-wave energy to heat.

Read more | >

The examination of a sample brought from asteroid Ryugu in outer space turned exciting for scientists when they found it had life forms on it. However, soon the excitement died down when they found that the microbes on the sample had actually originated on Earth.

The sample was brought to Earth in 2020 after being gathered in 2019 during Japan’s Hayabusa2 mission.

Scientists treated the Ryugu samples with great care and kept them under strict contamination controls, limiting their chance of contamination.

Read more | >

An exploration of the mysteries of the cosmic microwave background radiation.

https://www.patreon.com/johnmichaelgodier.

Music:

Cylinder Eight by Chris Zabriskie is licensed under a Creative Commons Attribution 4.0 license. https://creativecommons.org/licenses/by/4.0/

Source: http://chriszabriskie.com/cylinders/

Artist: http://chriszabriskie.com/

Continue reading “The Mysteries of the Cosmic Microwave Background Radiation” | >

In the vast reaches of space, invisible forces shape the behavior of charged particles in ways that are only now beginning to be fully understood.

A small team of astrophysicists at the University of California, Los Angeles, working with colleagues from the University of Texas at Dallas and the University of Colorado, Boulder, has found evidence that Alfvén waves in space plasmas speed up ion beams, resulting in the creation of small-scale acoustic waves that in turn generate heat in the magnetosphere.

In their study, published in the journal Physical Review Letters, the group used data from the four-spacecraft Magnetospheric Multiscale (MMS) mission that took place in 2015 to prove a about heat generation in the .

For several years, astronomers have been studying the impact of the striking the magnetopause, which defines the outer edges of the magnetosphere. Prior research has shown that as the solar wind arrives, Alfvén waves are generated and the resulting energy heats up the plasma in the magnetosphere. However, the plasma there is too thin to result in a cascade.

Read more | >

An international team of astronomers has employed the James Webb Space Telescope (JWST) to observe a supermassive Galactic open cluster known as Westerlund 1. Results of the observational campaign, presented in a paper published Nov. 20 on the arXiv preprint server, yield important insights about the structure and properties of this cluster.

Open clusters (OCs), formed from the same giant molecular cloud, are groups of stars loosely gravitationally bound to each other. So far, more than 1,000 of them have been discovered in the Milky Way, and scientists are still looking for more, hoping to find a variety of these stellar groupings. Expanding the list of known galactic and studying them in detail could be crucial for improving our understanding of the formation and evolution of our galaxy.

It is assumed that most takes place in massive clusters of stars, known as superstar clusters (SSCs). They are very massive young OCs usually containing a very large number of young, . The total mass of a typical SSC exceeds 10,000 solar masses.

Read more | >