Galactic Mergers Fail to Feed Black Holes

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The large black holes that reside at the center of galaxies can be hungry beasts. As dust and gas are forced into the vicinity around the black holes, it crowds up and jostles together, emitting lots of heat and light. But what forces that gas and dust the last few light years into the maw of these supermassive black holes?

It has been theorized that mergers between galaxies disturbs the gas and dust in a galaxy, and forces the matter into the immediate neighborhood of the black hole. That is, until a recent study of 140 galaxies hosting Active Galactic Nuclei (AGN) – another name for active black holes at the center of galaxies – provided strong evidence that many of the galaxies containing these AGN show no signs of past mergers.

The study was performed by an international team of astronomers. Mauricio Cisternas of the Max Planck Institute for Astronomy and his team used data from 140 galaxies that were imaged by the XMM-Newton X-ray observatory. The galaxies they sampled had a redshift between z= 0.3 – 1, which means that they are between about 4 and 8 billion light-years away (and thus, the light we see from them is about 4-8 billion years old).

They didn’t just look at the images of the galaxies in question, though; a bias towards classifying those galaxies that show active nuclei to be more distorted from mergers might creep in. Rather, they created a “control group” of galaxies, using images of inactive galaxies from the same redshift as the AGN host galaxies. They took the images from the Cosmic Evolution Survey (COSMOS), a survey of a large region of the sky in multiple wavelengths of light. Since these galaxies were from the same redshift as the ones they wanted to study, they show the same stage in galactic evolution. In all, they had 1264 galaxies in their comparison sample.

The way they designed the study involved a tenet of science that is not normally used in the field of astronomy: the blind study. Cisternas and his team had 9 comparison galaxies – which didn’t contain AGN – of the same redshift for each of their 140 galaxies that showed signs of having an active nucleus.

What they did next was remove any sign of the bright active nucleus in the image. This means that the galaxies in their sample of 140 galaxies with AGN would essentially appear to even a trained eye as a galaxy without the telltale signs of an AGN. They then submitted the control galaxies and the altered AGN images to ten different astronomers, and asked them to classify them all as “distorted”, “moderately distorted”, or “not distorted”.

Since their sample size was pretty manageable, and the distortion in many of the galaxies would be too subtle for a computer to recognize, the pattern-seeking human brain was their image analysis tool of choice. This may sound familiar – something similar is being done with enormous success with people who are amateur galaxy classifiers at Galaxy Zoo.

When a galaxy merges with another galaxy, the merger distorts its shape in ways that are identifiable – it will warp a normally smooth elliptical galaxy out of shape, and if the galaxy is a spiral the arms seem to be a bit “unwound”. If it were the case that galactic mergers are the most likely cause of AGN, then those galaxies with an active nucleus would be more probable to show distortion from this past merger.

The team went through this process of blinding the study to eliminate any bias that those looking at the images would have towards classifying AGN as more distorted. By both having a reasonably large sample size of galaxies and removing any bias when analyzing the images, they hoped to definitively show whether the correlation between AGN and mergers exists.

The result? Those galaxies with an Active Galactic Nucleus did not show any more distortion on the whole than those galaxies in the comparison sample. As the authors state in the paper, “Mergers and interactions involving AGN hosts are not dominant, and occur no more frequently than for inactive galaxies.”

This means that astronomers can’t point towards galactic mergers as the main reason for AGN. The study showed that at least 75% of AGN creation – at least between the last 4-8 billion years – must be from sources other than galactic mergers. Likely candidates for these sources include: “galactic harrassment”, those galaxies that don’t collide, but come close enough to gravitationally influence each other; the instability of the central bar in a galaxy; or the collision of giant molecular clouds within the galaxy.

Knowing that AGN aren’t caused in large part by galactic mergers will help astronomers to better understand the formation and evolution of galaxies. The active nuclei in galaxies that host them greatly influence galactic formation. This process is called ‘AGN feedback’, and the mechanisms and effects that result from the interplay between the energy streaming out of the AGN and the surrounding material in the center of a galaxy is still a hot topic of study in astronomy.

