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  • richardmitnick 9:37 pm on May 20, 2017 Permalink | Reply
    Tags: , , , Detecting sodium, , Earth's Mesosphere, Heliophysics Technology and Instrument Development for Science, Lidar instruments, NASA Goddard, World’s first space-based sodium lidar to study Earth’s poorly understood mesosphere   

    From Goddard: “NASA Aims to Create First-Ever Space-Based Sodium Lidar to Study Poorly Understood Mesosphere” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    [Dedicated to J.L.T. in the hope that he will keep Goddard and JHUAPL in view for his future.]

    May 16, 2017
    Lori Keesey
    NASA’s Goddard Space Flight Center

    1
    Mike Krainak (left) and Diego Janches recently won NASA follow-on funding to advance a spaceborne sodium lidar needed to probe Earth’s poorly understood mesosphere. Credits: NASA/W. Hrybyk

    A team of NASA scientists and engineers now believes it can leverage recent advances in a greenhouse-detecting instrument to build the world’s first space-based sodium lidar to study Earth’s poorly understood mesosphere.

    Scientist Diego Janches and laser experts Mike Krainak and Tony Yu, all of whom work at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, are leading a research-and-development effort to further advance the sodium lidar, which the group plans to deploy on the International Space Station if it succeeds in proving its flightworthiness.

    NASA’s Center Innovation Fund and the Heliophysics Technology and Instrument Development for Science programs are now funding the instrument’s maturation. However, the concept traces its heritage in part to NASA’s past investments in promising lidar instruments, called Sounders, originally created to measure carbon dioxide and methane in Earth’s atmosphere.

    From its berth on the orbiting outpost, the instrument would illuminate the complex relationship between the chemistry and dynamics of the mesosphere that lies 40-100 miles above Earth’s surface — the region where Earth’s atmosphere meets the vacuum of space.

    Given the progress the researchers have made with the Earth-observing sounding instruments, coupled with Goddard’s legacy in laser technology, they are optimistic about the instrument’s ultimate success.

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    With NASA technology-development funding, a Goddard team of scientists and engineers will advance a sodium lidar instrument for use in space. This image shows the laboratory breadboard. Credits: NASA/W. Hrybyk

    The Big Leverage

    “What we’re doing is leveraging what we learned with the CO2 and Methane Sounders,” Krainak said. Both instruments have demonstrated in multiple aircraft campaigns that they accurately measure greenhouse gases using lidar.

    Lidar involves pulsing a laser light off Earth’s surface. Like all atmospheric gases, carbon dioxide and methane absorb the light in narrow wavelength bands. By tuning the laser across those absorption lines, scientists can detect and then analyze the level of gases in that vertical path. The more gas along the light’s path, the deeper the absorption lines.

    “The same principle applies here,” Janches said. “Instead of carbon dioxide and methane, we’re detecting sodium because of what it can tell us about the small-scale dynamics occurring in the mesosphere.”

    Sodium — the sixth most abundant element in Earth’s crust — is a useful tracer for characterizing the mesosphere. Though this atmospheric layer contains other granules of metals, including iron, magnesium, calcium, and potassium — all produced by the evaporation of extraterrestrial dust when it encounters Earth’s atmosphere — sodium is easiest to detect. Literally, a layer of sodium exists in the mesosphere.

    Because of its relative abundance, sodium provides higher-resolution data that can reveal more information about the small-scale dynamics occurring in the upper atmosphere. From this, scientists can learn more about how weather in the lower atmosphere influences the border between the atmosphere and space.

    The group has begun developing its instrument, which is electronically tuned to the 589-nanometer range, or yellow light. While in orbit, the lidar would rapidly pulse the light at the mesospheric layer, down one to three kilometers over a swath measuring four to eight kilometers in width.

    The light’s interaction with sodium particles would cause them to glow or resonate. By detecting the glow-back, the lidar’s onboard spectrometer would analyze the light to determine how much sodium resided in the mesosphere, its temperature, and the speed at which the particles were moving.

    Scientists have used sodium lidars in ground-based measurements for at least four decades, but they never have gathered measurements from space. As a result, the data is limited in time and space and does not offer a global picture of the dynamics. With a specially designed spaceborne sodium lidar, however, scientists would be able to illuminate specific areas, revealing the small-scale dynamics that currently are the biggest unknown, Janches said.

    The team will use NASA’s funding to fine-tune the technology that locks the lidar onto the sodium lines. “It’s like a guitar string,” Krainak explained. “If you want a certain tone, you need to lock down the string at a particular length. It’s the same thing with the laser cavity length.”

    The team also plans to demonstrate an environmentally tested engineering test unit of the laser, thereby improving its technology-readiness level to six, which means that the technology is ready for flight development.

    “We’ve made significant progress on the laser,” Krainak said. “If we win, we could be the first space-based sodium laser spectrometer for remote sensing.”

    For more technology news, go to https://gsfctechnology.gsfc.nasa.gov/newsletter/Current.pdf

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.


    NASA/Goddard Campus

     
  • richardmitnick 12:31 pm on May 18, 2017 Permalink | Reply
    Tags: , , , , NASA Goddard, NASA Mission Uncovers Dance of Electrons in Spac,   

    From Goddard: “NASA Mission Uncovers Dance of Electrons in Space” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    May 18, 2017
    Mara Johnson-Groh
    mara.johnson-groh@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    Media contact: Lina Tran
    kathalina.k.tran@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

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    From video, via phys.org

    You can’t see them, but swarms of electrons are buzzing through the magnetic environment — the magnetosphere — around Earth. The electrons spiral and dive around the planet in a complex dance dictated by the magnetic and electric fields. When they penetrate into the magnetosphere close enough to Earth, the high-energy electrons can damage satellites in orbit and trigger auroras. Scientists with NASA’s Magnetospheric Multiscale, or MMS, mission study the electrons’ dynamics to better understand their behavior. A new study, published in Journal of Geophysical Research revealed a bizarre new type of motion exhibited by these electrons.

