вторник, 21 августа 2018 г.

Why Bennu? 10 Reasons

After traveling for two years and billions of kilometers from Earth, the OSIRIS-REx probe is only a few months away from its destination: the intriguing asteroid Bennu. When it arrives in December, OSIRIS-REx will embark on a nearly two-year investigation of this clump of rock, mapping its terrain and finding a safe and fruitful site from which to collect a sample.


The spacecraft will briefly touch Bennu’s surface around July 2020 to collect at least 60 grams (equal to about 30 sugar packets) of dirt and rocks. It might collect as much as 2,000 grams, which would be the largest sample by far gathered from a space object since the Apollo Moon landings. The spacecraft will then pack the sample into a capsule and travel back to Earth, dropping the capsule into Utah’s west desert in 2023, where scientists will be waiting to collect it.


This years-long quest for knowledge thrusts Bennu into the center of one of the most ambitious space missions ever attempted. But the humble rock is but one of about 780,000 known asteroids in our solar system. So why did scientists pick Bennu for this momentous investigation? Here are 10 reasons:


1. It’s close to Earth


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Unlike most other asteroids that circle the Sun in the asteroid belt between Mars and Jupiter, Bennu’s orbit is close in proximity to Earth’s, even crossing it. The asteroid makes its closest approach to Earth every 6 years. It also circles the Sun nearly in the same plane as Earth, which made it somewhat easier to achieve the high-energy task of launching the spacecraft out of Earth’s plane and into Bennu’s. Still, the launch required considerable power, so OSIRIS-REx used Earth’s gravity to boost itself into Bennu’s orbital plane when it passed our planet in September 2017.


2. It’s the right size


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Asteroids spin on their axes just like Earth does. Small ones, with diameters of 200 meters or less, often spin very fast, up to a few revolutions per minute. This rapid spinning makes it difficult for a spacecraft to match an asteroid’s velocity in order to touch down and collect samples. Even worse, the quick spinning has flung loose rocks and soil, material known as “regolith” — the stuff OSIRIS-REx is looking to collect — off the surfaces of small asteroids. Bennu’s size, in contrast, makes it approachable and rich in regolith. It has a diameter of 492 meters, which is a bit larger than the height of the Empire State Building in New York City, and rotating once every 4.3 hours.


3. It’s really old


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Bennu is a leftover fragment from the tumultuous formation of the solar system. Some of the mineral fragments inside Bennu could be older than the solar system. These microscopic grains of dust could be the same ones that spewed from dying stars and eventually coalesced to make the Sun and its planets nearly 4.6 billion years ago. But pieces of asteroids, called meteorites, have been falling to Earth’s surface since the planet formed. So why don’t scientists just study those old space rocks? Because astronomers can’t tell (with very few exceptions) what kind of objects these meteorites came from, which is important context. Furthermore, these stones, that survive the violent, fiery decent to our planet’s surface, get contaminated when they land in the dirt, sand, or snow. Some even get hammered by the elements, like rain and snow, for hundreds or thousands of years. Such events change the chemistry of meteorites, obscuring their ancient records.


4. It’s well preserved


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Bennu, on the other hand, is a time capsule from the early solar system, having been preserved in the vacuum of space. Although scientists think it broke off a larger asteroid in the asteroid belt in a catastrophic collision between about 1 and 2 billion years ago, and hurtled through space until it got locked into an orbit near Earth’s, they don’t expect that these events significantly altered it.


5. It might contain clues to the origin of life


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Analyzing a sample from Bennu will help planetary scientists better understand the role asteroids may have played in delivering life-forming compounds to Earth. We know from having studied Bennu through Earth- and space-based telescopes that it is a carbonaceous, or carbon-rich, asteroid. Carbon is the hinge upon which organic molecules hang. Bennu is likely rich in organic molecules, which are made of chains of carbon bonded with atoms of oxygen, hydrogen, and other elements in a chemical recipe that makes all known living things. Besides carbon, Bennu also might have another component important to life: water, which is trapped in the minerals that make up the asteroid.


6. It contains valuable materials


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Besides teaching us about our cosmic past, exploring Bennu close-up will help humans plan for the future. Asteroids are rich in natural resources, such as iron and aluminum, and precious metals, such as platinum. For this reason, some companies, and even countries, are building technologies that will one day allow us to extract those materials. More importantly, asteroids like Bennu are key to future, deep-space travel. If humans can learn how to extract the abundant hydrogen and oxygen from the water locked up in an asteroid’s minerals, they could make rocket fuel. Thus, asteroids could one day serve as fuel stations for robotic or human missions to Mars and beyond. Learning how to maneuver around an object like Bennu, and about its chemical and physical properties, will help future prospectors.