Mergers in the more distant past than 8 billion years might yet correlate with AGN – this study only rules out a certain population of these galaxies – and this is a question that the team plans to take on next, pending surveys by the Hubble Space Telescope and the James Webb Space Telescope. Their study will be published in the January 10 issue of the Astrophysical Journal, and a pre-print version is available on Arxiv.

Source: HST news release, Max Planck Institute for Astronomy, Arxiv paper

Over 400 Historic Space Artifacts up for Auction

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If you’re interested in owning an artifact or two from the history of spaceflight, now could be your chance to snag some up. From January 13-20, over 400 artifacts relating to the history of spaceflight will be up on the auction block at RR Auction. There’s a diverse number of different pieces, ranging from an Atlas I and II crow’s foot wrench to numerous items that flew aboard many of the Apollo missions and on Projects Mercury and Gemini.

There are even a few spare parts for the Shuttle, though it’s probably not a good idea to follow along in Johnny Cash’s footsteps; if you build a space shuttle one piece at a time, it’ll cost you more than a dime and I doubt you’ll want to fly it into space.

This auction is filled with loads of memorabilia – much of it signed by astronauts or other NASA personnel – from the Apollo missions. There is a US flag that flew with the Apollo 11 crew to the Moon and back, attached to a certificate signed by Armstrong, Aldrin and Collins. As you can imagine, this one is going to go for a lot – the bidding starts at $2500.

If you drill it out so it'll fit, and with a little help from an A-daptor kit, you could have a shuttle running just like a song. Image Credit: RR Auction. Mangled lyrics credit: The Man in Black

One piece that has been getting a lot of attention – and will probably also sell for quite a lot, given that it starts out at $1000 – is the original page from the November 1969 Playboy magazine featuring topless Playmate DeDe Lind. The page was stuck to a piece of cardboard aboard Apollo 12, and traveled all the way to the Moon and back aboard the Yankee Clipper.

It’s accompanied by a certificate of authenticity from Richard Gordon, the Apollo 12 Command Module pilot, which reads in part: “This cue card, which flew with me to the moon, has been in my sole possession and part of my personal space collection since my return from the moon in 1969 aboard America’s second lunar landing mission, and it remains one of the all-time greatest Apollo era astronaut ‘Gotcha’s!’” Historic, indeed.

Other items up on the block: lunar meteorites from the Hupe collection, telegrams sent out by Werner von Braun (inviting a friend to visit a launch on “Moonday”), and fifty-nine pieces of the Skylab oxygen tank that were recovered by three people in Australia after the space station was de-orbited in 1979.

Here’s a link to the entire collection for your perusal.

Source: Nerdist, RR Auction

Akatsuki Update: Fuel Pressure Drop Likely Caused Insertion Failure

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While JAXA is still trying to get an exact handle on the problems that the Akatsuki probe sent to Venus encountered, there is a little bit of news leaking out. JAXA held a press conference last night, and the Yomiuri Shimbun newspaper has a brief recap of the conference. During some of the systems checks on the probe, it also took a few images of Venus, and many of the instruments on the probe appear to be working okay – it’s the engine that’s having the most problems.

Here’s what is known so far: Akatsuki’s engine did perform a burn to slow it down, but 152 seconds into the burn the fuel pressure dropped and the probe became unbalanced. Because the retrofiring of the rockets failed to slow down the probe enough for Venus to capture it, it was unable to enter into orbit around the planet, and then went into safe mode.

As to what caused the sudden drop in fuel, JAXA currently suspects that there is a damaged pipe or valve that reduced the flow of helium into the engine, but that is still speculative. As the engine burns propellant (Akatsuki uses a hydrazine/nitrogen tetroxide engine), helium flows into the tank to maintain the pressure. Something failed in the helium injection flow, and precipitated a drop in internal tank pressure, reducing the flow of propellant and causing the engines to stop burning.

The ceramic nozzle of the engine is also thought to have been damaged by the misfiring, which may make the task of trying to get the probe to Venus when the chance comes around again in six years a daunting one.

