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Space News Update — April 24, 2015 —

Contents

In the News

Story 1:

NASA unveils 25th anniversary Hubble photo

Story 2:

First exoplanet visible light spectrum

Story 3:

Rosetta update: Two close flybys of an increasingly active comet

Departments

The Night Sky

ISS Sighting Opportunities

Space Calendar

NASA-TV Highlights

Food for Thought

Space Image of the Week

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1. NASA unveils 25th anniversary Hubble photo

A dramatic new photo taken by the Hubble Space Telescope to mark the observatory's 25th anniversary, showing a cluster of hot young stars shining in the heart of a nursery-like nebula some 20,000 light years from Earth, serves as a reminder of Hubble's enormous impact on astronomy and a glimpse of things to come, NASA's administrator said Thursday. Speaking at the Newseum in Washington, NASA Administrator Charlie Bolden, who served as pilot of the shuttle Discovery for Hubble's launch on April 24, 1990, said the astronauts all knew Hubble "was going to be something special. What we didn't realize was how special it really was going to be."

"Frankly, we never even thought the telescope would last this long," he said. "The original plan for Hubble, we were told, was maybe 15 years. The fact that we're still going strong a quarter century later is thanks to the Hubble heroes -- the scientists, the engineers and the astronauts who flew five missions to service Hubble in space." The photo chosen to mark the telescope's 25th anniversary shows a young cluster of about 3,000 stars known as Westerlund 2, embedded in a vast cloud of gas known as Gum 29 in the southern constellation Carina. The stars are among the hottest, brightest and most massive suns in the local neighborhood, releasing intense ultraviolet radiation and stellar "winds" that help shape the surrounding nebula.

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"The brilliant stars sculpt the gaseous terrain of the nebula and help create a successive generation of baby stars," according to a NASA description of the image. "When the stellar winds hit dense walls of gas, the shockwaves may spark a new torrent of star birth along the wall of the cavity. "The red dots scattered throughout the landscape are a rich population of newly-forming stars still wrapped in their gas-and-dust cocoons. These tiny, faint stars are between 1 million and 2 million years old -- relatively young stars -- that have not yet ignited the hydrogen in their cores. The brilliant blue stars seen throughout the image are mostly foreground stars." The anniversary image merges visible light data from Hubble's Advanced Camera for Surveys and infrared images taken by the Wide Field Camera 3. "As Frank Sinatra used to sing, the best is yet to come," Bolden said. "Thanks to the last servicing mission in 2009, Hubble is expected to continue to provide valuable data until 2020 and beyond. With two-and-a-half decades of historic, trail-blazing science already accomplished, we've come to realize and expect that there is still much more out there to discover."

Check out this link to read more about the HST story: Hubble Space Telescope marks 25 years in orbit

Source: CBS News Return to Contents

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2. First exoplanet visible light spectrum

The exoplanet 51 Pegasi b [1] lies some 50 light-years from Earth in the constellation of Pegasus. It was discovered in 1995 and will forever be remembered as the first confirmed exoplanet to be found orbiting an ordinary star like the Sun [2]. It is also regarded as the archetypal hot Jupiter -- a class of planets now known to be relatively commonplace, which are similar in size and mass to Jupiter, but orbit much closer to their parent stars.

Since that landmark discovery, more than 1900 exoplanets in 1200 planetary systems have been confirmed, but, in the year of the twentieth anniversary of its discovery, 51 Pegasi b returns to the ring once more to provide another advance in exoplanet studies.

The team that made this new detection was led by Jorge Martins from the Instituto de Astrofísica e Ciências do Espaço (IA) and the Universidade do Porto, Portugal, who is currently a PhD student at ESO in Chile. They used the HARPS instrument on the ESO 3.6-metre telescope at the La Silla Observatory in Chile.

Currently, the most widely used method to examine an exoplanet's atmosphere is to observe the host star's spectrum as it is filtered through the planet's atmosphere during transit -- a technique known as transmission spectroscopy. An alternative approach is to observe the system when the star passes in front of the planet, which primarily provides information about the exoplanet's temperature.

The new technique does not depend on finding a planetary transit, and so can potentially be used to study many more exoplanets. It allows the planetary spectrum to be directly detected in visible light, which means that different characteristics of the planet that are inaccessible to other techniques can be inferred.

