TL;DR
- A radio telescope in outback Western Australia has completed the deepest and broadest search at low frequencies for alien technologies, scanning a patch of sky known to include at least 10 million stars. Astronomers used the Murchison Widefield Array (MWA) telescope to explore hundreds of times more broadly than any previous search for extraterrestrial life.
- A new study posits that the major particle ejections off the near-Earth asteroid Bennu may be the consequence of impacts by small, sand-sized particles called meteoroids onto its surface as the object nears the Sun.
- In our Solar System, the eight planets and many other minor objects orbit in a flat plane around the Sun; but in some distant systems, planets orbit on an incline — sometimes a very steep one. New work could explain the architecture of multi-star systems in which planets are separated by wide gaps and do not orbit on the same plane as their host star’s equatorial center.
- Astronomers have known for two decades that the expansion of the universe is accelerating, but the physics of this expansion remains a mystery. Now, a team of researchers at the University of Hawaiʻi at Mānoa have made a novel prediction — the dark energy responsible for this accelerating growth comes from a vast sea of compact objects spread throughout the voids between galaxies. This conclusion is part of a new study published in The Astrophysical Journal.
- Cosmologists have zoomed in on the smallest clumps of dark matter in a virtual universe — which could help us to find the real thing in space.
- To the surprise of many planetary scientists, the oxidized iron mineral hematite has been discovered at high latitudes on the Moon.
- A team led by the University of Colorado Boulder is pioneering a new solution to the problem of spring cleaning on the moon: Why not zap away the grime using a beam of electrons?
- Astronomers have for the first time directly observed the columns of matter that build up newborn stars. This was observed in the young star TW Hydrae system located approximately 163 light years from Earth.
- NASA’s Juno mission orbiting Jupiter is seeking a long-term extension that would allow the spacecraft to carry out new studies of the planet and some of its largest moons.
- GREGOR, the largest solar telescope in Europe, has obtained unprecedented images of the fine-structure of the Sun. Following a major redesign of GREGOR’s optics, the Sun can be observed at a higher resolution than before from Europe.
- Upcoming industry events. And more!
Space industry in numbers
Last summer, the Space Foundation published the second-quarter findings of its 2019 issue of The Space Report, revealing that:
- The global space economy grew 8.1% in 2018 to USA 414.75 billion, exceeding USD 400 billion for the first time.
- Global launches in 2018 increased by 46% over the number of launches a decade ago.
- Global launches in 2018 exceeded 100 for the first time since 1990.
Analysts at Morgan Stanley and Goldman Sachs have predicted that economic activity in space will become a multi-trillion-dollar market in the coming decades. Morgan Stanley’s Space Team estimates that the roughly USD 350 billion global space industry could surge to over USD 1 trillion by 2040.
Space industry news
Chinese reusable experimental spacecraft releases object before returning to Earth
White House issues cybersecurity space policy
Rocket Lab launches first Photon satellite
NASA’s Juno spacecraft seeking extended mission at Jupiter
China’s Landspace raises $175 million for Zhuque-2 launch vehicles
Space Force: Too early to say if military will need ‘super heavy’ launch vehicles
Northrop Grumman receives $13.3 billion contract to develop next-generation ICBM
NOAA’s former satellite now providing weather data to the U.S. military
In stopgap funding bill, White House wants Space Force accounts separated from Air Force
Gerstenmaier warns against ending space station program prematurely
China carries out secretive launch of ‘reusable experimental spacecraft’
Study raises new concerns about lack of governing norms in space
Falcon 9 launch adds 60 Starlink satellites to orbit as constellation beta testing continues
Report sees ways Artemis supports sustainable human Mars exploration
Arianespace launches Vega on return-to-flight mission with 53 smallsats
Air Force Research Laboratory announces new space experiments
NASA and Northrop Grumman test SLS booster
MonacoSat planning second geostationary satellite
Eutelsat renews major broadcast contract • Cobham Advanced Electronic Solutions gets new CEO
Made In Space Europe and Momentus plan robotic spacecraft
NASA to seek proposals for lunar nuclear power system
Space Force to add hundreds of new members as airmen begin to transfer over
NASA space technology faces potential budget pressure
Lockheed Martin enlists Tyvak and Telesat for Space Development Agency contract
Pentagon report: China amassing arsenal of anti-satellite weapons
Intelsat buys Gogo commercial aviation business for $400 million
Musk emphasizes progress in Starship production over testing
Lockheed Martin, York Space to produce 20 satellites for Space Development Agency
PLD Space completes critical testing of its Teprel-B rocket engine
ULA investigating cause of Delta 4 Heavy mission abort
Tech executive Victoria Coleman named director of DARPA
China makes progress on spaceport project for sea launches
Rocket Lab returns to flight with Capella Space launch
SpaceX launches Argentine radar satellite, rideshare smallsats on Falcon 9 rocket
Report: Space Force improving delivery of orbit monitoring software
Space exploration
Dynamical Evolution of Simulated Particles Ejected From Asteroid Bennu
by Jay W. McMahon, Daniel J. Scheeres, Steven R. Chesley, Andrew French, Daniel Brack, Davide Farnocchia, Yu Takahashi, Benjamin Rozitis, Pasquale Tricarico, Erwan Mazarico, Beau Bierhaus, Joshua P. Emery, Carl W. Hergenrother, Dante S. Lauretta in Journal of Geophysical Research: Planets
A new study posits that the major particle ejections off the near-Earth asteroid Bennu may be the consequence of impacts by small, sand-sized particles called meteoroids onto its surface as the object nears the Sun.
