Chandra X-ray Observatory Celebrates Its 15th Anniversary

Image credit: NASA/CXC/SAO

In commemoration of the 15th anniversary of NASA’s Chandra X-ray Observatory, four newly processed images of supernova remnants dramatically illustrate Chandra’s unique ability to explore high-energy processes in the cosmos.

The images of the Tycho and G292.0+1.8 supernova remnants show how Chandra can trace the expanding debris of an exploded star and the associated shock waves that rumble through interstellar space at speeds of millions of miles per hour. The images of the Crab Nebula and 3C 58 show how extremely dense, rapidly rotating neutron stars produced when a massive star explodes can create clouds of high-energy particles light years across that glow brightly in X-rays.

Tycho: More than four centuries after Danish astronomer Tycho Brahe first observed the supernova that bears his name, the supernova remnant it created is now a bright source of X-rays. The supersonic expansion of the exploded star produced a shock wave moving outward into the surrounding interstellar gas, and another, reverse shock wave moving back into the expanding stellar debris. This Chandra image of Tycho reveals the dynamics of the explosion in exquisite detail. The outer shock has produced a rapidly moving shell of extremely high-energy electrons (blue), and the reverse shock has heated the expanding debris to millions of degrees (red and green). There is evidence from the Chandra data that these shock waves may be responsible for some of the cosmic rays – ultra-energetic particles – that pervade the Galaxy and constantly bombard the Earth.

G292.0+1.8: At a distance of about 20,000 light years, G292.0+1.8 is one of only three supernova remnants in the Milky Way known to contain large amounts of oxygen. These oxygen-rich supernovas are of great interest to astronomers because they are one of the primary sources of the heavy elements (that is, everything other than hydrogen and helium) necessary to form planets and people. The X-ray image from Chandra shows a rapidly expanding, intricately structured, debris field that contains, along with oxygen (yellow and orange), other elements such as magnesium (green) and silicon and sulfur (blue) that were forged in the star before it exploded.

The Crab Nebula: In 1054 AD, Chinese astronomers and others around the world noticed a new bright object in the sky. This “new star” was, in fact, the supernova explosion that created what is now called the Crab Nebula. At the center of the Crab Nebula is an extremely dense, rapidly rotating neutron star left behind by the explosion. The neutron star, also known as a pulsar, is spewing out a blizzard of high-energy particles, producing the expanding X-ray nebula seen by Chandra. In this new image, lower-energy X-rays from Chandra are red, medium energy X-rays are green, and the highest-energy X-rays are blue.

3C58: 3C58 is the remnant of a supernova observed in the year 1181 AD by Chinese and Japanese astronomers. This new Chandra image shows the center of 3C58, which contains a rapidly spinning neutron star surrounded by a thick ring, or torus, of X-ray emission. The pulsar also has produced jets of X-rays blasting away from it to both the left and right, and extending trillions of miles. These jets are responsible for creating the elaborate web of loops and swirls revealed in the X-ray data. These features, similar to those found in the Crab, are evidence that 3C58 and others like it are capable of generating both swarms of high-energy particles and powerful magnetic fields. In this image, low, medium, and high-energy X-rays detected by Chandra are red, green, and blue respectively.

ESA Presents . . . Once Upon A Time

ESA Presents: …there was a spacecraft called Rosetta. Rosetta had been travelling in space for 10 years, towards a comet called 67P/Churyumov-Gerasimenko. Before long, Rosetta was able to see the comet in the distance, and she took stunning pictures as she got closer and closer. There was only a little way to go now…

Enter our #RosettaAreWeThereYet contest – add your photo to the competition page

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45 Years Ago Today.

The Apollo 11 Lunar Module Eagle. Image Credit: NASA

The Apollo 11 Lunar Module Eagle, in a landing configuration was photographed in lunar orbit from the Command and Service Module Columbia.

Inside the module were Commander Neil A. Armstrong and Lunar Module Pilot Buzz Aldrin. The long rod-like protrusions under the landing pods are lunar surface sensing probes. Upon contact with the lunar surface, the probes sent a signal to the crew to shut down the descent engine.

