NASA Study Shows Oceanic Phytoplankton Declines in Northern Hemisphere

NASA - Aqua EOS Mission logo.

Sept. 23, 2015

The world's oceans have seen significant declines in certain types of microscopic plant-life at the base of the marine food chain, according to a new NASA study. The research, published Sept. 23 in Global Biogeochemical Cycles, a journal of the American Geophysical Union, is the first to look at global, long-term phytoplankton community trends based on a model driven by NASA satellite data.

Diatoms, the largest type of phytoplankton algae, have declined more than 1 percent per year from 1998 to 2012 globally, with significant losses occurring in the North Pacific, North Indian and Equatorial Indian oceans. The reduction in population may reduce the amount of carbon dioxide drawn out of the atmosphere and transferred to the deep ocean for long-term storage.

"Phytoplankton need carbon dioxide for photosynthesis, just like trees," said oceanographer and lead author Cecile Rousseaux, of Universities Space Research Association and NASA's Goddard Space Flight Center in Greenbelt, Maryland. Carbon dioxide (CO₂) from the atmosphere dissolves in cold ocean water. During a phytoplankton bloom, which can span hundreds of miles and be seen from space, the tiny organisms take up the dissolved CO₂ and convert it to organic carbon – a form that animals can use as food to grow, the essential base of the marine food web. Then when the phytoplankton cell dies, it sinks to the ocean floor, taking with it the carbon in its body.

Earth’s Oceans Show Decline In Microscopic Plant Life

Video above: This narrated video provides an overview of the study findings and features NASA scientist Cecile Rousseaux. Video Credits: NASA's Goddard Space Flight Center.

Because they are larger than other types of phytoplankton, diatoms can sink more quickly than smaller types when they die. A portion will circulate back to the surface because of ocean currents, and, like fertilizer, fuel another phytoplankton bloom. But the rest will settle on the sea floor miles below, where they will accumulate in sediment and be stored for thousands or millions of years. The process is one of the long-term storage options for carbon removed from the atmosphere.

The decline in diatoms is one of several regional shifts observed in four types of phytoplankton in the 15-year study period.

Rousseaux and her colleagues took ocean color measurements of chlorophyll, the green pigment plants produce as part of photosynthesis, from NASA's Sea-viewing Wide Field of View Sensor (SeaWiFS) that flew aboard the Geo Eye OrbView-2 satellite from 1997 to 2010 and the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA's Aqua satellite from 2002 to the present. The data show the total chlorophyll in the ocean of all the phytoplankton types combined together. In previous work, they had observed that in the Northern Hemisphere, total chlorophyll was declining – but they didn't know what types of phytoplankton were declining or why.

Image above: Phytoplankton blooms in the Barents Sea off the coast of Norway and Russia, shown in natural color from NASA's Aqua satellite on July 10, 2014. Without sampling the water directly it's impossible to know the type of phytoplankton, but past analyses suggest that the green bloom is diatoms and the white bloom is coccolithophores. Image Credits: NASA's Earth Observatory.

That's where the computer model of the ocean comes in. Informed by other satellite data and field observations from ocean buoys and ships, NASA's Ocean Biogeochemical Model recreates the conditions in the ocean, from its currents to the amount of sunlight and nutrients available in different ocean basins. Since different types of phytoplankton use up nutrients at different rates and amounts, the model allowed the researchers to distinguish between large diatoms and smaller phytoplankton: coccolithophores, chlorophytes, and tiny cyanobacteria.

"Inclusion of satellite data into this kind of biogeochemical modeling is really exciting," said oceanographer Jeremy Werdell at Goddard, who was not involved in the study. The challenge with studying phytoplankton communities is that satellites cannot always unequivocally distinguish between different types of phytoplankton or the nutrients levels that may be affecting them. Sampling from ships and other direct measures can't observe the entirety of the global oceans on high spatial and time scales.

NASA's Aqua satellite. Image Credit: NASA

"This kind of tool allows you to start exploring that problem in a way we're not able to do by using just a satellite alone, or just a model alone," said Werdell. "By combining satellite data, models, and additional environmental information, you can start telling a more holistic story."

