April 24, 2017April 28, 2017 by Evan Gough

Into The Submillimeter: The Early Universe’s Formation

A new study looked at 52 submillimeter galaxies to help us understand the early ages of our Universe. Image: University of Nottingham/Omar Almaini

In order to make sense of our Universe, astronomers have to work hard, and they have to push observing technology to the limit. Some of that hard work revolves around what are called sub-millimeter galaxies (SMGs.) SMGs are galaxies that can only be observed in the submillimeter range of the electromagnetic spectrum.

The sub-millimeter range is the waveband between the far-infrared and microwave wavebands. (It’s also called Terahertz radiation.) We’ve only had the capability to observe in the sub-millimeter range for a couple decades. We’ve also increased the angular resolution of telescopes, which helps us discern separate objects.

The submillimter wavelength is also called Terahertz Radiation, and is between Infrared and Microwave Radiation on the spectrum. Image: By Tatoute, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=6884073

SMGs themselves are dim in other wavelengths, because they’re obscured by dust. The optical light is blocked by the dust, and absorbed and re-emitted in the sub-millimeter range. In the sub-millimeter, SMGs are highly luminous; trillions of times more luminous than the Sun, in fact.

This is because they are extremely active star-forming regions. SMGs are forming stars at a rate hundreds of times greater than the Milky Way. They are also generally older, more distant galaxies, so they’re red-shifted. Studying them helps us understand galaxy and star formation in the early universe.

ALMA is an array of dishes located at the Atacama Desert in Chile. Image: ALMA (ESO/NAOJ/NRAO), O. Dessibourg

A new study, led by James Simpson of the University of Edinburgh and Durham University, has examined 52 of these galaxies. In the past, it was difficult to know the exact location of SMGs. In this study, the team relied on the power of the Atacama Large Millimeter/submillimeter array (ALMA) to get a much more precise measurement of their location. These 52 galaxies were first identified by the Submillimeter Common-User Bolometer Array (SCUBA-2) in the UKIDSS Ultra Deep Survey.

There are four major results of the study:

48 of the SMGs are non-lensed, meaning that there is no object of sufficient mass between us and them to distort their light. Of these, the team was able to constrain the red-shift (z) for 35 of them to a median range of z-2.65. When it comes to extra-galactic observations like this, the higher the red-shift, the further away the object is. (For comparison, the highest red-shift object we know of is a galaxy called GN-z11, at z=11.1, which corresponds to about 400 million years after the Big Bang.
Another type of galaxy, the Ultra-Luminous Infrared Galaxy (ULIRG) were thought to be evolved versions of SMGs. But this study showed that SMGs are larger and cooler than ULIRGs, which means that any evolutionary link between the two is unlikely.
The team calculated estimates of dust mass in these galaxies. Their estimates suggest that effectively all of the optical-to-near-infrared light from co-located stars is obscured by dust. They conclude that a common method in astronomy used to characterize astronomical light sources, called Spectral Energy Distribution (SED), may not be reliable when it comes to SMGs.
The fourth result is related to the evolution of galaxies. According to their analysis, it seems unlikely that SMGs can evolve into spiral or lenticular galaxies (a lenticular galaxy is midway between a spiral and an elliptical galaxy.) Rather, it appears that SMGs are the progenitors of elliptical galaxies.

The Pinwheel Galaxy (M101, NGC 5457) is a stunning example of a spiral galaxy. This study determines that there likely is no evolutionary link between sub-millimeter galaxies and spiral galaxies. Image: European Space Agency & NASA. CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=36216331

This study was a pilot study that the team hopes to extend to many other SMGs in the future.

April 22, 2017 by Evan Gough

Exciting New Views Of Opportunity’s Remarkable Landing Site

This image taken by the Mars Reconnaissance Orbiter's HiRise camera shows the bright landing platform left behind by NASA's Mars Exploration Rover Opportunity when it landed in 2004. Opportunity landed on the surface of Mars and then bounced and tumbled into the Eagle Crater. The image was taken on April 8, 2017. Image: NASA/JPL-Caltech/Univ. of Arizona

NASA’s eagle-eyed Mars Reconnaissance Orbiter (MRO) has captured orbital images of Opportunity’s Hole-In-One landing site, smack dab in the middle of Eagle Crater on the surface of Mars.

Opportunity arrived at Mars on January 25th, 2005. It’s landing was slowed by parachute, and cushioned by airbags. Once it hit the surface, it bounced its way into “Eagle Crater“, a feature a mere 22 meters across. Not a bad shot!

This is the first color image that the High Resolution Imaging Science Experiment (HiRise) has captured of Opportunity’s landing site. It shows the remarkable landing site inside the crater, where the landing pad was left behind after Opportunity rolled off of it and got going. It also shows the rover’s parachute and backshell.

It’s amazing that, given the relatively smooth surface in Opportunity’s landing area, the rover came to rest inside a small crater. When Opportunity “woke up” at its landing site, its first images were of the inside of Eagle Crater. This was the first look we ever got at the sedimentary rocks on Mars, taken by the rover’s navigation camera.

