Nancy Atkinson, Author at Universe Today

August 31, 2016September 1, 2016 by Nancy Atkinson

Going Viral: Why Alien Signals Get Everyone Excited

One of the 42 dishes in the Allen Telescope Array that searches for signals from space. Credit: Seth Shostak / SETI Institute.

So, that ‘strong’ signal from aliens everyone was so excited about this week? Turns out, it was probably something from Earth, maybe a satellite passing overhead or another object of “terrestrial origin,” the Russian researchers have concluded.

Yeah. Dang.

“This supports our initial assumption that the signal was made by human intelligence, not extraterrestrial intelligence,” said Doug Vakoch, President of METI International (Messaging Extraterrestrial Intelligence), a group doing follow-up observations of the star system HD 164595, where the signal was thought to maybe, perhaps originate.

When the news broke of the possible alien signal, SETI scientists were quick to temper the excitement with measured skepticism, saying more often than not, these signals end up being “natural radio transients” (stellar flare, active galactic nucleus, microlensing of a background source, etc.) or interference of a terrestrial nature (a passing satellite or a microwave oven, for example.)

But still, people were excited and the news went viral. Crazy viral.

“Being no stranger to how the media can hype SETI stories, I can sympathize with those at the center of the latest dustup,” said astronomer and SETI researcher Jason Wright from Penn State University. “It’s understandable that many content outlets, seeking ‘clickbait’ headlines, would spin this particular story in the most intriguing, exciting way, and once that happens a ‘bidding war’ of hype can make the story spin out of control.”

But is it all about clickbait? Since I’m part of the media (and admittedly was initially very excited about this story,) I’d like to think that the excitement and viral-tendencies of news about possible alien signals say more about humanity’s fervent hope that we aren’t alone in the cosmos, rather than who can get the most pageviews.

And I do know that researchers who dedicate their careers to the search for alien signals and Earth-like planets aren’t doing so just so they can keep telling us to not get excited. They, too, are hoping for that chance, that very remote possibility, that we’ve got company in our big and magnificent Universe.

“You can’t always be cynical,” said SETI senior astronomer Seth Shostak. “If a signal is looking promising, we are going to check it out.”

And that’s the thing, say the researchers. They get signals like this all the time.

“This is the sort of thing SETI researchers do all the time, because by the nature of the search, radio SETI experiments come across strong signals all the time,” Vakoch said via email. “At the end of the day, these need to be confirmed as coming from distant locations in space, and if we can’t, we need to consider them spurious. The unusual feature of HD 164595 is that this process of checking is being followed by the media.”

And while scientists were surprised (and maybe annoyed) at the amount of attention the ‘alien signal’ news got this week, there is an upside.

“The silver living here is that those who read the more responsible stories carefully will learn a lot about how SETI works,” Wright told Universe Today, “that communication SETI researchers see “one-off” signals all the time from both astronomical and terrestrial sources, in addition to perhaps the occasional instrumental glitch. Searches using arrays (like the ATA) have an automatic check against many of these, but in any event no one will be popping the champaign until a signal repeats enough for an independent telescope and instrument to detect it, and its intelligent origin is clear.”

“The public is getting an inside view of the usual process of following up interesting SETI candidates,” said Vakoch. “This helps the public understand the standard process of doing SETI: we find interesting signals, and then we see if we can verify them. If not, we move on.”

Vakoch and Wright said that the confirmation process, however, involves a lot of steps, and it’s not always easy or quick to follow-up. So, most of the time, determining the source of the signal takes time.

“Unlike Hollywood movies, where you get a quick “yes or no” about a possible signal from aliens,” Vakoch explained, “the real SETI confirmation process takes some time. It’s easy to think that all we need to do is get on the phone with an astronomer at another location, and we’re all set. But even when colleagues at other facilities are willing to observe, they may face technical limitations.”

The Allen Telescope Array (ATA). Credit: Seth Shostak / SETI Institute

Typical radio SETI searches look for narrowband signals, and most observatories aren’t set up to detect such signals on short notice. And even though radio observatories can make observations even when it’s cloudy, there can be other types of local interference at certain radio frequencies.

“If you need to do a real-time follow-up of a promising SETI signal, you might face significant roadblocks to a ready confirmation – even if the signal is really there,” Vakoch said.

Another upside of the recent media attention is that SETI researchers can let everyone know they aren’t getting much funding for this type of research, and the search could really use a lot more eyes and ears on the Universe, as Jill Tartar tweeted:

Re: HD 164595 – who knows? One telescope is not enough and an array is better.

— Jill Tarter (@jilltarter) August 30, 2016

“It’s all the more evident that we need to replicate these innovative optical SETI systems over and over,”Vakoch said, “so we can have a global network of modest-sized observatories ready for follow-up of promising SETI signals. Developing such a network is one of METI International’s top priorities as an organization.”

(You can support SETI here and find out more about METI and optical SETI here.)

Wright said while the public interest in SETI is great, sometimes the media (or the tin foil hat crowd or conspiracy theorists) can blow things out of proportion.

“This can make it hard for anyone doing SETI to talk about their work, because any mention of ‘strange’ or ‘candidate’ signals has the potential to enter that echo chamber,” he said.

Which can go viral.

But if anyone is worried that SETI researchers are keeping secrets or not telling the whole story, I can personally vouch that during this week, absolutely every SETI researcher I contacted answered all my questions in an extremely timely manner (and provided even more information than I was expecting) plus, other researchers contacted me, asking to be able to explain the signal and the process of how SETI works.