Launched in 2016, NASA’s OSIRIS-REx spacecraft is currently orbiting Bennu with the aim of briefly touching on the surface and obtaining a sample from the asteroid in October 2020, and then returning to Earth.
“While in orbit, the spacecraft has been sending images of Bennu back to Earth,” Bottke said. “One of the most significant things we’ve noticed is that the asteroid is frequently ejecting materials into space. Tiny rocks are just flying off its surface, yet there is no evidence that they are propelled by sublimating ice, as one might expect from a comet. The biggest events launch rocks as large as a few centimeters.”
Even more curious is the fact that the observed major ejection events tend to occur in the late afternoon on Bennu. Determined to get to the bottom of these events, Bottke reached out to Althea Moorhead at NASA’s Marshall Space Flight Center. Moorhead is a member of NASA’s Meteoroid Environment Office, a group that monitors and models meteoroids that may be hazardous to spacecraft.
“Over the years, Althea and her team have built a computer model that determines the number of tiny particles impacting spacecraft,” Bottke explained. “We used this software to calculate the number of meteoroid impacts Bennu would face in its current orbit.”
Many meteoroids originated on comets. As comets approach the Sun, pieces break off as a consequence of solar heating. Some comets even break apart, producing far more small particles than asteroid collisions in the asteroid belt. For this reason, comet fragments are thought to be the major source of meteoroids that fill the inner solar system.
Interpreting their modeling results, Bottke’s study suggests that as Bennu draws closer to the Sun in its orbit, it experiences a higher number of meteoroid impacts. Moreover, sand-sized meteoroids are predicted to hit Bennu with the force of a shotgun blast about once every two weeks, with most striking in the head-on direction. Their impact location on Bennu corresponds to late afternoon and early evening.
Furthermore, Bottke’s study points out that the Lunar Atmosphere and Dust Environment Explorer (LADEE) previously made similar observations about impacts on the Moon. As with Bennu, most meteoroids hit the Moon head-on (with head-on defined with respect to the motion of the Earth-Moon system around the Sun). The key difference between Bennu and the Moon is how they rotate around their spin axes. The Moon spins west to east, so head-on impacts correspond to sunrise. Bennu spins in the opposite direction, so head-on impacts hit near dusk.
At first, Bottke’s modeling work seem to predict that meteoroids would eject too little material from Bennu to explain the OSIRIS-REx observations. However, a better match could be obtained if Bennu has a weak porous surface. The possibility that Bennu has this property was recently strengthened by studies of the Bennu-like asteroid Ryugu, the target of Japan’s Hayabusa2 sample return mission. Using explosives to launch a small projectile into Ryugu, the Hayabusa2 team produced a crater that was larger than expected by most impact experts. If Bennu’s surface is indeed similar to Ryugu’s, meteoroid impacts should be capable of ejecting relatively large amounts of debris.
A triple-star system with a misaligned and warped circumstellar disk shaped by disk tearing
by Stefan Kraus, Alexander Kreplin, Alison K. Young, Matthew R. Bate, John D. Monnier, Tim J. Harries, Henning Avenhaus, Jacques Kluska, Anna S. E. Laws, Evan A. Rich, Matthew Willson, Alicia N. Aarnio, Fred C. Adams, Sean M. Andrews, Narsireddy Anugu, Jaehan Bae, et al. in Science
In our Solar System, the eight planets and many other minor objects orbit in a flat plane around the Sun; but in some distant systems, planets orbit on an incline — sometimes a very steep one. New work could explain the architecture of multi-star systems in which planets are separated by wide gaps and do not orbit on the same plane as their host star’s equatorial center.