An image of Venus taken by Akatsuki's Ultraviolet imager (UVI) at the 365 nm wavelength, the color is artificial. Field of View: 12 deg x 12 deg Image Credit: ISAS

JAXA is planning on doing some tests on the ground to maybe come to a workaround of this problem. There seems to be plenty of fuel left, which is good news, but the damaged nozzle is not. Maybe they’ll call in some Hayabusa team members, and pull it through.

The Christian Science Monitor reported yesterday that there is some speculation that something may have struck the probe, though this most recent press conference from JAXA makes no mention of it.

Also, Emily Lakdawalla at The Planetary Society Blog reprinted some tweets translated from Japanese that summarize details from the press conference, as well as the Yomiuri Shimbun article.

Source: Yomiuri Shimbun, ISAS, the Planetary Society Blog,

Nanosail-D Update: Things Look Grim

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We reported the successful ejection of the Nanosail-D nanosatellite from the satellite that it was launched with earlier this week. Well, the most recent release from NASA states that things might have turned out otherwise. Not only has the sail potentially failed to deploy, it’s currently unclear if the nanosatellite was even ejected.

In NASA’s own words on the mission site:

At this time, it is not clear that NanoSail-D ejected from the Fast, Affordable, Science and Technology Satellite (FASTSAT) as originally stated on Monday, Dec. 6. At the time of ejection, spacecraft telemetry data showed a positive ejection as reflected by confirmation of several of the planned on orbit ejection sequence events. The FASTSAT spacecraft ejection system data was also indicative of an ejection event. NanoSail-D was scheduled to unfurl on Dec. 9 at 12:30 a.m., and deployment hasn’t been confirmed. The FASTSAT team is continuing to trouble shoot the inability to make contact with NanoSail-D. The FASTSAT microsatellite and all remaining five onboard experiments continue to operate as planned.

What a bummer. This is all we have to go on right now – we’ll keep you posted as the situation develops over the weekend.

Source: NASA press release

Taking a Galaxy’s Temperature

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The role that supermassive black holes play in the formation of galaxies is a “hot” topic in astronomy. Using the Chandra X-Ray Observatory, an international team of astronomers have been able to create a temperature map of one galaxy, NGC 5813, which is located in the Virgo III Group of galaxies. The new map shows in unprecedented detail the history of various periods of activity of the Active Galactic Nucleus (AGN), which is associated with a supermassive black hole that resides at its center. They found that regular outbursts of the AGN maintained the temperature of the gas in the region of the galaxy, continually reheating the gas that would otherwise have cooled down.

Paper co-author Dr. Scott Randall of the Chandra Mission Planning Team at the Harvard-Smithsonian Center for Astrophysics said, “Although there are other systems that show AGN outburst shocks, this is still the only system where unambiguous shocks from multiple outbursts are seen. This allows us to directly measure the heating from shocks, and directly observe how often these shocks take place. Thus, at present NGC 5813 is *uniquely* well suited to the study of AGN heating.”

By studying images taken by the Chandra X-Ray Observatory, and combining these observations with those taken by the Giant Metrewave Radio Telescope (GMRT) and the Southern Astrophysical Research Telescope (SOAR), they were able to make out large cavities produced by periods of activity in the supermassive black hole. The researchers were able to determine that there were three pairs of large cavities, which corresponded to active outbursts of the galactic nucleus 3 million, 20 million and 90 million years ago (from our perspective here on Earth).

What makes the galaxy NGC 5813 especially suited to this study is its relative isolation from other galaxies that could influence the formation of these cavities – it is an older galaxy that is relatively undisturbed, allowing for these cavities in the gas to persist over such a long time period.

Current models of galaxy formation must take into account just how much of an influence the output of the supermassive black hole at the center of a galaxy has on the formation of stars within the galaxy, and the evolution of the shape and size of the galaxy as a whole. This process of “AGN feedback” has a dramatic influence on how the galaxy takes shape. The research by Dr. Randall, et. al shows an intimate portrait of this process.