“Nothing would make us more excited than to verify it,” said Bill Diamond, president and CEO of SETI, “But we have to observe it and look at the data.”

Aliens? “Strong” Signal Detected From Sun-Like Star Being Verified By SETI

RATAN-600 radio telescope located in Northern Caucasus in the Karachaevo-Circassian Republic of Russian Federation. . Credit: SAO RAS.

We’re not saying its aliens, but this could be the most enticing SETI-related signal from space since the famous “Wow! Signal” in 1977.

Over the weekend, interstellar expert Paul Gilster broke the news that “a strong signal” was detected by Russian radio astronomers from the region around the star HD 164595. This signal has attracted enough attention that two prominent SETI observatories are quickly making follow-up observations. Alan Boyle reports in Geekwire that the Allen Telescope Array in California has already been observing the star system and the Boquete Optical SETI Observatory in Panama will make an attempt this evening, if the weather is clear.

Doug Vakoch, the President of METI International (Messaging Extraterrestrial Intelligence) told Universe Today via email that the Allen Telescope Array has already completed its initial reconnaissance of HD 164595, “with no indications of alien technologies at radio frequencies.”

“The first step in following up a putative SETI signal is to look at the same frequency where it was first detected,” Vakoch said, and with the nil detection from the ATA, “now it’s time to search other parts of the electromagnetic spectrum.”

Vakoch said METI International will be observing HD 164595 for brief laser pulses from the Boquete Optical SETI Observatory in Panama as soon as weather permits.

“It looks like the Boquete Observatory will be hit by heavy thundershowers late this afternoon and into this evening,” he said, “so we’ll likely need to wait to observe until another night. Once the evening sky is clear in Boquete, we’ll have about an hour to observe in the direction of the constellation Hercules shortly after sunset.”

The signal from HD 164595 was originally detected on May 15, 2015, by the Russian Academy of Science-operated RATAN-600 radio telescope in Zelenchukskaya, Russia. It is located about 95 light years from Earth in the constellation Hercules. The signal had a wavelength of 2.7 cm, with an estimated amplitude of 750 mJy.

Gilster wrote on his Centauri Dreams website that the researchers have worked out the strength of the signal and that if “it came from an isotropic beacon, it would be of a power possible only for a Kardashev Type II civilization,” which means a civilization capable of harnessing the energy of the entire star, and developing something like a Dyson sphere surrounding the star, and transfer all the energy to the planet.

Freeman Dyson theorized that eventually, a civilization would be able to build a megastructure around its star to capture all its energy. Credit: SentientDevelopments.com

If the beam was narrow and sent directly to our Solar System, the researchers say it would be of a power available to a Kardashev Type I civilization, a type of civilization more advanced than us that is able to harness the full amount of solar power it receives from its star.

Of course, like any other signal, such as the recent study of the dimming light curve of KIC 8462852 (Tabby’s Star) that is still being researched, it is possible the signal comes from other “natural” events such microlensing of a background source or even comets as been proposed for both Tabby’s Star or the “Wow! Signal.”

The SETI website explains that narrow-band signals – ones that are only a few Hertz wide or less – are the mark of a purposely built transmitter. “Natural cosmic noisemakers, such as pulsars, quasars, and the turbulent, thin interstellar gas of our own Milky Way, do not make radio signals that are this narrow. The static from these objects is spread all across the dial.”

And so Gilster said “the signal is provocative enough that the RATAN-600 researchers are calling for permanent monitoring of this target.” You can see a graph of the signal on Centauri Dreams.

Update: A member of the SETI@Home team posted a note online that they were “unimpressed” with the paper from the Russian radio astronomers. “Because the receivers used were making broad band measurements, there’s really nothing about this “signal” that would distinguish it from a natural radio transient (stellar flare, active galactic nucleus, microlensing of a background source, etc.) There’s also nothing that could distinguish it from a satellite passing through the telescope field of view. All in all, it’s relatively uninteresting from a SETI standpoint.”

So, this detection might not be as exciting as originally reported. Also SETI senior astronomer Seth Shostak has now weighed in on the topic, also with measured skepticism on the excitement, with a post about this event on the SETI website.

What has probably fueled interest in this signal is the striking similarities between the star and our Sun. HD 164595 is a star just a tad smaller than our Sun (0.99 solar masses), with the exact same metallicity. The age of the star has been estimated at 6.3 billion years it is already known to have at least one planet, HD 164595 b, a Neptune-sized world that orbits the star every 40 days. And as we’ve seen with data from the Kepler spacecraft, with the detection of one planet comes the very high probability that more planets could orbit this star.

The signal has been traveling for 95 years, so it “occurred” (or was sent) in 1920 on Earth calendars. (There is a good discussion of this in the comment section on Gilster’s article.)

Why the Russian team has only made this detection public now is unclear and it may have only come out now because the team wrote a paper to be discussed at an upcoming SETI committee meeting during the 67th International Astronautical Congress in Guadalajara, Mexico, on Tuesday, September 27.

As Gilster wrote, “No one is claiming that this is the work of an extraterrestrial civilization, but it is certainly worth further study.”

Sources: Centauri Dreams, Alan Boyle on Geekwire, SETI

August 26, 2016September 26, 2016 by Nancy Atkinson

Citizen Scientists Help Crack 300 Year Old Mystery Of Eclipse Wind

Totality captured from the March 20, 2015 solar eclipse, as seen from the Svalbard Islands. Credit and Copyright: Tony Hoffman.