According to the model, the diatom declines are due to the uppermost layer of ocean water, called the mixed layer, becoming shallower. Taking into account seasonal variation, it shallowed by 1.8 meters (5.9 feet) over the 15-year study period.

The mixed layer is at the surface where waves and currents continually churn, drawing up nutrients from a deeper layer of water below. The upper section, or sometimes the whole mixed layer depending on how deep it is, receives sunlight. Together, these are the conditions that promote phytoplankton growth. But a shallower mixed layer has less volume, and thus can hold fewer nutrients, than a deeper mixed layer.

"The phytoplankton can run out of nutrients," said Rousseaux, which is what they observed in the nutrient levels essential to diatoms reported by the model. Why the mixed layer shallowed is still uncertain. One possibility is changes in winds, which cause some of the churning, she said.

The diatom decline, while statistically significant, is not severe, said Rousseaux. But it is something to monitor in the future as ocean conditions change, whether due to natural variation or climate change.

You can read the paper bellow at Global Biogeochemical Cycles.

Related links:

Global Biogeochemical Cycles: http://onlinelibrary.wiley.com/doi/10.1002/2015GB005139/abstract

Aqua Satellite: http://www.nasa.gov/mission_pages/aqua/index.html

Images (mentioned), Video (mentioned), Text, Credits: NASA's Earth Science News Team/Goddard Space Flight Center/Ellen Gray/Ashley Morrow.

Greetings, Orbiter.ch

Astronomers Identify a New Mid-size Black Hole

ESA - XMM-Newton Mission patch / NASA - Rossi X-ray Timing Explorer (RXTE) patch.

Sep. 23, 2015

Nearly all black holes come in one of two sizes: stellar mass black holes that weigh up to a few dozen times the mass of our sun or supermassive black holes ranging from a million to several billion times the sun’s mass. Astronomers believe that medium-sized black holes between these two extremes exist, but evidence has been hard to come by, with roughly a half-dozen candidates described so far.

A team led by astronomers at the University of Maryland and NASA’s Goddard Space Flight Center has found evidence for a new intermediate-mass black hole about 5,000 times the mass of the sun. The discovery adds one more candidate to the list of potential medium-sized black holes, while strengthening the case that these objects do exist. The team reported its findings in the September 21, 2015 online edition of Astrophysical Journal Letters.

The result follows up on a similar finding by some of the same scientists, using the same technique, published in August 2014. While the previous study accurately measured a black hole weighing 400 times the mass of the sun using data from NASA’s Rossi X-ray Timing Explorer (RXTE) satellite, the current study used data from the European Space Agency’s XMM-Newton satellite.

Image above: This image, taken with the European Southern Observatory’s Very Large Telescope, shows the central region of galaxy NGC1313. This galaxy is home to the ultraluminous X-ray source NCG1313X-1, which astronomers have now determined to be an intermediate-mass black hole candidate. NGC1313 is 50,000 light-years across and lies about 14 million light-years from the Milky Way in the southern constellation Reticulum. Image credit: Image Credit: European Southern Observatory (ESO).

“This result provides support to the idea that black holes exist on all size scales. When you describe something for the first time, there is always some doubt,” said lead author Dheeraj Pasham, a postdoctoral associate at the Joint Space-Science Institute, a research partnership between UMD’s Departments of Astronomy and Physics and NASA Goddard. “Identifying a second candidate with a different instrument puts weight behind both findings and gives us confidence in our technique.”

The new intermediate-mass black hole candidate, known as NGC1313X-1, is classified as an ultraluminous X-ray source, and as such is among the brightest X-ray sources in the nearby universe. It has proven hard to explain exactly why ultraluminous X-ray sources are so bright, however. Some astronomers suspect that they are intermediate-mass black holes actively drawing in matter, producing massive amounts of friction and X-ray radiation in the process.

Against this backdrop of haphazard X-ray fireworks created by NGC1313X-1, Pasham and his colleagues identified two repeating flares, each flashing at an unusually steady frequency. One flashed about 27.6 times per minute and the other about 17.4 times per minute. Comparing these two rates yields a nearly perfect 3:2 ratio. Pasham and his colleagues also found this 3:2 ratio in M82X-1, the black hole they identified in August 2014, although the overall frequency of flashing was much higher in M82X-1.