7. It will help us better understand other asteroids


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Astronomers have studied Bennu from Earth since it was discovered in 1999. As a result, they think they know a lot about the asteroid’s physical and chemical properties. Their knowledge is based not only on looking at the asteroid, but also studying meteorites found on Earth, and filling in gaps in observable knowledge with predictions derived from theoretical models. Thanks to the detailed information that will be gleaned from OSIRIS-REx, scientists now will be able to check whether their predictions about Bennu are correct. This work will help verify or refine telescopic observations and models that attempt to reveal the nature of other asteroids in our solar system.


8. It will help us better understand a quirky solar force …


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Astronomers have calculated that Bennu’s orbit has drifted about 280 meters (0.18 miles) per year toward the Sun since it was discovered. This could be because of a phenomenon called the Yarkovsky effect, a process whereby sunlight warms one side of a small, dark asteroid and then radiates as heat off the asteroid as it rotates. The heat energy thrusts an asteroid either away from the Sun, if it has a prograde spin like Earth, which means it spins in the same direction as its orbit, or toward the Sun in the case of Bennu, which spins in the opposite direction of its orbit. OSIRIS-REx will measure the Yarkovsky effect from close-up to help scientists predict the movement of Bennu and other asteroids. Already, measurements of how this force impacted Bennu over time have revealed that it likely pushed it to our corner of the solar system from the asteroid belt.


9. … and to keep asteroids at bay


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One reason scientists are eager to predict the directions asteroids are drifting is to know when they’re coming too-close-for-comfort to Earth. By taking the Yarkovsky effect into account, they’ve estimated that Bennu could pass closer to Earth than the Moon is in 2135, and possibly even closer between 2175 and 2195. Although Bennu is unlikely to hit Earth at that time, our descendants can use the data from OSIRIS-REx to determine how best to deflect any threatening asteroids that are found, perhaps even by using the Yarkovsky effect to their advantage.


10. It’s a gift that will keep on giving


Samples of Bennu will return to Earth on September 24, 2023. OSIRIS-REx scientists will study a quarter of the regolith. The rest will be made available to scientists around the globe, and also saved for those not yet born, using techniques not yet invented, to answer questions not yet asked.


Read the web version of this week’s “Solar System: 10 Things to Know” article HERE.


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Students Experience the Power of Controlling Satellites in Space


ISS – SPHERES Mission patch.


Aug. 21, 2018


Earth-bound electronic games can’t compete with actually controlling a squadron of miniature robotic satellites in space. Through the Synchronized Position Hold, Engage, Reorient Experimental Satellites- Zero Robotics (SPHERES-Zero-Robotics) challenge, students compete to experience this power and excitement.



Image above: Russian cosmonaut Andrei Borisenko and NASA astronaut Peggy Whitson help perform the finals of the Synchronized Position Hold, Engage, Reorient, Experimental Satellites (SPHERES) Zero Robotics competition on the station. Image Credit: NASA.


Using a trio of autonomous satellites on the International Space Station, SPHERES-Zero-Robotics gives students the chance to develop software to guide robots through a virtual obstacle course aboard the space station. High school students write algorithms for specific tasks for the volleyball-sized robotic satellites, and run them as virtual simulations on a computer and under realistic microgravity conditions in elimination rounds. Finalists have their programs sent to the station, where an astronaut loads them into the SPHERES satellites and monitors their movements to help determine a winning student team. The exciting final competition streams live at the European Space Agency (ESA) technology center in the Netherlands, European Space Research and Technology Center (ESTEC), and Massachusetts Institute of Technology.


The competition involves NASA, MIT, ESA and the Russian Space Agency (ROSCOSMOS). It is open to teams from high schools around the world. In the U.S., many states use the competition to introduce young people to the practical applications of science, technology, engineering, and math (STEM).


The satellites have their own power, propulsion, computers and navigation, using 12 small thrusters to rotate and move around. They have been used inside the station since 2006 to test autonomous rendezvous and docking maneuvers and liquid slosh in microgravity.



Image above: Using a trio of autonomous satellites on the International Space Station, SPHERES gives students the chance to develop software to guide robots through a virtual obstacle course onboard the space station. Image Credit: NASA.


The competition is about more than feeding the satellites sets of commands; local experts help students build critical engineering skills such as problem solving, design thought process, operations training and teamwork—all skills that could lead to the development of software to enable autonomous robots to accomplish complex tasks in the future. Their results could lead to important advances for satellite servicing and vehicle assembly in orbit.