Opportunity's navigation camera took this picture, one of the rover's first, of the inside of Eagle Crater. Exposed Martian rocks are visible. NASA/JPL — Opportunity’s navigation camera took this picture, one of the rover’s first, of the inside of Eagle Crater. Exposed Martian rocks are visible. NASA/JPL

After leaving Eagle Crater, Opportunity took a look back and captured a panoramic image. Plainly visible is the rover’s landing pad, the exposed sedimentary rock, and the rover’s tracks in the Martian soil.

This panorama image, called "Lion King" was assembled from 558 images totalling over 75 megabytes. The rock outcrop, the landing pad, and the rover's tracks are all clearly visible. Image: NASA/JPL/Cornell — This panorama image, called “Lion King” was assembled from 558 images totalling over 75 megabytes. The rock outcrop, the landing pad, and the rover’s tracks are all clearly visible. Image: NASA/JPL/Cornell

MRO arrived at Mars a couple years later, and by that time Opportunity had already left its landing site and made its way south to the much larger Victoria Crater.

When the Mars Reconnaissance Orbiter arrived at Mars, 2 years after Opportunity touched down there, Opportunity had left Eagle Crater and travelled the 6 km to Victoria Crater. By NASA/JPL/University of Arizona - http://photojournal.jpl.nasa.gov/catalog/PIA08813, Public Domain, https://commons.wikimedia.org/w/index.php?curid=4211043 — When the Mars Reconnaissance Orbiter arrived at Mars, 2 years after Opportunity touched down there, Opportunity had left Eagle Crater and travelled the 6 km to Victoria Crater. By NASA/JPL/University of Arizona – http://photojournal.jpl.nasa.gov/catalog/PIA08813, Public Domain, https://commons.wikimedia.org/w/index.php?curid=4211043

Opportunity is still chugging along, doing valuable work. And so is the MRO and its HiRise instrument. At this point, Opportunity has to be considered one of the most successful scientific undertakings ever.

April 21, 2017April 28, 2017 by Evan Gough

Are Drylanders The Minority On Habitable Worlds?

Artist's depiction of a waterworld. A new study suggests that Earth is in a minority when it comes to planets, and that most habitable planets may be greater than 90% ocean. Credit: David A. Aguilar (CfA)

If we want to send spacecraft to exoplanets to search for life, we better get good at building submarines.

A new study by Dr. Fergus Simpson, of the Institute of Cosmos Sciences at the University of Barcelona, shows that our assumptions about exo-planets may be wrong. We kind of assume that exoplanets will have land masses, even though we don’t know that. Dr. Simpson’s study suggests that we can expect lots of oceans on the habitable worlds that we might discover. In fact, ocean coverage of 90% may be the norm.

At the heart of this study is something called ‘Bayesian Statistics’, or ‘Bayesian Probability.’

Normally, we give something a probability of occurring—in this case a habitable world with land masses—based on our data. And we’re more confident in our prediction if we have more data. So if we find 10 exoplanets, and 7 of them have significant land masses, we think there’s a 70% chance that future exoplanets will have significant land masses. If we find 100 exoplanets, and 70 of them have significant land masses, then we’re even more confident in our 70% prediction.

Is Earth in the range of normal when it comes to habitable planets? Or is it an outlier, with both large land masses, and large oceans? Image: Reto Stöckli, Nazmi El Saleous, and Marit Jentoft-Nilsen, NASA GSFC

But the problem is, even though we’ve discovered lots of exoplanets, we don’t know if they have land masses or not. We kind of assume they will, even though the masses of those planets is lower than we expect. This is where the Bayesian methods used in this study come in. They replace evidence with logic, sort of.

In Bayesian logic, probability is assigned to something based on the state of our knowledge and on reasonable expectations. In this case, is it reasonable to expect that habitable exoplanets will have significant landmasses in the same way that Earth does? Based on our current knowledge, it isn’t a reasonable expectation.

According to Dr. Simpson, the anthropic principle comes into play here. We just assume that Earth is some kind of standard for habitable worlds. But, as the study shows, that may not be the case.

“Based on the Earth’s ocean coverage of 71%, we find substantial evidence supporting the hypothesis that anthropic selection effects are at work.” – Dr. Fergus Simpson.

In fact, Earth may be a very finely balanced planet, where the amount of water is just right for there to be significant land masses. The size of the oceanic basins is in tune with the amount of water that Earth retains over time, which produces the continents that rise above the seas. Is there any reason to assume that other worlds will be as finely balanced?

Dr. Simpson says no, there isn’t. “A scenario in which the Earth holds less water than most other habitable planets would be consistent with results from simulations, and could help explain why some planets have been found to be a bit less dense than we expected.” says Simpson.

Simpson’s statistical model shows that oceans dominate other habitable worlds, with most of them being 90% water by surface area. In fact, Earth is very close to being a water world. The video shows what would happen to Earth’s continents if the amount of water increased. There is only a very narrow window in which Earth can have both large land masses, and large oceans.

Dr. Simpson suggests that the fine balance between land and water on Earth’s surface could be one reason we evolved here. This is based partly on his model, which shows that land masses will have larger deserts the smaller the oceans are. And deserts are not the most hospitable place for life, and neither are they biodiverse. Also, biodiversity on land is about 25 times greater than biodiversity in oceans, at least on Earth.

Simpson says that the fine balance between land mass and ocean coverage on Earth could be an important reason why we are here, and not somewhere else.

