NASA’s SDO Sees Partial Eclipse in Space

NASA – Solar Dynamics Observatory (SDO) patch.

May 26, 2017

On May 25, 2017, NASA’s Solar Dynamics Observatory, or SDO, saw a partial solar eclipse in space when it caught the moon passing in front of the sun. The lunar transit lasted almost an hour, between 2:24 and 3:17 p.m. EDT, with the moon covering about 89 percent of the sun at the peak of its journey across the sun’s face. The moon’s crisp horizon can be seen from this view because the moon has no atmosphere to distort the sunlight.

While the moon’s edge appears smooth in these images, it’s actually quite uneven. The surface of the moon is rugged, sprinkled with craters, valleys and mountains. Peer closely at the image, and you may notice the subtle, bumpy outline of these topographical features.

Animation above: On May 25, 2017, NASA’s Solar Dynamics Observatory, or SDO, experienced a partial solar eclipse in space when it observed the moon passing in front of the sun. The lunar transit lasted about an hour, between 2:24 and 3:17 p.m. EDT, with the moon covering about 89 percent of the sun at the peak of its journey across the face of the sun. Animation Credits: NASA’s Goddard Space Flight Center/SDO/Joy Ng, producer.

Later this summer on Aug. 21, 2017, SDO will witness another lunar transit, but the moon will only barely hide part of the sun. However, on the same day, a total eclipse will be observable from the ground. A total solar eclipse — in which the moon completely obscures the sun — will cross the United States on a 70-mile-wide ribbon of land stretching from Oregon to South Carolina. Throughout the rest of North America — and even in parts of South America, Africa, Europe and Asia — a partial eclipse will be visible.

The moon’s rough, craggy terrain influences what we see on Earth during a total solar eclipse. Light rays stream through lunar valleys along the moon’s horizon and form Baily’s beads, bright points of light that signal the beginning and end of totality.

The moon’s surface also shapes the shadow, called the umbra, that races across the path of totality: Sunlight peeks through valleys and around mountains, adding edges to the umbra. These edges warp even more as they pass over Earth’s own mountain ranges. Visualizers used data from NASA’s Lunar Reconnaissance Orbiter, or LRO, coupled with NASA topographical data of Earth, to precisely map the upcoming eclipse in unprecedented detail. This work shows the umbral shape varies with time, and is not simply an ellipse, but an irregular polygon with slightly curved edges.

LRO is currently at the moon gathering data and revolutionizing our understanding of Earth’s nearest celestial neighbor. Knowing the shape of Earth and the moon plays a big part in accurately predicting the umbra’s shape as it falls on Earth, come Aug. 21.

SDO will see its partial eclipse in space just after the total eclipse exits the United States.

For more information about the upcoming total solar eclipse, visit eclipse2017.nasa.gov.

Related links:

NASA Satellites Ready When Stars and Planets Align: https://www.nasa.gov/feature/goddard/2017/nasa-satellites-ready-when-stars-and-planets-align

SDO Witnesses a Double Eclipse: http://orbiterchspacenews.blogspot.ch/2016/09/nasas-sdo-witnesses-double-eclipse.html

The Moon and Sun: Two NASA Missions Join Images: https://www.nasa.gov/mission_pages/LRO/news/sun-moon.html

NASA’s Solar Dynamics Observatory, or SDO: https://www.nasa.gov/mission_pages/sdo/main/index.html

NASA’s Lunar Reconnaissance Orbiter, or LRO: https://www.nasa.gov/mission_pages/LRO/overview/index.html

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

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CubeSats Deployed Before Upcoming Crew and Cargo Missions

ISS – Expedition 51 Mission patch.

May 26, 2017

More CubeSats were ejected from the International Space Station this week to explore the Earth’s upper atmosphere. Meanwhile, the Expedition 51 crew trained for a crew departure and cargo craft arrival.

NanoRacks, a private company with facilities on the space station, deployed a total of 17 CubeSats over two days this week from a satellite deployer outside the Japanese Kibo lab module. The tiny satellites will orbit Earth for up to two years observing Earth’s thermosphere and studying space weather.

Image above: A trio of CubeSats, with Earth’s limb and thin atmosphere in the background, is seen shortly after being ejected from a small satellite deployer outside Japan’s Kibo lab module. Image Credit: NASA.