Being able to witness a solar eclipse is certainly a distinct experience. Even though the spectacle is mostly visual, there can be other effects as well. The air can cool, and observers may notice a decrease in wind speed or a change in wind direction. There might even be an eerie silence.

Experiences like this have been noted for centuries, and famed astronomer Edmund Halley wrote of the ‘Chill and Damp which attended the Darkness’ during an eclipse in 1715, which he noted caused ‘some sense of Horror’ among those who were witnessing the event.

While most people would describe an eclipse as ‘awe-inspiring’ (and not horrifying at all) the atmospheric changes noted by observers over the years has been called the “eclipse wind.” And now, based on the observations of over 4,500 citizen scientists in the UK during the partial eclipse on March 20, 2015, this effect is not just a figment of anyone’s imagination; it is a real phenomenon.

Partial phases of the solar eclipse on March 20, 2015 as seen from the United Kingdom. Credit and copyright: Sarah and Simon Fisher. — Partial phases of the solar eclipse today as seen from the United Kingdom. Credit and copyright: Sarah and Simon Fisher.

The National Eclipse Weather Experiment (NEWEx) was a UK-wide citizen science project for collecting atmospheric data during that eclipse. Members of the public – including about 200 schools – recorded weather changes such as air temperature, wind speed, wind direction and cloud cover every five minutes during the eclipse. That data, submitted online, was compared with official data from the UK’s Met office observations, the United Kingdom’s national weather service.

“The NEWEx was, as far as we know, a world first, in measuring and analyzing eclipse changes in the weather on a national scale, in close to real time, through engagement of a network of citizen scientists,” wrote researchers Luke Barnard, Giles Harrison, Suzanne Gray and Antonio Portas from the University of Reading, in one of a series of new papers about eclipse meteorology published this week.

The data revealed that not only did the atmosphere cool during the eclipse – which is not surprising since solar radiation is being blocked by the Moon – but the winds and cloud cover also decreased. The cumulative effect is real, not just anecdotal, the team said.

The Data

NEWEx collected 15,606 meteorological observations from 309 locations within the UK and from those observations the science team was able to derive estimates of the near-surface air temperature, cloudiness and near-surface wind speed fields across many UK sites. The data submitted by citizen scientists were combined with Met Office surface weather stations and a network of roadside weather sensors that monitor highway conditions. The combination of data helped unravel the centuries-old mystery of the eclipse wind.

Geographical distribution of participants in the NEWEx citizen science project during the March 20, 2015 solar eclipse in the UK, with designations between schools (yellow squares) and non-schools (pink dots). Credit: Antonio M. Portas, Luke Barnard, Chris Scott, R. Giles Harrison.

From analysis of the data, they found that the wind change is caused by variations to the “boundary layer” – the area of air that usually separates high-level winds from those at the ground.

“There have been lots of theories about the eclipse wind over the years, but we think this is the most compelling explanation yet,” said Harrison in a press release from the University of Reading in the UK. “As the sun disappears behind the moon the ground suddenly cools, just like at sunset. This means warm air stops rising from the ground, causing a drop in wind speed and a shift in its direction, as the slowing of the air by the Earth’s surface changes.”

The measurements from citizen scientists clearly showed temperature drops and a decrease in clouds. The team did note that because of the low velocity of winds and some areas where cloud cover change was small, it was difficult for the participants to make some of the measurements. But the high level of participation across the UK provided enough data for the team to make their conclusions.

“Halley also relied on combining eclipse observations from amateur investigators across Britain. We have continued his approach,” Harrison said.

A total of 16 new papers and reports were published this week in a special ‘eclipse meteorology’ issue of the world’s oldest scientific journal, Philosophical Transactions of the Royal Society A. The special issue is published 301 years after Halley’s report of the eclipse in London in 1715 – and in exactly the same journal.

The team wrote that they hope a similar citizen science effort might take place in August 2017, when a total solar eclipse will be visible from North America, providing another opportunity to study eclipse-induced meteorology changes.
“NEWEx serves as a useful example of the strengths and challenges of using a citizen science approach to study eclipse-induced meteorological changes, and could provide a template for a similar study for the August 2017 eclipse,” the team said.

Sources: Paper: The National Eclipse Weather Experiment: an assessment of citizen scientist weather observations, Philosophical Transactions of the Royal Society A, University of Reading.

August 24, 2016 by Nancy Atkinson

Experience the Glorious Night Sky Over Yellowstone National Park

A still from the timelapse video 'Hades Exhales,' a timelapse journey through several of Yellowstone National Park's geyser basins. Credit and copyright: Harun Mehmedinovic/Skyglow Productions.

Tomorrow, August 25, 2016, the US National Park Service celebrates its 100th anniversary, and the NPS has been celebrating all year with their “Find Your Park” promotion. But the first national park, Yellowstone National Park, was created 144 years ago. Yellowstone is known for its dramatic canyons, lush forests, and flowing rivers, but might be most famous for its hot springs and gushing geysers.

This new timelapse offers you a chance to “find your dark skies” at Yellowstone, and features the many geysers there, showing the dramatic geothermal features under both day and night skies. But the night skies over these geyser explosions steal the show! It was filmed by Harun Mehmedinovicas part of the Skyglow Project, an ongoing crowdfunded project that explores the effects and dangers of urban light pollution in contrast with some of the most incredible dark sky areas in North America.

SKYGLOWPROJECT.COM : HADES EXHALES from Harun Mehmedinovic on Vimeo.

