samedi 18 novembre 2017

NASA Detects Solar Flare Pulses at Sun and Earth












NASA - Solar Dynamics Observatory (SDO) patch.

Nov. 18, 2017

When our Sun erupts with giant explosions — such as bursts of radiation called solar flares — we know they can affect space throughout the solar system as well as near Earth. But monitoring their effects requires having observatories in many places with many perspectives, much the way weather sensors all over Earth can help us monitor what’s happening with a terrestrial storm.

By using multiple observatories, two recent studies show how solar flares exhibit pulses or oscillations in the amount of energy being sent out. Such research provides new insights on the origins of these massive solar flares as well as the space weather they produce, which is key information as humans and robotic missions venture out into the solar system, farther and farther from home.

The first study spotted oscillations during a flare — unexpectedly — in measurements of the Sun’s total output of extreme ultraviolet energy, a type of light invisible to human eyes. On Feb. 15, 2011, the Sun emitted an X-class solar flare, the most powerful kind of these intense bursts of radiation. Because scientists had multiple instruments observing the event, they were able to track oscillations in the flare’s radiation, happening simultaneously in several different sets of observations.


Animation above: NASA’s Solar Dynamics Observatory captured these images of an X-class flare on Feb. 15, 2011. Animation Credits: NASA's Goddard Space Flight Center/SDO.

“Any type of oscillation on the Sun can tell us a lot about the environment the oscillations are taking place in, or about the physical mechanism responsible for driving changes in emission,” said Ryan Milligan, lead author of this first study and solar physicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the University of Glasgow in Scotland. In this case, the regular pulses of extreme ultraviolet light indicated disturbances — akin to earthquakes — were rippling through the chromosphere, the base of the Sun’s outer atmosphere, during the flare.

What surprised Milligan about the oscillations was the fact that they were first observed in extreme ultraviolet data from NOAA’s GOES — short for Geostationary Operation Environmental Satellite, which resides in near-Earth space. The mission studies the Sun from Earth’s perspective, collecting X-ray and extreme ultraviolet irradiance data — the total amount of the Sun’s energy that reaches Earth’s atmosphere over time.

This wasn’t a typical data set for Milligan. While GOES helps monitor the effects of solar eruptions in Earth’s space environment — known collectively as space weather — the satellite wasn’t initially designed to detect fine details like these oscillations.

When studying solar flares, Milligan more commonly uses high-resolution data on a specific active region in the Sun’s atmosphere to study the physical processes underlying flares. This is often necessary in order to zoom in on events in a particular area — otherwise they can easily be lost against the backdrop of the Sun’s constant, intense radiation.

“Flares themselves are very localized, so for the oscillations to be detected above the background noise of the Sun’s regular emissions and show up in the irradiance data was very striking,” Milligan said.

There have been previous reports of oscillations in GOES X-ray data coming from the Sun’s upper atmosphere, called the corona, during solar flares. What’s unique in this case is that the pulses were observed in extreme ultraviolet emission at frequencies that show they originated lower, in the chromosphere, providing more information about how a flare’s energy travels throughout through the Sun’s atmosphere.

To be sure the oscillations were real, Milligan and his colleagues checked corresponding data from other Sun-observing instruments on board NASA’s Solar Dynamics Observatory or SDO, for short: one that also collects extreme ultraviolet irradiance data and another that images the corona in different wavelengths of light. They found the exact same pulses in those data sets, confirming they were a phenomenon with its source at the Sun. Their findings are summarized in a paper published in The Astrophysical Journal Letters on Oct. 9, 2017.

These oscillations interest the scientists because they may be the result of a mechanism by which flares emit energy into space — a process we don’t yet fully understand. Additionally, the fact that the oscillations appeared in data sets typically used to monitor larger space patterns suggests they could play a role in driving space weather effects.

In the second study, scientists investigated a connection between solar flares and activity in Earth’s atmosphere. The team discovered that pulses in the electrified layer of the atmosphere — called the ionosphere — mirrored X-ray oscillations during a July 24, 2016, C-class flare. C-class flares are of mid-to-low intensity, and about 100 times weaker than X-flares.