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The host star's spectrum is used as a template to guide a search for a similar signature of light that is expected to be reflected off the planet as it describes its orbit. This is an exceedingly difficult task as planets are incredibly dim in comparison to their dazzling parent stars.

The signal from the planet is also easily swamped by other tiny effects and sources of noise [3]. In the face of such adversity, the success of the technique when applied to the HARPS data collected on 51 Pegasi b provides an extremely valuable proof of concept.

Jorge Martins explains: "This type of detection technique is of great scientific importance, as it allows us to measure the planet's realmass and orbital inclination, which is essential to more fully understand the system. It also allows us to estimate the planet's reflectivity, or albedo, which can be used to infer the composition of both the planet's surface and atmosphere."

51 Pegasi b was found to have a mass about half that of Jupiter's and an orbit with an inclination of about nine degrees to the direction to the Earth [4]. The planet also seems to be larger than Jupiter in diameter and to be highly reflective. These are typical properties for a hot Jupiter that is very close to its parent star and exposed to intense starlight.

HARPS was essential to the team's work, but the fact that the result was obtained using theESO 3.6-metre telescope, which has a limited range of application with this technique, is exciting news for astronomers. Existing equipment like this will be surpassed by much more advanced instruments on larger telescopes, such as ESO's Very Large Telescope and the future European Extremely Large Telescope [5].

"We are now eagerly awaiting first light of the ESPRESSO spectrograph on the VLT so that we can do more detailed studies of this and other planetary systems," concludes Nuno Santos, of the IA and Universidade do Porto, who is a co-author of the new paper.

Source: Eureka Alert Return to Contents

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3. Rosetta update: Two close flybys of an increasingly active comet

Posted By Emily Lakdawalla

In the two months since I last checked up on the Rosetta mission, the comet has heated up, displaying more and more jet activity. Perihelion is now only four months away, and the pictures are just getting more and more dramatic with time.

Rosetta has completed two close flybys -- one at a distance of only 6 kilometers, on February 14, and one at a distance of 14 kilometers on March 28. During both flybys, stray comet particles spoofed the star sensors that Rosetta uses to understand its orientation in space. Following the second flyby, pointing was affected enough that Rosetta's high-gain antenna rotated away from its Earth pointing, and the spacecraft eventually entered a protective safe mode. The spacecraft is fine and they are working to bring all the science instruments back online, but the entry into safe mode caused them to travel much farther from the comet than planned, and the navigational problems have forced the mission to replan their future trajectory and, consequently, science. It's all part of the fun challenge of doing something nobody's ever done before: orbit a comet as it approaches perihelion.

Rosetta's long residence at the comet paid off recently, as the OSIRIS science camera fortuitously caught a jet in the act of starting up. In an ESA blog post about the fortunate photos, principal investigator Holger Sierks is quoted as saying: "This was a chance discovery. No one has ever witnessed the wake-up of a dust jet before. It is impossible to plan such an image." In a sense, though, ESA was able to make this lucky observation happen by being at the comet for long enough to catch a lucky break.

Until January, Rosetta was flying in circular, "bound" orbits, with the comet holding the spacecraft to its path. But as the comet has gotten more active and begun to produce more gas and dust, that gas and dust exerts drag on the spacecraft, preventing Rosetta from being able to maintain these bound orbits. Since February, though, it has flown further away, on "unbound" orbits, meaning that the comet's gravity no longer constrains the spacecraft's path. With these unbound orbits, Rosetta must perform regular trajectory correction maneuvers to maintain proximity to the comet.

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When your spacecraft's orbit is unbound, a safe mode can mean a missed trajectory correction maneuver and an unplanned excursion. That's what happened during the March 28 flyby, summarized in detail in this blog post. An update from April 10 explains that Rosetta wound up in an escape trajectory and traveled as far as 400 kilometers away from the comet. There wasn't any real danger of Rosetta losing the comet, though, because the speeds involved are very slow and well within the capability of Rosetta's thrusters.

On April 1, a rocket firing began to return the spacecraft toward the comet, and it reached its target distance of 140 kilometers altitude on April 8. It is a terminator orbit, meaning that the spacecraft travels around the comet in an orbital plane that coincides with the night-day boundary, and it sees the comet at roughly half phase at all times. As of that update, the plan was to go into pyramid orbits with minimum altitudes of 100 kilometers throughout the rest of April.