The Skyglow Project works in collaboration with International Dark-Sky Association, a nonprofit organization fighting to educate the public about light pollution and to preserve the dark skies around the world.

Coming up this weekend, you can enjoy free admission to all 412 national parks from August 25-28, 2016. You can “find your park” and read about special events happening all around the country at FindYourPark.com

A still from the timelapse video 'Hades Exhales,' a timelapse journey through several of Yellowstone National Park's geyser basins. Credit: Harun Mehmedinovic/Skyglow Productions. — A still from the timelapse video ‘Hades Exhales,’ a timelapse journey through several of Yellowstone National Park’s geyser basins. Credit: Harun Mehmedinovic/Skyglow Productions.

Many thanks to Harun Mehmedinovic and Gavin Heffernan of Sunchaser Pictures for continuing their great work with the Skyglow Project and for sharing their incredible videos with Universe Today. Consider supporting their work, as all donations go towards the creation of more videos and images.

A still from the video 'Hades Exhales,' a timelapse journey through several of Yellowstone National Park's geyser basins. Credit and copyright: Harun Mehmedinovic/Skyglow Productions. — A still from the video ‘Hades Exhales,’ a timelapse journey through several of Yellowstone National Park’s geyser basins. Credit and copyright: Harun Mehmedinovic/Skyglow Productions.

August 4, 2016September 26, 2016 by Nancy Atkinson

HiRISE Drops 1,000 Stunning New Mars Images For Your Viewing Pleasure

A possible 'Recurring Slope Lineae (RSL), dark streaks on slopes that appeared to ebb and flow over time that may or may not be caused by water on Mars. This RSL is in Ceraunius Fossae. Credit: NASA/JPL/University of Arizona.

We frequently call the HiRISE camera on board the Mars Reconnaissance Orbiter “our favorite camera” and for good reason. HiRISE, the High Resolution Imaging Science Experiment, is the largest and most powerful camera ever flown on a planetary mission, sending back incredibly beautiful, high-resolution images of Mars. While previous cameras on other Mars orbiters can identify objects about the size of a school bus, HiRISE brings it to human scale, imaging objects as small as 3 feet (1 meter) across.

The HiRISE team has just released more than 1,000 new observations of Mars for the Planetary Data System archive, showing a wide range of gullies, dunes, craters, geological layering and other features on the Red Planet. Take a look at some of the highlights (click on each image for higher resolution versions and more info):

Chloride and Paleo Dunes in Terra Sirenum. Credit: NASA/JPL/University of Arizona.

MRO orbits at about 300 km above the Martian surface. The width of a HiRISE image covers about about 6 km, with a 1.2 km strip of color in the center. The length of the images can be up to 37 km. If you click on each of these images here, or go to the HiRISE website, you can see the full images in all their glory. To fully appreciate the images, you can download the special HiView application, which allows you to see the images in various formats.

Dunes Within Arkhangelsky Crater. Credit: NASA/JPL/University of Arizona

HiRISE has been nicknamed “The People’s Camera“ because the team allows the public to choose specific targets for the camera to image. Check out the HiWISH page here if you’d like a certain spot on Mars imaged.

Crater Near Hydaspis Chaos. Credit: NASA/JPL/University of Arizona.

The lead image (the link to the image on the HiRISE site is here) shows a possible recurring slope lineae (RSL), mysterious dark streaks on slopes that appeared to ebb and flow over time. They darken and appear to flow down steep slopes during warm seasons, and then fade in cooler seasons. One possibility is this is evidence of liquid water present on Mars today. Some scientists said it could be a salty, briny liquid water flowing down the slopes. But a recent analysis says the RSLs show no mineralogical evidence for abundant liquid water or its by-products, and so it might be mechanisms other than the flow of water — such as the freeze and thaw of carbon dioxide frost — as being the major drivers of recent RSLs.

Check out the full release of images from August 2016 here.

July 27, 2016August 15, 2016 by Nancy Atkinson

Goodbye Forever Philae; We Hardly Knew Ye

Philae's view via its CIVA instrument after landing. Credit: ESA/Rosetta/Philae/CIVA

You can’t say they didn’t try, but the news is sad nonetheless. ESA announced the mission for the Philae lander – the first spacecraft to ever land on a comet — is officially over. The system that enables communications between the Rosetta spacecraft and Philae – which sitting in a shaded region on Comet 67P/Churyumov-Gerasimenko – is being switched off on July 27, 2016, at 09:00 UTC.

“It’s time for me to say goodbye,” Philae tweeted on Tuesday. “Tomorrow, the unit on @ESA_Rosetta for communication with me will be switched off forever…”

Philae has mostly been in hibernation after its dramatic touchdown (actually, three or maybe four touchdowns) on Nov. 12, 2014 when it separated from the orbiting Rosetta spacecraft, flew, landed, bounced and then repeated that process for more than two hours across the surface. The harpoons that were to anchor Philae to the surface failed to fire, and scientists estimated the lander may have bounced as high as 3.2 kilometers (2 miles) before becoming wedged in the shadows of a cliff on the odd-shaped comet. The solar-powered lander quickly ran out of power, just hours after landing. Philae’s final location has been plotted but never actually seen by Rosetta.