Two Expedition 51 crew members are returning to Earth June 2 completing a 196 day mission in space. Soyuz Commander Oleg Novitskiy and Flight Engineer Thomas Pesquet practiced their descent today in their Soyuz MS-03 spacecraft. The duo are expected to land in Kazakhstan next Friday at 10:10 a.m. EDT.

The Dragon resupply ship, from SpaceX and loaded with brand new science experiments, will launch June 1 and arrive at the station June 4. NASA astronaut Jack Fischer will be at the robotics controls commanding the Canadarm2 to reach out and grapple Dragon. He and station Commander Peggy Whitson familiarized themselves today with the Dragon capture procedures and lighting conditions inside the cupola.

Related links:

CubeSats: https://www.nasa.gov/mission_pages/cubesats/index.html

NanoRacks: http://nanoracks.com/products/smallsat-deployment/

Soyuz MS-03: https://www.nasa.gov/feature/visiting-vehicle-launches-arrivals-and-departures

SpaceX: https://www.nasa.gov/spacex

Expedition 51: https://www.nasa.gov/mission_pages/station/expeditions/expedition51/index.html

Image (mentioned), Text, Credits: NASA/Mark Garcia.

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Camera on NASA’s Lunar Orbiter Survived 2014 Meteoroid Hit

NASA – Lunar Reconnaissance Orbiter (LRO) patch.

May 26, 2017

On Oct.13, 2014 something very strange happened to the camera aboard NASA’s Lunar Reconnaissance Orbiter (LRO). The Lunar Reconnaissance Orbiter Camera (LROC), which normally produces beautifully clear images of the lunar surface, produced an image that was wild and jittery. From the sudden and jagged pattern apparent in the image, the LROC team determined that the camera must have been hit by a tiny meteoroid, a small natural object in space. 

Image above: The first wild back-and-forth line records the moment on October 13, 2014 when the left Narrow Angle Camera’s radiator was struck by a meteoroid. Image Credits: NASA’s Goddard Space Flight Center/Arizona State University.

LROC is a system of three cameras mounted on the LRO spacecraft. Two Narrow Angle Cameras (NACs) capture high resolution black and white images. The third Wide Angle Camera captures moderate resolution images using filters to provide information about the properties and color of the lunar surface.

The NAC works by building an image one line at a time. The first line is captured, then the orbit of the spacecraft moves the camera relative to the surface, and then the next line is captured, and so on, as thousands of lines are compiled into a full image.

According to Mark Robinson, professor and principal investigator of LROC at ASU’s School of Earth and Space Exploration, the jittery appearance of the image captured is the result of a sudden and extreme cross-track oscillation of the camera. LROC researchers concluded that there must have been a brief violent movement of the left Narrow Angle Camera.

There were no spacecraft events like solar panel movements or antenna tracking that might have caused spacecraft jitter during this period. “Even if there had been, the resulting jitter would have affected both cameras identically,” says Robinson. “The only logical explanation is that the NAC was hit by a meteoroid.”

How big was the meteoroid?

During LROC’s development, a detailed computer model was made to insure the NAC would not fail during the severe vibrations caused by the launch of the spacecraft. The computer model was tested before launch by attaching the NAC to a vibration table that simulated launch. The camera passed the test with flying colors, proving its stability.

Using this detailed computer model, the LROC team ran simulations to see if they could reproduce the distortions seen on the Oct. 13 image and determine the size of the meteoroid that hit the camera. They estimate the impacting meteoroid would have been about half the size of a pinhead (0.8 millimeter), assuming a velocity of about 4.3 miles (7 kilometers) per second and a density of an ordinary chondrite meteorite (2.7 grams/cm3).

“The meteoroid was traveling much faster than a speeding bullet,” says Robinson. “In this case, LROC did not dodge a speeding bullet, but rather survived a speeding bullet!”

How rare is it that the effects of an event like this were captured on camera? Very rare, according to Robinson. LROC typically only captures images during daylight and then only about 10 percent of the day, so for the camera to be hit by a meteor during the time that it was also capturing images is statistically unlikely.

Image above: The Narrow Angle Camera sits on a bench in the clean room at Malin Space Science Systems. The radiator (right) extends off the electronics end and keeps the sensor cool while imaging the moon. Computer modeling shows the meteoroid impacted somewhere on the radiator. Image Credits: Malin Space Science Systems/Arizona State University.