    Electrons in a strong magnetic field usually exhibit a simple behavior: They spin tight spirals along the magnetic field. In a weaker field region, where the direction of the magnetic field reverses, the electrons go free style — bouncing and wagging back and forth in a type of movement called Speiser motion. New MMS results show for the first time what happens in an intermediate strength field. Then these electrons dance a hybrid, meandering motion — spiraling and bouncing about before being ejected from the region. This motion takes away some of the field’s energy and it plays a key role in magnetic reconnection, a dynamic process, which can explosively release large amounts of stored magnetic energy.

    NASA/MMS

    NASA MMS satellites in space


    With no guide field to confine them, electrons (yellow) wiggle back in forth. The electron’s increasing speed is shown by warmer color tracks. Credits: NASA’s Goddard Space Flight Center/Tom Bridgman

    “MMS is showing us the fascinating reality of magnetic reconnection happening out there,” said Li-Jen Chen, lead author of the study and MMS scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

    As MMS flew around Earth, it passed through an area of a moderate strength magnetic field where electric currents run in the same direction as the magnetic field. Such areas are known as intermediate guide fields. While inside the region, the instruments recorded a curious interaction of electrons with the current sheet, the thin layer through which the current travels. As the incoming particles encountered the region, they started gyrating in spirals along the guide field, like they do in a strong magnetic field, but in larger spirals. The MMS observations also saw signatures of the particles gaining energy from the electric field. Before long, the accelerated particles escaped the current sheet, forming high-speed jets. In the process, they took away some of the field’s energy, causing it to gradually weaken.


    In an intermediate strength magnetic guide field, the electrons spiral along the field, gaining energy until they are ejected from the reconnection layer. Credits: NASA’s Goddard Space Flight Center/Tom Bridgman

    The magnetic field environment where the electrons’ motions were observed was uniquely created by magnetic reconnection, which caused the current sheet to be tightly confined by bunched-up magnetic fields. The new results help the scientists better understand the role of electrons in reconnection and how magnetic fields lose energy.

    MMS measures the electric and magnetic fields it flies through, and counts electrons and ions to measure their energies and directions of motion. With four spacecraft flying in a compact, pyramid formation, MMS is able to see the fields and particles in three dimensions and look at small-scale particle dynamics, in a way never before achieved.

    “The time resolution of MMS is one hundred times faster than previous missions,” said Tom Moore, senior project scientist for MMS at NASA’s Goddard Space Flight Center. “That means we can finally see what’s going on in such narrow layers and will be able to better predict how fast reconnection occurs in various circumstances.”

    Understanding the speed of reconnection is essential for predicting the intensity of the explosive energy release. Reconnection is an important energy release process across the universe and is thought to be responsible for some shock waves and cosmic rays. Solar flares on the sun, which can trigger space weather, are also caused by magnetic reconnection.

    With two years under its belt, MMS has been revealing new and surprising phenomena near Earth. These discoveries enable us to better understand Earth’s dynamic space environment and how it affects our satellites and technology.

    MMS is now heading to a new orbit which will take it through magnetic reconnection areas on the side of Earth farther from the sun. In this region, the guide field is typically weaker, so MMS may see more of these types of electron dynamics.

    Related Links

    Learn more about NASA’s MMS mission

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.


    NASA/Goddard Campus

     
  • richardmitnick 1:33 pm on May 9, 2017 Permalink | Reply
    Tags: Blobs and Bubbles, , Dellingr, GRIDS-Gridded Retarding Ion Drift Sensor, INMS-Goddard-developed Ion-Neutral Mass Spectrometer, NASA Goddard, PetitSat-Plasma Enhancements in The Ionosphere-Thermosphere Satellite   

    From Goddard: “NASA Team Pursues Blobs and Bubbles with New PetitSat Mission” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    May 9, 2017
    Lori Keesey
    NASA’s Goddard Space Flight Center

    Figuring out how plasma bubbles and blobs affect one another and ultimately the transmission of communications, GPS, and radar signals in Earth’s ionosphere will be the job of a recently selected CubeSat mission.

    A team of NASA scientists and engineers, led by Jeffrey Klenzing and Sarah Jones, scientists at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, recently won NASA funding to build the Plasma Enhancements in The Ionosphere-Thermosphere Satellite. The mission, also known as petitSat, is a precursor to a possible Explorer-class mission and leverages several R&D-supported technologies, including the satellite bus itself.

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    The Goddard-led petitSat team is basing its mission on a 6U CubeSat — Dellingr. Goddard engineers developed this small satellite to show that CubeSats could be both reliable and cost effective also while gathering compelling scientific data. The black-colored device at the top of the Dellingr 3-D model depicts the Ion-Neutral Mass Spectrometer that also is flying on petitSat.
    Credits: NASA/W. Hrybyk

    When it launches from the International Space Station in 2021, the mission will study density irregularities in the mid and low-latitude ionosphere, which occupies a tiny fraction of the atmosphere and is basically an ionized layer coexisting with the thermosphere roughly 50 to 250 miles above Earth’s surface.

    The ionosphere is a plasma, an ionized gas consisting of positive ions and free electrons. It is important to long-distance radio communication because it reflects radio waves back to Earth. Consequently, any perturbations in the density of the plasma interfere with GPS and radar signals.

    These perturbations or irregularities come in the form of ionospheric depletions or bubbles, structures that contain fewer electrons, and enhancements or blobs that contain a greater number of electrons. “All these irregularities can distort the transmission of radio waves,” said Klenzing, the mission principal investigator.

    Blobs and Bubbles: A Different Story

    Previous studies of the blobs indicate that they can be the direct result of bubbles forming near the geomagnetic equator, Klenzing said. Other observations, however, tell a different story. The blobs can be observed in regions where bubbles do not extend and can form when bubbles do not.