Slow animation of images taken by Philae’s Rosetta Lander Imaging System, ROLIS, trace the lander’s descent to the first landing site, Agilkia, on Comet 67P/Churyumov–Gerasimenko on November 12, 2014. Credits: ESA/Rosetta/Philae/ROLIS/DLR — Slow animation of images taken by Philae’s Rosetta Lander Imaging System, ROLIS, trace the lander’s descent to the first landing site, Agilkia, on Comet 67P/Churyumov–Gerasimenko on November 12, 2014.
Credits: ESA/Rosetta/Philae/ROLIS/DLR

After months of silence, the team heard briefly from Philae on June 13, 2015, when it transmitted information on its power and computer subsystems. It then made seven intermittent contacts with Rosetta in the following weeks, with the last coming on July 9, but the communications were too short and unstable to transmit or receive any meaningful scientific or engineering data.

Since then, the Support System Processor Unit (ESS) on Rosetta was kept on in the unlikely chance that Philae would wake up and try to reestablish contact. The hope was that when the comet was closer to the Sun, it might receive enough light to power up.

But the reason for turning it off now is due to Rosetta’s own impending end of mission, coming on September 30, 2016 when it will make a controlled impact at the Ma’at region on the comet’s “head.” Emily Lakdawalla of The Planetary Society put together this annotated image of sites where Philae touched down and likely landed, and where Rosetta will end up:

The 19 regions identified on Comet 67P/Churyumov–Gerasimenko are separated by distinct geomorphological boundaries. Following the ancient Egyptian theme of the Rosetta mission, they are named for Egyptian deities. They are grouped according to the type of terrain dominant within each region. Five basic categories of terrain type have been determined: dust-covered (Ma’at, Ash and Babi); brittle materials with pits and circular structures (Seth); large-scale depressions (Hatmehit, Nut and Aten); smooth terrains (Hapi, Imhotep and Anubis), and exposed, more consolidated (‘rock-like’) surfaces (Maftet, Bastet, Serqet, Hathor, Anuket, Khepry, Aker, Atum and Apis). All three landing sites (Philae initial and final sites and the planned resting place of the Rosetta orbiter) are located on the northern part of the "head" of the comet. Base map: ESA / Rosetta / MPS for OSIRIS Team MPS / UPD / LAM / IAA / SSO / INTA / UPM / DASP / IDA. Landing site locations: Emily Lakdawalla. — The 19 regions identified on Comet 67P/Churyumov–Gerasimenko are separated by distinct geomorphological boundaries. Following the ancient Egyptian theme of the Rosetta mission, they are named for Egyptian deities. They are grouped according to the type of terrain dominant within each region. Five basic categories of terrain type have been determined: dust-covered (Ma’at, Ash and Babi); brittle materials with pits and circular structures (Seth); large-scale depressions (Hatmehit, Nut and Aten); smooth terrains (Hapi, Imhotep and Anubis), and exposed, more consolidated (‘rock-like’) surfaces (Maftet, Bastet, Serqet, Hathor, Anuket, Khepry, Aker, Atum and Apis). All three landing sites (Philae initial and final sites and the planned resting place of the Rosetta orbiter) are located on the northern part of the “head” of the comet.
Base map: ESA / Rosetta / MPS for OSIRIS Team MPS / UPD / LAM / IAA / SSO / INTA / UPM / DASP / IDA. Landing site locations: Emily Lakdawalla.

The team decided to keep “Rosetta’s listening channel on until it is no longer possible due to power constraints as we move ever further from the Sun towards the end of the mission,” said Patrick Martin, ESA’s Rosetta mission manager.

Martin said that by the end of this week, the spacecraft will be about 520 million km from the Sun, and will start facing a significant loss of power – about 4W per day. In order to continue scientific operations over the next two months and to maximize their return, it became necessary to start reducing the power consumed by the non-essential payload components on board.

But, Martin added that the mission of Philae and Rosetta will always be remembered as an incredible success.

“The combined achievements of Rosetta and Philae, rendezvousing with and landing on a comet, are historic high points in space exploration,” he said.

Philae did achieve 80% of its primary science goals in its short 64-hour active mission, as it took detailed images of the comet from above and on the surface, searched for organic compounds, and profiled the local environment and surface properties of the comet, “providing revolutionary insights into this fascinating world,” ESA said.

Sources: ESA, The Planetary Society, ESA blog

July 26, 2016September 20, 2016 by Nancy Atkinson

Large Impact Craters on Ceres Have Gone Missing

A depression on Ceres is possibly what’s left of one of the largest craters from Ceres’ earliest collisional history. Credit: SwRI/Simone Marchi.

Scientists have found a bit of a mystery at the dwarf planet Ceres. Yes, there are those intriguing bright spots inside numerous craters, which is a mystery that has mostly been solved (the bright areas likely made of bright salts leftover from the sublimation of a briny solution of sodium carbonate and ammonium chloride; read more details in this NASA article.)

But a new puzzle involves the craters themselves. In the rough and tumble environment of the asteroid belt, ancient Ceres was certainly pummeled by numerous large asteroids during its 4.5 billion-year lifetime. But yet, there are just a few large craters on Ceres.

How could that be?

“It is as though Ceres cures its own large impact scars and regenerates new surfaces, over and over,” said Dr. Simone Marchi, a senior research scientist at the Southwest Research Institute.

Scientists with NASA's Dawn mission were surprised to find that Ceres has no clear signs of truly giant impact basins. This image shows both visible (left) and topographic (right) mapping data from Dawn. Credit: NASA/JPL-Caltech/SwRI. — Scientists with NASA’s Dawn mission were surprised to find that Ceres has no clear signs of truly giant impact basins. This image shows both visible (left) and topographic (right) mapping data from Dawn. Credit: NASA/JPL-Caltech/SwRI.