European Space Agency’s XMM-Newton satellite

Although astronomers are not yet sure what causes these steady flashes, the presence of a clockwork 3:2 ratio appears to be a common feature of stellar mass black holes and possibly intermediate-mass black holes as well. The flashes are most likely caused by activity close to the black hole, where extreme gravity keeps all surrounding matter on a very tight leash, Pasham said.

The 3:2 ratios can also provide an accurate measure of a black hole’s mass. Smaller black holes will flash at a higher frequency, while larger black holes will flash less often.

“To make an analogy with acoustic instruments, if we imagine that stellar mass black holes are the violin and supermassive black holes are the double bass, then intermediate-mass black holes are the violoncello," said co-author Francesco Tombesi, an assistant research scientist in UMD’s Department of Astronomy who has a joint appointment at NASA Goddard via the Center for Research and Exploration in Space Science and Technology.

Pasham and Tombesi hope that identifying ultraluminous X-ray sources that exhibit the key 3:2 flashing ratio will yield many more intermediate-mass black hole candidates in the near future.

NASA’s Rossi X-ray Timing Explorer (RXTE) satellite

“Our method is purely empirical, it’s not reliant on models. That’s why it’s so strong,” Pasham explained. “We don’t know what causes these oscillations, but they appear to be reliable, at least in stellar mass black holes.”

NASA plans to launch a new X-ray telescope, the Neutron Star Interior Composition Explorer (NICER), in 2016. Pasham has already identified several potential intermediate-mass black hole candidates that he hopes to explore with NICER.

“Observing time is at a premium, so you need to build a case with an established method and a list of candidates the method can apply to,” Pasham explained. “With this result, we are in a good position to move forward and make more exciting discoveries.”

In addition to Pasham and Tombesi, UMD-affiliated co-authors include Astronomy Adjunct Assistant Professor Bradley Cenko and Astronomy Professor Richard Mushotzky.

The research paper, “Evidence for High-Frequency QPOs with a 3:2 Frequency Ratio from a 5000 Solar Mass Black Hole,” Dheeraj Pasham, Bradley Cenko, Abderahmen Zoghbi, Richard F. Mushotzky, Jon Miller and Francesco Tombesi, was published online September 21, 2015 in the journal Astrophysical Journal Letters.

Related links:

NASA Goddard: http://www.nasa.gov/centers/goddard/home/index.html

Joint Space-Science Institute: https://jsi.astro.umd.edu/

Center for Research and Exploration in Space Science and Technology: http://cresst.umd.edu/

European Southern Observatory (ESO): http://www.eso.org/public/

For more information about ESA's XMM-Newton, visit: http://sci.esa.int/xmm-newton/

For more information about NASA’s Rossi X-ray Timing Explorer (RXTE), visit: http://www.nasa.gov/centers/goddard/missions/rxte.html

Black Holes: http://www.nasa.gov/subject/6895/black-holes

Images, Text, Credits: NASA/Lynn Jenner/ESO/ESA.

Greetings, Orbiter.ch

Milky Way’s Black Hole Shows Signs of Increased Chatter

NASA - Chandra X-ray Observatory patch / ESA - XMM-Newton Mission patch.

Sep. 23, 2015

Three orbiting X-ray space telescopes have detected an increased rate of X-ray flares from the usually quiet giant black hole at the center of our Milky Way galaxy after new long-term monitoring. Scientists are trying to learn whether this is normal behavior that was unnoticed due to limited monitoring, or these flares are triggered by the recent close passage of a mysterious, dusty object.

By combining information from long monitoring campaigns by NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton, with observations by the Swift satellite, astronomers were able to carefully trace the activity of the Milky Way’s supermassive black hole over the last 15 years. The supermassive black hole, a.k.a. Sagittarius A*, weighs in at slightly more than 4 million times the mass of the Sun. X-rays are produced by hot gas flowing toward the black hole.