Dr. Randall explained, “This is an important result for stellar formation and galaxy evolution. The AGN heats the gas, preventing it from cooling and forming large amounts of stars. There have been several galaxy evolution models proposed that require this kind of “AGN feedback” near the centers of galaxies to explain the observed differences in galaxies. Here we show explicitly that this kind of feedback can and does take place, at least in this system.”

A labeled image of the various shock waves and cavities formed by the activity of the AGN. Image Credit: Credit: NASA/CXC/SAO/S.Randall et al.

As you can see in the image directly above, various outbursts of the AGN create shock waves in the gas near the center of the galaxy. As these shock waves expanded and the galaxy evolved over millions of years, the heat generated by the shocks spread outwards and into the gas surrounding NGC 5813. The gas between all of the galaxies in a cluster is called the intracluster medium (ICM). The heat – which is produced by the friction of the gases at the edge of each of the shock waves – radiates outward into the surrounding gas, increasing its temperature.

The output of the jets streaming from the supermassive black hole in the center vary over a span of roughly 10 million years, and the amount of energy that each outburst puts out is rather variable – the difference between the last two largest outbursts, for example, is almost an order of magnitude.

This process is cyclical, though the details of the mechanisms involved are still a topic that isn’t completely understood.

Dr. Randall explained this process as follows:

“…the gas cools radiatively, and flows in towards the AGN. The cool gas is rapidly accreted by the black hole, dirving [sic] an energetic outburst. The outburst heats the gas (via shocks), stopping the inflow and starving the AGN. The gas is then able to cool once more, and the cycle repeats, with, in this case, a period of about 10 million years. However, the fine details of how the jet and the ICM interact are not currently well uderstood [sic], and it is not clear how well this simple model describes reality. Our goal with the upcoming deep Chandra observation is to better understand the details of this process, most likely through comparisons with detailed numerical simulations.”

Further observations of NGC 5813 in the fall of 2011 using Chandra are in the works, Dr. Randall said. The results of their analysis will be published in the Astrophysical Journal. A preprint version of the paper, “Shocks and Cavities from Multiple Outbursts in the Galaxy Group NGC 5813: A Window to AGN Feedback,” is available on Arxiv.

Sources: Chandra press release, Arxiv paper, email interview with Dr. Scott Randall

The Zooniverse is Expanding: The Milky Way Project Begins Today

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From the folks that brought you the addictive citizen science projects Galaxy Zoo and Moon Zoo (among others), comes yet another way to explore our Universe and help out scientists at the same time. The Milky Way Project invites members of the public to look at images from infrared surveys of our Milky Way and flag features such as gas bubbles, knots of gas and dust and star clusters.

As with the other Zooniverse projects, the participation of the public is a core feature. Accompanying the Milky Way Project is a way for Zooniverse members – lovingly called “zooites” – to discuss the images they’ve cataloged. Called Milky Way Talk, users can submit images they find curious or just plain beautiful to the talk forum for discussion.

The Milky Way Project uses data from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) and the Multiband Imaging Photometer for Spitzer Galactic Plane Survey (MIPSGAL). These two surveys have imaged the Milky Way in infrared light at different frequencies. GLIMPSE at 3.6, 4.5, 5.8, and 8 microns, and MIPSGAL at 24 and 70 microns. In the infrared, things that don’t emit much visible light – such as large gas clouds excited by stellar radiation – are apparent in images.

The new project aims at cataloging bubbles, star clusters, knots of gas and dark nebulae. All of these objects are interesting in their own ways.

Bubbles – large structures of gas in the galactic plane – belie areas where young stars are altering the interstellar medium that surrounds them. They heat up the dust and/or ionize the gas that surrounds them, and the flow of particles from the star pushes the diffuse material surrounding out into bubble shapes.

The green knots are where the gas and dust are more dense, and might be regions that contain stellar nurseries. Similarly, dark nebulae – nebulae that appear darker than the surrounding gas – are of interest to astronomers because they may also point to stellar formation of high-mass stars.

Star clusters and galaxies outside of the Milky Way may also be visible in some of the images. Though the cataloging of these objects isn’t the main focus of the project, zooites can flag them in the images for later discussion. Just like in the other Zooniverse projects, which use data from robotic surveys, there is always the chance that you will be the first person ever to look at something in one of the images. You could even be like Galaxy Zoo member Hanny and discover something that astronomers will spend telescope time looking at!