“LROC was struck and survived to keep exploring the moon,” says Robinson, “thanks to Malin Space Science Systems’ robust camera design.”

“Since the impact presented no technical problems for the health and safety of the instrument, the team is only now announcing this event as a fascinating example of how engineering data can be used, in ways not previously anticipated, to understand what is happing to the spacecraft over 236,000 miles (380,000 kilometers) from the Earth,” said John Keller, LRO project scientist from NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Launched on June 18, 2008, LRO has collected a treasure trove of data with its seven powerful instruments, making an invaluable contribution to our knowledge about the moon.

Lunar Reconnaissance Orbiter or LRO. Image Credit: NASA

“A meteoroid impact on the LROC NAC reminds us that LRO is constantly exposed to the hazards of space,” says Noah Petro, deputy project scientist from NASA Goddard. “And as we continue to explore the moon, it reminds us of the precious nature of the data being returned.”

LRO is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, as a project under NASA’s Discovery Program. The Discovery Program is managed by NASA’s Marshall Spaceflight Center in Huntsville, Alabama, for the Science Mission Directorate at NASA Headquarters in Washington.

The Lunar Reconnaissance Orbiter Camera was developed at Malin Space Science Systems in San Diego, California and Arizona State University in Tempe.

LRO (Lunar Reconnaissance Orbiter): http://www.nasa.gov/mission_pages/LRO/main/index.html and http://www.nasa.gov/lro

Images (mentioned), Text, Credits: NASA’s Goddard Space Flight Center, by Nancy Neal Jones/Karl Hille.

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New NASA Mission to Study Mysterious Neutron Stars, Aid in Deep Space Navigation

ISS – International Space Station patch.

May 26, 2017

A new NASA mission is headed for the International Space Station next month to observe one of the strangest observable objects in the universe.

Launching June 1, the Neutron Star Interior Composition Explorer (NICER) will be installed aboard the space station as the first mission dedicated to studying neutron stars, a type of collapsed star that is so dense scientists are unsure how matter behaves deep inside it.

A neutron star begins its life as a star between about seven and 20 times the mass of our sun. When this type of star runs out of fuel, it collapses under its own weight, crushing its core and triggering a supernova explosion. What remains is an ultra-dense sphere only about 12 miles (20 kilometers) across, the size of a city, but with up to twice the mass of our sun squeezed inside. On Earth, one teaspoon of neutron star matter would weigh a billion tons.

“If you took Mount Everest and squeezed it into something like a sugar cube, that’s the kind of density we’re talking about,” said Keith Gendreau, the principal investigator for NICER at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Unlocking Secrets of Neutron Stars with NICER

Video above: Though we know neutron stars are small and extremely dense, there are still many aspects of these remnants of explosive deaths of other stars that we have yet to understand. NICER, a facility to be mounted on the outside of the International Space Station, seeks to find the answers to some of the questions still being asked about neutron stars. By capturing the arrival time and energy of the X-ray photons produced by pulsars emitted by neutron stars, NICER seeks to answer decades-old questions about extreme forms of matter and energy. Data from NICER will also be used in SEXTANT, an on-board demonstration of pulsar-based navigation. Video Credits: NASA’s Johnson Space Center.

Because neutron stars are so dense, scientists are uncertain how matter behaves in their interiors. In everyday experience, objects are composed of atoms. When neutron stars form, their atoms become crushed together and merge. As a result, the bulk of a neutron star is made up of tightly packed subatomic particles — primarily neutrons, as well as protons and electrons, in various states. NICER measurements will help scientists better understand how matter behaves in this environment.

“As soon as you go below the surface of a neutron star, the pressures and densities rise extremely rapidly, and soon you’re in an environment that you can’t produce in any lab on Earth,” said Columbia University research scientist Slavko Bogdanov, who leads the NICER light curve modeling group.

The only object known to be denser than a neutron star is its dark cousin, the black hole. A black hole forms when a star more than approximately 20 times the mass of our sun collapses. A black hole’s powerful gravity establishes a barrier known as an event horizon, which prevents direct observation. So scientists turn to neutron stars to study matter at nature’s most extreme observable limit.

