Colorful Impact Ejecta from Hargraves Crater

NASA - Mars Reconnaissance Orbiter (MRO) patch.

May 9, 2017

The collision that created Hargraves Crater impacted into diverse bedrock lithologies of ancient Mars. As a result, the impact ejecta is a rich mix of rock types with different colors and textures, as seen by NASA's Mars Reconnaissance Orbiter (MRO).

The crater is named after Robert Hargraves who discovered and studied meteorite impacts on the Earth.

This is a stereo pair with http://www.uahirise.org/ESP_049963_2005

The map is projected here at a scale of 50 centimeters (19.7 inches) per pixel. [The original image scale is 59.2 centimeters (22.4 inches) per pixel (with 2 x 2 binning); objects on the order of 178 centimeters (33.8 inches) across are resolved.] North is up.

The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington.

Mars Reconnaissance Orbiter (MRO): http://www.nasa.gov/mission_pages/MRO/main/index.html

Image, Text, Credits: NASA/Tony Greicius/JPL.

Best regards, Orbiter.ch

Merging Galaxies Have Enshrouded Black Holes

NASA - NuStar Mission patch.

May 9, 2017

Black holes get a bad rap in popular culture for swallowing everything in their environments. In reality, stars, gas and dust can orbit black holes for long periods of time, until a major disruption pushes the material in.

A merger of two galaxies is one such disruption. As the galaxies combine and their central black holes approach each other, gas and dust in the vicinity are pushed onto their respective black holes. An enormous amount of high-energy radiation is released as material spirals rapidly toward the hungry black hole, which becomes what astronomers call an active galactic nucleus (AGN).

A study using NASA's NuSTAR telescope shows that in the late stages of galaxy mergers, so much gas and dust falls toward a black hole that the extremely bright AGN is enshrouded. The combined effect of the gravity of the two galaxies slows the rotational speeds of gas and dust that would otherwise be orbiting freely. This loss of energy makes the material fall onto the black hole.

Image above: This illustration compares growing supermassive black holes in two different kinds of galaxies. A growing supermassive black hole in a normal galaxy would have a donut-shaped structure of gas and dust around it (left). In a merging galaxy, a sphere of material obscures the black hole (right). Image Credits: National Astronomical Observatory of Japan.

"The further along the merger is, the more enshrouded the AGN will be," said Claudio Ricci, lead author of the study published in the Monthly Notices Royal Astronomical Society. "Galaxies that are far along in the merging process are completely covered in a cocoon of gas and dust."

Ricci and colleagues observed the penetrating high-energy X-ray emission from 52 galaxies. About half of them were in the later stages of merging. Because NuSTAR is very sensitive to detecting the highest-energy X-rays, it was critical in establishing how much light escapes the sphere of gas and dust covering an AGN.

The study was published in the Monthly Notices of the Royal Astronomical Society. Researchers compared NuSTAR observations of the galaxies with data from NASA's Swift and Chandra and ESA's XMM-Newton observatories, which look at lower energy components of the X-ray spectrum. If high-energy X-rays are detected from a galaxy, but low-energy X-rays are not, that is a sign that an AGN is heavily obscured.

NASA's NuSTAR telescope. Image Credit: NASA

The study helps confirm the longstanding idea that an AGN's black hole does most of its eating while enshrouded during the late stages of a merger.

"A supermassive black hole grows rapidly during these mergers," Ricci said. "The results further our understanding of the mysterious origins of the relationship between a black hole and its host galaxy."

NuSTAR is a Small Explorer mission led by Caltech and managed by NASA's Jet Propulsion Laboratory for NASA's Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTAR's mission operations center is at UC Berkeley, and the official data archive is at NASA's High Energy Astrophysics Science Archive Research Center. ASI provides the mission's ground station and a mirror archive. JPL is managed by Caltech for NASA.

