Biologist Dr. Kathie Olsen, NASA’s newly appointed chief scientist, visited Goddard on July 13. Olsen serves as the administrator’s senior scientific advisor and principal interface with national and international science community.

"NASA’s chief scientist has a tremendous responsibility to represent the Agency’s scientific objectives to the outside world, including other Federal agencies, industry, academia, governmental organizations and the international community," Goldin remarked. "Dr. Olsen is a highly motivated and scientifically focused individual whose expertise both inside and outside the Agency will serve us well."

July 20^th marks the 30^th anniversary of Neil Armstrong’s and "Buzz" Aldrin’s first walk on the moon. What a spectacular accomplishment for humankind.

Six hours after the Lunar Module "Eagle" landed on the surface of the Moon, Neil Armstrong exited the craft and stepped into history. He was then joined by "Buzz" Aldrin. The two NASA astronauts spent a total of 21 hours on the lunar surface, gathering 46 pounds of moon rocks for return to Earth.

To celebrate the 30^th anniversary of the Apollo 11 moon landing, NASA employees are invited to a special showing of "Artistry in Space," an exhibit of 78 artworks from collections of the NASA Art Program and the National Air and Space Museum. This artwork will be on display July 21^st through July 23^rd 1 p.m. to 3 p.m. on Track 27 at Union Station in Washington, D.C. The exhibit also will be open to the general public July 24 and 25 from 10 a.m. to 5 p.m. on Track 10 at Union Station.

Your attendance and participation is requested at an important IT Security briefing scheduled for Wednesday, July 21, from 9 to 11 a.m. in the Bldg. 3 Auditorium. Refreshments will be served.

NASA’s Chief Information Officer and Security Officer (Lee Holcomb and Mark Borsi respectively) will speak to the Goddard community on important IT Security matters. Holcomb and Borsi will review NASA's efforts to more effectively respond to and pro-actively manage ongoing IT Security challenges within and around NASA. Time will be allotted for questions and answers.

(This is Part I of a two-part story featuring Goddard scientists’ intentions for Chandra. Part II will be included in next week’s edition of Goddard News.)

Dr. Paul Nandra will use Chandra to peer farther into the region surrounding a black hole than ever before. His target is galaxy PG 1404+226, thought to harbor a super massive black hole in its core.  Super massive black holes have mind-boggling masses of one million to one billion suns condensed in a region no larger than our solar system. Astronomers think they power a phenomenon called Active Galactic Nuclei (AGN), which appears as an outpouring of energy from a tiny region in the center of many galaxies. This energy is seen in radio waves, infrared, optical light and X-rays.

Because super massive black holes are so condensed (massive, yes, but squeezed to a dot within a galaxy), Nandra needs Chandra's high resolution to study them -- particularly high spectral resolution. Nandra won't be looking at black hole images, but rather the spectra of gas swirling into and around the black hole. Spectra (the plural of "spectrum") are like fingerprints. Nandra will be able to detect the type of matter near a black hole, its flow and its velocity. His goal is to find proof of matter actually flying back towards us at two-thirds the speed of light.

Nandra's interest in astronomy may or may not be deep-seated. "I was interested in astronomy as a child, at least according to my mother," Nandra said. "It wasn't until college that I took an astronomy course. Astrophysics seemed much more interesting than my particle physics courses."

Dr. Bram Boroson is studying a double-star system called 4U 1700-37. One of the stars is a supergiant, a million times brighter than our sun. The other star is most likely a neutron star, the remains of a giant star that blew apart and left a concentrated, ultra-dense core only a few miles in diameter. Boroson said that the neutron star's powerful gravitational force pulls in gas from the stellar wind produced by the supergiant. As this gas rushes towards that neutron star at one-third the speed of light, it heats to high temperatures and emits X-ray. With Chandra, Boroson hopes to learn more about stellar winds, as well as the feedback between the neutron star and the stellar wind.

Boroson needs an X-ray telescope to do this work because the hot gas is only visible in X-ray radiation, not visible light. It would be "invisible" to an optical telescope. With Chandra, he will examine the X-ray spectrum with detail much finer than any other X-ray telescope can provide. In doing so, he will be able to determine the speed and temperature of many different gas atoms.

Boroson finds X-ray astronomy awe-inspiring. "We only started seeing the universe in X-rays in 1962. Imagine if people had only started to see stars less than forty years ago! That's what it's like in X-ray astronomy. In our own Galaxy, we've found neutron stars a thousand trillion times denser than ordinary matter, spinning nearly a thousand times a second. We've also found black holes that shoot out jets of gas that appear (by an optical illusion) to be moving faster than light."