“Our understanding of the development of life may be far from complete, but it is not so dire that we must adhere to the conventional approximation that all habitable planets have an equal chance of hosting intelligent life,” Simpson concludes.

April 20, 2017April 28, 2017 by Evan Gough

Opportunity Leaving ‘Tribulation’ Behind

Opportunity took this panorama shot of "Rocheport Ridge" as it left Cape Tribulation. Rocheport is on the southern end of Cape Tribulation. Image:NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.

You’d have to be an intrepid explorer to investigate something named ‘Cape Tribulation’. Opportunity, NASA’s long-lived rover on Mars’ surface, has been just that. But Opportunity is now leaving Cape Tribulation behind, after being in that area since late 2014, or for about 30 months.

Cape Tribulation is the name given to a segment of crater rim at Endeavour Crater, where Opportunity has been for over 5 1/2 years. During that time, Opportunity reached some important milestones. While there, it surpassed 26 miles in distance travelled, the length of a marathon race. It also reached its highest elevation yet, and in ‘Marathon Valley’, it investigated clay outcrops seen from orbit. Opportunity also had some struggles there, when its flash memory stopped working, meaning all data had to be transmitted every day, or lost.

Sol 3906, January 19, 2015. Summit panorama from Cape Tribulation from the Opportunity Mars Rover. Credit: NASA/Arizona State University.

Before reaching Cape Tribulation 30 months ago, Opportunity investigated other parts of Endeavour Crater called “Cape York,” “Solander Point” and “Murray Ridge.”

Some of the named features at Endeavour Crater. Image: NASA/JPL-Caltech/MSSS

The rover’s next destination is Perseverance Valley, where it will investigate how it was carved out billions of years ago: by water, by wind, or perhaps flowing material lubricated by water. Before leaving Cape Tribulation, Opportunity captured the panoramic image of Rochefort Ridge, a section of the Endeavour Crater rim marked by grooves on its side.”The degree of erosion at Rocheport is fascinating,” said Opportunity Deputy Principal Investigator Ray Arvidson, of Washington University in St. Louis. “Grooves run perpendicular to the crest line. They may have been carved by water or ice or wind. We want to see as many features like this on the way to Perseverance Valley as we can, for comparison with what we find there.”

Endeavour crater is about 22km in diameter, and Perseverance Valley is about 2 football fields long. The goal at Endeavour is to investigate its segmented rim, where the oldest rocks ever investigated on Mars are exposed. Since the beginning of April, Opportunity has travelled about 98 meters, to a point where Cape Tribulation meets the plain around the crater.

“From the Cape Tribulation departure point, we’ll make a beeline to the head of Perseverance Valley…” – Opportunity Deputy Principal Investigator Ray Arvidson

“From the Cape Tribulation departure point, we’ll make a beeline to the head of Perseverance Valley, then turn left and drive down the full length of the valley, if we can,” Arvidson said. “It’s what you would do if you were an astronaut arriving at a feature like this: Start at the top, looking at the source material, then proceed down the valley, looking at deposits along the way and at the bottom.”

It’s the nature of those deposits that can give vital clues to how Perseverance Valley was formed. Arvidson said, “If it was a debris flow, initiated by a little water, with lots of rocks moving downhill, it should be a jumbled mess. If it was a river cutting a channel, we may see gravel bars, crossbedding, and what’s called a ‘fining upward’ pattern of sediments, with coarsest rocks at the bottom.”

Opportunity, and its sister rover Spirit, arrived at Mars in 2004, with a planned mission length of 90 days. Opportunity has surpassed that by over 12 years, and continues to perform extremely well in the Martian environment.

April 20, 2017April 28, 2017 by Evan Gough

The Bubbly Streams Of Titan

The appearing and disappearing feature observed in Titan's Lakes was dubbed "Magic Island". Image: NASA/JPL-Caltech/ASI/Cornell

Saturn’s largest Moon, Titan, is the only other world in our Solar System that has stable liquid on its surface. That alone, and the fact that the liquid is composed of methane, ethane, and nitrogen, makes it an object of fascination. The bright spot features that Cassini observed in the methane seas that dot the polar regions only deepen the fascination.

A new paper published in Nature Astronomy digs deeper into a phenomenon in Titan’s seas that has been puzzling scientists. In 2013, Cassini noticed a feature that wasn’t there on previous fly-bys of the same region. In subsequent images, the feature had disappeared again. What could it be?

One explanation is that the feature could be a disappearing island, rising and falling in the liquid. This idea took hold, but was only an initial guess. Adding to the mystery was the doubling in size of these potential islands. Others speculated that they could be waves, the first waves observed anywhere other than on Earth. Binding all of these together was the idea that the appearance and disappearance could be caused by seasonal changes on the moon.

Titan's dense, hydrocarbon rich atmosphere remains a focal point of scientific research. Credit: NASA — Titan’s dense, hydrocarbon rich atmosphere remains a focal point of scientific research. Credit: NASA

Now, scientists at NASA’s Jet Propulsion Laboratory (JPL) think they know what’s behind these so-called ‘disappearing islands,’ and it seems like they are related to seasonal changes.

The study was led by Michael Malaska of JPL. The researchers simulated the frigid conditions on Titan, where the temperature is -179.2 Celsius. At that temperature, some interesting things happen to the nitrogen in Titan’s atmosphere.