Ceres has lots of little craters, but the Dawn spacecraft, orbiting Ceres since early 2015, has found only 16 craters larger than 100 km, and none larger than 280 km (175 miles) across. Scientists who model asteroid collisions in our Solar System predicted Ceres should have amassed up to 10 to 15 craters larger than 400 kilometers (250 miles) wide, and at least 40 craters larger than 100 km (62 miles) wide.

By comparison, Dawn’s other target of study, the smaller asteroid Vesta, has several large craters, including one 500 kilometers (300 miles) in diameter, covering almost the entire south pole region.

While they aren’t visible now, the scientists say there are clues that large impact basins may be hidden beneath Ceres’ surface.

“We concluded that a significant population of large craters on Ceres has been obliterated beyond recognition over geological time scales, likely the result of Ceres’ peculiar composition and internal evolution,” Marchi said.

The top of this false-color image includes a grazing view of Kerwan, Ceres’ largest impact crater. This well-preserved crater is 280 km (175 miles) wide and is well defined with red-yellow high-elevation rims and a deep central depression shown in blue. Kerwan gradually degrades as one moves toward the center of the image into an 800-km (500-mile) wide, 4-km (2.5-mile) deep depression (in green) called Vendimia Planitia. This depression is possibly what’s left of one of the largest craters from Ceres’ earliest collisional history. Credit: SwRI/Simone Marchi.

There are hints of about three shallow depressions around 800 km (500 miles) wide, and Marchi said they could be what are called or planitiae, or ancient impact basins, left over from large collisions that took place early in Ceres’ history.

There are a few possible reasons why the big craters have been erased, and the scientists now have to figure out which reason or combination of reasons best explain their findings. One reason could be because of large amounts of water or ice in Ceres’ interior, which has long been suspected. Does the absence of large craters lend any insight into Ceres’ water content?

“It might,” Marchi said via email. “There is evidence for ice locally at the surface but it is not clear how much water ice there is in the subsurface.”

Marchi said the craters allow scientists to “probe” down to different depths, depending on their sizes, and that the missing large craters (greater than 100 km in diameter) can provide information on the properties on just the upper 100-200 km or so of Ceres’s outer shell.

Because ice is less dense than rock, the topography could “relax” over time — like what happens if you push on your skin, then take the pressure off, and it relaxes back to its original shape, although this happened extremely more slowly on Ceres. The scientists said that over geological timescales of several million years the water or ice would slowly flow and the craters would smooth out.

Additionally, recent analysis of the center of Ceres’ Occator Crater — where the largest bright areas are located — suggests that the salts found there could be remnants of a frozen ocean under the surface, and that liquid water could have been present in Ceres’ interior.

A recent paper constrains the amount of subsurface ice to be no more than 30-40%.

“However, the lack of large craters cannot be solely explained by the presence of 30-40% of water,” Marchi told Universe Today.

Another reason for the lack of large craters could be hydrothermal activity, such as geysers or cryovolcanoes, which could have flowed across the surface, possibly burying pre-existing large craters. Smaller impacts would have then created new craters on the resurfaced area. Hydrothermal activity has been linked to bright areas on Ceres, as well.

A close look at some of the craters on Ceres show cracked-like surfaces and other areas that looks like there was flow of the surface that “softened” some of the features. Marchi said the team is still working to clarify the Ceres’ peculiar composition and how cryolava or “low viscous material” could have caused the crater rims and bowls to “relax.”

The bright central spots near the center of Occator Crater are shown in enhanced color in this view from NASA's Dawn spacecraft. The view was produced by combining the highest resolution images taken in February 2016 (at image scales 115 feet (35 meters) per pixel of 35 meters with color images obtained in September 2015 at a lower resolution. Click for a highest-res view. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI — The bright central spots near the center of Occator Crater are shown in enhanced color in this view from NASA’s Dawn spacecraft. The view was produced by combining the highest resolution images taken in February 2016 (at image scales 115 feet (35 meters) per pixel of 35 meters with color images obtained in September 2015 at a lower resolution. Click for a highest-res view. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

“This is still work in progress,” he told Universe Today. “Ceres is far more richer than Vesta in terms of smooth, flow features. Given that they are in the same environment (e.g. similar impact speed with asteroids), one would think that the production of impact melts would be the same. Thus the fact that we see more flow features on Ceres is a confirmation of its peculiar composition. This may facilitate production of impact “melt” (or ‘mud’ if there is enough water and clays).”

Another reason for the lack of large craters is that smaller, later impacts could have erased the bigger older impact basins. But if that were the case, the older basins would seemingly be more visible than they are now.

But the answer to this puzzle might all come back to the intriguing bright areas on Ceres.

“The presence of ammoniated phyllosilicates, carbonates and salts is truly amazing,” Marchi said. “I think this peculiar composition and Ceres’ internal structure are responsible for the lack of large craters, although we do not know precisely what the obliteration mechanism is.”

Marchi said the large crater obliteration was active well after the late heavy bombardment era, or about 4 billion year ago, so the resurfacing is inextricably linked to Ceres itself and its internal evolution, not impact events.

“All this shows over and over how peculiar Ceres is,” Marchi said. “Beside being a transition object (at inner/outer solar system boundary), it is peculiar in composition, and now also in cratering record.”

Finding out more about Ceres’ interior is one of the more intriguing aspects of Dawn’s continued mission there.