“In our Solar System, the eight planets and many other minor objects orbit in a flat plane around the Sun; but in some distant systems, planets orbit on an incline — sometimes a very steep one,” Bae explained. “Understanding the origins of extremely oblique orbital angles such as these could help reveal details about the planetary formation process.”
Stars are born in nurseries of gas and dust called molecular clouds — often forming in small groups of two or three. These young stars are surrounded by rotating disks of leftover material, which accretes to form baby planets. The disk’s structure will determine the distribution of the planets that form from it, but much about this process remains unknown.
Led by University of Exeter’s Stefan Kraus, the team found the first direct evidence confirming the theoretical prediction that gravitational interactions between the members of multi-star systems can warp or break their disks, resulting in misaligned rings surrounding the stellar hosts.
Over a period of 11 years, the researchers made observations of the the GW Orionis triple-star system, located just over 1,300 light-years away in the Orion constellation. Their work was accomplished using the European Southern Observatory’s Very Large Telescope and the Atacama Large Millimeter/submillimeter Array — a radio telescope made up of 66 antennas.
“Our images reveal an extreme case where the disk is not flat at all, but is warped and has a misaligned ring that has broken away from the disk,” Kraus said.
Their findings were tested by simulations, which demonstrated that the observed disorder in the orbits of the three stars could have caused the disk to fracture into the distinct rings.
“We predict that many planets on oblique, wide-separation orbits will be discovered in future planet imaging campaigns,” said co-author Alexander Kreplin, also of the University of Exeter.
Bae concluded: “This system is a great example of how theory and observing can inform each other. I’m excited to see what we learn about this system and others like it with additional study.”
Support for this research was provided by the European Research Council under the European Commission’s Horizon 2020 program Seventh Framework program; the Science Technology and Facilities Council; the U.S. NSF; NASA; the research council of the KU Leuven; and the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy.
A SETI survey of the Vela region using the Murchison Widefield Array: Orders of magnitude expansion in search space
by C. D. Tremblay, S. J. Tingay in Publications of the Astronomical Society of Australia
A radio telescope in outback Western Australia has completed the deepest and broadest search at low frequencies for alien technologies, scanning a patch of sky known to include at least 10 million stars. Astronomers used the Murchison Widefield Array (MWA) telescope to explore hundreds of times more broadly than any previous search for extraterrestrial life.
Astronomers used the Murchison Widefield Array (MWA) telescope to explore hundreds of times more broadly than any previous search for extraterrestrial life.
The study, published today in Publications of the Astronomical Society of Australia, observed the sky around the Vela constellation. But in this part of the Universe at least, it appears other civilisations are elusive, if they exist.
The research was conducted by CSIRO astronomer Dr Chenoa Tremblay and Professor Steven Tingay, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR).
Dr Tremblay said the telescope was searching for powerful radio emissions at frequencies similar to FM radio frequencies, that could indicate the presence of an intelligent source.
These possible emissions are known as ‘technosignatures’.
“The MWA is a unique telescope, with an extraordinarily wide field-of-view that allows us to observe millions of stars simultaneously,” she said.
“We observed the sky around the constellation of Vela for 17 hours, looking more than 100 times broader and deeper than ever before.
“With this dataset, we found no technosignatures — no sign of intelligent life.”
Professor Tingay said even though this was the broadest search yet, he was not shocked by the result.
“As Douglas Adams noted in The Hitchhikers Guide to the Galaxy, ‘space is big, really big’.”
“And even though this was a really big study, the amount of space we looked at was the equivalent of trying to find something in the Earth’s oceans but only searching a volume of water equivalent to a large backyard swimming pool.
“Since we can’t really assume how possible alien civilisations might utilise technology, we need to search in many different ways. Using radio telescopes, we can explore an eight-dimensional search space.
“Although there is a long way to go in the search for extraterrestrial intelligence, telescopes such as the MWA will continue to push the limits — we have to keep looking.”
The MWA is a precursor for the instrument that comes next, the Square Kilometre Array (SKA), a 1.7 billion Euro observatory with telescopes in Western Australia and South Africa. To continue the Douglas Adams references, think of the MWA as the city-sized Deep Thought and the SKA as its successor: the Earth.
