Posted on by Elizabeth Howell

A Brief History Of Gliese 581d and 581g, The Planets That May Not Be

Goldilocks Zone
Artists impression of Gliese 581g. Credit: Lynette Cook/NSF

Two potentially habitable planets in the Gliese 581 system are just false signals arising out of starstuff, a new study said. Gliese 581d and 581g are (study authors said) instead indications of the star’s activity and rotation. It’s the latest twist in a long tale about the system as astronomers struggle to understand how many planets could be orbiting the star.

“Our improved detection of the real planets in this system gives us confidence that we are now beginning to sufficiently eliminate Doppler signals from stellar activity to discover new, habitable exoplanets, even when they are hidden beneath stellar noise,” stated Paul Robertson, a postdoctoral fellow at Penn State University, in a press release.

“While it is unfortunate to find that two such promising planets do not exist, we feel that the results of this study will ultimately lead to more Earth-like planets.”

Planets were first announced around the system in 2007 (by a research team led by Geneva’s Stephane Udry) including Gliese 581d. The system has been under heavy scrutiny since a team led by Steven Vogt of the University of Santa Cruz announced Gliese 581g in September 2010. Both 581d and 581g were considered to be in the “habitable” region around the dwarf star they orbited, meaning the spot that’s not too far or close to the star for liquid water to exist.

Potentially habitable exoplanets and exoplanet candidates as of July 3, 2014. Gliese 581d and 581g are crossed off in the catalog. Click for larger version. Credit: PHL @ UPR Arecibo
Potentially habitable exoplanets and exoplanet candidates as of July 3, 2014. Gliese 581d and 581g are crossed off in the catalog. Click for larger version. Credit: PHL @ UPR Arecibo

About two weeks after the discovery, another team led by Geneva University’s Francesco Pepe said it could not find indications of Gliese 581g in data from HARPS (High Accuracy Radial Velocity Planet Searcher), a telescope instrument frequently used at the European Southern Observatory to confirm exoplanets. It also cast doubt on the existence of Gliese 581f, announced by a team led by Geneva’s Michel Mayor in 2009. Other researchers examined the system, too, with mixed results.

Two years later, Vogt led another research team saying that analysis of an “extended dataset” from HARPS did show Gliese 581g. But in a press release at the time from the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo, its director (Abel Mendez) said the discovery would continue to be controversial. At the time he added the planet to the list of potentially habitable exoplanets the laboratory maintains. As of yesterday, both 581d and 581g are crossed off.

The uncertainty arises from the delicacy of looking for signals of small planets around much larger stars. Astronomers typically find planets through watching them pass across the face of a star, or measuring the tug that they exert on their parent star during their orbit. It is the nature of the tug on Gliese 581 that is so interesting astronomers.

Orbital Period
The orbits of planets in the Gliese 581 system are compared to those of our own solar system. The Gliese 581 star has about 30 percent the mass of our Sun, and the outermost planet is closer to its star than the Earth is to the Sun. The 4th planet, G, is a planet that could sustain life. Credit: Zina Deretsky, National Science Foundation

“These ‘Doppler shifts’ can result from subtle changes in the star’s velocity caused by the gravitational tugs of orbiting planets,” wrote Penn State in the press release yesterday.  “But Doppler shifts of a star’s ‘absorption lines’ also can result from magnetic events like sunspots originating within the star itself — giving false clues of a planet that does not actually exist.”

The researchers now say that only three planets exist around this star. It’s impossible to fully represent the debate in a single short news article, so we encourage you to look at some of the original literature. Here is a list of papers related to Gliese 581g and another for Gliese 581d. The new paper is available online in Science.