How Solar Flares Affect Earth

Video above: A team of scientists investigated a connection between solar flares and Earth’s atmosphere. They discovered pulses in the electrified layer of the atmosphere — called the ionosphere — mirrored X-ray oscillations during a July 24, 2016, flare. Video Credits: NASA’s Goddard Space Flight Center/Genna Duberstein.

Stretching from roughly 30 to 600 miles above Earth’s surface, the ionosphere is an ever-changing region of the atmosphere that reacts to changes from both Earth below and space above. It swells in response to incoming solar radiation, which ionizes atmospheric gases, and relaxes at night as the charged particles gradually recombine.

In particular, the team of scientists — led by Laura Hayes, a solar physicist who splits her time between NASA Goddard and Trinity College in Dublin, Ireland, and her thesis adviser Peter Gallagher — looked at how the lowest layer of the ionosphere, called the D-region, responded to pulsations in a solar flare.

“This is the region of the ionosphere that affects high-frequency communications and navigation signals,” Hayes said. “Signals travel through the D-region, and changes in the electron density affect whether the signal is absorbed, or degraded.”

The scientists used data from very low frequency, or VLF, radio signals to probe the flare’s effects on the D-region. These were standard communication signals transmitted from Maine and received in Ireland. The denser the ionosphere, the more likely these signals are to run into charged particles along their way from a signal transmitter to its receiver. By monitoring how the VLF signals propagate from one end to the other, scientists can map out changes in electron density.

Pooling together the VLF data and X-ray and extreme ultraviolet observations from GOES and SDO, the team found the D-region’s electron density was pulsing in concert with X-ray pulses on the Sun. They published their results in the Journal of Geophysical Research on Oct. 17, 2017.

“X-rays impinge on the ionosphere and because the amount of X-ray radiation coming in is changing, the amount of ionization in the ionosphere changes too,” said Jack Ireland, a co-author on both studies and Goddard solar physicist. “We’ve seen X-ray oscillations before, but the oscillating ionosphere response hasn’t been detected in the past.”

Solar Dynamics Observatory (SDO). Image Credit: NASA

Hayes and her colleagues used a model to determine just how much the electron density changed during the flare. In response to incoming radiation, they found the density increased as much as 100 times in just 20 minutes during the pulses — an exciting observation for the scientists who didn’t expect oscillating signals in a flare would have such a noticeable effect in the ionosphere. With further study, the team hopes to understand how the ionosphere responds to X-ray oscillations at different timescales, and whether other solar flares induce this response.

“This is an exciting result, showing Earth’s atmosphere is more closely linked to solar X-ray variability than previously thought,” Hayes said. “Now we plan to further explore this dynamic relationship between the Sun and Earth’s atmosphere.” 
Both of these studies took advantage of the fact that we are increasingly able to track solar activity and space weather from a number of vantage points. Understanding the space weather that affects us at Earth requires understanding a dynamic system that stretches from the Sun all the way to our upper atmosphere — a system that can only be understood by tapping into a wide range of missions scattered throughout space.

Related links:

September 2017’s Intense Solar Activity Viewed from Space: https://www.nasa.gov/feature/goddard/2017/september-2017s-intense-solar-activity-viewed-from-space

NASA’s ICON Explores the Boundary Between Earth and Space: https://www.nasa.gov/feature/goddard/2017/nasa-s-icon-explores-the-boundary-between-earth-and-space/

Journal of Geophysical Research:
On Oct. 9, 2017:
http://iopscience.iop.org/article/10.3847/2041-8213/aa8f3a/meta
On Oct. 17, 2017:
http://onlinelibrary.wiley.com/doi/10.1002/2017JA024647/abstract

NOAA’s GOES: https://www.nasa.gov/content/goes/

NASA’s Solar Dynamics Observatory or SDO: http://nasa.gov/sdo

Animation (mentioned), Image (mentioned), Video (mentioned), Text, Credits: NASA/Rob Garner.

Greetings, Orbiter.ch

Astronauts Take on Science, Plumbing and Cargo Duties












ISS - Expedition 53 Mission patch.

Nov. 18, 2017

Expedition 53 checked out a specialized microscope and worked on the International Space Station’s toilet today. More supplies and hardware are also being offloaded from the newly-arrived Cygnus cargo craft.