    They suggest that multiple mechanisms are at play, including fast-traveling waves coming from the thermosphere, a warm neutral atmospheric layer where most of the ionosphere resides. In fact, these wave-like thermospheric structures create waves in the ionosphere through ion-neutral drag — a phenomenon called Medium-Scale Traveling Ionospheric Disturbances, or MSTIDs. The resulting MSTIDs create electric fields that can transport energy from the summer hemisphere to the winter hemisphere. It is thought that the observed plasma blobs are the consequence of these electric fields.

    “Our mission will investigate the link between these two phenomena — enhanced plasma density measurements, or blobs, and the wave action in the thermosphere,” Klenzing said.

    To find out, the team will fly two instruments: a version of the Goddard-developed Ion-Neutral Mass Spectrometer, or INMS — the world’s smallest mass spectrometer that has flown on ExoCube, a CubeSat mission sponsored by the National Science Foundation — and the Gridded Retarding Ion Drift Sensor, or GRIDS, provided by Utah State University and Virginia Tech.

    The mass spectrometer will measure the densities of a variety of particles in the upper reaches of Earth’s atmosphere, observing how these densities change in response to daily and seasonal cycles. The university-provided instrument, meanwhile, will measure the distribution, motion, and velocity of ions.

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    PetitSat is flying a version of the Goddard-developed Ion-Neutral Mass Spectrometer (left) and the university-provided Gridded Retarding Ion Drift Sensor. Credits: NASA

    Dellingr-Based Mission

    The team will integrate its instruments on a Dellingr-based spacecraft. A team of Goddard engineers specifically created this 6U CubeSat to demonstrate that that these tiny craft could be reliable and cost-effective also while delivering compelling science. Dellingr, which also carries the INMS, magnetometers, and other technologies, is expected to launch in August.

    Unlike Dellingr whose solar panels are mounted on the side of the spacecraft, petitSat will fly deployable solar arrays — an enhancement that will allow mission operators to more easily point the arrays to the sun to recharge batteries. It also will carry a more advanced star tracker, said Jones, the INMS principal investigator.

    When petitSat is deployed 249 miles above Earth — consistent with the International Space Station’s orbit — the resulting data will be compared with that gathered by other ground- and space-based assets, Klenzing said. “Through comparative analysis, we will bring closure to our key science question: what is the link between plasma enhancements and MSTIDs. We’ve studied bits and pieces, but we’ve never had a full complement of instruments.”

    For more technology news, go to https://gsfctechnology.gsfc.nasa.gov/newsletter/Current.pdf

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.


    NASA/Goddard Campus

     
  • richardmitnick 4:30 pm on May 8, 2017 Permalink | Reply
    Tags: Berkeley, CME's, , NASA Goddard, , , Space Sciences Laboratory at University of California   

    From Goddard: “Space Weather Model Simulates Solar Storms From Nowhere” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    May 8, 2017
    Lina Tran
    kathalina.k.tran@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    Our ever-changing sun continuously shoots solar material into space. The grandest such events are massive clouds that erupt from the sun, called coronal mass ejections, or CMEs. These solar storms often come first with some kind of warning — the bright flash of a flare, a burst of heat or a flurry of solar energetic particles. But another kind of storm has puzzled scientists for its lack of typical warning signs: They seem to come from nowhere, and scientists call them stealth CMEs.

    Now, an international team of scientists, led by the Space Sciences Laboratory at University of California, Berkeley, and funded in part by NASA, has developed a model that simulates the evolution of these stealthy solar storms.


    SSL UC Berkeley campus


    Space Science Labs UC Berkeley

    The scientists relied upon NASA missions STEREO and SOHO for this work, fine-tuning their model until the simulations matched the space-based observations.

    NASA/STEREO spacecraft


    ESA/NASA SOHO

    Their work shows how a slow, quiet process can unexpectedly create a twisted mass of magnetic fields on the sun, which then pinches off and speeds out into space — all without any advance warning.

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    Watch the evolution of a stealth CME in this simulation. Differential rotation creates a twisted mass of magnetic fields on the sun, which then pinches off and speeds out into space. The image of the sun is from NASA’s STEREO. Colored lines depict magnetic field lines, and the different colors indicate in which layers of the sun’s atmosphere they originate. The white lines become stressed and form a coil, eventually erupting from the sun. Credits: NASA’s Goddard Space Flight Center/ARMS/Joy Ng, producer

    Compared to typical CMEs, which erupt from the sun as fast as 1800 miles per second, stealth CMEs move at a rambling gait — between 250 to 435 miles per second. That’s roughly the speed of the more common solar wind, the constant stream of charged particles that flows from the sun. At that speed, stealth CMEs aren’t typically powerful enough to drive major space weather events, but because of their internal magnetic structure they can still cause minor to moderate disturbances to Earth’s magnetic field.

    To uncover the origins of stealth CMEs, the scientists developed a model of the sun’s magnetic fields, simulating their strength and movement in the sun’s atmosphere. Central to the model was the sun’s differential rotation, meaning different points on the sun rotate at different speeds. Unlike Earth, which rotates as a solid body, the sun rotates faster at the equator than it does at its poles.

    The model showed differential rotation causes the sun’s magnetic fields to stretch and spread at different rates. The scientists demonstrated this constant process generates enough energy to form stealth CMEs over the course of roughly two weeks. The sun’s rotation increasingly stresses magnetic field lines over time, eventually warping them into a strained coil of energy. When enough tension builds, the coil expands and pinches off into a massive bubble of twisted magnetic fields — and without warning — the stealth CME quietly leaves the sun.

    Such computer models can help researchers better understand how the sun affects near-Earth space, and potentially improve our ability to predict space weather, as is done for the nation by the U.S. National Oceanic and Atmospheric Administration. A paper published in the Journal of Geophysical Research on Nov. 5, 2016, summarizes this work.