The new study reveals that Sagittarius A* (Sgr A* for short) has been producing one bright X-ray flare about every ten days. However, within the past year, there has been a ten-fold increase in the rate of bright flares from Sgr A*, at about one every day. This increase happened soon after the close approach to Sgr A* by a mysterious object called G2.

NASA Swift satellite

“For several years, we’ve been tracking the X-ray emission from Sgr A*. This includes also the close passage of this dusty object” said Gabriele Ponti of the Max Planck Institute for Extraterrestrial Physics in Germany. “A year or so ago, we thought it had absolutely no effect on Sgr A*, but our new data raise the possibility that that might not be the case."

Originally, astronomers thought G2 was an extended cloud of gas and dust. However, after passing close to Sgr A* in late 2013, its appearance did not change much, apart from being slightly stretched by the gravity of the black hole.   This led to new theories that G2 was not simply a gas cloud, but instead a star swathed in an extended dusty cocoon.

“There isn’t universal agreement on what G2 is,” said Mark Morris of the University of California at Los Angeles. “However, the fact that Sgr A* became more active not long after G2 passed by suggests that the matter coming off of G2 might have caused an increase in the black hole’s feeding rate.”

ESA XMM-Newton X-ray Observatory

While the timing of G2’s passage with the surge in X-rays from Sgr A* is intriguing astronomers see other black holes that seem to behave like Sgr A*. Therefore, it’s possible this increased chatter from Sgr A* may be a common trait among black holes and unrelated to G2. For example, the increased X-ray activity could be due to a change in the strength of winds from nearby massive stars that are feeding material to the black hole.

“It’s too soon to say for sure, but we will be keeping X-ray eyes on Sgr A* in the coming months,” said co-author Barbara De Marco, also of Max Planck. “Hopefully, new observations will tell us whether G2 is responsible for the changed behavior or if the new flaring is just part of how the black hole behaves.”

The analysis included 150 Chandra and XMM-Newton observations pointed at the center of the Milky Way over the last 15 years, extending from September 1999 to November 2014. An increase in the rate and brightness of bright flares from Sgr A* occurred after mid-2014, several months after the closest approach of G2 to the huge black hole.

NASA Chandra X-ray Observatory

If the G2 explanation is correct, the spike in bright X-ray flares would be the first sign of excess material falling onto the black hole because of the cloud’s close passage. Some gas would likely have been stripped off the cloud, and captured by the gravity of Sgr A*. It then could have started interacting with hot material flowing towards the black hole, funneling more gas toward the black hole that could later be consumed by Sgr A*.

A paper on these findings has been accepted by the Monthly Notices of the Royal Astronomical Society. A preprint is available online. NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.

Read More from NASA's Chandra X-ray Observatory: http://chandra.harvard.edu/photo/2015/sgra2/

For more Chandra images, multimedia and related materials, visit: http://www.nasa.gov/chandra

For more information about ESA's XMM-Newton, visit: http://sci.esa.int/xmm-newton/

For more information about Swift satellite, visit: http://www.nasa.gov/mission_pages/swift/main

Images, Text, Credits: NASA/ESA/Lee Mohon/CXC/MPE/G. Ponti et al.; Illustration: NASA/CXC/M. Weiss.

Greetings, Orbiter.ch

Rosetta reveals comet’s water-ice cycle

ESA - Rosetta Mission patch.

23 September 2015

ESA’s Rosetta spacecraft has provided evidence for a daily water-ice cycle on and near the surface of comets.

Comets are celestial bodies comprising a mixture of dust and ices, which they periodically shed as they swing towards their closest point to the Sun along their highly eccentric orbits.

The water-ice cycle of Rosetta’s comet

As sunlight heats the frozen nucleus of a comet, the ice in it – mainly water but also other ‘volatiles’ such as carbon monoxide and carbon dioxide – turns directly into a gas.

This gas flows away from the comet, carrying dust particles along. Together, gas and dust build up the bright halo and tails that are characteristic of comets.

Rosetta arrived at Comet 67P/Churyumov–Gerasimenko in August 2014 and has been studying it up close for over a year. On 13 August 2015, the comet reached the closest point to the Sun along its 6.5-year orbit, and is now moving back towards the outer Solar System.