Commander Randy Bresnik opened up the Fluids Integrated Rack this morning to take a look at its Light Microscopy Module (LMM), an advanced space microscope. He was troubleshooting the device and swapping out its cables. The LMM provides a facility to examine the microscopic properties of different types of fluids in microgravity.


Image above: The six-member Expedition 53 crew poses for a portrait inside the Japanese Kibo laboratory module with the VICTORY art spacesuit that was hand-painted by cancer patients in Russia and the United States. On the right (from top to bottom) are European Space Agency astronaut Paolo Nespoli, cosmonaut Sergey Ryazanskiy of Roscosmos and Expedition 53 Commander Randy Bresnik of NASA.

European Space Agency Paolo Nespoli worked on space plumbing throughout the day in the station’s restroom, the Waste and Hygiene Compartment (WHC). The veteran station resident removed and replaced valves and sensors in the WHC as part regular preventative maintenance.

More crew supplies and research gear are being unloaded from Cygnus today to outfit the crew and continue ongoing space science experiments. NASA astronaut Joe Acaba was unpacking food, batteries and computer gear for stowage throughout the station. The second-time station resident was also removing Genes in Space gear and blood sample kits for upcoming science work.

Related links:

Light Microscopy Module (LMM): https://www.nasa.gov/mission_pages/station/research/experiments/541.html

Genes in Space: https://www.nasa.gov/mission_pages/station/research/experiments/2524.html

Expedition 53: https://www.nasa.gov/mission_pages/station/expeditions/expedition53/index.html

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

Image, Text, Credits: NASA/Mark Garcia.

Best regards, Orbiter.ch

NASA Launches NOAA Weather Satellite to Improve Forecasts












ULA - Delta II / JPSS-1 Mission poater.

Nov. 18, 2017


Image above: At Vandenberg Air Force Base's Space Launch Complex 2, the Delta II rocket engines roar to life. The 1:47 a.m. PST (4:47 a.m. EST), liftoff begins the Joint Polar Satellite System-1, or JPSS-1, mission. JPSS is the first in a series four next-generation environmental satellites in a collaborative program between NOAA and NASA.

NASA has successfully launched for the National Oceanic and Atmospheric Administration (NOAA) the first in a series of four highly advanced polar-orbiting satellites, equipped with next-generation technology and designed to improve the accuracy of U.S. weather forecasts out to seven days.

The Joint Polar Satellite System-1 (JPSS-1) lifted off on a United Launch Alliance Delta II rocket from Vandenberg Air Force Base, California, at 1:47 a.m. PST Saturday.

Approximately 63 minutes after launch the solar arrays on JPSS-1 deployed and the spacecraft was operating on its own power. JPSS-1 will be renamed NOAA-20 when it reaches its final orbit. Following a three-month checkout and validation of its five advanced instruments, the satellite will become operational.

NASA Launches NOAA Weather Satellite to Improve Forecasts

“Launching JPSS-1 underscores NOAA’s commitment to putting the best possible satellites into orbit, giving our forecasters -- and the public -- greater confidence in weather forecasts up to seven days in advance, including the potential for severe, or impactful weather,” said Stephen Volz, director of NOAA’s Satellite and Information Service.

JPSS-1 will join the joint NOAA/NASA Suomi National Polar-orbiting Partnership satellite in the same orbit and provide meteorologists with observations of atmospheric temperature and moisture, clouds, sea-surface temperature, ocean color, sea ice cover, volcanic ash, and fire detection. The data will improve weather forecasting, such as predicting a hurricane’s track, and will help agencies involved with post-storm recovery by visualizing storm damage and the geographic extent of power outages.

“Emergency managers increasingly rely on our forecasts to make critical decisions and take appropriate action before a storm hits,” said Louis W. Uccellini, director of NOAA’s National Weather Service. “Polar satellite observations not only help us monitor and collect information about current weather systems, but they provide data to feed into our weather forecast models.”

JPSS-1 has five instruments, each of which is significantly upgraded from the instruments on NOAA’s previous polar-orbiting satellites. The more-detailed observations from JPSS will allow forecasters to make more accurate predictions. JPSS-1 data will also improve recognition of climate patterns that influence the weather, such as El Nino and La Nina.