    Related

    New Space Weather Model Helps Simulate Magnetic Structure of Solar Storms
    NASA Scientists Demonstrate Technique to Improve Particle Warnings that Protect Astronauts

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.


    NASA/Goddard Campus

     
  • richardmitnick 7:32 am on April 25, 2017 Permalink | Reply
    Tags: , , , Heliosphere, Heliotail, NASA Goddard,   

    From Goddard: “NASA’s Cassini, Voyager Missions Suggest New Picture of Sun’s Interaction with Galaxy” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    April 24, 2017
    Sarah Frazier
    sarah.frazier@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    New data from NASA’s Cassini mission, combined with measurements from the two Voyager spacecraft and NASA’s Interstellar Boundary Explorer, or IBEX, suggests that our sun and planets are surrounded by a giant, rounded system of magnetic field from the sun — calling into question the alternate view of the solar magnetic fields trailing behind the sun in the shape of a long comet tail.

    NASA/Voyager 1

    NASA/ESA/ASI Cassini Spacecraft

    NASA/IBEX

    The sun releases a constant outflow of magnetic solar material — called the solar wind — that fills the inner solar system, reaching far past the orbit of Neptune. This solar wind creates a bubble, some 23 billion miles across, called the heliosphere. Our entire solar system, including the heliosphere, moves through interstellar space. The prevalent picture of the heliosphere was one of comet-shaped structure, with a rounded head and an extended tail. But new data covering an entire 11-year solar activity cycle show that may not be the case: the heliosphere may be rounded on both ends, making its shape almost spherical. A paper on these results was published in Nature Astronomy on April 24, 2017.

    “Instead of a prolonged, comet-like tail, this rough bubble-shape of the heliosphere is due to the strong interstellar magnetic field — much stronger than what was anticipated in the past — combined with the fact that the ratio between particle pressure and magnetic pressure inside the heliosheath is high,” said Kostas Dialynas, a space scientist at the Academy of Athens in Greece and lead author on the study.

    1
    New data from NASA’s Cassini, Voyager and Interstellar Boundary Explorer missions show that the heliosphere — the bubble of the sun’s magnetic influence that surrounds the inner solar system — may be much more compact and rounded than previously thought. The image on the left shows a compact model of the heliosphere, supported by this latest data, while the image on the right shows an alternate model with an extended tail. The main difference is the new model’s lack of a trailing, comet-like tail on one side of the heliosphere. This tail is shown in the old model in light blue.
    Credits: Dialynas, et al. (left); NASA (right)

    An instrument on Cassini, which has been exploring the Saturn system over a decade, has given scientists crucial new clues about the shape of the heliosphere’s trailing end, often called the heliotail. When charged particles from the inner solar system reach the boundary of the heliosphere, they sometimes undergo a series of charge exchanges with neutral gas atoms from the interstellar medium, dropping and regaining electrons as they travel through this vast boundary region. Some of these particles are pinged back in toward the inner solar system as fast-moving neutral atoms, which can be measured by Cassini.

    “The Cassini instrument was designed to image the ions that are trapped in the magnetosphere of Saturn,” said Tom Krimigis, an instrument lead on NASA’s Voyager and Cassini missions based at Johns Hopkins University’s Applied Physics Laboratory in Laurel, Maryland, and an author on the study. “We never thought that we would see what we’re seeing and be able to image the boundaries of the heliosphere.”

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    Many other stars show tails that trail behind them like a comet’s tail, supporting the idea that our solar system has one too. However, new evidence from NASA’s Cassini, Voyager and Interstellar Boundary Explorer missions suggest that the trailing end of our solar system may not be stretched out in a long tail. From top left and going counter clockwise, the stars shown are LLOrionis, BZ Cam and Mira. Credits: NASA/HST/R.Casalegno/GALEX

    Because these particles move at a small fraction of the speed of light, their journeys from the sun to the edge of the heliosphere and back again take years. So when the number of particles coming from the sun changes — usually as a result of its 11-year activity cycle — it takes years before that’s reflected in the amount of neutral atoms shooting back into the solar system.

    Cassini’s new measurements of these neutral atoms revealed something unexpected — the particles coming from the tail of the heliosphere reflect the changes in the solar cycle almost exactly as fast as those coming from the nose of the heliosphere.

    “If the heliosphere’s ‘tail’ is stretched out like a comet, we’d expect that the patterns of the solar cycle would show up much later in the measured neutral atoms,” said Krimigis.

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    5
    4
    The heliosphere is the bubble-like region of space dominated by the Sun, which extends far beyond the orbit of Pluto. Plasma “blown” out from the Sun, known as the solar wind, creates and maintains this bubble against the outside pressure of the interstellar medium, the hydrogen and helium gas that permeates the Milky Way Galaxy. The solar wind flows outward from the Sun until encountering the termination shock, where motion slows abruptly. The Voyager spacecraft have actively explored the outer reaches of the heliosphere, passing through the shock and entering the heliosheath, a transitional region which is in turn bounded by the outermost edge of the heliosphere, called the heliopause. The overall shape of the heliosphere is controlled by the interstellar medium through which it is traveling, as well as the Sun, and is not perfectly spherical.[1] The limited data available and unexplored nature[2] of these structures have resulted in many theories.
    Wikipedia.

    But because patterns from solar activity show just as quickly in tail particles as those from the nose, that implies the tail is about the same distance from us as the nose. This means that long, comet-like tail that scientists envisioned may not exist at all — instead, the heliosphere may be nearly round and symmetrical.

    A rounded heliosphere could come from a combination of factors. Data from Voyager 1 show that the interstellar magnetic field beyond the heliosphere is stronger than scientists previously thought, meaning it could interact with the solar wind at the edges of the heliosphere and compact the heliosphere’s tail.