Hubble Finds a Sombrero 28 Million Light Years from Earth.

The Sombrero Galaxy. Image Credit: The Hubble Space Telescope, NASA/STScI/AURA

NASA’s Hubble Space Telescope has trained its sharp eye on one of the universe’s most stately and photogenic galaxies, Messier 104. The galaxy’s hallmark is a brilliant white, bulbous core encircled by the thick dust lanes comprising the spiral structure of the galaxy. As seen from Earth, the galaxy is tilted nearly edge-on. We view it from just six degrees north of its equatorial plane. This brilliant galaxy was named the Sombrero because in visible light it resembles a broad rimmed and high-topped Mexican hat.

M104 is just beyond the limit of the naked eye, but is easily seen through small telescopes. It lies at the southern edge of the rich Virgo cluster of galaxies. It is one of the most massive objects in that group, equivalent to 800 billion suns. The galaxy is 50,000 light-years across and is located 28 million light-years from Earth.

Hubble easily resolves M104′s rich system of 2,000 globular clusters-believed to be 10 times as many as orbit our Milky Way galaxy. The ages of the clusters are similar to those of the clusters in the Milky Way, ranging from 10-13 billion years. A smaller disk is embedded in the bright core of M104, and is tilted relative to the large disk. X-ray emission hints that there is material falling into the compact core, where a black hole as massive as 1 billion suns resides.

The Hubble Heritage Team took these observations in May-June 2003 with the space telescope’s advanced camera for surveys. Images were taken in three filters (red, green, and blue) to yield a natural-color image. The team took six pictures of the galaxy and then stitched them together to create the final composite image.

Ocean Ecosystem Study Weighs Anchor Today From Narragansett, Rhode Island

The Research Vessel Endeavor is the floating laboratory that scientists will use for the ocean-going portion of the SABOR field campaign this summer. Image Credit: Tom Glennon/University of Rhode Island

NASA embarks this week on a coordinated ship and aircraft observation campaign off the Atlantic coast of the United States, an effort to advance space-based capabilities for monitoring microscopic plants that form the base of the marine food chain.

This summer image of the Gulf of Mexico was created from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument that flies about NASA's Aqua satellite. Reds and oranges represent high concentrations of phytoplankton and river sediment. Credit: Goddard SVS

Phytoplankton, tiny ocean plants that absorb carbon dioxide and deliver oxygen to Earth’s atmosphere, play a major role in the global cycling of atmospheric carbon between the ocean and the atmosphere. NASA has long used satellites to make observations of the concentration of phytoplankton worldwide, but new types of tools are needed if scientists are to understand how and why different species and concentrations of phytoplankton change from year to year.

For three weeks, NASA’s Ship-Aircraft Bio-Optical Research (SABOR) experiment will bring together marine and atmospheric scientists to tackle the optical issues associated with satellite observations of phytoplankton.

Technician Richard Hare installs instruments on NASA's UC-12 aircraft at NASA’s Langley Research Center in preparation for the airborne portion of the SABOR field campaign. Image Credit: David C. Bowman/NASA Langley

On Friday, July 18, researchers aboard the National Science Foundation’s Research Vessel Endeavor, operated by the University of Rhode Island, will depart from Narragansett, Rhode Island, to study ocean ecosystems from the Gulf of Maine to the Bahamas. NASA’s UC-12 airborne laboratory, based at NASA’s Langley Research Center in Hampton, Virginia, will make coordinated science flights beginning Sunday, July 20.

“By improving our in-water and aircraft-based measurements of particles and material in the ocean, including phytoplankton, SABOR will advance understanding of marine ecology and the carbon cycle,” said Paula Bontempi, ocean biology and biogeochemistry program manager at NASA Headquarters in Washington.