“Due to the increased sensitivity, the SKA low-frequency telescope to be built in Western Australia will be capable of detecting Earth-like radio signals from relatively nearby planetary systems,” said Professor Tingay.
“With the SKA, we’ll be able to survey billions of star systems, seeking technosignatures in an astronomical ocean of other worlds.”
The MWA is located at the Murchison Radio-astronomy Observatory, a remote and radio quiet astronomical facility established and maintained by CSIRO — Australia’s national science agency. The SKA will be built at the same location but will be 50 times more sensitive and will be able to undertake much deeper SETI experiments.
Widespread hematite at high latitudes of the Moon
by Shuai Li, Paul G. Lucey, Abigail A. Fraeman, Andrew R. Poppe, Vivian Z. Sun, Dana M. Hurley and Peter H. Schultz in Science Advances
To the surprise of many planetary scientists, the oxidized iron mineral hematite has been discovered at high latitudes on the Moon, according to a study published today in Science Advances led by Shuai Li, assistant researcher at the Hawai’i Institute of Geophysics and Planetology (HIGP) in the UH Mānoa School of Ocean and Earth Science and Technology (SOEST).
Iron is highly reactive with oxygen — forming reddish rust commonly seen on Earth. The lunar surface and interior, however, are virtually devoid of oxygen, so pristine metallic iron is prevalent on the Moon and highly oxidized iron has not been confirmed in samples returned from the Apollo missions. In addition, hydrogen in solar wind blasts the lunar surface, which acts in opposition to oxidation. So, the presence of highly oxidized iron-bearing minerals, such as hematite, on the Moon is an unexpected discovery.
“Our hypothesis is that lunar hematite is formed through oxidation of lunar surface iron by the oxygen from the Earth’s upper atmosphere that has been continuously blown to the lunar surface by solar wind when the Moon is in Earth’s magnetotail during the past several billion years,” said Li.
To make this discovery, Li, HIGP professor Paul Lucey and co-authors from NASA’s Jet Propulsion Laboratory (JPL) and elsewhere analyzed the hyperspectral reflectance data acquired by the Moon Mineralogy Mapper (M3) designed by NASA JPL onboard India’s Chandrayaan-1 mission.
This new research was inspired by Li’s previous discovery of water ice in the Moon’s polar regions in 2018.
“When I examined the M3 data at the polar regions, I found some spectral features and patterns are different from those we see at the lower latitudes or the Apollo samples,” said Li. “I was curious whether it is possible that there are water-rock reactions on the Moon. After months investigation, I figured out I was seeing the signature of hematite.”
The team found the locations where hematite is present are strongly correlated with water content at high latitude Li and others found previously and are more concentrated on the nearside, which always faces the Earth.
“More hematite on the lunar nearside suggested that it may be related to Earth,” said Li. “This reminded me a discovery by the Japanese Kaguya mission that oxygen from the Earth’s upper atmosphere can be blown to the lunar surface by solar wind when the Moon is in the Earth’s magnetotail. So, Earth’s atmospheric oxygen could be the major oxidant to produce hematite. Water and interplanetary dust impact may also have played critical roles”
“Interestingly, hematite is not absolutely absent from the far-side of the Moon where Earth’s oxygen may have never reached, although much fewer exposures were seen,” said Li. “The tiny amount of water (< ~0.1 wt.%) observed at lunar high latitudes may have been substantially involved in the hematite formation process on the lunar far-side, which has important implications for interpreting the observed hematite on some water poor S-type asteroids.”
“This discovery will reshape our knowledge about the Moon’s polar regions,” said Li. “Earth may have played an important role on the evolution of the Moon’s surface.”
The research team hopes the NASA’s ARTEMIS missions can return hematite samples from the polar regions. The chemical signatures of those samples can confirm their hypothesis whether the lunar hematite is oxidized by Earth’s oxygen and may help reveal the evolution of the Earth’s atmosphere in the past billions of years.
Implications of Symmetry and Pressure in Friedmann Cosmology. III. Point Sources of Dark Energy that Tend toward Uniformity
by K. S. Croker, J. Runburg, D. Farrah in The Astrophysical Journal
Astronomers have known for two decades that the expansion of the universe is accelerating, but the physics of this expansion remains a mystery. Now, a team of researchers at the University of Hawaiʻi at Mānoa have made a novel prediction — the dark energy responsible for this accelerating growth comes from a vast sea of compact objects spread throughout the voids between galaxies.