Related link:

Monthly Notices of the Royal Astronomical Society: https://academic.oup.com/mnras/article/468/2/1273/2939810/Growing-supermassive-black-holes-in-the-late

For more information on NuSTAR, visit:

http://www.nasa.gov/nustar

http://www.nustar.caltech.edu

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

Greetings, Orbiter.ch

NASA Delivers Detectors for ESA's Euclid Spacecraft

ESA - Euclid Mission logo.

May 9, 2017

Three detector systems for the Euclid mission, led by ESA (European Space Agency), have been delivered to Europe for the spacecraft's near-infrared instrument. The detector systems are key components of NASA's contribution to this upcoming mission to study some of the biggest questions about the universe, including those related to the properties and effects of dark matter and dark energy -- two critical, but invisible phenomena that scientists think make up the vast majority of our universe.

"The delivery of these detector systems is a milestone for what we hope will be an extremely exciting mission, the first space mission dedicated to going after the mysterious dark energy," said Michael Seiffert, the NASA Euclid project scientist based at NASA's Jet Propulsion Laboratory, Pasadena, California, which manages the development and implementation of the detector systems.

Euclid will carry two instruments: a visible-light imager (VIS) and a near-infrared spectrometer and photometer (NISP). A special light-splitting plate on the Euclid telescope enables incoming light to be shared by both instruments, so they can carry out observations simultaneously.

Image above: This artist's concept shows ESA's Euclid spacecraft, to which NASA is contributing. Image Credits: ESA/C. Carreau.

The spacecraft, scheduled for launch in 2020, will observe billions of faint galaxies and investigate why the universe is expanding at an accelerating pace. Astrophysicists think dark energy is responsible for this effect, and Euclid will explore this hypothesis and help constrain dark energy models. This census of distant galaxies will also reveal how galaxies are distributed in our universe, which will help astrophysicists understand how the delicate interplay of the gravity of dark matter, luminous matter and dark energy forms large-scale structures in the universe.

Additionally, the location of galaxies in relation to each other tells scientists how they are clustered. Dark matter, an invisible substance accounting for over 80 percent of matter in our universe, can cause subtle distortions in the apparent shapes of galaxies. That is because its gravity bends light that travels from a distant galaxy toward an observer, which changes the appearance of the galaxy when it is viewed from a telescope. Euclid's combination of visible and infrared instruments will examine this distortion effect and allow astronomers to probe dark matter and the effects of dark energy.

Detecting infrared light, which is invisible to the human eye, is especially important for studying the universe's distant galaxies. Much like the Doppler effect for sound, where a siren's pitch seems higher as it approaches and lower as it moves away, the frequency of light from an astronomical object gets shifted with motion. Light from objects that are traveling away from us appears redder, and light from those approaching us appears bluer. Because the universe is expanding, distant galaxies are moving away from us, so their light gets stretched out to longer wavelengths. Between 6 and 10 billion light-years away, galaxies are brightest in infrared light. 

JPL procured the NISP detector systems, which were manufactured by Teledyne Imaging Sensors of Camarillo, California. They were tested at JPL and at NASA's Goddard Space Flight Center, Greenbelt, Maryland, before being shipped to France and the NISP team.

Each detector system consists of a detector, a cable and a "readout electronics chip" that converts infrared light to data signals read by an onboard computer and transmitted to Earth for analysis. Sixteen detectors will fly on Euclid, each composed of 2040 by 2040 pixels. They will cover a field of view slightly larger than twice the area covered by a full moon. The detectors are made of a mercury-cadmium-telluride mixture and are designed to operate at extremely cold temperatures.

"The U.S. Euclid team has overcome many technical hurdles along the way, and we are delivering superb detectors that will enable the collection of unprecedented data during the mission," said Ulf Israelsson, the NASA Euclid project manager, based at JPL.

Delivery to ESA of the next set of detectors for NISP is planned in early June. The Centre de Physique de Particules de Marseille, France, will provide further characterization of the detector systems. The final detector focal plane will then be assembled at the Laboratoire d'Astrophysique de Marseille, and integrated with the rest of NISP for instrument tests.