On Titan, it rains. But the rain is composed of extremely cold methane. As that methane falls to the surface, it absorbs significant amounts of nitrogen from the atmosphere. The rain hits Titan’s surface and collects in the lakes on the moon’s polar regions.

The researchers manipulated the conditions in their experiments to mirror the changes that occur on Titan. They changed the temperature, the pressure, and the methane/ethane composition. As they did so, they found that nitrogen bubbled out of solution.

“Our experiments showed that when methane-rich liquids mix with ethane-rich ones — for example from a heavy rain, or when runoff from a methane river mixes into an ethane-rich lake — the nitrogen is less able to stay in solution,” said Michael Malaska of JPL. This release of nitrogen is called exsolution. It can occur when the seasons change on Titan, and the seas of methane and ethane experience a slight warming.

“Thanks to this work on nitrogen’s solubility, we’re now confident that bubbles could indeed form in the seas, and in fact may be more abundant than we’d expected,” said Jason Hofgartner of JPL, a co-author of the study who also works on Cassini’s radar team. These nitrogen bubbles would be very reflective, which explains why Cassini was able to see them.

The first-ever images of the surface of a new moon or planet are always exciting. The Huygens probe was launched from Cassini to the surface of Titan, but was not able investigate the lakes and seas on the surface. Image Credit: ESA/NASA/JPL/University of Arizona

The seas on Titan may be what’s called a prebiotic environment, where chemical conditions are hospitable to the appearance of life. Some think that the seas may already be home to life, though there’s no evidence of this, and Cassini wasn’t equipped to investigate that premise. Some experiments have shown that an atmosphere like Titan’s could generate complex molecules, and even the building blocks of life.

NASA and others have talked about different ways to explore Titan, including balloons, a drone, splashdown landers, and even a submarine. The submarine idea even received a NASA grant in 2015, to develop the idea further.

So, mystery solved, probably. Titan’s bright spots are neither islands nor waves, but bubbles.

Cassini’s mission will end soon, and it’ll be quite some time before Titan can be investigated further. The question of whether Titan’s seas are hospitable to the formation of life, or whether there may already be life there, will have to wait. What role the nitrogen bubbles play in Titan’s life question will also have to wait.

April 19, 2017April 28, 2017 by Evan Gough

Art History NASA Style

This illustration of a double-cylinder space colony is from the 1970's, by artist Rick Guidice. Image: NASA Ames Research Center

To some, art and science are opposed to one another. Art is aesthetics, expression, and intuition, while science is all cold, hard, rational thought. But that’s a simplistic understanding. They’re both quintessential human endeavours, and they’re both part of the human spirit.

Some at NASA have always understood this, and there’s actually an interesting, collaborative history between NASA and the art world, that reaches back several decades. Not the kind of art that you see hanging in elite galleries in the world’s large cities, but the kind of art that documents achievements in space exploration, and that helps us envision what our future could be.

Mitchell Jamieson produced this painting of astronaut Gordon Cooper. Titled "First Steps", it documents Cooper's first steps after exiting his Mercury spacecraft in 1963, after Cooper had completed 22 orbits of Earth. Image Credit: Mitchell Jamieson/Courtesy of the Smithsonian National Air and Space Museum — Mitchell Jamieson produced this painting of astronaut Gordon Cooper. Titled “First Steps”, it documents Cooper’s first steps after exiting his Mercury spacecraft in 1963, after Cooper had completed 22 orbits of Earth. Image Credit: Mitchell Jamieson/Courtesy of the Smithsonian National Air and Space Museum

Back in 1962, when NASA was 4 years old, NASA administrator James Webb put the wheels in motion for a collaboration between NASA and American artists. Artist Bruce Stevenson had been commissioned to produce a portrait of Alan Shepard. Shepard, of course, was the first American in space. He piloted the first Project Mercury flight, MR-3, in 1961. When Webb saw it, he got a bright idea.

When Stevenson brought is portrait of Shepard to NASA headquarters, James Webb thought that Stevenson wanted to paint portraits of all seven Mercury astronauts. But Webb thought a group portrait would be even better. The group portrait was never produced, but it got Webb thinking. In a memo, he said “…we should consider in a deliberate way just what NASA should do in the field of fine arts to commemorate the …historic events” of the American space program.

That set in motion a framework that exists to this day. Beyond just portraits, Webb wanted artists to produce paintings that would convey the excitement around the entire endeavour of space flight, and what the deeper meaning behind it might be. He wanted artists to capture all of the excitement around the preparation and countdown for launches, and activities in space.

This 1963 painting by artist Paul Calle captures the lift-off of the Saturn V Moon rocket. Image: Paul Calle, NASA

That’s when the NASA collaboration with artists began. A young artist named James Dean was assigned to the program, and he took a page out of the Air Force’s book, which established its own art program in 1954.

There’s a whole cast of characters involved, each one contributing to the success of the program. One such person was John Walker, Director of the National Gallery. He was enthusiastic, saying in a talk in 1965 that “the present space exploration effort by the United States will probably rank among the more important events in the history of mankind.” History has certainly proven those words to be true.