Also, here are some past Universe Today stories about the system:

Posted on by Shannon Hall

Chandra Image May Rival July 4th Fireworks

A new composite of NGC 4258 features X-rays from Chandra (blue), radio waves from the VLA (purple), optical data from Hubble (yellow and blue), and infrared with Spitzer (red). Image Credit: Chandra

While Fourth of July festivities tonight may bring brilliant colors blazing across the night sky, only 23 million light-years away is another immense cosmic display, complete with a supermassive black hole, shock waves, and vast reservoirs of gas.

The night sky never ceases to amaze. And NGC 4258, also known as Messier 106, is a sight to be seen. A new image from NASA’s Chandra X-ray Observatory is shedding light on one of the galaxy’s most startling features: instead of two spiral arms, typical for any massive spiral galaxy, it appears to have four (imaged above in blue and purple).

Although the second pair of arms can be seen in visible light images as ghostly wisps of gas, they are prominent in images outside the visible spectrum, such as those using X-ray or radio waves. Unlike normal arms, they are made up of hot gas rather than stars, and their origin has remained a mystery.

Astronomers now think the arms — so-called anomalous for their atypical features — are indirectly caused by the supermassive black hole at NGC 4258’s heart.

Images from multiple telescopes help paint a complete picture. Radio data taken with the Very Large Array show that the supermassive black hole is producing powerful jets. As these jets travel through the galactic matter, they disrupt the surrounding gas and generate shock waves. These shock waves, seen by NASA’s Spitzer Space Telescope, heat the anomalous arms — composed of reservoirs of gas as massive as about 10 million Suns — to thousands of degrees.

Finally, the recent Chandra X-ray image also reveals huge bubbles of hot gas above and below the plane of the galaxy. These bubbles indicate that although much of the gas was originally in the disk of the galaxy, it was heated to such high temperatures that it was ejected into the outer regions by the jets from the supermassive black hole.

The results provide drastic implications for the fate of the galaxy. Most of the gas in the disk of the galaxy has been ejected, causing stars to form at a rate ten times slower than the Milky Way. Further, astronomers estimate that all of the remaining gas will be ejected within the next 300 million years.

Although NGC 4258 is currently a sight to be seen in any small telescope, like the best fireworks display followed by smoke, its death is inescapable.

The results were published in The Astrophysical Journal Letters and are available online.

Posted on by Ken Kremer

Mars One Soliciting Your Research Ideas for 2018 Robotic Red Planet Lander

Mars One proposes Phoenix-like lander for first privately funded mission to the Red Planet slated to blastoff in 2018. This film solar array experiment would provide additional power. Credit: Mars One

Would you like to send your great idea for a research experiment to Mars and are searching for a method of transport?

The Mars One non-profit foundation that’s seeking settlers for a one-way trip to establish a permanent human colony on the Red Planet starting in the mid-2020’s, is now soliciting science and marketing proposals in a worldwide competition for their unmanned forerunner mission – the 2018 Mars One technology demonstration lander.

The Dutch-based Mars One team announced this week that they are seeking requests for proposals for seven payloads that would launch in August 2018 on humanities first ever privately financed robotic Red Planet lander.

Mars One hopes that the 2018 lander experiments will set the stage for liftoff of the first human colonists in 2024. Crews of four will depart every two years.

Artist's conception of Mars One human settlement. Credit: Mars One/Brian Versteeg
Artist’s conception of Mars One human settlement. Credit: Mars One/Brian Versteeg

The 2018 lander structure would be based on NASA’s highly successful 2007 Phoenix Mars lander – built by Lockheed Martin – which discovered and dug into water ice buried just inches beneath the topsoil in the northern polar regions of the Red Planet.

Mars One has contracted with Lockheed Martin to build the new 2018 lander.

Lockheed is also currently assembling another Phoenix-like lander for NASA named InSight which is scheduled to blast off for Mars in 2016.

The payloads being offered fall under three categories; four science demonstration payloads, a single university science experiment, and two payload spaces up for sale to the highest bidder for science or marketing or “anything in between.”

The science payload competition is open to anyone including universities, research bodies, and companies from around the world.