For more information about Euclid, visit: http://sci.esa.int/Euclid

Image (mentioned), Text, Credits: NASA/Tony Greicius/JPL/Elizabeth Landau/ESA/René Laureijs/Giuseppe Racca.

Best regards, Orbiter.ch

Alaska Tundra Source of Early-Winter Carbon Emissions

NASA logo.

May 8, 2017

Warmer temperatures and thawing soils may be driving an increase in emissions of carbon dioxide from Alaskan tundra to the atmosphere, particularly during the early winter, according to a new study supported by NASA and the National Oceanic and Atmospheric Administration (NOAA). More carbon dioxide released to the atmosphere will accelerate climate warming, which, in turn, could lead to the release of even more carbon dioxide from these soils.

A new paper led by Roisin Commane, an atmospheric researcher at Harvard University in Cambridge, Massachusetts, finds the amount of carbon dioxide emitted from northern tundra areas between October and December each year has increased 70 percent since 1975. Commane and colleagues analyzed three years of aircraft observations from NASA’s Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) airborne mission to estimate the spatial and seasonal distribution of Alaska’s carbon dioxide emissions. They also studied NOAA’s 41-year record of carbon dioxide measured from ground towers in Barrow (the name recently changed back to Utqiagvik), Alaska. The aircraft data provided unprecedented spatial information, while the ground data provided long-term measurements not available anywhere else in the Arctic. Results of the study are published today in the Proceedings of the National Academy of Sciences.

The soils that encircle the high northern reaches of the Arctic (above 60 degrees North latitude) hold vast amounts of carbon in the form of undecayed organic matter from dead vegetation. This vast store, accumulated over thousands of years, contains enough carbon to double the current amount of carbon dioxide in Earth's atmosphere.

During the Arctic summer, the upper layers of soil thaw and microbes decompose this organic matter, producing carbon dioxide. When cold temperatures return in October, the thawed soil layers begin to cool, but high rates of carbon dioxide emissions continue until the soil freezes completely.

“In the past, refreezing of soils may have taken a month or so, but with warmer temperatures in recent years, there are locations in Alaska where tundra soils now take more than three months to freeze completely,” said Commane. “We are seeing emissions of carbon dioxide from soils continue all the way through this early winter period."

“Data from Barrow show steady increases of both atmospheric carbon dioxide and temperature in late fall and early winter,” said co-author Colm Sweeney of the Cooperative Institute for Research in Environmental Sciences in Boulder, Colorado. “This new research demonstrates the critical importance of these long-term monitoring sites in verifying the subtle feedbacks, such as increases in carbon dioxide, which may amplify the unprecedented warming we are seeing throughout the Arctic.”

Image above: Winter sun setting over the tundra polygons in northern Alaska in November 2015. As winter sets in and snow settles, the soils take time to freeze completely and continue to emit carbon dioxide long into the new year. Image Credits: NASA/JPL-Caltech/Charles Miller.

CARVE flew an instrumented NASA aircraft to measure atmospheric carbon dioxide and other greenhouse gases over Alaska from April to November in 2012, 2013 and 2014. These data, along with satellite data on the vegetation status and ground data to provide a year-round context and a long-term record, gave the scientists a detailed picture of carbon emissions at the regional level.

“One of CARVE’s main objectives was to challenge the idea that carbon dioxide respiration stopped as soon as the snow fell and the land surface froze,” said Charles Miller, a scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, and CARVE principal investigator. “The CARVE flights prove that microbial respiration continues in tundra soils months after the surface has frozen.”

By comparing simultaneous measurements of atmospheric carbon dioxide and carbon monoxide, Commane and her co-authors split apart their estimates of the total carbon budget of Alaska into contributions from the three major sources of atmospheric carbon: burning of fossil fuels by people; wildfires; and microbes decomposing organic matter in the soil. In sparsely populated Alaska, the soil microbes were a much bigger source of atmospheric carbon than fossil fuel burning. Wildfires were a big source of atmospheric carbon in just one year of the CARVE experiment, 2013.