A key feature that Rosetta’s scientists are investigating is the way in which activity on the comet and the associated outgassing are driven, by monitoring the increasing activity on and around the comet since Rosetta’s arrival.

Comet at perihelion

Scientists using Rosetta’s Visible, InfraRed and Thermal Imaging Spectrometer, VIRTIS, have identified a region on the comet’s surface where water ice appears and disappears in sync with its rotation period. Their findings are published today in the journal Nature.

“We found a mechanism that replenishes the surface of the comet with fresh ice at every rotation: this keeps the comet ‘alive’,” says Maria Cristina De Sanctis from INAF-IAPS in Rome, Italy, lead author of the study. 

The team studied a set of data taken in September 2014, concentrating on a one square km region on the comet’s neck. At the time, the comet was about 500 million km from the Sun and the neck was one of the most active areas.

As the comet rotates, taking just over 12 hours to complete a full revolution, the various regions undergo different illumination.

Hapi region

“We saw the tell-tale signature of water ice in the spectra of the study region but only when certain portions were cast in shadow,” says Maria Cristina.

“Conversely, when the Sun was shining on these regions, the ice was gone. This indicates a cyclical behaviour of water ice during each comet rotation.”

The data suggest that water ice on and a few centimetres below the surface ‘sublimates’ when illuminated by sunlight, turning it into gas that then flows away from the comet. Then, as the comet rotates and the same region falls into darkness, the surface rapidly cools again.

However, the underlying layers remain warm owing to the sunlight they received in the previous hours, and, as a result, subsurface water ice keeps sublimating and finding its way to the surface through the comet’s porous interior.

But as soon as this ‘underground’ water vapour reaches the cold surface, it freezes again, blanketing that patch of comet surface with a thin layer of fresh ice.

Eventually, as the Sun rises again over this part of the surface on the next comet day, the molecules in the newly formed ice layer are the first to sublimate and flow away from the comet, restarting the cycle.

“We suspected such a water ice cycle might be at play at comets, on the basis of theoretical models and previous observations of other comets but now, thanks to Rosetta's extensive monitoring at 67P/Churyumov–Gerasimenko, we finally have observational proof,” says Fabrizio Capaccioni, VIRTIS principal investigator at INAF-IAPS in Rome, Italy.

Water ice and surface temperature at Hapi

From these data, it is possible to estimate the relative abundance of water ice with respect to other material. Down to a few cm deep over the region of the portion of the comet nucleus that was surveyed, water ice accounts for 10–15% of the material and appears to be well-mixed with the other constituents.

The scientists also calculated how much water vapour was being emitted by the patch that they analysed with VIRTIS, and showed that this accounted for about 3% of the total amount of water vapour coming out from the whole comet at the same time, as measured by Rosetta’s MIRO microwave sensor.

“It is possible that many patches across the surface were undergoing the same diurnal cycle, thus providing additional contributions to the overall outgassing of the comet,” adds Dr Capaccioni.

The scientists are now busy analysing VIRTIS data collected in the following months, as the comet’s activity increased around the closest approach to the Sun.

“These initial results give us a glimpse of what is happening underneath the surface, in the comet’s interior,” concludes Matt Taylor, ESA Rosetta Project Scientist.

“Rosetta is capable of tracking changes on the comet over short as well as longer time scales, and we are looking forward to combining all of this information to understand the evolution of this and other comets.”

Notes for Editors:

“The diurnal cycle of water ice on comet 67P/Churyumov-Gerasimenko,” by Maria Cristina De Sanctis et al. is published in the 24 September 2015 issue of Nature.

The results are based on images and spectra taken at visible and infrared wavelengths of light on 12–14 September 2014 with VIRTIS.

These results will be presented next week at the European Planetary Science Congress, taking place from 27 September to 2 October 2015 in Nantes, France.

About Rosetta:

Rosetta is an ESA mission with contributions from its Member States and NASA. Rosetta’s Philae lander is contributed by a consortium led by DLR, MPS, CNES and ASI.