This Norman Rockwell painting is from 1965, and shows astronauts Gus Grissom and John Young suiting up for the first Gemini flight in March, 1965. NASA loaned Rockwell a spacesuit for the painting. Image: Norman Rockwell, NASA Art Program

Walker went on to say that it was the artists’ job “…not only to record the physical appearance of the strange new world which space technology is creating, but to edit, select and probe for the inner meaning and emotional impact of events which may change the destiny of our race.”

And that’s what they did. Artists like Norman Rockwell, Andy Warhol, Peter Hurd, Annie Liebowitz, Robert Rauschenberg, and others, all took part in the program.

Artist Peter Hurd painted the launch of Skylab in 1973. Image Credit: Peter Hurd, Courtesy of National Air and Space Museum, Smithsonian Institution

In the 1970’s, thinkers like Gerard K. O’Neill began to formulate ideas of what human colonies in space might look like. NASA held a series of conferences where these ideas were shared and explored. Artists Rick Guidice and Don Davis created many paintings and illustrations of what colony designs like Bernal Spheres, Double Cylinders, and Toroidal Colonies might look like.

This piece by artist Don Davis depicts the end-cap of a cylindrical colony. Notice the suspension bridge, and people enjoying themselves by a river. Image: Don Davis, NASA Ames Research Center

This cut-away image of a Bernal Sphere colony was created by artist Rick Guidice. Image: Rick Guidice, NASA Ames Research Center

NASA continues to work with artists, though the nature of the relationship has changed over the decades. Artists are often used to flesh out new discoveries when images are not available. Cassini’s so-called Grand Finale, when it will orbit between Saturn and its rings 22 times before crashing into the planet, was conceptualized by an unnamed artist.

An artist's illustration of the Cassini probe's Grand Finale. Image: NASA/JPL/CalTech — An artist’s illustration of the Cassini probe’s Grand Finale. Image: NASA/JPL/CalTech

The recent discovery of the exoplanets in the TRAPPIST-1 system was huge news. It still is. But TRAPPIST-1 is over 40 light years away, and NASA relied on artists to bring the discovery to life. This illustration was widely used to help us understand what planets orbiting the TRAPPIST-1 Red Dwarf might look like.

Illustration showing the possible surface of TRAPPIST-1f, one of the newly discovered planets in the TRAPPIST-1 system. Credits: NASA/JPL-Caltech

NASA now has quite a history of relying on art to convey what words can’t do. Space colonies, distant solar systems, and spacecraft ending their missions on other worlds, have all relied on the work of artists. But if I had to choose a favorite, it would probably be the 1981 water color by artist Henry Casselli. It makes you wonder what it’s like for an individual to take part in these species-defining endeavours. Just one person, sitting, contemplating, and preparing.

This Henry Casselli watercolor shows astronaut John Young preparing for a launch on April 12, 1981. What must he have been thinking as he prepared for the first flight of the Space Shuttle Program? Image: Henry Casselli, Courtesy NASA Art Program

April 18, 2017April 28, 2017 by Evan Gough

Ceres Prank Lands Bart Simpson In Detention For Eternity

Do you see Bart Simpson's face on these surface features on Ceres? Researchers studying the surface of the dwarf planet for evidence of the presence of ice do. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA, taken by Dawn Framing Camera

Human-kind has a long history of looking up at the stars and seeing figures and faces. In fact, there’s a word for recognizing faces in natural objects: pareidolia. But this must be the first time someone has recognized Bart Simpson’s face on an object in space.

Researchers studying landslides on the dwarf planet Ceres noticed a pattern that resembles the cartoon character. The researchers, from the Georgia Institute of Technology, are studying massive landslides that occur on the surface of the icy dwarf. Their findings are reinforcing the idea that Ceres has significant quantities of frozen water.

Dwarf planet Ceres is the largest object in the asteroid belt between Mars and Jupiter. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA, taken by Dawn Framing Camera

In a new paper in the journal Nature Geoscience, the team of scientists, led by Georgia Tech Assistant Professor and Dawn Science Team Associate Britney Schmidt, examined the surface of Ceres looking for morphologies that resemble landslides here on Earth.

Research shows us that Ceres probably has a subsurface shell that is rich with water-ice. That shell is covered by a layer of silicates. Close examination of the type, and distribution, of landslides at different latitudes adds more evidence to the sub-surface ice theory.

Ceres is pretty big. At 945 km in diameter, it’s the largest object in the asteroid belt between Mars and Jupiter. It’s big enough to be rounded by its own gravity, and it actually comprises about one third of the mass of the entire asteroid belt.

Type 1 landslides on Ceres are large and occur at higher latitudes. Image: Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA, taken by Dawn Framing Camera

The team used observations from the Dawn Framing Camera to identify three types of landslides on Ceres’ surface:

Type 1 are large, rounded features similar to glacier features in the Earth’s Arctic region. These are found mostly at high latitudes on Ceres, which is where most of the ice probably is.
Type 2 are the most common. They are thinner and longer than Type 1, and look like terrestrial avalanche deposits. They’re found mostly at mid-latitudes on Ceres. The researchers behind the study thought one of them looked like Bart Simpson’s face.
Type 3 occur mostly at low latitudes near Ceres’ equator. These are always found coming from large impact craters, and probably formed when impacts melted the sub-surface ice.