    The structure of the heliosphere plays a big role in how particles from interstellar space — called cosmic rays — reach the inner solar system, where Earth and the other planets are.

    “This data that Voyager 1 and 2, Cassini and IBEX provide to the scientific community is a windfall for studying the far reaches of the solar wind,” said Arik Posner, Voyager and IBEX program scientist at NASA Headquarters in Washington, D.C., who was not involved with this study.

    “As we continue to gather data from the edges of the heliosphere, this data will help us better understand the interstellar boundary that helps shield the Earth environment from harmful cosmic rays.”

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.


    NASA/Goddard Campus

     
  • richardmitnick 3:28 pm on April 17, 2017 Permalink | Reply
    Tags: , NASA Goddard, NASA Team Explores Using LISA Pathfinder as 'Comet Crumb' Detector   

    From Goddard: “NASA Team Explores Using LISA Pathfinder as ‘Comet Crumb’ Detector” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    April 17, 2017
    Francis Reddy
    francis.j.reddy@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    ESA/LISA Pathfinder

    LISA Pathfinder, a mission led by ESA (the European Space Agency) with contributions from NASA, has successfully demonstrated critical technologies needed to build a space-based observatory for detecting ripples in space-time called gravitational waves.

    ESA/eLISA

    Now a team of NASA scientists hopes to take advantage of the [Pathfinder] spacecraft’s record-breaking sensitivity to map out the distribution of tiny dust particles shed by asteroids and comets far from Earth.

    Most of these particles have masses measured in micrograms, similar to a small grain of sand. But with speeds greater than 22,000 mph (36,000 kph), even micrometeoroids pack a punch. The new measurements could help refine dust models used by researchers in a variety of studies, from understanding the physics of planet formation to estimating impact risks for current and future spacecraft.


    In a proof-of-concept study, NASA scientists are exploring using ESA’s (the European Space Agency) LISA Pathfinder spacecraft as a micrometeoroid detector. When tiny particles shed by asteroids and comets impact LISA Pathfinder, its thrusters work to quickly counteract any change in the spacecraft’s motion. Researchers are monitoring these signals to learn more about the impacting particles.
    Credits: NASA’s Goddard Space Flight Center

    “We’ve shown we have a novel technique and that it works,” said Ira Thorpe, who leads the team at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The next step is to carefully apply this technique to our whole data set and interpret the results.”

    The mission’s primary goal was to test how well the spacecraft could fly in formation with an identical pair of 1.8-inch (46 millimeter) gold-platinum cubes floating inside it. The cubes are test masses intended to be in free fall and responding only to gravity.

    The spacecraft serves as a shield to protect the test masses from external forces. When LISA Pathfinder responds to pressure from sunlight and microscopic dust impacts, the spacecraft automatically compensates by firing tiny bursts from its micronewton thrusters to prevent the test masses from being disturbed.

    Scientists call this drag-free flight. In its first two months of operations in early 2016, LISA Pathfinder demonstrated the process with a precision some five times better than its mission requirements, making it the most sensitive instrument for measuring acceleration yet flown. It has now reached the sensitivity level needed to build a full multi-spacecraft gravitational wave observatory.

    “Every time microscopic dust strikes LISA Pathfinder, its thrusters null out the small amount of momentum transferred to the spacecraft,” said Goddard co-investigator Diego Janches. “We can turn that around and use the thruster firings to learn more about the impacting particles. One team’s noise becomes another team’s data.”

    Much of what we know about interplanetary dust is limited to Earth’s neighborhood, thanks in large part to NASA’s Long Duration Exposure Facility (LDEF).

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    The LDEF in Low Earth Orbit

    Launched into Earth orbit by the space shuttle Challenger in April 1984 and retrieved by the space shuttle Columbia in January 1990, LDEF hosted dozens of experiments, many of which were designed to better understand the meteoroid and orbital debris environment.

    The different compositions, orbits and histories of different asteroids and comets naturally produce dust with a range of masses and velocities. Scientists suspect the smallest and slowest particles are enhanced in Earth’s neighborhood, so the LDEF results are not representative of the wider solar system.

    “Small, slow particles near a planet are most susceptible to the planet’s gravitational pull, which we call gravitational focusing,” Janches said. This means the micrometeoroid flux near Earth should be much higher than that experienced by LISA Pathfinder, located about 930,000 miles (1.5 million kilometers) closer to the sun.

    To find the impacts, Tyson Littenberg at NASA’s Marshall Space Flight Center in Huntsville, Alabama, adapted an algorithm he originally developed to search for gravitational waves in data from the ground-based detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO), located in Livingston, Louisiana, and Hanford, Washington. In fact, it was one of many algorithms that played a role in the discovery of gravitational waves by LIGO, announced in February 2016.

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    “The way it works is that we come up with a guess of what the signal might look like, then study how LIGO or LISA Pathfinder would react if this guess were true,” Littenberg explained. “For LIGO, we’re guessing about the waveform, the peaks and valleys of the gravitational wave. For LISA Pathfinder, we’re guessing about an impact.”

    To map out the probability of likely sources, the team generates millions of different scenarios describing what the source might be and compares them to what the spacecraft actually detects.

    In response to an impact, LISA Pathfinder fires its thrusters to counteract both the minute “push” from the strike and any change in the spacecraft’s spin. Together, these quantities allow the researchers to determine the impact’s location on the spacecraft and reconstruct the micrometeoroid’s original trajectory. This may allow the team to identify individual debris streams and perhaps relate them to known asteroids and comets.

    “This is a very nice collaboration,” said Paul McNamara, the LISA Pathfinder project scientist at ESA’s Directorate of Science in Noordwijk, the Netherlands. “This is data we use for doing our science measurements, and as an offshoot of that, Ira and his team can tell us about microparticles hitting the spacecraft.”