This image is full of objects that are interesting to astronomers for study. You can help them pick out which things to study. Image Credit: Spitzer/The Milky Way Project

The GLIMPSE-MIPSGAL surveys were performed by the Spitzer Space Telescope. Over 440,000 images – all taken in the infrared – are in the catalog and need to be sifted through. This is a serious undertaking, one that cannot be accomplished by graduate students in astronomy alone.

In cataloging these bubbles for subsequent analysis, Milky Way Project members can help astronomers understand both the interstellar medium and the stars themselves imaged by the survey. It will also help them to make a map of the Milky Way’s stellar formation regions.

As with the other Zooniverse projects, this newest addition relies on the human brain’s ability to pick out patterns. Diffuse or oddly-shaped bubbles – such as those that appear “popped” or are elliptical – are difficult for a computer to analyze. So, it’s up to willing members of the public to help out the astronomy community. The Zooniverse community boasts over 350,000 members participating in their various projects.

A little cataloging and research of these gas bubbles has already been done by researchers. The Milky Way Project site references work by Churchwell, et. al, who cataloged over 600 of the bubbles and discovered that 75% of the bubbles they looked at were created by type B4-B9 stars, while 0-B3 stars make up the remainder (for more on what these stellar types mean, click here).

A zoomable map that uses images from the surveys – and has labeled a lot of the bubbles that have been already cataloged by the researchers- is available at Alien Earths.

For an extensive treatment of just how important these bubbles are to understanding stars and their formation, the paper “IR Dust Bubbles: Probing the Detailed Structure and Young Massive Stellar Populations of Galactic HII Regions” by Watson, et. al is available here.

If you want to get cracking on drawing bubbles and cataloging interesting features of our Milky Way, take the tutorial and sign up today.

Sources: The Milky Way Project, Arxiv, GLIMPSE

Breaking News: Watch A Gigantic Looping Solar Prominence

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The Solar Dynamics Observatory never fails to deliver absolutely stunning images from the Sun: as of 18:49 UT today, the above picture is what the Sun looked like in the ultraviolet spectrum. The prominence that you are seeing looping off the Sun is estimated at over 700,000 km across, which is about the radius of the entire Sun. Amazing!

You can head over to the Solar Dynamics Observatory site to watch this gigantic loop of solar plasma develop in real time.

There’s nothing to worry about here on Earth, though – we are safe from such activity on the Sun, even if that prominence is big enough swallow up thousands of Earths. There is no coronal-mass ejection or flare to go along with this prominence, both phenomena on the Sun that can reach Earth and mess with satellites and our power grid.

As you can see (or rather, not see) in this visible light image below, the flare seems to only be visible in the ultraviolet. Other spectra of the Sun as imaged by the SDO are available here. Why is this? Phil Plait, the Bad Astronomer, explains it best:

“In visible light, the light from the extremely thin material in the prominence is totally overwhelmed by the intense emission from the Sun’s surface, and is invisible. It’s only when we filter out most of the Sun’s light (and let through light specifically given off by the plasma in the prominence) that we can see it at all,” he wrote.

The Sun in the visible light spectrum, as seen from SDO at 18:00 UT. The two visible sunspots seem to be unrelated to this large prominence. Image Credit: SDO

This video shows the buildup up this most recent spectacular solar show, as this portion of the Sun comes into view from a 48-hour period between December 4th and 6th:

[UPDATE]: Here is a video that shows the prominence eruption as it expanded:

Spaceweather.com also has some other fantastic images that are linked to on their front page. Prominences like this can come crashing down quickly when they become unstable, so head over to the SDO site to watch the action as it develops!

Source: The Bad Astronomer, SDO

NASA’s Nanosail-D Released into the Winds of Space

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Despite being an idea rattling around inside the head of engineers and space enthusiasts for over 40 years, solar sails have never really gained much traction in the way of actual deployment. Today, NASA has taken an important step towards testing solar sail technology for use in future spacecraft.