Image above: Animated still image of the NICER payload aboard the International Space Station. Image Credits: NASA’s Goddard Space Flight Center.

“Neutron stars represent a natural density limit for stable matter that you can’t exceed without becoming a black hole,” said Goddard’s Zaven Arzoumanian, NICER deputy principal investigator and science lead. “We don’t know what happens to matter near this maximum density.”

In order to study this limit, NICER will observe rapidly rotating neutron stars, also known as pulsars. These stars can rotate hundreds of times per second, faster than the blades of a household blender. Pulsars also possess enormously strong magnetic fields, trillions of times stronger than Earth’s. The combination of fast rotation and strong magnetism accelerates particles to nearly the speed of light. Some of these particles follow the magnetic field to the surface, raining down on the magnetic poles and heating them until they form so-called hot spots that glow brightly in X-ray light.

“NICER is designed to see the X-ray emission from those hot spots,” Arzoumanian said. “As the spots sweep toward us, we see more intensity as they move into our sightline and less as they move out, brightening and dimming hundreds of times each second.”

A neutron star’s gravity is so strong it warps space-time, the fabric of the cosmos, distorting our view of the star’s surface and its sweeping hot spots. NICER will measure brightness changes related to these distortions as the star spins. This will allow scientists to determine the pulsar’s radius, a key measurement needed to fully understand its interior structure.

“Once we have a measure of the mass and radius, we can tie those results directly into the nuclear physics of what goes on when you compress so much mass into such a small volume,” Arzoumanian said.

Animation above: Animation of the NICER payload aboard the International Space Station. Animation Credits: NASA’s Goddard Space Flight Center.

In addition to understanding how neutron stars are put together, NICER’s observations will also help scientists better understand the critical mass a star must achieve before it can turn into a black hole. This is particularly important in systems where neutron stars orbit another star, allowing them to pull material off the companion star and gain more mass.

“The more neutron stars we observe at high masses, the higher the mass threshold becomes for a star turning into a black hole,” said NICER science team member Alice Harding at Goddard. “Understanding what that critical mass is will help us determine how many black holes and neutron stars there are in the universe.”

NICER will also provide scientists and technologists with a unique opportunity to make advances in deep space navigation. Its X-ray measurements will record the arrival times of pulses from each neutron star it observes, using the regular emissions of pulsars as ultra-precise cosmic clocks, rivaling the accuracy of atomic clocks such as those used inside GPS satellites. Built-in flight software — developed for the Station Explorer for X-ray Timing and Navigation Technology (SEXTANT) demonstration — can see how the predicted arrival of X-ray pulses from a given neutron star changes as NICER moves in its orbit. The difference between expected and actual arrival times allows SEXTANT to determine NICER’s orbit solely by observing pulsars.

Although spacecraft in Earth orbit use the same GPS system that helps drivers navigate on the ground, there’s no equivalent system available for spacecraft traveling far beyond Earth.

“Unlike GPS satellites, which just orbit around Earth, pulsars are distributed across our galaxy,” said Jason Mitchell, the SEXTANT project manager at Goddard. “So we can use them to form a GPS-like system that can support spacecraft navigation throughout the solar system, enabling deep-space exploration in the future.”

Installation on the space station provides scientists and technologists with an opportunity to develop a multi-purpose mission on an established platform.

“With the NICER-SEXTANT mission, we have an excellent opportunity to use the International Space Station to demonstrate technology that will lead us into the outer solar system and beyond, and tell us about some of the most exciting objects in the sky,” Gendreau said.

NICER is an Astrophysics Mission of Opportunity within NASA’s Explorer program, which provides frequent flight opportunities for world-class scientific investigations from space utilizing innovative, streamlined and efficient management approaches within the heliophysics and astrophysics science areas. NASA’s Space Technology Mission Directorate supports the SEXTANT component of the mission, demonstrating pulsar-based spacecraft navigation.

Related Links:

NASA’s NICER mission website: https://www.nasa.gov/nicer

More information on SEXTANT: https://gameon.nasa.gov/projects/deep-space-x-ray-navigation-and-communication/

Download NICER-SEXTANT multimedia resources: https://svs.gsfc.nasa.gov/Gallery/NICER.html

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

NASA’s Goddard Space Flight Center, by Claire Saravia/Rob Garner.Source  Orbiter.ch