    Its distant location, sensitivity to low-mass particles, and ability to measure the size and direction of impacting particles make LISA Pathfinder a unique instrument for studying the population of micrometeoroids in the inner solar system. But it’s only the beginning.

    “This is a proof of concept, but we’d hope to repeat this technique with a full gravitational wave observatory that ESA and NASA are currently studying for the future,” said Thorpe. “With multiple spacecraft in different orbits and a much longer observing time, the quality of the data should really improve.”

    LISA Pathfinder is managed by ESA and includes contributions from NASA Goddard and NASA’s Jet Propulsion Laboratory in Pasadena, California. The mission launched on Dec. 3, 2015, and began orbiting a point called Earth-sun L1, roughly 930,000 miles (1.5 million km) from Earth in the sun’s direction, in late January 2016.

    LISA stands for Laser Interferometer Space Antenna, a space-based gravitational wave observatory concept that has been studied in great detail by both NASA and ESA. It is a concept being explored for the third large mission of ESA’s Cosmic Vision Plan, which seeks to launch a gravitational wave observatory in 2034.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.


    NASA/Goddard Campus

     
  • richardmitnick 3:03 pm on April 15, 2017 Permalink | Reply
    Tags: , NASA Goddard, NOAA GOES - S   

    From Goddard: “NOAA’s GOES-S Satellite in Thermal Vacuum Testing” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    April 14, 2017
    Editor: Karl Hille

    1
    In March, NOAA’s Geostationary Operational Environmental Satellite-S (GOES-S) satellite was lifted into a thermal vacuum chamber to test its ability to function in the cold void of space in its orbit 22,300 miles above the Earth.

    2
    NOAA GOES-R Satellite Black Wing

    The most complicated and challenging test is thermal vacuum where a satellite experiences four cycles of extreme cold to extreme heat in a giant vacuum chamber. To simulate the environment of space, the chamber is cooled to below minus 100 degrees Celsius or minus 148 degrees Fahrenheit and air is pumped out.

    The test simulates the temperature changes GOES-S will encounter in space, as well as worst case scenarios of whether the instruments can come back to life in case of a shut down that exposes them to even colder temperatures. In this photo from March 8, the GOES-S satellite was lowered into the giant vacuum chamber at Lockheed Martin Space Systems, Denver, Colorado. GOES-S will be in the thermal vacuum chamber for 45 days. As of March 30, two of four thermal cycles were complete.

    GOES-S is the second in the GOES-R series. The GOES-R program is a collaborative development and acquisition effort between the National Oceanic and Atmospheric Administration and NASA.

    The GOES-R series of satellites will help meteorologists observe and predict local weather events, including thunderstorms, tornadoes, fog, flash floods, and other severe weather. In addition, GOES-R will monitor hazards such as aerosols, dust storms, volcanic eruptions, and forest fires and will also be used for space weather, oceanography, climate monitoring, in-situ data collection, and for search and rescue.

    For more information about GOES-S, visit:
    http://www.goes-r.gov or
    http://www.nasa.gov/goes

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.


    NASA/Goddard Campus

     
  • richardmitnick 11:54 am on March 31, 2017 Permalink | Reply
    Tags: , NASA Goddard, ,   

    From Goddard: “NASA Observations Reshape Basic Plasma Wave Physics” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    March 31, 2017
    Mara Johnson-Groh
    mara.johnson-groh@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    When NASA’s Magnetospheric Multiscale — or MMS — mission was launched, the scientists knew it would answer questions fundamental to the nature of our universe — and MMS hasn’t disappointed.


    MMS stacked


    MMS in flight

    A new finding, presented in a paper in Nature Communications, provides observational proof of a 50-year-old theory and reshapes the basic understanding of a type of wave in space known as a kinetic Alfvén wave. The results, which reveal unexpected, small-scale complexities in the wave, are also applicable to nuclear fusion techniques, which rely on minimizing the existence of such waves inside the equipment to trap heat efficiently.


    Credits: NASA’s Goddard Space Flight Center/Genna Duberstein
    Access mp4 video here .

    Kinetic Alfvén waves have long been suspected to be energy transporters in plasmas — a fundamental state of matter composed of charged particles — throughout the universe. But it wasn’t until now, with the help of MMS, that scientists have been able to take a closer look at the microphysics of the waves on the relatively small scales where the energy transfer actually happens.

    “This is the first time we’ve been able to see this energy transfer directly,” said Dan Gershman, lead author and MMS scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the University of Maryland in College Park. “We’re seeing a more detailed picture of Alfvén waves than anyone’s been able to get before.”

    The waves could be studied on a small scale for the first time because of the unique design of the MMS spacecraft. MMS’s four spacecraft fly in a compact 3-D pyramid formation, with just four miles between them — closer than ever achieved before and small enough to fit between two wave peaks. Having multiple spacecraft allowed the scientists to measure precise details about the wave, such as how fast it moved and in what direction it travelled.


    In a typical Alfvén wave, the particles (yellow) move freely along the magnetic field lines (blue).
    Credits: NASA Goddard’s Scientific Visualization Studio/Tom Bridgman, data visualizer
    Access mp4 video here .

    Previous multi-spacecraft missions flew at much larger separations, which didn’t allow them to see the small scales — much like trying to measure the thickness of a piece of paper with a yardstick. MMS’s tight flying formation, however, allowed the spacecraft to investigate the shorter wavelengths of kinetic Alfvén waves, instead of glossing over the small-scale effects.

    “It’s only at these small scales that the waves are able to transfer energy, which is why it’s so important to study them,” Gershman said.

    As kinetic Alfvén waves move through a plasma, electrons traveling at the right speed get trapped in the weak spots of the wave’s magnetic field. Because the field is stronger on either side of such spots, the electrons bounce back and forth as if bordered by two walls, in what is known as a magnetic mirror in the wave. As a result, the electrons aren’t distributed evenly throughout: Some areas have a higher density of electrons, and other pockets are left with fewer electrons. Other electrons, which travel too fast or too slow to ride the wave, end up passing energy back and forth with the wave as they jockey to keep up.