Type 3 landslides on Ceres occur at low latitudes at large craters, and form when ice is melted by impacts. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA, taken by Dawn Framing Camera

The authors of the study say that finding larger landslides further away from the equator is significant, because that’s where most of the ice is.

“Landslides cover more area in the poles than at the equator, but most surface processes generally don’t care about latitude,” said Schmidt, a faculty member in the School of Earth and Atmospheric Sciences. “That’s one reason why we think it’s ice affecting the flow processes. There’s no other good way to explain why the poles have huge, thick landslides; mid-latitudes have a mixture of sheeted and thick landslides; and low latitudes have just a few.”

Key to understanding these results is the fact that these types of processes have only been observed before on Earth and Mars. Earth, obviously, has water and ice in great abundance, and Mars has large quantities of sub-surface ice as well. “It’s just kind of fun that we see features on this small planet that remind us of those on the big planets, like Earth and Mars,” Schmidt said. “It seems more and more that Ceres is our innermost icy world.”

“These landslides offer us the opportunity to understand what’s happening in the upper few kilometers of Ceres,” said Georgia Tech Ph.D. student Heather Chilton, a co-author on the paper. “That’s a sweet spot between information about the upper meter or so provided by the GRaND (Gamma Ray and Neutron Detector) and VIR (Visible and Infrared Spectrometer) instrument data, and the tens of kilometers-deep structure elucidated by crater studies.”

It’s not just the presence of these landslides, but the frequency of them, that upholds the icy-mantle idea on Ceres. The study showed that 20% to 30% of craters on Ceres larger than 10 km have some type of landslide. The researchers say that upper layers of Ceres’ could be up to 50% ice by volume.

April 15, 2017April 28, 2017 by Evan Gough

NASA Releases Spellbinding Images Of Earth At Night

Composite image of continental U.S. at night, 2016. Credits: NASA Earth Observatory images by Joshua Stevens, using Suomi NPP VIIRS data from Miguel Román, NASA's Goddard Space Flight Center

NASA strives to explore space and to expand our understanding of our Solar System and beyond. But they also turn their keen eyes on Earth in an effort to understand how our planet is doing. Now, they’re releasing a new composite image of Earth at night, the first one since 2012.

We’ve grown accustomed to seeing these types of images in our social media feeds, especially night-time views of Earth from the International Space Station. But this new image is much more than that. It’s part of a whole project that will allow scientists—and the rest of us—to study Earth at night in unprecedented detail.

Night-time views of Earth have been around for 25 years or so, usually produced several years apart. Comparing those images shows clearly how humans are changing the face of the planet. Scientists have been refining the imaging over the years, producing better and more detailed images.

The team behind this is led by Miguel Román of NASA’s Goddard Space Flight Center. They’ve been analyzing data and working on new software and algorithms to improve the quality, clarity, and availability of the images.

This new work stems from a collaboration between the National Oceanic and Atmospheric Administration (NOAA) and NASA. In 2011, NASA and NOAA launched a satellite called the Suomi National Polar-orbiting Partnership (NPP) satellite. The key instrument on that satellite is the Visible Infrared Imaging Radiometer Suite (VIIRS), a 275 kg piece of equipment that is a big step forward in Earth observation.

VIIRS detects photons of light in 22 different wavelengths. It’s the first satellite instrument to make quantitative measurements of light emissions and reflections, which allows researchers to distinguish the intensity, types and the sources of night lights over several years.

Composite image of Mid-Atlantic and Northeastern U.S. at night, 2016. Credits: NASA Earth Observatory images by Joshua Stevens, using Suomi NPP VIIRS data from Miguel Román, NASA's Goddard Space Flight Center — Composite image of Mid-Atlantic and Northeastern U.S. at night, 2016.
Credits: NASA Earth Observatory images by Joshua Stevens, using Suomi NPP VIIRS data from Miguel Román, NASA’s Goddard Space Flight Center

Producing these types of maps is challenging. The raw data from SUOMI NPP and its VIIRS instrument has to be skillfully manipulated to get these images. The main challenge is the Moon itself.

As the Moon goes through its different phases, the amount of light hitting Earth is constantly changing. Those changes are predictable, but they still have to be accounted for. Other factors have to be managed as well, like seasonal vegetation, clouds, aerosols, and snow and ice cover. Other changes in the atmosphere, though faint, also affect the outcome. Phenomenon like auroras change the way that light is observed in different parts of the world.

The newly released maps were made from data throughout the year, and the team developed algorithms and code that picked the clearest night views each month, ultimately combining moonlight-free and moonlight-corrected data.

A glittering night-time map of Europe. Looks like there's a Kraftwerk concert happening in Dusseldorf! NASA Earth Observatory images by Joshua Stevens, using Suomi NPP VIIRS data from Miguel Román, NASA's Goddard Space Flight Center — A glittering night-time map of Europe. Looks like there’s a Kraftwerk concert happening in Dusseldorf! NASA Earth Observatory images by Joshua Stevens, using Suomi NPP VIIRS data from Miguel Román, NASA’s Goddard Space Flight Center

The SUOMI NPP satellite is in a polar orbit, and it observes the planet in vertical swaths that are about 3,000 km wide. With its VIIRS instrument, it images almost every location on the surface of the Earth, every day. VIIRS low-light sensor has six times better spatial resolution for distinguishing night lights, and 250 times better resolution overall than previous satellites.