"Tundra soils appear to be acting as an amplifier of climate change," said co-author Steve Wofsy, a Harvard atmospheric scientist. "We need to carefully monitor what it's doing up there, even late in the year when everything looks frozen and dormant."

“The entire Alaska region is responding to climate change,” said professor Donatella Zona of San Diego State University in California, who was not affiliated with the study. “Surface measurements suggest that the amount of carbon lost from Arctic ecosystems to the atmosphere in the fall might have been increasing over the past decades. By better capturing these cold season processes and putting previous smaller-scale measurements into a bigger context, this study will help scientists improve climate models and predictions of Arctic climate change."

Commane, Sweeney, Miller and their colleagues plan to expand on this work with NASA's Arctic-Boreal Vulnerability Experiment (ABoVE) field campaign, now in its second season in Alaska and northwest Canada. As part of the broader ABoVE effort, they will make airborne measurements of carbon dioxide and methane each month from April through October.

Related links:

Earth Research Findings: https://www.nasa.gov/subject/7782/earth-research-findings

Climate: https://www.nasa.gov/subject/3127/climate

Image (mentioned), Text, Credits: NASA/Tony Greicius/Earth Science News Team, written by Ellen Gray/JPL/Alan Buis.

Greetings, Orbiter.ch

Space Weather Model Simulates Solar Storms From Nowhere

ESA & NASA - SOHO Mission patch / NASA - STEREO Mission logo.

May 8, 2017

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

Animation above: 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. Animation 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.

Solar and Heliospheric Observatory or SOHO. Image Credits: ESA/NASA

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.

Image above: Artist's conceptual drawing of the two spacecraft STEREO in orbit around the sun. Image Credit: NASA.

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 articles:

New Space Weather Model Helps Simulate Magnetic Structure of Solar Storms: http://orbiterchspacenews.blogspot.ch/2017/01/new-space-weather-model-helps-simulate.html

NASA Scientists Demonstrate Technique to Improve Particle Warnings that Protect Astronauts: http://orbiterchspacenews.blogspot.ch/2017/03/nasa-scientists-demonstrate-technique.html

Related links:

Journal of Geophysical Research: http://onlinelibrary.wiley.com/doi/10.1002/2016JA023432/full

SOHO (Solar and Heliospheric Observatory): http://www.nasa.gov/mission_pages/soho/index.html and http://sci.esa.int/soho/

STEREO (Solar TErrestrial RElations Observatory): http://www.nasa.gov/mission_pages/stereo/main/index.html

Space Weather: https://www.nasa.gov/subject/3165/space-weather

Images (mentioned), Animation (mentioned), Text, Credits: NASA's Goddard Space Flight Center, by Lina Tran/Rob Garner.

Greetings, Orbiter.ch

Hail the Hexagon

NASA - Cassini International logo.

May 8, 2017

Saturn's hexagonal polar jet stream is the shining feature of almost every view of the north polar region of Saturn. The region, in shadow for the first part of the Cassini mission, now enjoys full sunlight, which enables Cassini scientists to directly image it in reflected light.

Although the sunlight falling on the north pole of Saturn is enough to allow us to image and study the region, it does not provide much warmth. In addition to being low in the sky (just like summer at Earth's poles), the sun is nearly ten times as distant from Saturn as from Earth. This results in the sunlight being only about 1 percent as intense as at our planet.

This view looks toward Saturn from about 31 degrees above the ring plane. The image was taken with the Cassini spacecraft wide-angle camera on Jan. 22, 2017 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 939 nanometers.

The view was obtained at a distance of approximately 560,000 miles (900,000 kilometers) from Saturn. Image scale is 33 miles (54 kilometers) per pixel.

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about the Cassini-Huygens mission visit https://saturn.jpl.nasa.gov and https://www.nasa.gov/cassini. The Cassini imaging team homepage is at https://ciclops.org and ESA's website: http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Image, Text, Credits: NASA/Tony GreiciusJPL-Caltech/Space Science Institute.

Greetings, Orbiter.ch

Is Climate Changing Cloud Heights? Too Soon to Say

NASA - EOS Terra Mission patch.