Marchi is lead author of the paper, “The Missing Large Impact Craters on Ceres,” published in the July 26, 2016, issue of Nature Communications.

Sources: Email exchange with Marchi, SwRI, JPL

July 23, 2016September 20, 2016 by Nancy Atkinson

Two Nearby Potentially Habitable Planets Are Rocky Worlds

An artist’s depiction of planets transiting a red dwarf star in the TRAPPIST-1 System. Credit: NASA/ESA/STScl

When Hubble first observed the atmospheric conditions of an extrasolar planet in 2000, it opened up that entire field of study. Now, Hubble has conducted the first preliminary study of the atmospheres of Earth-sized, relatively nearby worlds and found “indications that increase the chances of habitability on two exoplanets,” say the researchers.

The planets, TRAPPIST-1b and TRAPPIST-1c, were discovered earlier this year and are approximately 40 light-years away. At the time of their discovery, it was unknown if the worlds were gas planets or rocky worlds, but Hubble’s most recent observations suggest that both planets have compact atmospheres, similar to those of rocky planets such as Earth, Venus, and Mars instead of thick, puffy atmospheres, similar to that of the gas planets like Jupiter.

“Now we can say that these planets are rocky. Now the question is, what kind of atmosphere do they have?” said Julien de Wit of the Massachusetts Institute of Technology, who led a team of scientists to observe the planets in near-infrared light using Hubble’s Wide Field Camera 3. “The plausible scenarios include something like Venus, with high, thick clouds and an atmosphere dominated by carbon dioxide, or an Earth-like atmosphere dominated by nitrogen and oxygen, or even something like Mars with a depleted atmosphere. The next step is to try to disentangle all these possible scenarios that exist for these terrestrial planets.”

Structure of the TRAPPIST-1 exosystem. The green is the star's habitable zone. Credit: Planetary Habitability Lab. — Structure of the TRAPPIST-1 exosystem. The green is the star’s habitable zone. Credit: Planetary Habitability Lab.

The exoplanets were originally discovered by the TRAPPIST telescope at ESO’s La Silla observatory in Chile, which, like the Kepler telescope, looks for planetary transits (TRAPPIST stands for Transiting Planets and Planetesimals Small Telescope) observing dips in a star’s light from planets passing in front of it from Earth’s point of view.

The star, TRAPPIST-1, is an ultracool dwarf star and is very small and dim. TRAPPIST-1b completes an orbit around the star in just 1.5 days and TRAPPIST-1c in 2.4 days, and the planets are between 20 and 100 times closer to their star than the Earth is to the sun. Both are tidally locked, where one side of these worlds might be hellish and uninhabitable, but conditions might permit a limited region of habitability on the other side. And because of the star’s faintness, researchers think that TRAPPIST-1c may be within the star’s habitable zone, where moderate temperatures could allow for liquid water to pool.

“A rocky surface is a great start for a habitable planet, but any life on the TRAPPIST-1 planets is likely to have a much harder time than life on Earth,” said Joanna Barstow, an astrophysicist at University College London, who was not involved with the research. “Of course, our ideas of habitability are very narrow because we only have one planet to look at so far, and life might well surprise us by flourishing in what we think of as unlikely conditions.”

The researchers used spectroscopy to decode the light and reveal clues to the chemical makeup of the planets’ atmospheres. While the content of the atmospheres is unknown and are scheduled for more observations, the low concentration of hydrogen and helium has scientists excited about the implications.

The team realized a rare double transit was going to take place, when the two planets would almost simultaneously pass in front of their star, but they only knew two weeks in advance. They took a chance, and taking advantage of Hubble’s ability to do observations on short notice, they wrote up a proposal in a day.

“We thought, maybe we could see if people at Hubble would give us time to do this observation, so we wrote the proposal in less than 24 hours, sent it out, and it was reviewed immediately,” de Wit said. “Now for the first time we have spectroscopic observations of a double transit, which allows us to get insight on the atmosphere of both planets at the same time.”

Using Hubble, the team recorded a combined transmission spectrum of TRAPPIST-1b and c, meaning that as first one planet then the other crossed in front of the star, they were able to measure the changes in wavelength as the amount of starlight dipped with each transit.

“The data turned out to be pristine, absolutely perfect, and the observations were the best that we could have expected,” de Wit says. “The force was certainly with us.”

“These initial Hubble observations are a promising first step in learning more about these nearby worlds, whether they could be rocky like Earth, and whether they could sustain life,” says Geoff Yoder, acting associate administrator for NASA’s Science Mission Directorate in Washington. “This is an exciting time for NASA and exoplanet research.”

The team’s paper was published in Nature.

Sources: MIT, NASA

July 21, 2016September 20, 2016 by Nancy Atkinson

The Moon’s Mare Imbrium Was Hit By Protoplanetary Size Impactor

A photo of the full moon, taken from Apollo 11 on its way home to Earth, from about 18,520 km (10,000 nm) away. Credit: NASA

The asteroid that punched an “eye” in the Moon is about 10 times more massive than originally thought. Researchers say a protoplanet-sized body slammed into the Moon about 3.8 billion years ago, creating the area called Imbrium Basin that forms the right eye of the so-called “Man in the Moon.” Additionally, this large body also indicates that protoplanet-sized asteroids may have been common in the early solar system, putting the “heavy” into the Late Heavy Bombardment.

“We show that Imbrium was likely formed by an absolutely enormous object, large enough to be classified as a protoplanet,” said Pete Schultz from Brown University. “This is the first estimate for the Imbrium impactor’s size that is based largely on the geological features we see on the Moon.”