“Previously, the only payloads that have landed on Mars are those which NASA has selected,” said Bas Lansdorp, Co-founder & CEO of Mars One, in a statement. “We want to open up the opportunity to the entire world to participate in our mission to Mars by sending a certain payload to the surface of Mars.”

The four science demonstration payloads will test some of the technologies critical for establishing the future human settlement. They include soil acquisition experiments to extract water from the Martian soil into a useable form to test technologies for future human colonists; a thin film solar panel to demonstrate power production; and a camera system working in combination with a Mars-synchronous communications satellite to take a ‘real time’ look on Mars.

3 Footpads of Phoenix Mars Lander atop Martian Ice. Phoenix thrusters blasted away Martian soil and exposed water ice. Proposed Mars InSight mission will build a new Phoenix-like lander from scratch to peer deep into the Red Planet and investigate the nature and size of the mysterious Martian core. Credit: Ken Kremer, Marco Di Lorenzo, Phoenix Mission, NASA/JPL/UA/Max Planck Institute
3 Footpads of Phoenix Mars Lander atop Martian Ice
Phoenix thrusters blasted away Martian soil and exposed water ice. Proposed Mars One 2018 mission will build a new Phoenix-like lander from scratch to test technologies for extracting water into a useable form for future human colonists. NASA’s InSight 2016 mission will build a new Phoenix-like lander to peer deep into the Red Planet and investigate the nature and size of the mysterious Martian core. Credit: Ken Kremer, Marco Di Lorenzo, Phoenix Mission, NASA/JPL/UA/Max Planck Institute

The single University competition payload is open to universities worldwide and “can include scientific experiments, technology demonstrations or any other exciting idea.” Click here for – submission information.

Furthermore two of the payloads are for sale “to the highest bidder” says Mars One in a statement and request for proposals document.

The payloads for sale “can take the form of scientific experiments, technology demonstrations, marketing and publicity campaigns, or any other suggested payload,” says Mars One.

“We are opening our doors to the scientific community in order to source the best ideas from around the world,” said Arno Wielders, co-founder and chief technical officer of Mars One.

Image shows color MOLA relief with US lander landing sites (Image credit NASA/JPL-Caltech/Arizona State University). Yellow box indicates Mars One Precursor landing regions under consideration.
Image shows color MOLA relief with US lander landing sites (Image credit NASA/JPL-Caltech/Arizona State University). Yellow box indicates Mars One Precursor landing regions under consideration.

“The ideas that are adopted will not only be used on the lander in 2018, but will quite possibly provide the foundation for the first human colony on Mars. For anyone motivated by human exploration, there can be no greater honor than contributing to a manned mission to Mars.”

Click here for the Mars One 2018 Lander ‘Request for Proposals.’

Over 200,000 Earthlings applied to Mars One to become future human colonists. That list has recently been narrowed to 705.

Stay tuned here for Ken’s continuing Curiosity, Opportunity, Orion, SpaceX, Boeing, Orbital Sciences, commercial space, MAVEN, MOM, Mars and more planetary and human spaceflight news.

Ken Kremer

…………….

Learn more about NASA’s Mars missions and Orbital Sciences Antares ISS launch on July 11 from NASA Wallops, VA in July and more about SpaceX, Boeing and commercial space and more at Ken’s upcoming presentations.

July 10/11: “Antares/Cygnus ISS Launch from Virginia” & “Space mission updates”; Rodeway Inn, Chincoteague, VA, evening

Posted on by Nancy Atkinson

Astrophoto: A ‘Mistakenly’ Beautiful View of the Crescent Moon and Leaning Tower of Pisa

The crescent Moon and the Leaning Tower of Pisa together for a beautiful nighttime view. Credit and copyright: Giuseppe Petricca.

A mistake led to this stunning image of the crescent Moon and the Tower of Pisa this week.