Dr. Mike Corcoran is leading two Chandra observations. The first is a study of a strange, unstable and extremely massive star called Eta Carinae, one of the largest star known. With Chandra, he will be able to obtain a high-resolution spectrum of the star's X-rays. The goal is to determine where the X-rays are coming from and how they are produced. Dr. Corcoran thinks that Eta Carinae may really be two stars, not one.

The second observation is that of a "starburst-type" region of newly formed stars in the Milky Way. This will provide a detailed look at X-rays from a large numbers of stars in a dense region, and thusly will also help astronomers interpret the X-rays they see from more distant "starburst" galaxies.

For Corcoran, X-ray astronomy is the study of extremes. "X-ray astronomy is particularly interesting since the ways in which stars and other objects in space produce X-rays involve very extreme physical conditions. When you see X-ray emission, you're usually looking at extremes of temperature, magnetism or gravity. These extreme conditions are difficult or impossible to duplicate on earth, but (surprisingly!) they're very common in space. X-ray astronomy is the best way to study them."

Dr. Steve Drake will use Chandra to study the coronae, or outer atmospheres, of two distant stars: Algol (Beta Persei) and UX Arietis. He will determine their temperature structure, densities, and the types of atoms present there. For Drake, an X-ray telescope of Chandra's quality is crucial for his line of work. Determining the abundance of elements at such great distances requires high spectral resolution -- the kind that Chandra delivers. In fact, Drake will investigate the reported "under-abundances" of common metals, such as iron, silicon and magnesium. Theory predicts concentrations of these metals in stars to be higher than what's actually being observed. Drake will see if the low numbers are "real" or maybe the result of weaker telescopes with lower spectral resolution. He will also look for variation in elemental abundance over time, especially during periods when solar flares occur.

Drake has been intrigued by stellar coronae ever since he worked on observations of our sun. "I previously worked on the Solar Maximum Mission project, which studied solar flares. We noticed that the flares appeared in ultraviolet radiation just before appearing in X-ray. Fascinated by the relationship, we soon learned to use the ultraviolet instrument as a trigger to prompt the X-ray instrument to better capture the flares. This stimulated my interest in coronae in general, particularly in those of active stars, like Algol and UX Arietis, which can be 10,000 times more powerful than the sun's corona."

Dr. Koji Mukai will use Chandra to study a well-known white dwarf star, called V1223 Sgr, that is accreting gas from a more-or-less normal star nearby. Together, these stars are called cataclysmic variables. As gas funnels onto the white dwarf, it heats to high temperatures and emits X-rays. The name "cataclysmic variable" denotes the way the brightness of X-rays changes over time. In the case of V1223 Sgr, the X-ray brightness doubles every 12 minutes, quite regularly. V1223 Sgr is one of the brightest cataclysmic variables in X-ray.

Mukai will take advantage of Chandra's high spectral resolution to study the spectra of iron atoms in the gas surrounding V1223 Sgr. Spectra, the plural of "spectrum," are produced when light passes through a prism, as we often see in rainbows. Like visible light's rainbow, X-rays can also be characterized into spectra, and these spectra serve as fingerprints of the atoms emitting the X-rays. Mukai said that studying iron spectra will reveal physical conditions on the white dwarf, such as its temperature and pressure.

Mukai said the cataclysmic variables are always full of surprises. "You can't stop observing these cataclysmic variables, because every time you think you understand them, they do something new and exciting. I use X-rays telescopes because X-rays happen to be one of the energy ranges that cataclysmic variables emit their energies."

Dr. Richard Mushotzky, one of the Interdisciplinary scientists in the Chandra Science Working Group, has several projects lined up for Chandra -- from black holes and quasars to map-making and identifying new objects.

He said that one of the recent discoveries from the last year and a half has been that most massive galaxies contain 'dynamical' black holes near their centers. The evidence comes from studying the motion of stars. Think about how the earth follows a particular orbit around the sun, which is due to the sun's gravity. In many elliptical galaxies, some central, compact source with very strong gravity must be present for the stars to move the way they do. When astronomers think of compact sources and strong gravity, one word comes to mind: black holes.

Mushotzky hopes Chandra will find more proof of these massive black holes, and he's pointing the X-ray satellite toward the Virgo cluster of galaxies. "Previous X-ray observations of these galaxies have shown little or no evidence for x-ray emission from these black holes," he said. "However, Chandra, with its excellent angular resolution, will be able to go 100-times fainter."

What Mushotzky will be looking for are X-rays from hot gas swirling into or shooting away from the black hole. After more proof of the black holes is available, the follow-up question will be why are these black hole regions so dim in X-ray energy? Perhaps the X-ray energy is generated near the black hole but can't get out through the flow of incoming gas. Or perhaps the black hole is simply inefficient in producing X-rays.