In the mid-1960s, physicists first suggested that stellar collapse should not form true black holes, but should instead form Generic Objects of Dark Energy (GEODEs). Unlike black holes, GEODEs do not ‘break’ Einstein’s equations with singularities. Instead, a spinning layer surrounds a core of dark energy. Viewed from the outside, GEODEs and black holes appear mostly the same, even when the “sounds” of their collisions are measured by gravitational wave observatories.
Because GEODEs mimic black holes, it was assumed they moved through space the same way as black holes. “This becomes a problem if you want to explain the accelerating expansion of the universe,” said UH Mānoa Department of Physics and Astronomy research fellow Kevin Croker, lead author of the study. “Even though we proved last year that GEODEs, in principle, could provide the necessary dark energy, you need lots of old and massive GEODEs. If they moved like black holes, staying close to visible matter, galaxies like our own Milky Way would have been disrupted.”
Croker collaborated with UH Mānoa Department of Physics and Astronomy graduate student Jack Runburg, and Duncan Farrah, a faculty member at the UH Institute for Astronomy and the Physics and Astronomy department, to investigate how GEODEs move through space. The researchers found that the spinning layer around each GEODE determines how they move relative to each other. If their outer layers spin slowly, GEODEs clump more rapidly than black holes. This is because GEODEs gain mass from the growth of the universe itself. For GEODEs with layers that spin near the speed of light, however, the gain in mass becomes dominated by a different effect and the GEODEs begin to repel each other. “The dependence on spin was really quite unexpected,” said Farrah. “If confirmed by observation, it would be an entirely new class of phenomenon.”
The team solved Einstein’s equations under the assumption that many of the oldest stars, which were born when the universe was less than 2 percent of its current age, formed GEODEs when they died. As these ancient GEODEs fed on other stars and abundant interstellar gas, they began to spin very rapidly. Once spinning quickly enough, the GEODEs’ mutual repulsion caused most of them to ‘socially distance’ into regions that would eventually become the empty voids between present-day galaxies.
This study supports the position that GEODEs can solve the dark energy problem while remaining in harmony with different observations across vast distances. GEODEs stay away from present-day galaxies, so they do not disrupt delicate star pairs counted within the Milky Way. The number of ancient GEODEs required to solve the dark energy problem is consistent with the number of ancient stars. GEODEs do not disrupt the measured distribution of galaxies in space because they separate away from luminous matter before it forms present-day galaxies. Finally, GEODEs do not directly affect the gentle ripples in the afterglow of the Big Bang, because they are born from dead stars hundreds of millions of years after the release of this cosmic background radiation.
The researchers were cautiously optimistic about their results. “It was thought that, without a direct detection of something different than a Kerr [Black Hole] signature from LIGO-Virgo [gravitational wave observatories], you’d never be able to tell that GEODEs existed,” said Farrah. Croker added, “but now that we have a clearer understanding of how Einstein’s equations link big and small, we’ve been able to make contact with data from many communities, and a coherent picture is beginning to form.”
According to Runburg, whose primary research interest is unrelated to GEODEs, “the most exciting consequence, for me, is that previously disconnected communities of researchers now have common ground. When different communities work together, the whole always becomes something greater than the sum of the parts.”
Universal structure of dark matter haloes over a mass range of 20 orders of magnitude
by Wang, J., Bose, S., Frenk, C.S. et al. in Nature
Cosmologists have zoomed in on the smallest clumps of dark matter in a virtual universe — which could help us to find the real thing in space.
An international team of researchers, including Durham University, UK, used supercomputers in Europe and China to focus on a typical region of a computer-generated universe.
The zoom they were able to achieve is the equivalent of being able to see a flea on the surface of the Moon. This allowed them to make detailed pictures and analyses of hundreds of virtual dark matter clumps (or haloes) from the very largest to the tiniest.
Dark matter particles can collide with dark matter anti-particles near the centre of haloes where, according to some theories, they are converted into a burst of energetic gamma-ray radiation.
Their findings, published in the journal Nature, could mean that these very small haloes could be identified in future observations by the radiation they are thought to give out.
Co-author Professor Carlos Frenk, Ogden Professor of Fundamental Physics at the Institute for Computational Cosmology, at Durham University, UK, said:
“By zooming in on these relatively tiny dark matter haloes we can calculate the amount of radiation expected to come from different sized haloes.