The change in Rosetta's trajectory unfortunately meant a complete replanning of targeted science observations and a reconsideration of the entire orbit strategy, which involved a few more of these close flybys. As of April 10, not all the instruments had been returned to normal operation yet.

Meanwhile, the unplanned excursion from the comet has not affected Rosetta's plans to listen for the Philae lander. Philae mission manager Stefan Ulamec still does not expect conditions to favor Philae's waking until at least next month, but listening campaigns were conducted over a period of about a week beginning March 12 and April 12, just in case.

Throughout all of this work, the NavCam is continuing to photograph the comet to good effect. ESA has begun to release NavCam data using its archive image browser, which presently only contains Rosetta data. It includes NavCam data from the cruise phase of the mission (which was already public; I worked through that archive and blogged about some of the images a while ago), and also includes early images from the comet phase of the mission. As of this writing, it contains images taken through August 1, when Rosetta had approached to within 850 kilometers of the comet. They plan to release images on a monthly basis, eventually catching up to the point that they release pictures approximately six months after the images were originally taken.

Source: The Planetary Society Return to Contents

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The Night Sky

Source: Sky & Telescope Return to Contents

Friday, April 24

The Moon tonight sits on (or near) one side of a big,

almost equilateral triangle: bright Jupiter to the Moon's upper left, Pollux upper right of the Moon, and

Procyon to the Moon's lower left.

Saturday, April 25

First-quarter Moon (exact at 7:55 p.m. EDT). Jupiter shines closer to the upper left of the Moon this

evening. Jupiter poses directly above the Moon as the night grows late. Although they may look close

together, Jupiter is nearly 2,000 times farther away — and 40 times larger in diameter.

Sunday, April 26

After dark now the Big Dipper has turned to lie almost upside down; face east-northeast and look very high.

Its handle arcs around toward Arcturus a little more

than a Dipper-length to the Dipper's lower right.

Monday, April 27

The waxing gibbous Moon shines under Regulus this

evening, as shown here.

Among the moons of Jupiter, telescope users in the western half of North America can watch the shadow

of Io eclipse Europa from 10:59 to 11:02 p.m. PDT. At mid-eclipse, Europa will be dimmed by 1.4

magnitudes.

(Now that Jupiter is far from opposition, we see shadows in the Jovian system falling far enough sideways that an eclipsed satellite and its eclipser appear widely separated in a telescope's view. So we can see the eclipsed satellite dimming by

itself, uncontaminated by the light of the eclipser. The tables in Sky & Telescope for these events presume that the two satellites appear blended and give their combined magnitude. See Bob King's article Catch the Last Best Antics of Jupiter’s

Moons.)

Tuesday, April 28

Look very low in the northeast in twilight to catch the rising of Vega, the "Summer Star." By nightfall it's up in better view.

Once Vega wins clear of the thick low air, it shines as the equal of Arcturus, the "Spring Star" high in the east very far to the upper right.

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ISS Sighting Opportunities

Date Visible Max Height Appears Disappears

Fri Apr 24, 8:20 PM 3 min 21° 18 above WSW 11 above S

Sighting information for other cities can be found at NASA’s Satellite Sighting Information

NASA-TV Highlights (all times Eastern Daylight Time)

8 p.m., Friday, April 24 - “Hubble 25th Anniversary Tribute” -- Live from the Smithsonian’s National Air and Space Museum (all channels) 2:15 a.m., Saturday, April 25 - Coverage of the Undocking of the ISS Progress 57 Cargo Ship from the ISS (all channels) 10 a.m., Saturday, April 25 - “Hubble 25th Anniversary Family Day” -- Event Live from the Smithsonian’s National Air and Space Museum- Steven F. Udvar Hazy Center (NTV-1 (Public), NTV-3 (Media)) 9:10 a.m., Monday, April 27 - ISS Expedition 43 In-Flight Educational Event for ESA with the Italian Space Agency and Flight Engineer Samantha Cristoforetti of the European Space Agency - JSC (all channels) 2:45 a.m., Tuesday, April 28 - Coverage of the Launch of the ISS Progress 59 Cargo Ship to the ISS (all channels) 8:30 a.m., Tuesday, April 28 - Coverage of the Docking of the ISS Progress 59 Cargo Ship to the ISS (all channels)

Watch NASA TV on the Net by going to the NASA website.