“Zero Robotics aims to inspire the next generation of scientists and engineers,” said Jeff Hoffman, veteran NASA astronaut and SPHERES principal investigator with MIT. “We wanted to provide students with the chance to interact directly with NASA and space. This competition encourages them to develop their math and science skills as well as an appreciation for the physics involved in space engineering.”


The program helps teachers connect with students, said Shannon Bales, a STEM lead with the Alabama Afterschool Community Network, an initiative to promote positive development and learning when students are out of school. Bales said it is exciting for students to see the results of their hard work culminate with an astronaut running their programming live on the space station.



Image above: NASA astronaut Barry Wilmore conducts a dry run of the SPHERES Zero Robotics competition. Image Credit: NASA.


“It’s so rewarding for them and for us,” Bales said. “Last year, a parent told me their son really came out of his shell after Zero Robotics and how much he loved working on it. The program is making a difference in students’ lives and that’s why we do it.” The students have fun, exercise creativity, and learn valuable problem-solving skills, and feel like they are contributing to NASA research, she added.


The SPHERES-Zero-Robotics program provides students a unique and valuable opportunity to engage in space research and see the possibility of being a part of NASA’s mission to explore. No mere game can compete with that.


Related links:


SPHERES-Zero-Robotics: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=679


Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html


International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html


Images (mentioned), Text, Credits: NASA/Michael Johnson/JSC/International Space Station Program Science Office/Bill Hubscher/Melissa Gaskill.


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Wulfenite | #Geology #GeologyPage #Mineral Location: Jianshan…


Wulfenite | #Geology #GeologyPage #Mineral


Location: Jianshan Mine, Ruoqiang Co., Xinjiang Autonomous Region, China


Size: 8.5 x 7.0 x 2.5 cm (small-cabinet)


Photo Copyright © Weinrich Minerals


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Rhodochrosite | #Geology #GeologyPage #Mineral Location: Sweet…


Rhodochrosite | #Geology #GeologyPage #Mineral


Location: Sweet Home Mine, Park Co., Colorado, USA

Size: 3.0 x 2.5 x 2.0 cm (thumbnail)


Photo Copyright © Weinrich Minerals


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Tract Down Lining our insides, epithelial tissues are a sort…


Tract Down


Lining our insides, epithelial tissues are a sort of skin stretching across our organs, each a mosaic of different cells and chemicals. In the conducting airways of the respiratory tract – where air is warmed and cleaned and as we breathe – scientists found a ‘new’ type of cell poking out of the epithelium. These pulmonary ionocytes are growing up like tulips (although 10,000 times smaller) in the upper respiratory tract of mice. Humans have them, too. The mysterious cells appear to ‘switch on’, or express, high levels of CFTR – a gene mutated in cystic fibrosis, suggesting an important role for these cells in future treatments. This discovery is part of a larger census of cells in healthy and damaged airways – useful information for future studies looking for changes during disease or ageing.


Written by John Ankers



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Comet 21P passes through Cassiopeia

Comet 21P/Giacobini-Zinner has been well placed throughout June and July for northern hemisphere observers as the icy ball of dust passed through the high altitude, summer constellations of Cygnus and Cepheus. Now the comet (which has now reached magnitude 9) heads in to Cassiopeia through the first half of August followed by Camelopardalis. Between the 16-19 August, the comet will pass approximately 2° from the Heart and Soul nebula’s (IC1805 and IC1848) which would make for a decent widefield photographic opportunity.


The Northbolt Branch Observatories released this time-lapse video of 21P on August 05, 2018. With 37 days to go until perihelion on 10/11 September, the comet is expected to reach magnitude 7. Although this is just outside the realms of naked eye visibility for most, it will make for a good binocular or telescope observing.




Courtesy of Northbolt Branch Observatories



Finder Charts










01-22 August 2018


Comet 21P Finder Chart 3  Comet 21P Finder Chart 2

Click images to enlarge



 


Comet 21P Live Position Data


The post Comet 21P passes through Cassiopeia appeared first on Comet Watch.


Carn Liath Iron Age Broch, A9 Road to Wick, The Highlands, Scotland, 20.8.18.A beautiful...











Carn Liath Iron Age Broch, A9 Road to Wick, The Highlands, Scotland, 20.8.18.


A beautiful Iron Age coastal defensive structure for a community complete with a cell and multiple floors.