Related links:

Rosetta Mission: http://www.esa.int/Our_Activities/Space_Science/Rosetta

Rosetta at Astrium: http://www.astrium.eads.net/en/programme/rosetta-1go.html

Rosetta at DLR: http://www.dlr.de/dlr/en/desktopdefault.aspx/tabid-10394/

Ground-based comet observation campaign: http://www.rosetta-campaign.net/home

ESA Rosetta blog: http://blogs.esa.int/rosetta/

Images, Text, Credits: ESA/Rosetta/VIRTIS/INAF-IAPS/OBS DE PARIS-LESIA/DLR; M.C. De Sanctis et al (2015); Comet: ESA/Rosetta/NavCam – CC BY-SA IGO 3.0.

Best regards, Orbiter.ch

A Cosmic Rose With Many Names

ESO - European Southern Observatory logo.

Sept. 23, 2015

The star formation region Messier 17

This new image of the rose-coloured star forming region Messier 17 was captured by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile. It is one of the sharpest images showing the entire nebula and not only reveals its full size but also retains fine detail throughout the cosmic landscape of gas clouds, dust and newborn stars.

The nebula pictured here may have had more names bestowed upon it over the ages than any other object of its kind. Although officially known as Messier 17, its nicknames include: the Omega Nebula, the Swan Nebula, the Checkmark Nebula, the Horseshoe Nebula and — lest those with more of a more marine bent miss out — the Lobster Nebula.

The star-forming region Messier 17 in the constellation of Sagittarius

Messier 17 is located about 5500 light-years from Earth near the plane of the Milky Way and in the constellation of Sagittarius (The Archer). The object spans a big section of the sky — its gas and dust clouds measure about 15 light-years across. This material is fueling the birth of new stars and the wide field of view of the new picture reveals many stars in front of, in, or behind Messier 17.

The nebula appears as a complex red structure with some graduation to pink. Its colouring is a signature of glowing hydrogen gas. The short-lived blue stars that recently formed in Messier 17 emit enough ultraviolet light to heat up surrounding gas to the extent that it begins to glow brightly. In the central region the colours are lighter, and some parts appear white. This white colour is real — it arises as a result of mixing the light from the hottest gas with the starlight reflected by dust.

Digitized Sky Survey Image of the Omega Nebula (M 17)

The gas in the nebula is estimated to have more than 30 000 times the mass of the Sun. Messier 17 also contains an open star cluster of 35 stars, which is known as NGC 6618 [1]. The total number of stars in the nebula, however, is much higher — there are almost 800 stars in the centre with even more forming in its outer regions.

Throughout this rosy glow, the nebula shows a web of darker regions of dust that obscure the light. This obscuring material is also glowing and — although these areas are dark in this visible-light image — they look bright when observed using infrared cameras.

Zooming in on the star formation region Messier 17

The nebula owes its official name to the French comet hunter Charles Messier who included the nebula as the seventeenth object in his famous astronomical catalogue in 1764 [2]. But even with a name as bland as Messier 17, this flowery nebula still looks dazzling.

This picture comes from the ESO Cosmic Gems programme [3].

A close looks at the star formation region Messier 17

Notes:

[1] This designation is also sometimes used for the entire star formation region.

[2] The astronomer Jean Philippe de Chéseaux discovered the object in 1745, but his discovery did not receive widespread attention. Thus, Messier independently rediscovered and catalogued it almost 20 years later.

[3] The ESO Cosmic Gems programme is an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. All data collected may also be suitable for scientific purposes, and are made available to astronomers through ESO’s science archive.

More information:

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links:

3D animation of Messier 17: http://www.eso.org/public/videos/eso50messier173d/

A wide view of Messier 17 from the VST: http://www.eso.org/public/switzerland-it/images/eso1119a/

A view of the nebula’s core from the VLT: http://www.eso.org/public/news/eso1201/

ESO Cosmic Gems programme: http://www.eso.org/public/outreach/gems.html

Images, Text, Credits: ESO/IAU and Sky & Telescope/Digitized Sky Survey 2. Acknowledgment: Davide De Martin/Videos: ESO, N. Risinger (skysurvey.org), DSS. Music: Johan Monell (www.johanmonell.com).

Best regards, Orbiter.ch

NASA’s Space Launch System is the Rocket for the Ride to Mars

NASA - Space Launch System (SLS) logo.