The Nanosail-D spacecraft was launched Friday, Nov. 19 at 8:25 p.m. EST from Kodiak Island, Alaska, and was piggybacking on another satellite, both aboard a Minotaur IV rocket. It has successfully been ejected from the launch vehicle as of today, and is on its own. Though the sails have yet to deploy, this is already an achievement that bodes well for the future of both solar sail and small satellite technology.

The Nanosail-D satellite – commonly described as “loaf of bread” sized – was ejected from the Fast, Affordable, Science and Technology Satellite (FASTSAT) at 1:31 a.m. EST December 6th. Not only is this NASA’s first attempt at deploying a solar sail in space, but this also marks the first time a nanosatellite has been ejected from another satellite, proving that this is a reliable way to get multiple satellites into orbit at the same time.

Nanosail-D is a nanosatellite – or cubesat – designed to test the potential for solar sails in atmospheric braking. Such sails – made from a an ultra-thin and light material, in this case the polymer CP1 – could potentially be used to propel a spacecraft outside of our Solar System. The Nanosail-D sail will be deployed in low-Earth orbit, about 650 km (400 miles) up. The sail will be used to show how such technology could slow down satellites when they need to de-orbit.

Currently, de-orbiting satellites involves maneuvering them into a lower and lower orbit using the engines of the satellite, which necessitates more propellant aboard the spacecraft simply to dispose of it properly. Nanosail-D will deploy a solar sail and orbit for 70-120 days, eventually spiraling into the Earth’s atmosphere to burn up.

Since it will be orbiting so close to the Earth, its potential for testing solar sails as propulsion is not the focus of the mission; however, the deployment of a solar sail is itself a huge engineering challenge. Nanosail-D will be the perfect experiment to test out whether the method NASA will be using to unfurl the sail is workable in space.

Immediately after the ejection earlier today, a timer started a three-day countdown. Once it reaches zero, it will go boom – that is, four booms will spring out from the small satellite, and within five seconds the sail will be fully extended to its 100 square foot (10 square meter) sail-span.

The first Nanosail-D, unfurled in the lab with the mission team. Image Credit: NASA

Dean Alhorn, NanoSail-D principal investigator and aerospace engineer at the Marshall Space Flight Center explains on the mission page, “The deployment works in the exact opposite way of carpenter’s measuring tape. With a measuring tape, you pull it out, which winds up a spring, and when you let it go it is quickly pulled back in. With NanoSail-D, we wind up the booms around the center spindle. Those wound-up booms act like the spring. Approximately seven days after launch, it deploys the sail off the center spindle.”

There have been other attempts at launching and deploying solar sails before, but once deployed, Nanosail D will be the longest-running solar sail experiment yet attempted. Both JAXA and the Russian space agency have deployed successful solar sail experiments.

JAXA launched a clover-shaped sail aboard a sounding rocket in 2004, and the experiment lasted about 400 seconds. They also launched the IKAROS spacecraft in May, 2010, which is currently en-route to Venus, and will fly to the opposite side of Sun from Earth. The Russians deployed a 20-meter diameter mirror successfully aboard the Progress M-15 resupply mission to Mir in 1993. Named Znamya 2, the mirror cast a 5km (3 mile)-wide bright spot on the ground that swept across southern France to western Russia, and orbited for several hours before burning up.

The Planetary Society is probably the most vocal and enthusiastic organization in support of solar sail technology. They are currently developing a solar sail similar to that of Nanosail-D, called Lightsail-1. The society attempted a launch of a solar sail called Cosmos 1 in 2005, but the rocket carrying the satellite did not fire during its second stage, and the craft was lost.

Nanosail-D is in its second iteration. The first spacecraft was commissioned in early 2008, and the team – astrophysicists and engineers at the Marshall Space Flight Center and the Ames Research Center – had four months to put together a workable satellite. It launched aboard a Falcon 1 rocket in August of 2008, but the rocket burned up in the atmosphere. If engineers are good at one thing, it’s redundancy – the team had constructed a second Nanosail-D, and had ample time to work out some of the bugs and develop the technology even more.