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2018 August 21 Glowing Elements in the Soul Nebula Image Credit…


2018 August 21


Glowing Elements in the Soul Nebula
Image Credit & Copyright: Jesús M.Vargas & Maritxu Poyal


Explanation: Stars are forming in the Soul of the Queen of Aethopia. More specifically, a large star forming region called the Soul Nebula (IC 1898) can be found in the direction of the constellation Cassiopeia, who Greek mythology credits as the vain wife of a King who long ago ruled lands surrounding the upper Nile river. The Soul Nebula houses several open clusters of stars, a large radio source known as W5, and huge evacuated bubbles formed by the winds of young massive stars. Located about 6,500 light years away, the Soul Nebula spans about 100 light years and is usually imaged next to its celestial neighbor the Heart Nebula (IC 1805). The featured image is a composite of three exposures in different colors: red as emitted by hydrogen gas, yellow as emitted by sulfur, and blue as emitted by oxygen.


∞ Source: apod.nasa.gov/apod/ap180821.html


Tealing Earth House Photoset 1, nr. Dundee, Scotland,…








Tealing Earth House Photoset 1, nr. Dundee, Scotland, 20.8.18.


A subterranean chamber built in the first or second century CE for storage or defence.


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Bricks from Moon dust


ESA – European Space Agency patch.


20 August 2018


Lunar masonry starts on Earth. European researchers are working with Moon dust simulants that could one day allow astronauts to build habitats on our natural satellite and pave the way for human space exploration.


The surface of the Moon is covered in grey, fine, rough dust. This powdery soil is everywhere – an indigenous source that could become the ideal material for brickwork. You can crush it, burn it and compress it.



 1.5 tonne building block

“Moon bricks will be made of dust,” says Aidan Cowley, ESA’s science advisor with a wealth of experience in dealing with lunar soil. “You can create solid blocks out of it to build roads and launch pads, or habitats that protect your astronauts from the harsh lunar environment.”


European teams see Moon dust as the starting point to building up a permanent lunar outpost and breaking explorers’ reliance on Earth supplies.



Spaceship EAC – studying lunar regolith

Lunar dust “made in Europe”


Lunar soil is a basaltic material made up of silicates, a common feature in planetary bodies with volcanism.


“The Moon and Earth share a common geological history, and it is not difficult to find material similar to that found on the Moon in the remnants of lava flows,” explains Aidan.


Around 45 million years ago, eruptions took place in a region around Cologne, in Germany. Researches from the nearby European Astronaut Centre (EAC) found that the volcanic powder in the area is a good match with what lunar dust is made of. And there is plenty of it.



3D-printed lunar base design

The lunar dust substitute ‘made in Europe’ already has a name: EAC-1.


The Spaceship EAC initiative is working with EAC-1 to prepare technologies and concepts for future lunar exploration.


“One of the great things about the lunar soil is that 40% of it is made up of oxygen,” adds Aidan. One Spaceship EAC project studies how to crack the oxygen in it and use it to help astronauts extend their stay on the Moon.


Moon’s magnetic call


Bombarded with constant radiation, lunar dust is electrically charged. This can cause particles to lift off the surface. Erin Tranfield, a member of ESA’s lunar dust topical team, insists that we still need to fully understand its electrostatic nature.


Scientists do not yet know its chemical charge, nor the consequences for building purposes. Trying to recreate the behaviour of lunar dust in a radiation environment, Erin ground the surface of lunar simulants. She managed to activate the particles, but erased the properties of the surface.



Lunar attraction (Eclipse of 27 July, 2018)

“This gives us one more reason to go back to the Moon. We need pristine samples from the surface exposed to the radiation environment,” says Erin. For this biologist who dreams of being the first woman on the Moon, a few sealed grams of lunar dust would be enough.


Related links:


Spaceship EAC initiative: http://www.esa.int/About_Us/EAC/European_researchers_invited_to_board_Spaceship_EAC


European vision for space exploration: http://www.esa.int/Our_Activities/Human_Spaceflight/A_new_European_vision_for_space_exploration


Exploration of the Moon: http://exploration.esa.int/moon/


Lunar exploration interactive guide: http://lunarexploration.esa.int/#/intro


Images, Video, Text, Credits: ESA/Foster + Partners/CESAR–M.Castillo.


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Tealing Earth House Photoset 2, nr. Dundee, Scotland, 20.8.18.









Tealing Earth House Photoset 2, nr. Dundee, Scotland, 20.8.18.


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Infant exoplanet weighed by Hipparcos and Gaia


ESA – Gaia Mission patch.


20 August 2018


The mass of a very young exoplanet has been revealed for the first time using data from ESA’s star mapping spacecraft Gaia and its predecessor, the quarter-century retired Hipparcos satellite.