Astrophotographer Giuseppe Petricca from Italy had in mind a certain shot he wanted to take of the crescent Moon on June 29. “So I went out during the evening to do so,” he told Universe Today via email. “Unfortunately, I totally miscalculated the time! But, luckily, in the end, I managed to get an even more captivating shot.”

The Moon has a bit of Earthshine and a reddish glow from its low elevation in the sky, snuggling up to the Leaning Tower of Pisa. “Truly a beautiful combination and an awesome scenery. Impossible to not take a picture of it!” Giuseppe said.

This photograph was taken with a Nikon Coolpix P90 Bridge Camera on tripod, ISO 100, f4.5, 2.5″ exposure.

Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.

Posted on by David Dickinson

A Spectacular Set of Conjuctions on Tap for the Moon, Mars and Saturn this Weekend

Saturn passing behind the lunar limb on May 15th.

Got clear skies this July 4th weekend? The Moon passes some interesting cosmic environs in the coming days, offering up some photogenic pairings worldwide and a spectacular trio of occultations for those well placed observers who find themselves along the footprint of these events.

Stellarium
The path of the Moon on July 5th, 6th and 7th. Credit: Stellarium

First, let’s look at our closest natural neighbor in space. The Moon reaches first quarter phase on Saturday, July 5th at 11:59 Universal Time (UT)/7:59 AM EDT. First Quarter is a great time to observe the Moon, as the craters along the jagged terminator where the Sun is just starting to rise stand out in stark profile. Watch for the Lunar Straight Wall and the alphabet soup of elusive features known as the Lunar X or Purbach Cross and Lunar V on evenings right around First Quarter phase.

Starry Night
Mars off of the limb of the Moon as seen from North America on the evening of July 5th. Credit: Starry Night.

Our first conjunction stop on this weekend’s lunar journey is the planet Mars. Although the Moon occults — that is, passes in front of a given planet from our Earthly perspective — exactly 16 naked eye planets in 2014 (24 if you add in Uranus events and 1 Ceres and 4 Vesta on September 28th), the Moon will only occult Mars once in 2014, on the night of July 5th/6th. Northern South America and southern Central America will have a front row seat, while the rest of North America will see a close pass less than one degree from the lunar limb. This will still present a fine photographic opportunity, as it’ll be possible to snag Mars and the limb of the Moon in the same field of view. The Moon will be 56% illuminated during the conjunction, and Mars will present an 88% illuminated disk 9.2” across shining at magnitude +0.3.

Occult 4.0
The occultation path for Mars. Graphics created using Occult 4.0.

Both will be 96 degrees east of the Sun during geocentric (Earth-centered) conjunction, which occurs around 1:00 UT on July 6th or 9:00 PM EDT on the evening of the 5th. For those positioned to catch the occultation, it’ll take about a minute for “Mars set” to occur on the lunar limb. The last occultation of Mars occurred on May 9th, 2013 and the next won’t happen ‘til March 21st, 2015.

Virginis
The footprint of Lambda Virginis…

Next up, the Moon occults the +4.5th magnitude star Lambda Virginis on July 7th centered on 8:26 UT. This event is well placed for observers in Hawaii on the evening of July 6th. Located 187 light years distant, the light that you’re seeing departed the far-flung star on 1827, only to be interrupted by the pesky limb of our Moon a second prior to arrival on Earth. This star is also of note as it’s a spectroscopic binary, and while you won’t be able to resolve the pair at a tiny separation of just 0.0002” apart, you just might be able to see the pair “wink out” in a step wise fashion that betrays its binary nature. The Moon misses the brightest star in Virgo (Spica) this month, as it’s wrapped up a series of occultations of the star in early 2014 and won’t resume until 2024. Aldebaran, Antares and Regulus also lie along the Moon’s path on occasion, and the next cycle of bright star occultations resume with Aldebaran in January 2015. You can check out a list of fainter naked eye stars occulted by the Moon this year here courtesy of the International Occultation Timing Association.