“Most of this radiation would be emitted by dark matter haloes too small to contain stars and future gamma-ray observatories might be able to detect these emissions, making these small objects individually or collectively ‘visible’.
“This would confirm the hypothesised nature of the dark matter, which may not be entirely dark after all.”
Most of the matter in the universe is dark (apart from the gamma radiation they emit in exceptional circumstances) and completely different in nature from the matter that makes up stars, planets and people.
The universe is made of approximately 27 per cent dark matter with the rest largely consisting of the equally mysterious dark energy. Normal matter, such as planets and stars, makes up a relatively small five per cent of the universe.
Galaxies formed and grew when gas cooled and condensed at the centre of enormous clumps of this dark matter — so-called dark matter haloes.
Astronomers can infer the structure of large dark matter haloes from the properties of the galaxies and gas within them.
The biggest haloes contain huge collections of hundreds of bright galaxies, called galaxy clusters, weighing a 1,000 trillion times more than our Sun.
However, scientists have no direct information about smaller dark matter haloes that are too tiny to contain a galaxy. These can only be studied by simulating the evolution of the Universe in a large supercomputer.
The smallest are thought to have the same mass as the Earth according to current popular scientific theories about dark matter that underlie the new research.
The simulations were carried out using the Cosmology Machine supercomputer, part of the DiRAC High-Performance Computing facility in Durham, funded by the Science and Technology Facilities Council (STFC), and computers at the Chinese Academy of Sciences.
By zooming-in on the virtual universe in such microscopic detail, the researchers were able to study the structure of dark matter haloes ranging in mass from that of the Earth to a big galaxy cluster.
Surprisingly, they found that haloes of all sizes have a very similar internal structure and are extremely dense at the centre, becoming increasingly spread out, with smaller clumps orbiting in their outer regions.
The researchers said that without a measure scale it was almost impossible to tell an image of a dark matter halo of a massive galaxy from one of a halo with a mass a fraction of the Sun’s.
Co-author Professor Simon White, of the Max Planck Institute of Astrophysics, Germany, said: “We expect that small dark matter haloes would be extremely numerous, containing a substantial fraction of all the dark matter in the universe, but they would remain mostly dark throughout cosmic history because stars and galaxies grow only in haloes more than a million times as massive as the Sun.
“Our research sheds light on these small haloes as we seek to learn more about what dark matter is and the role it plays in the evolution of the universe.”
GREGOR: Optics redesign and updates from 2018–2020
by Lucia Kleint, Thomas Berkefeld, Miguel Esteves, Thomas Sonner, Reiner Volkmer, Karin Gerber, Felix Krämer, Olivier Grassin, Svetlana Berdyugina in Astronomy & Astrophysics
GREGOR, the largest solar telescope in Europe, which is operated by a German consortium and located on Teide Observatory, Spain, has obtained unprecedented images of the fine-structure of the Sun. Following a major redesign of GREGOR’s optics, carried out by a team of scientists and engineers from the Leibniz Institute for Solar Physics (KIS), the Sun can be observed at a higher resolution than before from Europe.
The Sun is our star and has a profound influence on our planet, life, and civilization. By studying the magnetism on the Sun, we can understand its influence on Earth and minimize damage of satellites and technological infrastructure. The GREGOR telescope allows scientists to resolve details as small as 50 km on the Sun, which is a tiny fraction of the solar diameter of 1.4 million km. This is as if one saw a needle on a soccer field perfectly sharp from a distance of one kilometer.
“This was a very exciting, but also extremely challenging project. In only one year we completely redesigned the optics, mechanics, and electronics to achieve the best possible image quality.” said Dr. Lucia Kleint, who led the project and the German solar telescopes on Tenerife. A major technical breakthrough was achieved by the project team in March this year, during the lockdown, when they were stranded at the observatory and set up the optical laboratory from the ground up. Unfortunately, snow storms prevented solar observations. When Spain reopened in July, the team immediately flew back and obtained the highest resolution images of the Sun ever taken by a European telescope.
Prof. Dr. Svetlana Berdyugina, professor at the Albert-Ludwig University of Freiburg and Director of the Leibniz Institute for Solar Physics (KIS), is very happy about the outstanding results: “The project was rather risky because such telescope upgrades usually take years, but the great team work and meticulous planning have led to this success. Now we have a powerful instrument to solve puzzles on the Sun.” The new optics of the telescope will allow scientists to study magnetic fields, convection, turbulence, solar eruptions, and sunspots in great detail. First light images obtained in July 2020 reveal astonishing details of sunspot evolution and intricate structures in solar plasma.