Brian Cairns. NASA

One obstacle in observing marine ecosystems from space is that atmospheric particles interfere with the measurement. Brian Cairns of NASA’s Goddard Institute for Space Studies (GISS) in New York will lead a team flying a polarimeter instrument to address this issue. From an altitude of about 30,000 feet, the instrument will measure properties of reflected light, such as brightness and the magnitude of polarization. These measurements define the concentration, size, shape, and composition of particles in the atmosphere.

NASA Langley’s UC-12 twin turbo-prop aircraft flew all over the Midwest, supporting a mission trying to capture thermal images of the space shuttle Discovery. Credit: NASA/Kathy Barnstorff.

These polarimeter measurements of reflected light provide valuable context for data from another instrument on the UC-12 designed to reveal how plankton and optical properties vary with depth in the water.

Chris Hostetler. NASA





Chris Hostetler of Langley is leading a group to test a prototype lidar (light detection and ranging) system, the High Spectral Resolution Lidar-1 (HSRL-1), which uses a laser to probe the ocean to a depth of about 160 feet. These data will reveal how phytoplankton concentrations change with depth along with the amount of light available for photosynthesis.

Knowledge of the vertical distribution of phytoplankton is needed to understand their productivity, which largely drives the functioning of ocean ecosystems. These data will allow NASA scientists to improve satellite-based estimates of how much atmospheric carbon dioxide is absorbed by the ocean.

Dr. Alex Gilerson

Simultaneous measurements from the ship will provide a close-up perspective, as well as validate measurements from the aircraft. Alex Gilerson of the City College of New York will lead a group on the ship operating an array of instruments including an underwater video camera equipped with polarization vision, which can accurately and continuously measure key characteristics of the sky and the water while underway.

Dr. Ivona Cetinic

A team led by Ivona Cetinic, of the University of Maine in Walpole, will analyze water samples for carbon, as well as pump seawater continuously through various on-board instruments to measure how ocean particles, including phytoplankton, interact with light.

Another group led by Mike Behrenfeld of Oregon State University in Corvallis will employ a new technique to directly measure phytoplankton biomass along with photosynthesis.

Professor Behrenfeld.

“The goal is to develop mathematical relationships that allow scientists to calculate the biomass of the phytoplankton from optical signals measured from space, and thus to be able to monitor how ocean phytoplankton change from year to year and figure out what causes these changes,” Behrenfeld said.

NASA satellites contributing to SABOR include the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), which observes clouds and tiny particles in Earth’s atmosphere, as well as the Terra and Aqua satellites, which measure atmospheric, land and marine processes.

Analysis of the combined data from ship, aircraft and satellites is expected to help guide preparation for a new advanced ocean satellite mission called the Pre-Aerosol, Clouds, and ocean Ecosystem (PACE) mission. PACE will extend observations of ocean ecology, biogeochemical cycling and ocean productivity begun by NASA in the late 1970s with the Coastal Zone Color Scanner and continued with the Sea-viewing Wide Field-of-view-Sensor (SeaWiFS) and the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on Terra and Aqua.

SABOR is funded by the Earth Science Division in the Science Mission Directorate at NASA Headquarters. Project management and support will be provided by the Earth Science Project Office at NASA’s Ames Research Center in Moffett Field, California. Other mission scientists include researchers at the Naval Research Laboratory and WET Labs, Inc., in Narragansett, Rhode Island.

NASA monitors Earth’s vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth’s interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.


Steve Cole
Headquarters, Washington

Michael Cabbage
Goddard Institute for Space Studies, New York

Russian meteorite sheds light on dinosaur extinction mystery.

This incredible picture of the Russian meteorite was taken by professional photographer Marat Akhmetaleyev .

A long-standing debate about the source of the asteroid that impacted the Earth and caused the extinction of the dinosaurs has been put to rest thanks to the Chelyabinsk meteorite that disintegrated over Russia in February 2013, a new paper published in the journal Icarus shows.

Astronomers have debated whether the dinosaur killer was linked to the breakup of a large asteroid forming the Baptistina Asteroid Family (BAF) beyond Mars, some of which ended up on Earth-crossing orbits. The asteroid impacting Earth is thought to have been dark and carbonaceous. The BAF hypothesis was bolstered by them being dark and with a spectral shape similar to carbonaceous meteorites.