Doug Huie, a research technician at the University of Alabama in Huntsville, prepares the spacecraft for launch testing. The spacecraft measures 4 inches wide, 4 inches deep and 13 inches long, and weighs 9 pounds. (10cm X 10cm X 33 cm, 4kg) Image Credit: NASA

The Planetary Society almost had a chance to launch Nanosail-D, according to Louis Friedman, executive director of the The Planetary Society, they were contacted by the team developing Nanosail-D after the failed initial launch attempt, and asked if they would like to help launch the second Nanosail-D spacecraft. The Planetary Society agreed, but the team then found space aboard the FASTSAT launch. Consequently, Lightsail-D was borne out of this brief collaboration.

The timer is silently counting down what promises to be an exciting mission, and potential milestone in the future of spaceflight. Watch this space for further developments on the mission.

Sources: NASA press release, The Planetary Society, NASA Science, NASA Nanosail-D fact-sheet

Calm Down: NASA Hasn’t Found any Aliens

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You may have heard in your wanderings through the blogosphere and in the internet today that NASA will be holding a press conference on December 2nd in which they will make an announcement regarding information the search for extraterrestrial life. And that this announcement involves astrobiology, the study of life outside what we know about here on Earth. While true, it is nothing to get worked up about.

Speculation abounds that this is, “the big one,” and that an announcement will be made that extraterrestrial life has been discovered. You can find this speculation at Kottke.org, io9, Gawker, and a lot of other places.

To be clear, there is almost no chance that the press release will be announcing little green men or little brown bacteria anywhere. Follow along for the long explanation below the fold.

Here’s what the press release is titled: “NASA Sets News Conference on Astrobiology Discovery: Science Journal Has Embargoed Details Until 2 p.m. EST On Dec. 2”. All this means is that Science Journal will be publishing some results related to astrobiology that are under embargo until that time. The embargo system is a basically a way of allowing journalists to see scientific results and get interviews and do research on an article before it’s published, but only if they promise to publish their information after the original publication does so. It makes sense, and it works most of the time to the benefit of almost everyone.

NASA regularly – like every day – announces upcoming press conferences and releases, and embargoed press releases float around to science writers like those of us here at Universe Today. This in itself is nothing out of the ordinary, and anyone with an email address can sign up to have these announcements delivered to their inbox or view them on NASA’s website. These emails are meant mainly to notify members of the press that there is something coming up worthy of being a phone-in listener of, the details of which require you to have press credentials.

The press release goes on to say,

“NASA will hold a news conference at 2 p.m. EST on Thursday, Dec. 2, to discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life. Astrobiology is the study of the origin, evolution, distribution and future of life in the universe.
The news conference will be held at the NASA Headquarters auditorium at 300 E St. SW, in Washington. It will be broadcast live on NASA Television and streamed on the agency’s website at http://www.nasa.gov.
Participants are:
– Mary Voytek, director, Astrobiology Program, NASA Headquarters, Washington
– Felisa Wolfe-Simon, NASA astrobiology research fellow, U.S. Geological Survey, Menlo Park, Calif.
– Pamela Conrad, astrobiologist, NASA’s Goddard Space Flight Center, Greenbelt, Md.
– Steven Benner, distinguished fellow, Foundation for Applied Molecular Evolution, Gainesville, Fla.
– James Elser, professor, Arizona State University, Tempe”

And that’s about it. My first reaction to this was that they had potentially made the discovery of exotic, new organic molecules in an exoplanetary atmosphere, or that some chemical conducive to the existence of life as we know it was possibly found on some body in the Solar System. Announcements like this come out of NASA all of the time.

Just because some of the participants do work in fields that are related to oceanography or ecology or biology, does not mean that their services are required here to help make an announcement that life other than that on Earth has been discovered, as other speculative bloggers might think.

As Nancy wrote in a post earlier today, extraterrestrial life is very much of interest to Universe Today readers. Which is why she’ll be listening in on that news conference Thursday, and reporting what findings are released.

Extraterrestrial life is very much of interest to probably most of the population of our planet, too, and the fact that we have the tools necessary to potentially make this discovery within the next few hundred years (or sooner), is really, really exciting.