Sep. 22, 2015

NASA is going to Mars, and here on Earth, the agency’s Marshall Space Flight Center in Huntsville, Alabama, is the first stop for building the world’s most powerful rocket for the ride – the Space Launch System (SLS).

The SLS will be NASA’s first exploration-class vehicle since the Saturn V took American astronauts to the moon more than 40 years ago. It will expand our reach in the solar system, launching crews aboard the new Orion spacecraft to explore multiple, deep-space destinations. A fleet of robotic spacecraft and rovers are already on and around Mars, but to fly to and land humans safely on Mars requires a next-generation spacecraft – Orion. SLS will ensure it gets there.

Image above: Artist concept of the Block I SLS, which will later evolve to a Block 2 configuration that will enable missions even farther into our solar system, including Mars. Image Credits: NASA/MSFC.

The first SLS rocket, known as the Block I configuration with a 70-metric-ton (77 ton) lift capability, will be powered by twin boosters and four RS-25 engines. The next planned evolution of the SLS, Block 1B, would use a more powerful exploration upper stage to enable more ambition missions and a 105-metric-ton lift capacity, while a later evolution, Block 2, would add a pair of advanced solid or liquid propellant boosters to provide a 130-metric-ton (143-ton) lift capacity. In each configuration, SLS will continue to use the same core stage and four RS-25 engines.

The initial Block 1 configuration of SLS will stand 322 feet tall, higher than the Statue of Liberty. It will produce 8.4 million pounds of thrust at liftoff, the equivalent of 13,400 locomotive engines, and be capable of carrying 154,000 pounds of payload, about the same as 12 fully grown elephants. Block 1B and Block 2 each will be more than 363 feet tall, which is taller than the Saturn V rocket. The Block 2 configuration will provide 9.2 million pounds of thrust at liftoff and weigh 6.5 million pounds.

Marshall manages the SLS Program for the agency and has unique capabilities for the design and testing of different parts of the rocket. Marshall is the hub for work on several structural test articles for both the core and the upper stage of the rocket. Teledyne Brown Engineering of Huntsville is the prime contractor for the launch vehicle stage adapter, which connects the SLS core stage and the upper stage.

Two new test stands also are being built at Marshall to perform structural loads testing for the core stage, which is being manufactured at NASA’s Michoud Assembly Facility in New Orleans. Avionics and the flight computer also will be housed in the SLS core stage. Marshall has installed a structure and simulation capability to test the avionics system and model the environments the vehicle will experience during launch. The Boeing Company of Chicago is the prime contractor for the SLS core stage, including its avionics.

Marshall also oversees RS-25 testing at NASA’s Stennis Space Center near Bay St. Louis, Mississippi, and booster qualification testing at prime contractor Orbital ATK’s test facility in Promontory, Utah. The SLS Program has an inventory of 16 RS-25 flight engines being upgraded for SLS specifications, built by prime contractor Aerojet Rocketdyne of Sacramento, California.

On the program side, SLS recently completed its critical design review at Marshall. The in-depth review – the first in almost 40 years for a NASA exploration class vehicle -- provides a final look at the design and development of the integrated rocket before full-scale fabrication begins. “We’ve picked the right vehicle for the journey to Mars," said Garry Lyles, chief engineer for the SLS Program Office at the Marshall Center.

More SLS work at Marshall:

Base heating testing
Anti-geyser testing
Hydrogen Burn-Off Igniter testing
Scale-Model Acoustic testing
http://www.nasa.gov/sls/sls-smat-test-aug2014.html

Related links:

Block I configuration: http://www.nasa.gov/sites/default/files/files/SLS-Fact-Sheet_aug2014-finalv3.pdf

Core stage: http://www.nasa.gov/pdf/756702main_SLS_Core_Stage.pdf

RS-25 testing: https://www.youtube.com/watch?v=GAIC4jnKl8s&index=2&list=PLBEXDPatoWBmX3yrpEObbUoNF5rbbNcgX

Booster qualification testing: https://www.youtube.com/watch?v=Qn6OvHofcoo&list=PLBEXDPatoWBmX3yrpEObbUoNF5rbbNcgX&index=20

For more information on SLS, visit: http://www.nasa.gov/sls

Image (mentioned), Text, Credits: NASA Marshall Space Flight Center/Kimberly Henry/Lee Mohon.

