Zebra Stripes in Outer Space

“Zebra Stripes in Outer Space”:
Long-standing mystery of radiation belt signature explained

In an article recently accepted in the Journal of Geophysical Research, Dr. Solène Lejosne, post-doctoral fellow at the UC Berkeley’s Space Sciences Laboratory and Pr. Juan G. Roederer, Professor Emeritus from the Geophysical Institute of Alaska, propose a new theory to explain a feature of the Earth’s Van Allen radiation belt particles that has defied satisfactory explanation for half a century.

This feature has been given the name “zebra stripes” by space physicists because it shows up as a zebra-like pattern in energy spectrograms, Continue reading

MAVEN Studies Mars Upper Atmosphere to Determine “What Happened to the Atmosphere”

The MAVEN mission is the first spacecraft specifically designed to study Mars’ upper atmosphere. MAVEN’s goal is to understand how Mars lost its thick, early atmosphere to space, and how this in turn caused it to lose its once hospitable climate.

MAVEN’s orbit gives it the most comprehensive view of the Martian atmosphere to date. Circling the red planet every 4.5 hours on an elliptical path, MAVEN passes close to the north and south poles at an inclination of 75 degrees. This allows MAVEN to gather a north-south swath of data with each pass. At the same time, Mars itself rotates eastward beneath MAVEN, giving the orbiter longitudinal coverage. The combination of MAVEN’s orbit and Mars’ daily rotation provides a complete picture of the Martian atmosphere every day.

(Video credit: NASA’s Goddard Scientific Visualization Studio)
NASA Goddard
NASA – National Aeronautics and Space Administration

Ancient regions on Mars bear signs of abundant water—such as features resembling valleys and deltas, and minerals that only form in the presence of liquid water. Scientists think that billions of years ago, the atmosphere of Mars was much denser and warm enough to form rivers, lakes, and perhaps even oceans of water. As the planet cooled and lost its global magnetic field, the solar wind and solar storms eroded away to space a significant amount of the planet’s atmosphere, turning ‪#‎Mars‬ into the cold, arid desert we see today. The goal of MAVEN is to determine how much of Mars’ atmosphere and water have been lost to space, and how these processes have changed the climate on the Red Planet over its history.

NASA’s Van Allen Probes Revolutionize View of Radiation Belts

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About 600 miles from Earth’s surface is the first of two donut-shaped electron swarms, known as the Van Allen Belts, or the radiation belts. Understanding the shape and size of the belts, which can shrink and swell in response to incoming radiation from the sun, is crucial for protecting our technology in space. The harsh radiation isn’t good for satellites’ health, so scientists wish to know just which orbits could be jeopardized in different situations.

Since the 1950s, when scientists first began forming a picture of these rings of energetic particles, our understanding of their shape has largely remained unchanged—a small, inner belt, a largely-empty space known as the slot region, and then the outer belt, which is dominated by electrons and which is the larger and more dynamic of the two. But a new study of data from NASA’s Van Allen Probes reveals that the story may not be so simple.

The complete article is here.

NuSTAR observes stellar corpses in the Andromeda galaxy

Andromeda Collapse

NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, has captured the best high-energy X-ray view yet of a portion of our nearest large, neighboring galaxy, Andromeda. The space mission has observed 40 “X-ray binaries” — intense sources of X-rays comprised of a black hole or neutron star that feeds off a stellar companion.

The results will ultimately help researchers better understand the role of X-ray binaries in the evolution of our universe. According to astronomers, these energetic objects may play a critical role in heating the intergalactic bath of gas in which the very first galaxies formed.

“Andromeda is the only large spiral galaxy where we can see individual X-ray binaries and study them in detail in an environment like our own,” said Daniel Wik of NASA Goddard Space Flight Center in Greenbelt, Maryland, who presented the results at the 227th meeting of American Astronomical Society in Kissimmee, Florida. “We can then use this information to deduce what’s going on in more distant galaxies, which are harder to see.”

The complete article courtesy of NuSTAR/Caltech

MAVEN Navigation Update

(Image credit: NASA/GSFC)

(Image credit: NASA/GSFC)

As the #MAVEN spacecraft orbits #Mars, its elliptical orbit precesses and incurs changes over time. In order for scientists to acquire the data they need from Mars’ upper atmosphere, the spacecraft must remain within a specific corridor around Mars. The team regularly monitors and models MAVEN’s orbit to ensure that targeted densities are maintained throughout the mission

The MAVEN navigation team performs Orbit Trim Maneuvers (OTMs) about once every two weeks in order to maintain the targeted atmospheric density corridor.

The last OTM, performed on Dec. 29 (on orbit number 2429), lowered the periapsis altitude by 11.3 km to near 139 km, where the density of Mars’ atmosphere is 0.17 kg/km³. The orbit period for MAVEN is currently 4 hours 31.2 minutes with an Earth to MAVEN distance of 1.69 A.U.

Article Courtesy of NASA’s MAVEN Mission to Mars

NASA’s LADEE Mission Shows the Force of Meteoroid Strikes on Lunar Exosphere

Artist’s concept of NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft in orbit above the moon. Credits: NASA Ames / Dana Berry

Artist’s concept of NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft in orbit above the moon.
Credits: NASA Ames / Dana Berry

What is the force of a meteoroid when it strikes our moon? New data from our LADEE mission shows us. The data reveals, for the first time, that meteoroid strikes cause a predictable increase in the abundance of two key elements within the lunar exosphere.

The Complete article is found here.

NuSTAR Finds Cosmic Clumpy Doughnut Around Black Hole

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The most massive black holes in the universe are often encircled by thick, doughnut-shaped disks of gas and dust. This deep-space doughnut material ultimately feeds and nourishes the growing black holes tucked inside.

Until recently, telescopes weren’t able to penetrate some of these doughnuts, also known as tori.

“Originally, we thought that some black holes were hidden behind walls or screens of material that could not be seen through,” said Andrea Marinucci of the Roma Tre University in Italy, lead author of a new Monthly Notices of the Royal Astronomical Society study describing results from NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, and the European Space Agency’s XMM-Newton space observatory.

The complete story, courtesy of Caltech is here.