Saturn
… and the occultation footprint  for Saturn.

And finally, the Moon visits Saturn, now residing just over the border in the astronomical constellation of Libra. This occultation occurs just 49 hours after the Mars event at 2:00 UT on July 8th (10:00 PM EDT on the evening of July 7th) and favors observers in the southernmost tip of South America. As with Mars, North America will see a close miss, although it will also be possible to squeeze Saturn in the same field of view as the Moon at low power, though it’ll sit about a degree of off its limb. We’re in a cycle of occultations of Saturn this year, with 11 occurring in 2014 and the next on August 4th. The reason for this is that Saturn moves much more slowly across the sky than Mars from our perspective, making for a relatively sluggish moving target for the Moon. Saturn shines at +0.6 magnitude as the 75% illuminated Moon passes by and subtends 42” with rings and will take about five minutes to pass fully behind the Moon.

These events will make for some great pics and animation sequences for sure… can you spot Saturn or Mars near the lunar limb with binoculars or a telescope before sunset? Or catch ‘em in the frame during a local fireworks show? Let us know, if enough pics surface on Universe Today’s Flickr page, we may do a post weekend roundup!  

Posted on by Nancy Atkinson

Watch Live as Astronomers Look for Object ‘G2’ in Observing Run Webcast from the Keck Observatory

This simulation shows the possible behavior of a gas cloud that has been observed approaching the black hole at the center of the Milky Way. Graphic by ESO/MPE/Marc Schartmann.

Wondering about the latest news on the intriguing object called ‘G2’ that is making its closest approach to the supermassive black hole at the center of our galaxy? You might be able to get the latest update on this object in real time during a rare live-streamed observing run from the W. M. Keck Observatory in Hawaii. Watch live above.

The two 10-meter Keck Observatory telescopes on the summit of Mauna Kea will be steered by astronomer Andrea Ghez and her team of observers from the UCLA Galactic Center Group for two nights to study our galaxy’s supermassive black hole, with an attempt to focus in on the enigmatic G2 to see if it is still intact. They’ll also be setting up a test for Einstein’s General Relativity and gathering more data on what they describe as The Paradox of Youth: young objects paradoxically developing around the black hole.

Here’s the time for the livestream in various timezones:

July 3, 2014 @ 9 pm – 10 pm Hawaii
July 4, 2014 @ Midnight – 1 am Pacific
July 4, 2014 @ 3 am – 4 am Eastern

The most previous observations by the Keck Observatory in Hawaii, according to an Astronomer’s Telegram from May 2, 2014 show that the gas cloud called ‘G2’ was surprisingly still intact, even during its closest approach to the supermassive black hole. This means G2 is not just a gas cloud, but likely has a star inside.

“We conclude that G2, which is currently experiencing its closest approach, is still intact, in contrast to predictions for a simple gas cloud hypothesis and therefore most likely hosts a central star,” said the May 2 Telegram. “Keck LGSAO observations of G2 will continue in the coming months to monitor how this unusual object evolves as it emerges from periapse passage.”

For additional info, see our two previous articles about G2:

Gas Cloud or Star? Mystery Object Heading Towards our Galaxy’s Supermassive Black Hole is Doomed
Object “G2? Still Intact at Closest Approach to Galactic Center, Astronomers Report

Posted on by Fraser Cain

Why Do People Go Crazy During a Full Moon?

Why Do People Go Crazy During a Full Moon?

Have you ever heard that people go crazy during a full Moon? What’s going on to cause all this lunacy? Or maybe, just maybe, it’s all a myth and nothing special ever happens during full moons.

If I went crazy, like real actual cluster-cuss crazy, you might call me a lunatic. Or you might say I suffered from lunacy. What does that even mean? This word comes from lunaticus, meaning “of the moon” or moonstruck. It was more popular during the late 1800’s, yet it still hangs around.