Return to Contents

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Space Calendar

Apr 24 - [Apr 17] 25th Anniversary (1990), STS-31 Launch (Space Shuttle Discovery, Hubble

Space Telescope Deployment)

Apr 24 - [Apr 24] SICRAL 2 (Syracuse 3C)/ Thor 7 Ariane 5 Launch

Apr 24 - MESSENGER, Orbital Change Maneuver 17 (OCM-17)

Apr 24 - Comet 10P/Tempel At Opposition (1.415 AU)

Apr 24 - Centaur Object 10199 Chariklo Occults UCAC4-267-153296 (14.3 Magnitude Star)

Apr 24 - Asteroid 2843 Yeti Closest Approach To Earth (1.140 AU)

Apr 24 - Asteroid 8749 Beatles Closest Approach To Earth (1.476 AU)

Apr 24 - 45th Anniversary (1970), Mao 1 Launch (1st Chinese Satellite)

Apr 25 - [Apr 18] Astronomy Day

Apr 25 - Comet C/2014 R1 (Borisov) Closest Approach To Earth (1.776 AU)

Apr 25 - [Apr 23] Asteroid 2015 HE10 Near-Earth Flyby (0.020 AU)

Apr 25 - [Apr 19] Asteroid 2015 HK Near-Earth Flyby (0.052 AU)

Apr 25 - Asteroid 3554 Amun Closest Approach To Earth (0.564 AU)

Apr 25 - Asteroid 295565 Hannover Closest Approach To Earth (1.913 AU)

Apr 25 - Asteroid 991 McDonalda Closest Approach To Earth (2.221 AU)

Apr 25 - Griffith Observatory Star Party, Los Angeles, California

Apr 26 - Comet 185P/Petriew At Opposition (4.260 AU)

Apr 26 - Comet 244P/Scotti At Opposition (4.350 AU)

Apr 26 - Kuiper Belt Object 2010 EK139 At Opposition (36.479 AU)

Apr 27 - TurkmenAlem 52E/MonacoSat Falcon 9 Launch

Apr 27 - Comet 22P/Kopff Closest Approach To Earth (1.390 AU)

Apr 27 - Comet 268P/Bernardi Perihelion (2.420 AU)

Apr 27 - Asteroid 2015 FG120 Near Earth Flyby (0.073 AU)

Apr 27 - Asteroid 4769 Castalia Closest Approach To Earth (0.404 AU)

Apr 27 - Asteroid 8489 Boulder Closest Approach To Earth (1.832 AU)

Apr 27 - Asteroid 64070 NEAT Closest Approach To Earth (2.004 AU)

Apr 27 - William Keck's 135th Birthday (1880)

Apr 28 - [Apr 21] Progress M-27 Soyuz U Launch (International Space Station 59P)

Apr 28 - [Apr 23] Comet C/2015 F2 (Polonia) Perihelion (1.210 AU)

Apr 28 - [Apr 18] Asteroid 2015 GB14 Near-Earth Flyby (0.023 AU)

Apr 28 - Asteroid 21459 Chrisrussell Closest Approach To Earth (1.149 AU)

Apr 28 - Asteroid 6000 United Nations Closest Approach To Earth (2.018 AU)

Apr 28 - Mark Boslough's 60th Birthday (1955)

Apr 28 - Jan Oort's 115th Birthday (1900)

Source: JPL Space Calendar Return to Contents

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Food for Thought

NASA 3-D Prints First Full-Scale Copper Rocket Engine Part

When you think of copper, the penny in your pocket may come to mind; but NASA engineers are trying to save taxpayers millions of pennies by 3-D printing the first full-scale, copper rocket engine part.

“Building the first full-scale, copper rocket part with additive manufacturing is a milestone for aerospace 3-D printing,” said Steve Jurczyk, associate administrator for the Space Technology Mission Directorate at NASA Headquarters in Washington. “Additive manufacturing is one of many technologies we are embracing to help us continue our journey to Mars and even sustain explorers living on the Red Planet.”

Numerous complex parts made of many different materials are assembled to make engines that provide the thrust that powers rockets. Additive manufacturing has the potential to reduce the time and cost of making rocket parts like the copper liner found in rocket combustion chambers where super-cold propellants are mixed and heated to the extreme temperatures needed to send rockets to space.