Keeping a focus on elliptical galaxies, Mushotzky will also search for X-ray binaries. These are two-star systems that emit X-ray energy. They've never been seen in elliptical galaxies, mainly because elliptical galaxies are so far away and no X-ray telescope could peer that far.

"We should be able to see for the first time a whole population of X-ray binaries in elliptical galaxies," said Mushotzky. "New discoveries, whatever they may be. And, whatever results we attain will be exciting. If we don't see any, that will be exciting too."

Still within the Virgo cluster of galaxies, Mushotzky will create precision maps of the temperature and chemical abundance of the gas. For this, he relies on Chandra's superior spectral resolution. He said a bonus of the Virgo observations will be studying quasars far behind the cluster. He is interested in the way gas from the cluster affects quasar observations. Perhaps the gas bends or magnifies the quasar light, creating a space mirage.

Dr. Gerard Williger is studying the region of the sky toward a distant quasar, called Q 1429-007, which is billions of light-years away. The quasar appears to have two identical images, which implies that there is a large mass in front of it whose gravity bends the quasar light to form two images in our direction. This is called a gravitational lens, and the culprit might be a galaxy cluster in between the quasar and us. Massive clusters can contain around 1,000 galaxies. More importantly, they also have a lot of hot gas between the galaxies, making a type of cosmic "soup". The multi-million-degree gas gives off X-rays.

Astronomers have looked for the cluster of galaxies using optical telescopes, but so far haven't found it. Williger thinks that it may be a "dark cluster", one with lots of mass, but with few optically bright galaxies. The best way to detect it, he said, would be to use an powerful X-ray satellite like Chandra to search for the hot gas within the cluster.

Dark clusters were only discovered two years ago -- using an X-ray satellite. Chandra can distinguish even finer detail and can tell the difference between a point source (for example, the quasar which is behind the cluster that Williger is looking for) and an extended source, such as the cluster itself.

Williger said that studying X-rays can be very insightful. "X-rays are one of many wavelengths which astronomers use to find out about the universe," Williger reported. "NASA Goddard is a center of excellence for X-ray astronomy, so it is natural to use the expertise here to help me to do research with X-rays."

Other Goddard scientists collaborating with Williger are Alain Smette, Richard Mushotzky and Demos Kazanas .

Dr. Tahir Yaqoob will study the galaxy NGC 5548, which is thought to harbor a supermassive black hole in its core. Supermassive black holes have mind-boggling masses of one million to one billion suns condensed in a region no larger than our solar system. Astronomers think they power a phenomenon called Active Galactic Nuclei, which appears as an outpouring of energy from a tiny region in the center of many galaxies, including NGC 5548. This energy is seen in radio waves, infrared, optical light and X-rays.

Many astronomers are using Chandra to study AGN. Yaqoob's focus is on QPOs, which stands for Quasi-Periodical Oscillations. QPOs in NGC 5548 would yield information about the dynamics of the material being swallowed by a black hole. QPOs are commonly seen in X-ray binary systems, a system of two stars emitting X-rays. Reports of QPOs in AGN are very rare, and NGC 5548 is one of those rare objects. A QPO was detected by EXOSAT, an X-ray satellite from the 1980s, but the result was very controversial due to the weakness of the signal.

Family Science Night at National Air and Space Museum

The Challenger Center for Space Science Education and the Museum, together with NASA’s Human Exploration and Development of Space enterprise, the Office of Space Science and the Education Division, invite all Goddard civil servants and contractors to a special FREE Family Science Night on either Aug. 16 or 17.

The Museum can only offer this program if 400 or more attendees sign up. If you are interested in attending this event, sign up on the Internet at the following site: http://www.challenger.org/fsn/nasahqi no later than July 23.

Hours for this special event are from 8 p.m. to 9:45 p.m. Included are 20 minutes to explore the Milestones of Flight and Space Hall galleries and "How Big is Big?" – an exciting talk by Dr. Jeff Goldstein, Challenger Center's Director of Space Science Research. Children of all ages are asked to put on their thinking caps because audience participation will be important. The evening will conclude with the IMAX film "Cosmic Voyage" – a flight through the universe.

Center Director Al Diaz recently approved new traffic management policies and procedures for Goddard that will take effect Aug. 2. Point assessment for traffic violations on Center are as follows:
                                                                

Employees are reminded to yield the right-of-way to pedestrians in crosswalks, to observe Center speed limits, stop signs, parking restrictions, mandatory seat belt use and the display of NASA/GSFC badges.

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