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NASA's Lunar Reconnaissance Orbiter’s Dance with Eclipses

NASA - Lunar Reconnaissance Orbiter (LRO) patch.

Sep. 22, 2015

On the evening of Sept. 27, 2015, into the early morning of Sept. 28 EDT, operators of NASA’s Lunar Reconnaissance Orbiter (LRO) will wait as Earth blots out the sun and the moon goes dark. The flight operations team at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, have seen LRO safely through three lunar eclipses in about a year and a half. Although it is certainly not an ordinary night, science operations planner Dawn Myers at Goddard said the team knows the routine.

“We have a method and it works well,” she said. “It’s always stressful during the approach of the eclipse, but we follow the same procedures every time and we haven’t had any trouble.”

Artist's rendering of LRO spacecraft

Preparations begin months before the solar-powered spacecraft begins its journey into Earth’s shadow as scientists, engineers and the flight operations team meet to discuss what is possible.

Not every spacecraft can overcome the temperature drop and lack of sunlight associated with an eclipse. NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) just barely survived one in April 2014, which was a “testament to its great engineering,” LRO deputy project scientist Noah Petro at Goddard said. LADEE scientists and engineers originally planned a 100-day mission during a period that would not include an eclipse.

LRO, by contrast, can withstand hours in the cold and dark. During its original mission to collect information about the lunar environment, the flight operations team shut down most of LRO’s systems to conserve battery power as the lunar eclipse passed. Now, in its extended mission, LRO scientists embrace new possibilities, extending their scientific exploration to include eclipses and other events that can reveal more of the moon’s secrets.

An instrument on LRO called Diviner is perfect for this purpose. As a radiometer, Diviner measures both the reflective energy off the surface of the moon and infrared emissions that indicate the temperature at the surface. By leaving this one instrument on during the eclipse, they could make valuable observations. But could they keep it on for the duration?

“Our power engineer looked at past eclipses and evaluated whether it would be feasible for us to leave an instrument on,” Myers said. “He told us if the voltage drops below a certain level, we would have to shut the instrument off, but that hasn’t happened yet.”

Not only could they leave Diviner on, but also a star tracker and its associated heaters for improved navigation.

One by one by one, the instruments shut off, plunging the spacecraft into hibernation. From the operations facility at Goddard, science operations personnel take shifts over 24 hours to watch and monitor the spacecraft from the pre-heat period, all the way through recovery the next day when they slowly bring each instrument back to operational status. During the eclipse, lasting just over an hour, only Diviner keeps its eye on the moon, fulfilling a purpose totally outside the scope of its original design.

Petro said the science is worth the effort. As the moon, and by extension LRO, passes into Earth’s shadow, the temperature drops rapidly – nearly 280 degrees Fahrenheit (138 degrees Celsius), in minutes as the sunlight disappears.

“The rapid cooling of the surface during an eclipse gives us a view of how the top few centimeters cool differently than during a normal lunar night,” Petro said. “From this we learn about the size of particles at the surface.”

Still, LRO can only observe so much, moving in a narrow line across the moon’s surface, never seeing all of it in one pass. With each eclipse, the spacecraft reveals more to eager scientists. This particular eclipse will be especially important as, for the first time, prior to the eclipse, LRO will be pass over the moon’s surface at local noon time when it is nearly at its warmest. This means that LRO will be able to measure a dramatic drop in temperature resulting in a very unique set of measurements. Every eclipse feeds more data into the story, but so far Petro said the observations mainly fuel more questions.

Every bit of information scientists can collect from this mission is important. Petro said it may even help inform decisions about a potential lunar colony at a later date.

LRO was launched June 18, 2009, for what was to be a two-year mission. Now in its sixth year, the mission is funded through October 2016.

For more information about LRO, visit: http://www.nasa.gov/lro

Image, Text, Credits: NASA’s Goddard Space Flight Center/Ashley Morrow.

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