JPSS-1 satellite

The JPSS program is a partnership between NOAA and NASA through which they will oversee the development, launch, testing and operation all the satellites in the series. NOAA funds and manages the program, operations and data products. NASA develops and builds the instruments, spacecraft and ground system and launches the satellites for NOAA. JPSS-1 launch management was provided by NASA’s Launch Services Program based at the agency's Kennedy Space Center in Florida.

“Today’s launch is the latest example of the strong relationship between NASA and NOAA, contributing to the advancement of scientific discovery and the improvement of the U.S. weather forecasting capability by leveraging the unique vantage point of space to benefit and protect humankind,” said Sandra Smalley, director of NASA’s Joint Agency Satellite Division.

Ball Aerospace designed and built the JPSS-1 satellite bus and Ozone Mapping and Profiler Suite instrument, integrated all five of the spacecraft’s instruments and performed satellite-level testing and launch support. Raytheon Corporation built the Visible Infrared Imaging Radiometer Suite and the Common Ground System. Harris Corporation built the Cross-track Infrared Sounder. Northrop Grumman Aerospace Systems built the Advanced Technology Microwave Sounder and the Clouds and the Earth's Radiant Energy System instrument.

To learn more about the JPSS-1 mission, visit:

http://www.jpss.noaa.gov/ and https://www.nesdis.noaa.gov/jpss-1

Images, Video, Text, Credits: NASA/Sean Potter.

Greetings, Orbiter.ch

vendredi 17 novembre 2017

Taking a Spin on Plasma Space Tornadoes with NASA Observations












NASA - Magnetospheric Multiscale Mission (MMS) patch.

Nov. 17, 2017

Interplanetary space is hardly tranquil. High-energy charged particles from the Sun, as well as from beyond our solar system, constantly whizz by. These can damage satellites and endanger astronaut health — though, luckily for life on Earth, the planet is blanketed by a protective magnetic bubble created by its magnetic field. This bubble, called the magnetosphere, deflects most of the harmful high-energy particles.

Nevertheless, some sneak through — and at the forefront of figuring out just how this happens is NASA’s Magnetospheric Multiscale mission, or MMS. New results show that tornado-like swirls of space plasma create a boundary tumultuous enough to let particles slip into near Earth space.


Animation above: This simulation of the boundary shows how areas of low density plasma, shown by blue, mix with areas of higher density plasma, red, forming turbulent tornadoes of plasma. Animation Credits: NASA/Takuma Nakamura.

MMS, launched in 2015, uses four identical spacecraft flying in a pyramid formation to take a three-dimensional look at the magnetic environment around Earth. The mission studies how particles transfer into the magnetosphere by focusing on the causes and effects of magnetic reconnection — an explosive event where magnetic field lines cross, launching electrons and ions from the solar wind into the magnetosphere.

By combining observations from MMS with new 3-D computer simulations, scientists have been able to investigate the small-scale physics of what’s happening at our magnetosphere’s borders for the first time. The results, recently published in a paper in Nature Communications, are key for understanding how the solar wind sometimes enters Earth’s magnetosphere, where it can interfere with satellites and GPS communications.

Inside the magnetosphere, the density of the space plasma — charged particles, like electrons and ions — is much lower than the plasma outside, where the solar wind prevails. The boundary, called the

magnetopause, becomes unstable when the two different density regions move at different rates. Giant swirls, called Kelvin Helmholtz waves, form along the edge like crashing ocean waves. The once-smooth boundary becomes tangled and squeezed, forming plasma tornadoes, which act as portholes for the transportation of charged particles from the solar wind into the magnetosphere.


Image above: Kelvin-Helmholtz waves, with their classic surfer's wave shape, are found in nature wherever two fluids meet, such as in these clouds. Image Credits: Danny Ratcliffe.

Kelvin Helmholtz waves are found across the universe wherever two materials of different density move past one another. They can be seen in cloud formations around Earth and have even been observed in other planetary atmospheres in our solar system.