Fragment of Chelyabinsk meteorite, showing the fusion crust -- the result of a previous collision or near miss with another planetary body or with the sun. Credit: Dr. Victor Sharygin

Analysis of the Chelyabinsk meteorite shows that shock produced during catastrophic disruption of a large asteroid can darken otherwise bright silicate material. Shock darkening was first reported by Dan Britt (now at the University of Central Florida) in the early 1990s. The Chelyabinsk meteorite has both bright unshocked and dark shocked material. However, the details of the spectra of the dark Chelyabinsk material closely reproduces spectral signatures seen with members of the Baptistina Asteroid Family, said Planetary Science Institute Research Scientist Vishnu Reddy, lead author of “Chelyabinsk meteorite explains unusual spectral properties of Baptistina Asteroid Family” that appears in Icarus.

“Shock and impact melt can make bright asteroids dark,” Reddy said. “In other words, not all dark asteroids are rich in carbon as once thought.” The latest measurements rule out the possibility for the Baptistina family being the source of the K/T impactor, he added.

“The link between the K/T impacator, thought to be carbonaceous, and BAF, has been proved invalid,” Reddy said.

The double layer of the K/T boundary is clearly seen. The lower ejecta layer is a light gray claystone that's easiest to spot and contains ejecta from the impact. The upper layer is much darker and contains the extraterrestrial iridium spike from the impactor.

K–T extinction, abbreviation of Cretaceous–Tertiary extinction, also called K–Pg extinction orCretaceous–Paleogene extinction,  a global extinction event responsible for eliminating approximately 80 percent of all species of animals at or very close to the boundary between theCretaceous and Paleogene periods, about 66 million years ago. The K–T extinction was characterized by the elimination of many lines of animals that were important elements of the Mesozoic Era (252.2 million to 66 million years ago), including nearly all of the dinosaurs and many marine invertebrates. The event receives its name from the German word Kreide, meaning “chalk,” and the word Tertiary, which was traditionally used to describe the period of time spanning the Paleogene and Neogene periods. The K–T extinction ranks third in severity of the five major extinction episodes that punctuate the span of geologic time.

Chelyabinsk provided a great opportunity to see the mixture of shocked and unshocked material in a single meteorite, Reddy said while cautioning that no clear evidence exists that the Russian meteorite itself came from the Baptistina family.

“The new finding has implications for hazards from Near-Earth Objects and for mining asteroids for space-based resources,” Reddy said. “A potential target identified as primitive and rich in volatiles/organics and carbon based on its spectral colors could in fact be just shocked material with entirely different composition.”

PSI researchers David P. O’Brien and Lucille Le Corre were among the co-authors on the paper.
Journal reference: Icarus
Provided by Planetary Science Institute

Comet Shoemaker-Levy 9 . . . Twenty Years Later

Comet Shoemaker-Levy 9 Approaches Jupiter. This composite is assembled from separate images of Jupiter and comet Shoemaker-Levy 9, as imaged by the NASA/ESA Hubble Space Telescope in 1994.

The freight train of Shoemaker-Levy 9 fragments before they crashed into Jupiter.

Twenty years ago, human and robotic eyes observed the first recorded impact between cosmic bodies in the solar system, as fragments of comet Shoemaker-Levy 9 slammed into the atmosphere of Jupiter. Between July 16 and July 22, 1994, space- and Earth-based assets managed by NASA’s Jet Propulsion Laboratory in Pasadena, California, joined an armada of other NASA and international telescopes, straining to get a glimpse of the historic event:

  • NASA’s Galileo spacecraft, still a year-and-a-half out from its arrival at Jupiter, had a unique view of fireballs that erupted from Jupiter’s southern hemisphere as the comet fragments struck.
  • NASA’s Hubble Space Telescope, using the JPL-developed and -built Wide Field and Planetary Camera 2, observed the comet and the impact scars it left on Jupiter.
  • The giant radio telescopes of NASA’s Deep Space Network — which perform radio and radar astronomy research in addition to their communications functions — were tasked with observing radio emissions from Jupiter’s radiation belt, looking for disturbances caused by comet dust.
  • NASA’s Voyager 2 spacecraft, then about 3.7 billion miles (6 billion kilometers) from Jupiter, observed the impacts with its ultraviolet spectrometer and a planetary radio astronomy instrument.
  • The Ulysses spacecraft also made observations during the comet impact from about 500 million miles (800 million kilometers) away. Ulysses observed radio transmissions from Jupiter with its combined radio wave and plasma wave instrument.

The “freight train” of fragments smashed into Jupiter with the force of 300 million atomic bombs. The fragments created huge plumes that were 2,000 to 3,000 kilometers (1,200 to 1,900 miles) high, and heated the atmosphere to temperatures as hot as 30,000 to 40,000 degrees Celsius (53,000 to 71,000 degrees Fahrenheit). Shoemaker-Levy 9 left dark, ringed scars that were eventually erased by Jupiter’s winds.

Impact marks on Jupiter's cloud tops.

While the impact was dramatic, it was more than a show. It gave scientists an opportunity to gain new insights into Jupiter, Shoemaker-Levy 9 and cosmic collisions in general. Researchers were able to deduce the composition and structure of the comet. The collision also left dust floating on the top of Jupiter’s clouds. By watching the dust spread across the planet, scientists were able to track high-altitude winds on Jupiter for the first time. And by comparing changes in the magnetosphere with changes in the atmosphere following the impact, scientists were able to study the relation-ship between them.

An infrared image of Jupiter showing the bright polar caps and the familiar red storm (at right). The bright spots in the southern hemisphere are the aftermath of fragments of comet Shoemaker Levy, which struck in 1994. Photo Credit: Photo: James Graham, Imke de Pater, Mike Brown, Mike Liu, Garrett Jernigan, Marina Fomenkova, Andy Ingersoll, Phil Marcus, W. M. Keck Observatory.

Scientists have calculated that the comet was originally about 1.5 to 2 kilometers (0.9 to 1.2 miles) wide. If a similar-sized object were to hit Earth, it would be devastating. The impact might send dust and debris into the sky, creating a haze that would cool the atmosphere and absorb sunlight, enveloping the entire planet in darkness. If the haze lasted long enough, plant life would die – along with the people and animals that depend on it to survive.

These kinds of collisions were more frequent in the early solar system. In fact, comet impacts were probably the main way that elements other than hydrogen and helium got to Jupiter.

Today, impacts of this size probably occur only every few centuries – and pose a real threat.

The late Gene Shoemaker, David Levy, Carolyn Shoemaker the discoverers of comet Shoemaker Levy), and Charles S. Morris. This was taken during one of the last Shoemaker-Levy observing runs at Palomar. Courtesy ©1997 Jean Mueller.

Shoemaker-Levy 9 was discovered by Carolyn and Gene Shoemaker and David Levy in a photograph taken on 18 March 1993 with the 0.4-meter Schmidt telescope at Mt. Palomar.

The work of scientists in studying the Shoemaker-Levy 9 impact raised awareness about the potential for asteroid impacts on Earth and the need for predicting them ahead of time, important factors in the formation of NASA’s Near-Earth Object Program Office. The NEO Program Office coordinates NASA-sponsored efforts to detect, track and characterize potentially hazardous asteroids and comets that could approach Earth.

The Galileo mission was managed by NASA’s Jet Propulsion Laboratory in Pasadena, California, for the agency’s Science Mission Directorate. JPL also manages the Voyager mission and the Deep Space Network for NASA. NASA’s Near-Earth Object Program at NASA Headquarters, Washington, manages and funds the search, study and monitoring of asteroids and comets whose orbits periodically bring them close to Earth. JPL manages the Near-Earth Object Program Office for NASA’s Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology, Pasadena.


Preston Dyches
Jet Propulsion Laboratory, Pasadena, Calif.