    In a kinetic Alfvén wave, some particles become trapped in the weak spots of the wave’s magnetic field and ride along with the wave as it moves through space.
    Credits: NASA Goddard’s Scientific Visualization Studio/Tom Bridgman, data visualizer
    Access mp4 video here .

    The wave’s ability to trap particles was predicted more than 50 years ago but hadn’t been directly captured with such comprehensive measurements until now. The new results also showed a much higher rate of trapping than expected.

    This method of trapping particles also has applications in nuclear fusion technology. Nuclear reactors use magnetic fields to confine plasma in order to extract energy. Current methods are highly inefficient as they require large amounts of energy to power the magnetic field and keep the plasma hot. The new results may offer a better understanding of one process that transports energy through a plasma.

    “We can produce, with some effort, these waves in the laboratory to study, but the wave is much smaller than it is in space,” said Stewart Prager, plasma scientist at the Princeton Plasma Physics Laboratory in Princeton, New Jersey. “In space, they can measure finer properties that are hard to measure in the laboratory.”

    This work may also teach us more about our sun. Some scientists think kinetic Alfvén waves are key to how the solar wind — the constant outpouring of solar particles that sweeps out into space — is heated to extreme temperatures. The new results provide insight on how that process might work.

    Throughout the universe, kinetic Alfvén waves are ubiquitous across magnetic environments, and are even expected to be in the extra-galactic jets of quasars. By studying our near-Earth environment, NASA missions like MMS can make use of a unique, nearby laboratory to understand the physics of magnetic fields across the universe.

    Related Link

    Learn more about NASA’s MMS Mission

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.


    NASA/Goddard Campus

     
  • richardmitnick 7:42 am on March 25, 2017 Permalink | Reply
    Tags: , , , NASA Goddard,   

    From Goddard: “OSIRIS-REx asteroid search tests instruments, science team” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    March 24, 2017
    Erin Morton
    morton@orex.lpl.arizona.edu
    University of Arizona, Tucson

    Nancy Neal Jones
    nancy.n.jones@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    1
    The path of the Main Belt asteroid 12 Victoria, as imaged by NASA’s OSIRIS-REx spacecraft on Feb. 11, 2017, during the mission’s Earth-Trojan Asteroid Search. This animation is made of a series of five images taken by the spacecraft’s MapCam camera that were then cropped and centered on Victoria. The images were taken about 51 minutes apart and each was exposed for 10 seconds. Credits: NASA/Goddard/University of Arizona


    OSIRIS-REx spacecraft

    During an almost two-week search, NASA’s OSIRIS-REx mission team activated the spacecraft’s MapCam imager and scanned part of the surrounding space for elusive Earth-Trojan asteroids — objects that scientists believe may exist in one of the stable regions that co-orbits the sun with Earth. Although no Earth-Trojans were discovered, the spacecraft’s camera operated flawlessly and demonstrated that it could image objects two magnitudes dimmer than originally expected.

    The spacecraft, currently on its outbound journey to the asteroid Bennu, flew through the center of Earth’s fourth Lagrangian area — a stable region 60 degrees in front of Earth in its orbit where scientists believe asteroids may be trapped, such as asteroid 2010 TK7 discovered by NASA’s Wide-field Infrared Survey Explorer (WISE) satellite in 2010. Though no new asteroids were discovered in the region that was scanned, the spacecraft’s cameras MapCam and PolyCam successfully acquired and imaged Jupiter and several of its moons, as well as Main Belt asteroids.

    “The Earth-Trojan Asteroid Search was a significant success for the OSIRIS-REx mission,” said OSIRIS-REx Principal Investigator Dante Lauretta of the University of Arizona, Tucson. “In this first practical exercise of the mission’s science operations, the mission team learned so much about this spacecraft’s capabilities and flight operations that we are now ahead of the game for when we get to Bennu.”

    The Earth Trojan survey was designed primarily as an exercise for the mission team to rehearse the hazard search the spacecraft will perform as it approaches its target asteroid Bennu. This search will allow the mission team to avoid any natural satellites that may exist around the asteroid as the spacecraft prepares to collect a sample to return to Earth in 2023 for scientific study.

    The spacecraft’s MapCam imager, in particular, performed much better than expected during the exercise. Based on the camera’s design specifications, the team anticipated detecting four Main Belt asteroids. In practice, however, the camera was able to detect moving asteroids two magnitudes fainter than expected and imaged a total of 17 Main Belt asteroids. This indicates that the mission will be able to detect possible hazards around Bennu earlier and from a much greater distance that originally planned, further reducing mission risk.

    Scientists are still analyzing the implications of the search’s results for the potential population of Earth-Trojan asteroids and will publish conclusions after a thorough study of mission data.

    NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s observation planning and processing. Lockheed Martin Space Systems in Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the agency’s New Frontiers Program for its Science Mission Directorate in Washington.

    For more information on OSIRIS-REx, visit:

    http://www.nasa.gov/osirisrex and http://www.asteroidmission.org

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    NASA Goddard Campus
    NASA/Goddard Campus
    NASA

     
  • richardmitnick 9:24 am on March 20, 2017 Permalink | Reply
    Tags: , , , , Equinox, Lunar Eclipse, NASA Goddard, NASA Satellites Ready When Stars and Planets Align, , Solstice, , Transits   

    From Goddard: “NASA Satellites Ready When Stars and Planets Align” A NASA Tour de Force 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    March 17, 2017
    Mara Johnson-Groh
    mara.johnson-groh@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    1
    No image caption. No image credit

    The movements of the stars and the planets have almost no impact on life on Earth, but a few times per year, the alignment of celestial bodies has a visible effect. One of these geometric events — the spring equinox — is just around the corner, and another major alignment — a total solar eclipse — will be visible across America on Aug. 21, with a fleet of NASA satellites viewing it from space and providing images of the event.