Using large-scale computer simulations of this mixing, performed at the Oak Ridge National Laboratory in Oak Ridge, Tennessee, on the Titan supercomputer, and comparing them to observations MMS took while passing through such a region in space, scientists were able to show that the tornadoes were extremely efficient at transporting charged particles — much more so than previously thought. The comparisons between the simulations and observations allowed the scientists to measure the exact dimensions of the tornadoes. They found these tornadoes to be both large and small — ones reaching 9,300 miles spawned smaller tornadoes 60 to 90 miles wide and over 125 miles long.

MMS recently moved into a new orbit, flying on the far side of Earth, away from the Sun. Here too, it will continue to study magnetic reconnection, but focus instead on how energy and particles interact within Earth’s magnetosphere, in the long trailing magnetotail. Understanding such fundamental processes in Earth’s neighborhood helps improve our situational awareness of the space that surrounds us — crucial information as it becomes ever more filled with satellites and communications systems we depend on.

Related Links:

Learn more about the Magnetospheric Multiscale Mission: https://www.nasa.gov/mission_pages/mms/index.html

Learn more about NASA’s research on the Sun-Earth environment: https://www.nasa.gov/mission_pages/sunearth/index.html

Animation (mentioned9, Image (mentioned), Text, Credits: NASA/Rob Garner.

Greetings, Orbiter.ch

Jovian Tempest












NASA - JUNO Mission logo.

Nov. 17, 2017


This color-enhanced image of a massive, raging storm in Jupiter’s northern hemisphere was captured by NASA’s Juno spacecraft during its ninth close flyby of the gas giant planet.

The image was taken on Oct. 24, 2017 at 10:32 a.m. PDT (1:32 p.m. EDT). At the time the image was taken, the spacecraft was about 6,281 miles (10,108 kilometers) from the tops of the clouds of Jupiter at a latitude of 41.84 degrees. The spatial scale in this image is 4.2 miles/pixel (6.7 kilometers/pixel).

The storm is rotating counter-clockwise with a wide range of cloud altitudes. The darker clouds are expected to be deeper in the atmosphere than the brightest clouds. Within some of the bright “arms” of this storm, smaller clouds and banks of clouds can be seen, some of which are casting shadows to the right side of this picture (sunlight is coming from the left). The bright clouds and their shadows range from approximately 4 to 8 miles (7 to 12 kilometers) in both widths and lengths. These appear similar to the small clouds in other bright regions Juno has detected and are expected to be updrafts of ammonia ice crystals possibly mixed with water ice.

Juno spacecraft orbiting Jupiter

Citizen scientists Gerald Eichstädt and Seán Doran processed this image using data from the JunoCam imager.

JunoCam's raw images are available for the public to peruse and process into image products at: http://www.missionjuno.swri.edu/junocam   

More information about Juno is at:

https://www.nasa.gov/juno and http://missionjuno.swri.edu

Image, Animation, Text, Credits: NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstädt/Seán Doran.

Greetings, Orbiter.ch

Hubble’s Cosmic Search for a Missing Arm












NASA - Hubble Space Telescope patch.

Nov. 17, 2017


This new picture of the week, taken by the NASA/ESA Hubble Space Telescope, shows the dwarf galaxy NGC 4625, located about 30 million light-years away in the constellation of Canes Venatici (The Hunting Dogs). The image, acquired with the Advanced Camera for Surveys (ACS), reveals the single major spiral arm of the galaxy, which gives it an asymmetric appearance. But why is there only one such spiral arm, when spiral galaxies normally have at least two?

Astronomers looked at NGC 4625 in different wavelengths in the hope of solving this cosmic mystery. Observations in the ultraviolet provided the first hint: in ultraviolet light the disk of the galaxy appears four times larger than on the image depicted here. An indication that there are a large number of very young and hot — hence mainly visible in the ultraviolet — stars forming in the outer regions of the galaxy. These young stars are only around one billion years old, about 10 times younger than the stars seen in the optical center. At first astronomers assumed that this high star formation rate was being triggered by the interaction with another, nearby dwarf galaxy called NGC 4618.

They speculated that NGC 4618 may be the culprit “harassing” NGC 4625, causing it to lose all but one spiral arm. In 2004 astronomers found proof for this claim. The gas in the outermost regions of the dwarf galaxy NGC 4618 has been strongly affected by NGC 4625.