Telescope optics are very complex systems of mirrors, lenses, glass cubes, filters and further optical elements. If only one element is not perfect, for example due to fabrication issues, the performance of the whole system suffers. This is similar to wearing glasses with the wrong prescription, resulting in a blurry vision. Unlike for glasses, it is however very challenging to detect which elements in a telescope may be causing issues. The GREGOR team found several of those issues and calculated optics models to solve them. For example, astigmatism is one of such optical problems, which affects 30–60% people’s vision, but also complex telescopes. At GREGOR this was corrected by replacing two elements with so-called off-axis parabolic mirrors, which had to be polished to 6 nm precision, about 1/10000 of the diameter of a hair. Combined with several further enhancements the redesign led to the sharp vision of the telescope.
European researchers have access to observations with the GREGOR telescope through national programs and a program funded by the European commission. New scientific observations are starting in September 2020.
Albert-Ludwig University Freiburg founded in 1457 offers undergraduate and graduate studies in all important disciplines today. The Leibniz Institute for Solar Physics (KIS) located in Freiburg is a public foundation and a member of the Leibniz Association. It carries out fundamental research on the Sun and other stars.
A measure of the size of the magnetospheric accretion region in TW Hydrae
by GRAVITY Collaboration in Nature
A team including researchers from the Institute for Astrophysics of the University of Cologne has for the first time directly observed the columns of matter that build up newborn stars. This was observed in the young star TW Hydrae system located approximately 163 light years from Earth. This result was obtained with the Very Large Telescope Interferometer (VLTI) and its GRAVITY instrument of the European Southern Observatory (ESO) in Chile. The article ‘A measure of the size of the magnetospheric accretion region in TW Hydrae’ has been published in a recent issue of Nature.
The formation of stars in the Galaxy involves processes in which primordial matter such as gas and dust present in the giant molecular clouds is rapidly aggregated via gravity to form a protostar. This ‘accretion’ of gas occurs through the disk that forms around the newborn star and represents the major mechanism of supply of material to the growing central baby star. These so-called protoplanetary disks are one of the key ingredients to explain the formation of very diverse exoplanets that are to date frequently discovered orbiting our closest neighbours.
Based on theoretical and observational evidence, many scenarios were hypothesized to describe the mechanism of interaction between the star and the parent circumstellar disk, like for instance the funnelling and accretion of host gas onto the central star along the local magnetic field. But this could never be directly observed and proven so far with any telescope. The main reason is that the level of details of the image — astronomers talk about angular resolution — necessary to observe what happens very close to the star was simply out of reach. For comparison, detecting these events would be like discerning a small one-cubic meter box on the surface of the Moon. With a normal telescope, this is not possible. However, with an interferometer like the VLTI in Chile and its instrument GRAVITY, which delivers unprecedented angular resolution in the infrared, such a precise observation has now become possible. An interferometer collects and combines the light from different telescopes a few hundred meters apart, which provides the same level of accuracy as a hypothetical giant telescope with a comparable diameter.
With the contribution of members of Cologne’s Institute for Astrophysics, astrophysicists from several European institutions exploited the GRAVITY instrument at the VLTI to probe the closest regions around the young solar analog TW Hydrae, which is thought to be the most representative example of what our Sun may have looked like at the time of its formation, more than 5 billion years ago. By measuring very precisely the typical angular size of the very inner gaseous regions — using a particular infrared atomic transition of the hot hydrogen gas — the scientists were able to directly prove that the hot gas emission was indeed resulting from magnetospheric accretion taking place very close to the stellar surface. ‘This is an important milestone in our attempt to confirm the mechanisms at work in the field of star formation’, said Professor Lucas Labadie, co-author of the paper. ‘We now want to extend such exploration to other young stars of different nature to understand how the evolution of the circumstellar disk, the birthplace of planets, goes.’
The team is part of the GRAVITY collaboration, named after the instrument that was co-developed by the University of Cologne and which combines interferometrically the four large 8-m telescopes of ESO in Chile. The team members include Lucas Labadie, Rebekka Grellmann, Andreas Eckart, Matthew Horrobin, Christian Straubmeier and Michael Wiest. ‘This result illustrates what is the unique potential of interferometry at the VLTI’, added Dr Christian Straubmeier, team member and co-investigator of the GRAVITY instrument in Cologne. ‘This is why we decided to look ahead and develop the upgrade GRAVITY+ in the hope of being able to observe and image even fainter objects than what GRAVITY currently does.’