    To understand the basics of celestial alignments, here is information on equinoxes, solstices, full moons, eclipses and transits:

    Equinox

    Earth spins on a tilted axis. As our planet orbits around the sun, that tilt means that during half of the year, the Northern Hemisphere receives more daylight — its summertime — and during the other half of the year, the Southern Hemisphere does. Twice a year, Earth is in just the right place so that it’s lined up with respect to the sun, and both hemispheres of the planet receive the same amount of daylight. On these days, there are almost equal amounts of day and night, which is where the word equinox — meaning “equal night” in Latin — comes from. The equinox marks the onset of spring with a transition from shorter to longer days for half the planet, along with more direct sunlight as the sun rises higher above the horizon. In 2017, in the Northern Hemisphere, the spring equinox occurs on March 20. Six months later, fall begins with the autumnal equinox on Sept. 22.

    2
    During the equinoxes, both hemispheres receive equal amounts of daylight. Image not to scale. Credits: NASA’s Goddard Space Flight Center/Genna Duberstein

    Solstice

    As Earth continues along in its orbit after the equinox, it eventually reaches a point where its tilt is at the greatest angle to the plane of its orbit — and the point where one half of the planet is receiving the most daylight and the other the least. This point is the solstice — meaning “sun stands still” in Latin — and it occurs twice a year. These days are our longest and shortest days, and mark the change of seasons to summer and winter.

    3
    During the solstices, Earth reaches a point where its tilt is at the greatest angle to the plane of its orbit, causing one hemisphere to receive more daylight than the other. Image not to scale.
    Credits: NASA’s Goddard Space Flight Center/Genna Duberstein

    Full Moon and New Moon

    As Earth goes around the sun, the moon is also going around Earth. There is a point each month when the three bodies align with Earth between the sun and the moon. During this phase, viewers on Earth can see the full face of the moon reflecting light from the sun — a full moon. The time between full moons is about four weeks — 29.5 days to be exact. Halfway between full moons, the order of the three bodies reverses and the moon lies between the sun and Earth. During this time, we can’t see the moon reflecting the sun’s light, so it appears dark. This is the new moon.

    4
    When the moon’s orbit around Earth lines up on the same plane as Earth’s orbit around the sun, its shadow is cast across the planet. Image not to scale. Credits: NASA’s Goddard Space Flight Center/Genna Duberstein

    Lunar Eclipse

    Sometimes, during a full moon, Earth lines up perfectly between the moon and the sun, so its shadow is cast on the moon. From Earth’s viewpoint, we see a lunar eclipse. The plane of the moon’s orbit around Earth isn’t precisely aligned with the plane of the Earth’s orbit around the sun so on most months we don’t see an eclipse. The next lunar eclipse — which will be visible throughout much of Asia, Europe, Africa and Australia — will occur on Aug. 7.

    5
    When the moon falls completely in Earth’s shadow, a total lunar eclipse occurs. Only light travelling through Earth’s atmosphere, which is bent into the planet’s shadow, is reflected off
    the moon, giving it a reddish hue. Image not to scale. Credits: NASA’s Goddard Space Flight Center/Genna Duberstein

    Solar Eclipse

    A solar eclipse happens when the moon blocks our view of the sun. This can only happen at a new moon, when the moon’s orbit positions it between the sun and Earth — but this doesn’t happen every month. As mentioned above, the plane of the moon’s orbit around Earth isn’t precisely aligned with the plane of the Earth’s orbit around the sun so, from Earth’s view, on most months we see the moon passing above or below the sun. A solar eclipse happens only on those new moons where the alignment of all three bodies are in a perfectly straight line.

    When the moon blocks all of the sun’s light, a total eclipse occurs, but when the moon is farther away — making it appear smaller from our vantage point on Earth — it blocks most, but not all of the sun. This is called an annular eclipse, which leaves a ring of the sun’s light still visible from around the moon. This alignment usually occurs every year or two, but is only visible from a small area on Earth.

    On Aug. 21, a total solar eclipse will move across America. While lunar eclipses are visible from entire hemispheres of Earth, a total solar eclipse is visible only from a narrow band along Earth’s surface. Since this eclipse will take about an hour and a half to cross an entire continent, it is particularly important scientifically, as it allows observations from many places for an extended duration of time. NASA has funded 11 projects to take advantage of the 2017 eclipse and study its effects on Earth as well as study the sun’s atmosphere.

    6
    When the moon’s orbit around Earth lines up on the same plane as Earth’s orbit around the sun, its shadow is cast across the planet. Image not to scale. Credits: NASA’s Goddard Space Flight Center/Genna Duberstein

    Transits


    Planet transit. NASA/Ames

    An eclipse is really just a special kind of transit — which is when any celestial body passes in front of another. From Earth we are able to watch transits such as Mercury and Venus passing in front of the sun. But such transits also offer a way to spot new distant worlds. When a planet in another star system passes in front of its host star, it blocks some of the star’s light — making it appear slightly dimmer. By watching for changes in the amount of light over time, we can deduce the presence of a planet. This method has been used to discover thousands of planets, including the TRAPPIST-1 planets.

    7
    The seven planets that orbit the Trappist-1 star, in order of their distance from the star, compared to Earth’s solar system. https://www.thestar.com/news/world/2017/02/22/what-to-know-about-the-newly-discovered-trappist-1-solar-system.html

    8
    During a transit, a planet passes in between us and the star it orbits. This method is commonly used to find new exoplanets in our galaxy. Image not to scale.
    Credits: NASA’s Goddard Space Flight Center/Genna Duberstein

    For more information about how NASA looks at these events, visit:

    http://www.nasa.gov/sunearth

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    NASA Goddard Campus
    NASA/Goddard Campus
    NASA

     
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