Mare Imbrium or the Sea of Showers is highlighted in this map of the moon. The other large, dark spots are also basins created from asteroid impacts. Credit: NASA

The Imbrium Basin is easily seen when the Moon is full, as a dark patch in the Moon’s northwestern quadrant. It is about 750 miles across, and a closer look shows the basin is surrounded by grooves and gashes that radiate out from the center of the basin, plus a second set of grooves with a different alignment that have puzzled astronomers for decades.

To re-enact the impact, Schultz used the Vertical Gun Range at the NASA Ames Research Center to conduct hypervelocity impact experiments. This facility has a 14-foot cannon that fires small projectiles at up to 25,750 km/hr (16,000 miles per hour), and high-speed cameras record the ballistic dynamics. During his experiments, Schultz noticed that in addition to the usual crater ejecta from the impact, the impactors themselves – if large enough — had a tendency to break apart when they first made contact with the surface. Then these chunks would continue to travel at a high speeds, skimming along and plowing across the surface, creating grooves and gouges.

Grooves and gashes associated with the Imbrium Basin on the Moon have long been puzzling. New research shows how some of these features were formed and uses them to estimate the size of the Imbrium impactor. The study suggests it was big enough to be considered a protoplanet. NASA/Northeast Planetary Data Center/Brown University

The results showed the second set of grooves were likely formed by these large chunks of the impactor that sheared off on initial contact with the surface.

“The key point is that the grooves made by these chunks aren’t radial to the crater,” Schultz said in a press release. “They come from the region of first contact. We see the same thing in our experiments that we see on the Moon — grooves pointing up-range, rather than the crater.”

The second set of groove trajectories could be used to estimate the impactor’s size. Schultz worked with David Crawford of the Sandia National Laboratories to generate computer models of the physics of various sizes of impactors, and they were able to estimate the impactor that created Imbrium Basin to be more than 250 km (150 miles) across, which is two times larger in diameter and 10 times more massive than previous estimates. This puts the impactor in the range of being the size of a protoplanet.

“That’s actually a low-end estimate,” Schultz said. “It’s possible that it could have been as large as 300 kilometers.”
Previous estimates, Schultz said, were based solely on computer models and yielded a size estimate of only about 50 miles in diameter.

Schultz and his colleagues also used the same methods to estimate the sizes of impactors related to several other basins on the Moon, for example, the Moscoviense and Orientale basins on the Moon’s far side, which yielded impactor sizes of 100 and 110 kilometers across respectively, larger than some previous estimates.

Combining these new estimates with the fact that there are even larger impact basins on the Moon and other planets, Schultz concluded that protoplanet-sized asteroids may have been common in the early solar system, and he called them the “lost giants” of the Late Heavy Bombardment, a period of intense comet and asteroid bombardment thought to have pummeled the Moon and all the planets including the Earth about 4 to 3.8 billion years ago.

“The Moon still holds clues that can affect our interpretation of the entire solar system,” he said. “Its scarred face can tell us quite a lot about what was happening in our neighborhood 3.8 billion years ago.”

Schultz’s study was published in Nature.

Source: Brown University

July 20, 2016April 8, 2018 by Nancy Atkinson

Apollo 11 Landing 47 Years Ago; See it Through New Eyes

Buzz Aldrin Gazes at Tranquility Base during the Apollo 11 moonwalk in an image taken by Neil Armstrong. Credit: NASA

Looking for a way to commemorate the 47th anniversary of the Apollo 11 mission landing on the Moon? Here are a few different ways look back on this historic event and take advantage of advances in technology or new data.

Below is a video that uses data from the Lunar Reconnaissance Orbiter and its amazing suite of cameras, offering a side-by-side view of Apollo 11’s descent, comparing footage originally shot from the Eagle lunar module’s window with views created from reconstructed LRO imagery. This is a fun way to re-live the landing — 1202 alarms and all — while seeing high definition views of the lunar surface.

The National Air and Space Museum in Washington, DC has a special way to mark the Apollo 11 anniversary. They have posted online high-resolution 3-D scans of the command module Columbia, the spacecraft that carried astronauts Neil Armstrong, Buzz Aldrin and Michael Collins to the Moon. This very detailed model allows you to explore the entire spacecraft’s interior, which, if you’ve ever visited the Air & Space museum and seen Columbia in person, you probably know is a tremendous ‘upgrade,’ since you can only see a portion of the interior through couple of small hatches and windows. The Smithsonian is also making the data files of the model available for download so it can be 3-D printed or viewed with virtual-reality goggles. Find all the details here.

While 3D scanning the Apollo 11 Command Module, museum staff uncovered writing on the interior walls of the module.The main control panel of the spacecraft contains essential switches and indicators that had to be referred to and operated during the most crucial aspects of the flight. Numbers and references written by hand onto the panel can be checked against the audio and written transcripts from the mission to provide a more vivid picture of just what transpired. Credit: Smithsonian Institution.

Here’s a remastered version of the original mission video as aired in July 1969 depicting the Apollo 11 astronauts conducting several tasks during the moonwalk (EVA) operations on the surface of the moon, which lasted approximately 2.5 hours.

If you’re pressed for time, here’s a quick look at the entire Apollo 11 mission, all in just 100 seconds from Spacecraft Films:

Here’s a very cool detailed look at the Apollo 11 launch in ultra-slow motion, with narration:

Enjoy, and happy anniversary!