May 6, 2017

Image above: Climate change may eventually change global cloud heights, but scientists need a longer data set to know whether that's happening already. Image Credit: NASA.

A new analysis of 15 years of NASA satellite cloud measurements finds that clouds worldwide show no definitive trend during this period toward decreasing or increasing in height. The new study updates an earlier analysis of the first 10 years of the same data that suggested cloud heights might be getting lower.

Clouds are both Earth's cooling sunshade and its insulating blanket. Currently their cooling effect prevails globally. But as Earth warms, the characteristics of clouds over different global regions -- their thickness, brightness and height -- are expected to change in ways that scientists don't fully understand. These changes could either amplify warming or slow it. Pinning down some of the uncertainties around clouds is one of the biggest challenges in determining the future rate of global climate change.

The study used data from the Multi-angle Imaging Spectroradiometer (MISR) instrument on NASA's Terra satellite. Using nine cameras pointing at Earth at different angles, it records images in four visible and near-infrared wavelengths. The images allow researchers to distinguish the amounts, types and heights of clouds. Launched in December 1999 with a planned six-year mission life, MISR was built and is operated by NASA's Jet Propulsion Laboratory in Pasadena, California.

Five years ago, Roger Davies, Buckley-Glavish professor of climate physics at the University of Auckland, New Zealand, and a colleague analyzed the first 10 years of MISR data. Their results suggested that cloud heights had lowered over the decade, raising the possibility that climate change effects on clouds might already be discernible.

In the new study published recently in the Journal of Geophysical Research – Atmospheres, Davies and colleagues from JPL incorporated an additional five years of data into their analysis and reanalyzed the first 10 years. In particular, they were sleuthing for factors related to the instrument or image processing that might have made clouds appear artificially high in the first years of the mission.

Artist's concept of Terra satellite. Image Credit: NASA

The researchers checked several possible factors and found they were all insignificant except one, a change in the Terra satellite's equator-crossing time. Terra crosses the equator at the same local times of day on each orbit. Its morning equator-crossing time was originally planned for 10:30 a.m., but due to launch timing, Terra initially crossed the equator at 10:45 a.m. instead. To bring it back to the planned time, spacecraft operators slowly adjusted its orbit over the first two years.

Davies knew this time change wasn't significant in terms of clouds themselves -- clouds don't change much during 15 minutes in mid-morning. In the new analysis, however, he discovered that the change was significant in a different way: it reduced the ability to detect high clouds in the MISR images by reducing the occurrence of sun-glint. Sun-glint appears in satellite images when sunlight reflects off Earth's surface at the same angle that the satellite is viewing the surface -- as if Earth's surface were at the point of a giant V and the sun and satellite were on the two arms of the V. Thin, high clouds are easier to detect in the presence of sun-glint, so the first images with more sun-glint appeared to have more high clouds than the later images.

Once the researchers corrected for the sun-glint issue and added the new years of data, they saw no statistically significant trend in cloud height over the 15-year period.

Cloud heights do, however, vary considerably from year to year in connection with weather and climate phenomena. La Niña and El Niño events have the strongest effect, with the 2008 La Niña lowering global clouds on average by 130 feet (40 meters) and El Niño events pushing them upward. Beyond that, the researchers found differences in Southern Hemisphere and Northern Hemisphere cloud behavior and regional correlations that warrant further investigation.

With cloud heights naturally varying so much, Davies thinks it could take another 15 years of data to spot any possible global effects of climate change. "All we can say at the moment is that the global trends in cloud heights, if they are there, are being swamped by El Niño-La Niña fluctuations," he said. "It will take a lot longer till we can tease out these long-term trends."

For more on MISR, visit: http://www-misr.jpl.nasa.gov/

Terra Satellite: http://www.nasa.gov/mission_pages/terra/index.html

Images (mentioned), Text, Credits: NASA/Tony Greicius/Earth Science News Team, written by Carol Rasmussen/JPL/Alan Buis.

Greetings, Orbiter.ch