What do all those numbers mean? The team hopes that their new techniques, combined with the power of VIIRS, will create images with extraordinary resolution: the ability to distinguish a single highway lamp, or fishing boat, anywhere on the surface of Earth.

Composite image of Nile River and surrounding region at night, 2016. Credits: NASA Earth Observatory images by Joshua Stevens, using Suomi NPP VIIRS data from Miguel Román, NASA's Goddard Space Flight Center — Composite image of Nile River and surrounding region at night, 2016.
Credits: NASA Earth Observatory images by Joshua Stevens, using Suomi NPP VIIRS data from Miguel Román, NASA’s Goddard Space Flight Center

Beyond thought-provoking eye-candy for the rest of us, these images of night-time Earth have practical benefits to researchers and planners.

“Thanks to VIIRS, we can now monitor short-term changes caused by disturbances in power delivery, such as conflict, storms, earthquakes and brownouts,” said Román. “We can monitor cyclical changes driven by reoccurring human activities such as holiday lighting and seasonal migrations. We can also monitor gradual changes driven by urbanization, out-migration, economic changes, and electrification. The fact that we can track all these different aspects at the heart of what defines a city is simply mind-boggling.”

These three composite images provide full-hemisphere views of Earth at night. The clouds and sun glint — added here for aesthetic effect — are derived from MODIS instrument land surface and cloud cover products. Credits: NASA Earth Observatory images by Joshua Stevens, using Suomi NPP VIIRS data from Miguel Román, NASA's Goddard Space Flight Center — These three composite images provide full-hemisphere views of Earth at night. The clouds and sun glint — added here for aesthetic effect — are derived from MODIS instrument land surface and cloud cover products.
Credits: NASA Earth Observatory images by Joshua Stevens, using Suomi NPP VIIRS data from Miguel Román, NASA’s Goddard Space Flight Center

These maps of night-time Earth are a powerful tool. But the newest development will be a game-changer: Román and his team aim to provide daily, high-definition views of Earth at night. Daily updates will allow real-time tracking of changes on Earth’s surface in a way never before possible.

Maybe the best thing about these upcoming daily night-time light maps is that they will be publicly available. The SUOMI NPP satellite is not military and its data is not classified in any way. They hope to have these daily images available later this year. Once the new daily light-maps of Earth are available, it’ll be another powerful tool in the hands of researchers and planners, and the rest of us.

These maps will join other endeavours like NASA-EOSDIS Worldview. Worldview is a fascinating, easy-to-use data tool that anyone can access. It allows users to look at satellite images of the Earth with user-selected layers for things like dust, smoke, draught, fires, and storms. It’s a powerful tool that can change how you understand the world.

April 13, 2017April 28, 2017 by Evan Gough

Researchers Image Dark Matter Bridge Between Galaxies

This false color, composite image shows two galaxies, white, connected by a bridge of dark matter, red. The two galaxies are about 40 light years apart. Image: S. Epps & M. Hudson / University of Waterloo

Dark matter is mysterious stuff, because we can’t really “see” it. But that hasn’t stopped scientists from researching it, and from theorizing about it. One theory says that there should be filament structures of dark matter connecting galaxies. Scientists from the University of Waterloo have now imaged one of those dark matter filaments for the first time.

The two scientists, Seth D. Epps and Michael J. Hudson, present their results in a paper at the Monthly Notices of the Royal Astronomy Society.

Theory predicts that filaments of dark matter connect galaxies together, by reaching from the dark matter halo of one galaxy to the same halo in another galaxy. Other researchers have found dark matter filaments connecting entire galaxy clusters, but this is the first time that filaments have been imaged between individual galaxies.

“This image moves us beyond predictions to something we can see and measure.” – Mike Hudson, University of Waterloo

“For decades, researchers have been predicting the existence of dark-matter filaments between galaxies that act like a web-like superstructure connecting galaxies together,” said Mike Hudson, a professor of astronomy at the University of Waterloo. “This image moves us beyond predictions to something we can see and measure.”

Dark matter makes up about 25% of the Universe. But it doesn’t shine, reflect, or interact with light in any way, so it’s difficult to study. The only way we can really study it is by observing gravity. In this study, the pair of astronomers used the weak gravitational lensing technique.

Weak gravitational lensing relies on the effect that mass has on light. Enough concentrated mass in the foreground—dark matter in this case—will warp light from distant sources in the background.

When dealing with something as large as a super-massive Black Hole, gravitational lensing is quite pronounced. But galaxy-to-galaxy filaments of dark matter are much less dense than a black hole, so their individual effect is minimal. What the astronomers needed was the combined data from multiple galaxy pairs in order to detect the weak gravitational lensing.

Key to this study is the Canada-France-Hawaii Telescope. It performed a multi-year sky survey that laid the groundwork for this study. The researchers combined lensing images of over 23,000 pairs of galaxies 4.5 billion light years away. The resulting composite image revealed the filament bridge between the two galaxies.