Dust mitigation technology for lunar exploration utilizing an electron beam
by B. Farr, X. Wang, J. Goree, I. Hahn, U. Israelsson, M. Horányi in Acta Astronautica
A team led by the University of Colorado Boulder is pioneering a new solution to the problem of spring cleaning on the moon: Why not zap away the grime using a beam of electrons?
The research, published recently in the journal Acta Astronautica, marks the latest to explore a persistent, and perhaps surprising, hiccup in humanity’s dreams of colonizing the moon: dust. Astronauts walking or driving over the lunar surface kick up huge quantities of this fine material, also called regolith.
“It’s really annoying,” said Xu Wang, a research associate in the Laboratory for Atmospheric and Space Physics (LASP) at CU Boulder. “Lunar dust sticks to all kinds of surfaces — spacesuits, solar panels, helmets — and it can damage equipment.”
So he and his colleagues developed a possible fix — one that makes use of an electron beam, a device that shoots out a concentrated (and safe) stream of negatively-charged, low-energy particles. In the new study, the team aimed such a tool at a range of dirty surfaces inside of a vacuum chamber. And, they discovered, the dust just flew away.
“It literally jumps off,” said lead author Benjamin Farr, who completed the work as an undergraduate student in physics at CU Boulder.
The researchers still have a long way to go before real-life astronauts will be able to use the technology to do their daily tidying up. But, Farr said, the team’s early findings suggest that electron-beam dustbusters could be a fixture of moon bases in the not-too-distant future.
Spent gunpowder
The news may be music to the ears of many Apollo-era astronauts. Several of these space pioneers complained about moon dust, which often resists attempts at cleaning even after vigorous brushing. Harrison “Jack” Schmitt, who visited the moon as a member of Apollo 17 in 1972, developed an allergic reaction to the material and has said that it smelled like “spent gunpowder.”
The problem with lunar dust, Wang explained, is that it isn’t anything like the stuff that builds up on bookshelves on Earth. Moon dust is constantly bathed in radiation from the sun, a bombardment that gives the material an electric charge. That charge, in turn, makes the dust extra sticky, almost like a sock that’s just come out of the drier. It also has a distinct structure.
“Lunar dust is very jagged and abrasive, like broken shards of glass,” Wang said.
The question facing his group was then: How do you unstick this naturally clingy substance?
Electron beams offered a promising solution. According to a theory developed from recent scientific studies of how dust naturally lofts on the lunar surface, such a device could turn the electric charges on particles of dust into a weapon against them. If you hit a layer dust with a stream of electrons, Wang said, that dusty surface will collect additional negative charges. Pack enough charges into the spaces in between the particles, and they may begin to push each other away — much like magnets do when the wrong ends are forced together.
“The charges become so large that they repel each other, and then dust ejects off of the surface,” Wang said.
Electron showers
To test the idea, he and his colleagues loaded a vacuum chamber with various materials coated in a NASA-manufactured “lunar simulant” designed to resemble moon dust.
And sure enough, after aiming an electron beam at those particles, the dust poured off, usually in just a few minutes. The trick worked on a wide range of surfaces, too, including spacesuit fabric and glass. This new technology aims at cleaning the finest dust particles, which are difficult to remove using brushes, Wang said. The method was able to clean dusty surfaces by an average of about 75–85%.
“It worked pretty well, but not well enough that we’re done,” Farr said.
The researchers are currently experimenting with new ways to increase the cleaning power of their electron beam.
But study coauthor Mihály Horányi, a professor in LASP and the Department of Physics at CU Boulder, said that the technology has real potential. NASA has experimented with other strategies for shedding lunar dust, such as by embedding networks of electrodes into spacesuits. An electron beam, however, might be a lot cheaper and easier to roll out.
Horányi imagines that one day, lunar astronauts could simply leave their spacesuits hanging up in a special room, or even outside their habitats, and clean them after spending a long day kicking up dust outside. The electrons would do the rest.
“You could just walk into an electron beam shower to remove fine dust,” he said.
Other coauthors on the new research include John Goree of the University of Iowa and Inseob Hahn and Ulf Israelsson of the Jet Propulsion Laboratory.
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