Surely it must still be an important and useful diagnostic medical term. As when the Moon is full, everyone goes crazy. It’s called the lunar effect. Everyone knows that. Right?

People have theorized for thousands of years that the Moon has all kinds of impacts on us. It affects fertility, crime rates, dog attacks, and increases blood loss during surgery. It must be a full Moon, they say. Full moon tomorrow night! All the crazies will be out! they say.

So what causes all this moon madness. What makes us sprout metaphorical canines and race around in a fugue state hungry for manflesh when the moon is full? Are we experiencing tidal forces from the Moon on our internal organ juices? Is it a result of us evolving lockstep with the lunar cycle? Perhaps the light coming from the Moon affects our visual cortex in a way to stimulate the animalistic parts of the brain? It has been with us for so long as a belief, there must be something to it. Right?

Nope, it’s all a myth. All of it. Tidal effects on behaviour aren’t happening. We experience two high and two low tides every day, and it has nothing to do with the phase of the Moon. In fact, your body experiences more gravity from your chair than it does from the Moon. If the motion of blood was somehow that reactive, should you step into a full elevator everyone would pass out with all the blood rushing to their extremities pulled by your gravity.

No way! You say! It’s true! Because the Moon is closer when it’s full, and its tug on our “materia” and “humors” is stronger. Unfortunately for this theory, our Moon travels an elliptical orbit, and the time when the Moon is closest has nothing to do with when it’s full.

The Moon can be full and close – supermoon. Or it can be full but farther away – minimoon.

Full Moon Rising Over Northwest Georgia on June 22nd, 2013. Credit and copyright: Stephen Rahn.
Full Moon Rising Over Northwest Georgia on June 22nd, 2013. Credit and copyright: Stephen Rahn.

In 1985, a team of scientists did a meta study, looking at 37 separate research papers that attempted to study the Moon’s impact on all aspects of humanity. They found papers that demonstrated a correlation, and then promptly found the mistakes in the research. They found absolutely no evidence. We don’t get into more car accidents. Hospital rooms aren’t more crowded. Werewolves aren’t apparently a thing.

We do notice the coincidences, when something strange occurs and there happens to be a full Moon. But we don’t notice all the times when there wasn’t a full Moon. To learn more about this, I’d suggest heading over to the wonderful blog “You are not so smart” by David McRaney, and reading up on “Confirmation Bias”.

So, where did this idea come from? Historians suspect it’s possible that the brightness of a full moon disturbed people’s sleep schedules.

I’m partial to the idea that in history, the full Moon was a high time for people to be active at night, favoring work or travel by the light of the full moon. So, perhaps there were more accidents.

But not any more. People are superstitious about mundane things like black cats, ladders and broken mirrors, it’s not surprising they’re superstitious about our beautiful and bright companion prettying up the sky almost every night.

What do you think? What’s your favorite full moon superstition? Tell us in the comments below.

Posted on by Jason Major

Rosetta Watches Comet 67P Tumbling Through Space

Animation of Comet 67P/Churyumov-Gerasimenko as seen by Rosetta on June 27-28, 2014

This is really getting exciting! ESA’s Rosetta spacecraft (and the piggybacked Philae lander) are in the home stretch to arrive at Comet 67P/Churyumov-Gerasimenko in 34 days and the comet is showing up quite nicely in Rosetta’s narrow-angle camera. The animation above, assembled from 36 NAC images acquired last week, shows 67P/C-G rotating over a total elapsed time of 12.4 hours. No longer just an extra-bright pixel, it looks like a thing now!

The animation, although fascinating, only hints at the “true” shape of the comet’s nucleus. Reflected light does create a bloom effect in the imaging sensor, especially at such small resolutions, expanding the apparent size of the comet beyond its 4-by-4-pixel size. But rest assured that much, much better images are on the way as Rosetta gets closer and closer.

Read more: How Big is Rosetta’s Comet?