“On the inside of the paper-edge-thin copper liner wall, temperatures soar to over 5,000 degrees Fahrenheit, and we have to keep it from melting by recirculating gases cooled to less than 100 degrees above absolute zero on the other side of the wall,” said Chris Singer, director of the Engineering Directorate at NASA’s Marshall Space Flight Center in Huntsville, Alabama, where the copper rocket engine liner was manufactured. “To circulate the gas, the combustion chamber liner has more than 200 intricate channels built between the

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inner and outer liner wall. Making these tiny passages with complex internal geometries challenged our additive manufacturing team.”

A selective laser melting machine in Marshall’s Materials and Processing Laboratory fused 8,255 layers of copper powder to make the chamber in 10 days and 18 hours. Before making the liner, materials engineers built several other test parts, characterized the material and created a process for additive manufacturing with copper.

“Copper is extremely good at conducting heat,” explained Zach Jones, the materials engineer who led the manufacturing at Marshall. “That’s why copper is an ideal material for lining an engine combustion chamber and for other parts as well, but this property makes the additive manufacturing of copper challenging because the laser has difficulty continuously melting the copper powder.”

Only a handful of copper rocket parts have been made with additive manufacturing, so NASA is breaking new technological ground by 3-D printing a rocket component that must withstand both extreme hot and cold temperatures and has complex cooling channels built on the outside of an inner wall that is as thin as a pencil mark. The part is built with GRCo-84, a copper alloy created by materials scientists atNASA’s Glenn Research Center in Cleveland, Ohio, where extensive materials characterization helped validate the 3-D printing processing parameters and ensure build quality. Glenn will develop an extensive database of mechanical properties that will be used to guide future 3-D printed rocket engine designs. To increase U.S. industrial competitiveness, data will be made available to American manufacturers inNASA’s Materials and Processing Information System (MAPTIS) managed by Marshall.

“Our goal is to build rocket engine parts up to 10 times faster and reduce cost by more than 50 percent,” said Chris Protz, the Marshall propulsion engineer leading the project. “We are not trying to just make and test one part. We are developing a repeatable process that industry can adopt to manufacture engine parts with advanced designs. The ultimate goal is to make building rocket engines more affordable for everyone.”

Manufacturing the copper liner is only the first step of the Low Cost Upper Stage-Class Propulsion Project funded by NASA’s Game Changing Development Programin the Space Technology Mission Directorate. NASA’s Game Changing Program funds the development of technologies that will revolutionize future space endeavors, including NASA’s journey to Mars. The next step in this project is for Marshall engineers to ship the copper liner to NASA’s Langley Research Center in Hampton, Virginia, where an electron beam freedom fabrication facility will direct deposit a nickel super-alloy structural jacket onto the outside of the copper liner. Later this summer, the engine component will be hot-fire tested at Marshall to determine how the engine performs under extreme temperatures and pressures simulating the conditions inside the engine as it burns propellant during a rocket flight.

Source: NASA Return to Contents

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Space Image of the Week

VOLCANIC LIGHTNING: For the first time in more than 42 years, the Calbuco volcano in southern Chile

has erupted. Two blasts in 24 hours on April 22nd sent plumes of ash and volcanic gases shooting at least 33,000 feet high, well into the altitudes where planes fly. One of the eruptions occured at night and put on a spectacular display of volcanic lightning.

Researchers have long known that volcanic eruptions produce strong lightning. Findings published in a 2012 Eos article reveal that the largest volcanic storms can rival massive supercell thunderstorms in the American midwest. But why? Volcanic lightning is not well understood.

Lightning is nature's way of correcting an imbalance of electric charge. In ordinary thunderstorms, one part of a thundercloud becomes positively charged, and another part becomes negatively charged. This charge comes from collisions between particles: e.g., droplets of water and crystals of ice rub together, creating static electricity in much the same way as woolen socks rubbed against carpet. Lightning arcs between charge-separated regions.

Something similar must be happening inside volcanic plumes. One hypothesis holdsthat catapulting magma bubbles or volcanic ash are themselves electrically charged, and by their motion create charge-separated areas. Another possibility is that particles of volcanic ash collide with each other and become charged through triboelectric rubbing. In short, no one knows. It is a beautiful and terrifying mystery.

Stay tuned for more images as the eruption of Calbuco continues.

Source: Space Weather Return to Contents