“By using this technique, we’re not only able to see that these dark matter filaments in the universe exist, we’re able to see the extent to which these filaments connect galaxies together.” – Seth D. Epps, University of Waterloo

We still don’t know what dark matter is, but the fact that scientists were able to predict these filaments, and then actually find them, shows that we’re making progress understanding it.

We’ve known about the large scale structure of the Universe for some time, and we know that dark matter is a big part of it. Galaxies tend to cluster together, under the influence of dark matter’s gravitational pull. Finding a dark matter bridge between galaxies is an intriguing discovery. It at least takes a little of the mystery out of dark matter.

April 13, 2017April 28, 2017 by Evan Gough

NASA Bombshell: Key Ingredient For Life Discovered On Enceladus

Scientists recently determined that a certain strain of Earth bacteria could thrive under conditions found on Enceladus. Credit: NASA/JPL/Space Science Institute

NASA has announced the discovery of hydrogen in the plumes on Enceladus. This is huge news, and Cassini scientists have looked forward to this day. What it means is that there is a potential source of energy for microbes in the oceans of Enceladus, and that energy from the Sun is not required to support life.

We’ve known about the plumes on Enceladus for a while now, and Cassini has even flown through those plumes to determine their content. But hydrogen was never discovered until now. What it means is that there is a geochemical source for hydrogen in Enceladus’ ocean, coming from the interaction between warm water and rocks.

“This is the closest we’ve come, so far, to identifying a place with some of the ingredients needed for a habitable environment.” – Thomas Zurbuchen, NASA.

This is a capstone finding, according to NASA. As far as we know, life needs three things to exist: water, energy, and the right chemicals. We know it has the necessary chemicals, we know it has water, and we now know it has a source of energy.

On Earth, hydrothermal vents deep in the ocean floor provide the energy for a web of life reliant on those vents. Bacteria live there, forming the base of a food chain that can include tube worms, shrimp, and other life forms. This discovery points to the possibility that similar communities might exist in the sub-surface ocean of Enceladus.

“This is the closest we’ve come, so far, to identifying a place with some of the ingredients needed for a habitable environment,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate at Headquarters in Washington.

Microbes in Enceladus’ ocean could use the hydrogen in a process called methanogenesis. They obtain energy by combining hydrogen with dissolved carbon dioxide in the water. This process produces a methane by-product. Methanogenesis is a bedrock process at the root of life here on Earth.

“Confirmation that the chemical energy for life exists within the ocean of a small moon of Saturn is an important milestone in our search for habitable worlds beyond Earth,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.

Hubble Confirms Plumes On Europa

NASA has also announced that the Hubble Space Telescope has confirmed the presence of plumes on another of our Solar System’s icy moons, Europa.

These plumes were first seen by the Hubble in 2014, but were never seen again. Since repeatability is key in science, those findings were put on the back burner. But in 2016, NASA announced today, Hubble spotted them again, in the same place. This is the same spot that the Galileo probe noticed a thermal hot spot.

We don’t know if Europa has hydrogen in its oceans, but it’s easy to see where this is going. NASA’s excitement is palpable.

What’s Next?

NASA’s Europa Clipper mission will visit Europa and determine the thickness of its ice layer, as well as the depth and salinity of its ocean. It will also analyze the atmosphere and the composition of the plumes. Europa Clipper will fill in a lot of gaps in our understanding.

Europa Clipper will be launched around 2022, but a mission to Enceladus will have to wait a little longer. One mission under consideration in NASA’s Discovery program is ELF, Enceladus Life Finder. ELF would fly through Enceladus’ plumes 8 or 10 times, taking more detailed samples of their content.

This enhanced-color Cassini view of southern latitudes on Enceladus features the bluish “tiger stripe” fractures that rip across the south polar region. These tiger stripes form over hydrothermal vents in the ocean, the source of Enceladus’ plumes. Credits: NASA/JPL-Caltech/Space Science Institute

The discovery of hydrogen in the plumes of Enceladus is huge news any way you look at it. But that discovery begs the question: Are we doing it all wrong? Are we looking for life in the wrong places?

The search for life elsewhere in the Universe, so far, has mostly revolved around exoplanets. And then refining that search to identify exoplanets that are in the habitable zones of their stars. We’re searching for other Earths, basically.

But maybe we should be changing our focus. Maybe it’s the ice worlds, including icy exomoons, that are the most likely targets for our search. This new evidence from NASA’s Cassini mission, and from the Hubble Space Telescope, suggests that in our Solar System at least, they are the best place to search.

One Final Ingredient Needed?

There’s a fourth ingredient needed for life. Once there is water, energy, and the necessary chemicals, life needs time to get going. How much time, we’re not exactly certain. But this is where Enceladus and Europa are different.

Europa is about 4 billion years old, or so we think. That’s only half a billion years younger than Earth, and we think life started on Earth about 3.5 billion years ago. This hints that, if conditions on Europa are favorable, life has had a long time to get going. Of course, that doesn’t mean it has.

On the other hand, Enceladus is probably much younger. A study of the orbits of Saturn’s moons suggests that Enceladus may only be 100 million years old. If that’s true, it’s not very much time for life to get going.

The hydrogen discovery is huge news. There are still a lot of questions, of course, and lots to be debated. But confirming a source of energy on Enceladus builds the case for the same type of hydrothermal vent life that we see on Earth.

Now all we need is a mission to Enceladus.