The spacecraft was about 86,000 km (53,440 miles) from 67P/C-G when the images were acquired. Since that time it has cut that distance in half, and by this weekend it will be less than 36,000 km (22,370 miles) from the comet. After more than a decade of traveling around the inner Solar System Rosetta is finally arriving at its goal! Click here to see where Rosetta is now.

Stay tuned for more exciting updates from Rosetta, and learn more about the mission below:

Source: ESA’s Rosetta blog

Animation credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA 

Posted on by Nancy Atkinson

Astronauts Keep an Eye on Tropical Storm Arthur from the Space Station

Astronauts on the International Space Station took this image of Tropical Storm Arthur on July 2, 2014. Credit: Reid Wiseman/NASA.

The first storm of the Atlantic hurricane season is easily visible from space. International Space Station astronaut Reid Wiseman tweeted this picture of the storm, saying, “Just flew over Tropical Storm Arthur – hoping it heads to sea. Looks mean.”

Forecasters said the storm is slowly strengthening off Florida’s east coast, but will move up the coast just in time for the July 4th holiday in the US. While Tropical Storm Arthur is likely to stay offshore while it cruises by Florida, it might become a hurricane by Thursday. The National Hurricane Center reported at 2 pm EDT Wednesday that a tropical storm warning is in effect for all of coastal North Carolina with a hurricane watch the for the portion of the state that extends into the Atlantic Ocean. As of the time of the report, Tropical Storm Arthur was about 160 km (100 miles) east of Daytona Beach, Florida and 378 km (235 miles) south of Charleston, South Carolina.

A graphic showing Tropical Storm Force Wind Speed Probabilities for Tropical Storm Arthur, from July 2 through July 7. Credit: National Hurricane Center/NOAA.
A graphic showing Tropical Storm Force Wind Speed Probabilities for Tropical Storm Arthur, from July 2 through July 7. Credit: National Hurricane Center/NOAA.

For current information about this storm, see the National Hurricane Center’s website.

Posted on by Elizabeth Howell

Ancient Asteroid Impacts Left Serpentine Traces On Vesta: Study

The asteroid Vesta as seen by the Dawn spacecraft. Credit: NASA/JPL-Caltech/UCAL/MPS/DLR/IDA

While “dark materials” may leave some of us thinking about a certain Philip Pullman book series, on the asteroid Vesta its presence belies something equally exotic: old smaller asteroid impacts on its surface.

The dark stuff on the lighter surface has puzzled researchers since it was discovered in 2011 (and has been brought up in other studies), but a new team says it has found that serpentine is among the components.  Because that mineral can’t survive temperatures that are more than 400 degrees Celsius (752 degrees Fahrenheit), this means that scenarios such as volcanic eruptions can’t have caused it. This leaves only smaller asteroids, the team says.

“These meteorites are regarded as fragments of carbon-rich asteroids. The impacts must have been comparatively slow, because an asteroid crashing at high speeds would have produced temperatures too high to sustain serpentine,” the Max Planck Institute for Solar System Research stated.

Image of the crater Numisia on Vesta, where researchers found the spectral signature of serpentine. Picture taken by NASA's Dawn spacecraft. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Image of the crater Numisia on Vesta, where researchers found the spectral signature of serpentine. Picture taken by NASA’s Dawn spacecraft. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

 

“In a previous study, scientists from the MPS had calculated how dark material would be distributed on Vesta as a result of a low-speed oblique impact. Their results are consistent with the distribution of dark material on the edge of one of the two large impact basins in the southern hemisphere.”

The results came from analyzing images the NASA Dawn spacecraft took of Vesta between July 2011 and September 2012. The researchers recalibrated the data and also backed up their results by examining serpentine in laboratory conditions.

The research was published in the journal Icarus and you can also read a summary of the research here, from a presentation at the 2014 Lunar and Planetary Science Conference.

Source: Max Planck Institute for Solar System Research