But just because it’s exciting doesn’t mean we have to jump all over a NASA press release that includes the words “extraterrestrial life” or “precursor to life on Mars” and make wild speculations. When that announcement is made (or if, depending on how you choose to solve the Drake Equation), you can be sure that it will be very closely guarded until being made public, and after that the President will likely have some things to say.

For some more level-headed analysis, Keith Cowing at Nasa Watch has some much more reasonable speculation that the announcement involves arsenic biochemistry. The Bad Astronomer, Phil Plait, also has a good debunking of the rampant speculation, and makes some good points about how NASA can create press releases in the future that have better-worded announcements.

So calm down – but don’t stop looking up! Keep being excited about all of the genuinely cool and exciting developments we’re currently making with regards to space.

Source: NASA press release

Exoplanet Discovery Lists top 500

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It was only a little over a year ago that the 400th extrasolar planet was confirmed, but time flies when you’re discovering exoplanets. The 19th of November 2010 marked the date that over 500 exoplanets had been confirmed on The Extrasolar Planets Encyclopedia.

Though it’s an arbitrary number to celebrate, the fact that we’ve confirmed the existence over 500 exoplanets since their initial discovery 20 years ago is deserving of merriment. Discovery of exoplanets has really ramped up over the last few years, thanks in part to the ESA’s COROT satellite, the Hubble and Spitzer space telescopes, the Keck Interferometer, and the improvement of observational techniques to discover and confirm exoplanets. NASA’s Kepler spacecraft has over 700 candidates for exoplanets. Only 7 planets have been confirmed after being discovered by the Kepler spacecraft so far, though.

Jean Schneider, an astrobiologist at the Paris-Meudon Observatory, keeps up a database of the confirmed exoplanetary discoveries at The Extrasolar Planets Encyclopedia. He posted a warning about how muddle the declaration of “the discovery of the 500th exoplanet” could be. He wrote in the warning:

“The number of exoplanets, recored for instance at http://exoplanet.eu is necessarily subject to some uncertainty for several reasons:
– the mass limit below which a substellar object is called a planet
is somewhat arbitrary
– the mass measurement is always affected by some instrumental inaccuracy
– whatever this mass limit is, the true mass for most planets is subject
to some uncertainty, intrinsic to the detection method (unkown
inclination of the orbit, modelisation of planet atmosphere)
– some planet detections, even published in refereed papers, are sometimes
retracted afterwards

For all these reasons
1/ The boundary between “confirmed”/”unconfirmed” planets is somewhat fuzzy
2/ The number of planet candidates at http://exoplanet.eu ;(collected
in the survey of professional litterature, conferences or websites)
is affected by an uncertainty of a few units.”

In essence, to say that there is a “500th exoplanet” is really not possible, given that there needs to be confirmation of the planet. Even after that confirmation, there could be the possible retraction of the planet from the database. 5 confirmations were posted on the 19th, all of them published in refereed papers and discovered in 2010. This kicked the total over 500. But then another was announced the next day, and it was discovered in 2007 but only recently confirmed. So, putting a number on the 500th extrasolar planet to be confirmed is pretty much impossible, arbitrary at best.

Schneider was interviewed by Scientific American on just why he is the keeper of the encyclopedia, and some of his thoughts on the discoveries made so far and the future of the field. The text of the interview is available here.

Complicating matters even further, there is another running tally of extrasolar planets maintained by the NASA’s Jet Propulsion Laboratory at PlanetQuest. Their count on the 22nd of November was only 497, and today rests at 500. The Extrasolar Planets Encyclopedia now stands at 504.

PlanetQuest has this video that succinctly describes the history of extrasolar planet discovery, for those interested:

Even if it’s arbitrary, you can still have that “500th exoplanet” party if you’d like, complete with Kepler satellite-shaped hats. Nobody will likely stop you; if they do, there will likely be another few dozen planets discovered – or a few retracted – by then anyways, making their point rather moot.

Source: MSNBC, PlanetQuest and The Extrasolar Planets Encyclopedia