Hubble Space Telescope (HST)

For images and more information about Hubble, visit:

http://hubblesite.org/
http://www.nasa.gov/hubble
http://www.spacetelescope.org/

Image, Animation, Text,  Credits: ESA/Hubble & NASA/Text Credits: European Space Agency/NASA/Karl Hille.

Best regards, Orbiter.ch

jeudi 16 novembre 2017

Lava or Not, Exoplanet 55 Cancri e Likely to have Atmosphere












NASA - Spitzer Space Telescope patch.

November 16, 2017


Image above: The super-Earth exoplanet 55 Cancri e, depicted with its star in this artist's concept, likely has an atmosphere thicker than Earth's but with ingredients that could be similar to those of Earth's atmosphere. Image Credits: NASA/JPL.

Twice as big as Earth, the super-Earth 55 Cancri e was thought to have lava flows on its surface. The planet is so close to its star, the same side of the planet always faces the star, such that the planet has permanent day and night sides. Based on a 2016 study using data from NASA's Spitzer Space Telescope, scientists speculated that lava would flow freely in lakes on the starlit side and become hardened on the face of perpetual darkness. The lava on the dayside would reflect radiation from the star, contributing to the overall observed temperature of the planet.

Now, a deeper analysis of the same Spitzer data finds this planet likely has an atmosphere whose ingredients could be similar to those of Earth's atmosphere, but thicker. Lava lakes directly exposed to space without an atmosphere would create local hot spots of high temperatures, so they are not the best explanation for the Spitzer observations, scientists said.

"If there is lava on this planet, it would need to cover the entire surface," said Renyu Hu, astronomer at NASA's Jet Propulsion Laboratory, Pasadena, California, and co-author of a study published in The Astronomical Journal. "But the lava would be hidden from our view by the thick atmosphere."

Using an improved model of how energy would flow throughout the planet and radiate back into space, researchers find that the night side of the planet is not as cool as previously thought. The "cold" side is still quite toasty by Earthly standards, with an average of 2,400 to 2,600 degrees Fahrenheit (1,300 to 1,400 Celsius), and the hot side averages 4,200 degrees Fahrenheit (2,300 Celsius). The difference between the hot and cold sides would need to be more extreme if there were no atmosphere.

"Scientists have been debating whether this planet has an atmosphere like Earth and Venus, or just a rocky core and no atmosphere, like Mercury. The case for an atmosphere is now stronger than ever," Hu said.

Researchers say the atmosphere of this mysterious planet could contain nitrogen, water and even oxygen -- molecules found in our atmosphere, too -- but with much higher temperatures throughout. The density of the planet is also similar to Earth, suggesting that it, too, is rocky. The intense heat from the host star would be far too great to support life, however, and could not maintain liquid water.

Spitzer Space Telescope. Image Credits: NASA/JPL

Hu developed a method of studying exoplanet atmospheres and surfaces, and had previously only applied it to sizzling, giant gaseous planets called hot Jupiters. Isabel Angelo, first author of the study and a senior at the University of California, Berkeley, worked on the study as part of her internship at JPL and adapted Hu's model to 55 Cancri e.

In a seminar, she heard about 55 Cancri e as a potentially carbon-rich planet, so high in temperature and pressure that its interior could contain a large amount of diamond.

"It's an exoplanet whose nature is pretty contested, which I thought was exciting," Angelo said.

Spitzer observed 55 Cancri e between June 15 and July 15, 2013, using a camera specially designed for viewing infrared light, which is invisible to human eyes. Infrared light is an indicator of heat energy. By comparing changes in brightness Spitzer observed to the energy flow models, researchers realized an atmosphere with volatile materials could best explain the temperatures.

There are many open questions about 55 Cancri e, especially: Why has the atmosphere not been stripped away from the planet, given the perilous radiation environment of the star?

"Understanding this planet will help us address larger questions about the evolution of rocky planets," Hu said.

NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at IPAC at Caltech. Caltech manages JPL for NASA. For more information about Spitzer, visit:

http://spitzer.caltech.edu

https://www.nasa.gov/spitzer

Images (mentioned), Text, Credits: NASA/JPL/Elizabeth Landau.

Greetings, Orbiter.ch