Astronomers Ignas Snellen and Anthony Brown from Leiden University, the Netherlands, deduced the mass of the planet Beta Pictoris b from the motion of its host star over a long period of time as captured by both Gaia and Hipparcos.


The planet is a gas giant similar to Jupiter but, according to the new estimate, is 9 to 13 times more massive. It orbits the star Beta Pictoris, the second brightest star in the constellation Pictor.



Beta Pictoris system

The planet was only discovered in 2008 in images captured by the Very Large Telescope at the European Southern Observatory in Chile. Both the planet and the star are only about 20 million years old – roughly 225 times younger than the Solar System. Its young age makes the system intriguing but also difficult to study using conventional methods.


“In the Beta Pictoris system, the planet has essentially just formed,” says Ignas. “Therefore we can get a picture of how planets form and how they behave in the early stages of their evolution. On the other hand, the star is very hot, rotates fast, and it pulsates.”


This behaviour makes it difficult for astronomers to accurately measure the star’s radial velocity – the speed at which it appears to periodically move towards and away from the Earth. Tiny changes in the radial velocity of a star, caused by the gravitational pull of planets in its vicinity, are commonly used to estimate masses of exoplanets. But this method mainly works for systems that have already gone through the fiery early stages of their evolution.


In the case of Beta Pictoris b, upper limits of the planet’s mass range had been arrived at before using the radial velocity method. To obtain a better estimate, the astronomers used a different method, taking advantage of Hipparcos’ and Gaia’s measurements that reveal the precise position and motion of the planet’s host star in the sky over time.



Astrometric measurements to detect exoplanets

“The star moves for different reasons,” says Ignas. “First, the star circles around the centre of the Milky Way, just as the Sun does. That appears from the Earth as a linear motion projected on the sky. We call it proper motion. And then there is the parallax effect, which is caused by the Earth orbiting around the Sun. Because of this, over the year, we see the star from slightly different angles.”


And then there is something that the astronomers describe as ‘tiny wobbles’ in the trajectory of the star across the sky – minuscule deviations from the expected course caused by the gravitational pull of the planet in the star’s orbit. This is the same wobble that can be measured via changes in the radial velocity, but along a different direction – on the plane of the sky, rather than along the line of sight.


“We are looking at the deviation from what you expect if there was no planet and then we measure the mass of the planet from the significance of this deviation,” says Anthony. “The more massive the planet, the more significant the deviation.”



ESA’s Gaia

To be able to make such an assessment, astronomers need to observe the trajectory of the star for a long period of time to properly understand the proper motion and the parallax effect.


The Gaia mission, designed to observe more than one billion stars in our Galaxy, will eventually be able to provide information about a large amount of exoplanets. In the 22 months of observations included in Gaia’s second data release, published in April, the satellite has recorded the star Beta Pictoris about thirty times. That, however, is not enough.


“Gaia will find thousands of exoplanets, that’s still on our to-do list,” says Timo Prusti, ESA’s Gaia project scientist. “The reason that the exoplanets can be expected only late in the mission is the fact that to measure the tiny wobble that the exoplanets are causing, we need to trace the position of stars for several years.”



ESA’s Hipparcos

Combining the Gaia measurements with those from ESA’s Hipparcos mission, which observed Beta Pictoris 111 times between 1990 and 1993, enabled Ignas and Anthony to get their result much faster. This led to the first successful estimate of a young planet’s mass using astrometric measurements.


“By combining data from Hipparcos and Gaia, which have a time difference of about 25 years, you get a very long term proper motion,” says Anthony.


“This proper motion also contains the component caused by the orbiting planet. Hipparcos on its own would not have been able to find this planet because it would look like a perfectly normal single star unless we had measured it for a much longer time.


“Now, by combining Gaia and Hipparcos and looking at the difference in the long term and the short term proper motion, we can see the effect of the planet on the star.”


The result represents an important step towards better understanding the processes involved in planet formation, and anticipates the exciting exoplanet discoveries that will be unleashed by Gaia’s future data releases.


Notes for Editors:


“The mass of the young planet Beta Pictoris b through the astrometric motion of its host star,” by I. Snellen and A. Brown is published in Nature Astronomy, 20 August 2018: https://www.nature.com/articles/s41550-018-0561-6


Related links:


Gaia: http://www.esa.int/Our_Activities/Space_Science/Gaia


Vodcast: Charting the Galaxy – from Hipparcos to Gaia: http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=45772&fattributeid=885


The billion-pixel camera: http://www.esa.int/Our_Activities/Space_Science/Exploring_space/The_billion-pixel_camera


ESA/ESO/A-M. Lagrange et al.


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