Posted on by Nancy Atkinson

More than 100 km of Liquid Water Beneath Pluto’s Surface

New Horizon's July 2015 flyby of Pluto captured this iconic image of the heart-shaped region called Tombaugh Regio. Credit: NASA/JHUAPL/SwRI.

What lies beneath Pluto’s icy heart? New research indicates there could be a salty “Dead Sea”-like ocean more than 100 kilometers thick.

“Thermal models of Pluto’s interior and tectonic evidence found on the surface suggest that an ocean may exist, but it’s not easy to infer its size or anything else about it,” said Brandon Johnson from Brown University. “We’ve been able to put some constraints on its thickness and get some clues about composition.”

Research by Johnson and his team focused Pluto’s “heart” – a region informally called Sputnik Planum, which was photographed by the New Horizons spacecraft during its flyby of Pluto in July of 2015.

New Horizons’ Principal Investigator Alan Stern called Sputnik Planum “one of the most amazing geological discoveries in 50-plus years of planetary exploration,” and previous research showed the region appears to be constantly renewed by current-day ice convection.

Like a cosmic lava lamp, a large section of Pluto's icy surface in Sputnik Planum is being constantly renewed by a process called convection that replaces older surface ices with fresher material. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
Like a cosmic lava lamp, a large section of Pluto’s icy surface in Sputnik Planum is being constantly renewed by a process called convection that replaces older surface ices with fresher material. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

The heart is a 900 km wide basin — bigger than Texas and Oklahoma combined — and at least the western half of it appears to have been formed by an impact, likely by an object 200 kilometers across or larger.

Johnson and colleagues Timothy Bowling of the University of Chicago and Alexander Trowbridge and Andrew Freed from Purdue University modeled the impact dynamics that created a massive crater on Pluto’s surface and also looked at the dynamics between Pluto and its moon Charon.

The two are tidally locked with each other, meaning they always show each other the same face as they rotate. Sputnik Planum sits directly on the tidal axis linking the two worlds. That position suggests that the basin has what’s called a positive mass anomaly — it has more mass than average for Pluto’s icy crust. As Charon’s gravity pulls on Pluto, it would pull proportionally more on areas of higher mass, which would tilt the planet until Sputnik Planum became aligned with the tidal axis.

So instead of being a hole in the ground, the crater actually has been filled back in. Part of it has been filled in by the convecting nitrogen ice. While that ice layer adds some mass to the basin, it isn’t thick enough on its own to make Sputnik Planum have positive mass.

The Mountainous Shoreline of Sputnik Planum on Pluto. Great blocks of Pluto’s water-ice crust appear jammed together in the informally named al-Idrisi mountains. Some mountain sides appear coated in dark material, while other sides are bright. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
The Mountainous Shoreline of Sputnik Planum on Pluto. Great blocks of Pluto’s water-ice crust appear jammed together in the informally named al-Idrisi mountains. Some mountain sides appear coated in dark material, while other sides are bright. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

The rest of that mass, Johnson said, may be generated by a liquid lurking beneath the surface.

Johnson and his team explained it like this:

Like a bowling ball dropped on a trampoline, a large impact creates a dent on a planet’s surface, followed by a rebound. That rebound pulls material upward from deep in the planet’s interior. If that upwelled material is denser than what was blasted away by the impact, the crater ends up with the same mass as it had before the impact happened. This is a phenomenon geologists refer to as isostatic compensation.

Water is denser than ice. So if there were a layer of liquid water beneath Pluto’s ice shell, it may have welled up following the Sputnik Planum impact, evening out the crater’s mass. If the basin started out with neutral mass, then the nitrogen layer deposited later would be enough to create a positive mass anomaly.

“This scenario requires a liquid ocean,” Johnson said. “We wanted to run computer models of the impact to see if this is something that would actually happen. What we found is that the production of a positive mass anomaly is actually quite sensitive to how thick the ocean layer is. It’s also sensitive to how salty the ocean is, because the salt content affects the density of the water.”

The models simulated the impact of an object large enough to create a basin of Sputnik Planum’s size hitting Pluto at a speed expected for that part in the solar system. The simulation assumed various thicknesses of the water layer beneath the crust, from no water at all to a layer 200 kilometers thick.

The scenario that best reconstructed Sputnik Planum’s observed size depth, while also producing a crater with compensated mass, was one in which Pluto has an ocean layer more than 100 kilometers thick, with a salinity of around 30 percent.

“What this tells us is that if Sputnik Planum is indeed a positive mass anomaly —and it appears as though it is — this ocean layer of at least 100 kilometers has to be there,” Johnson said. “It’s pretty amazing to me that you have this body so far out in the solar system that still may have liquid water.”

Johnson he and other researchers will continue study the data sent back by New Horizons to get a clearer picture Pluto’s intriguing interior and possible ocean.

Further reading: Brown University, New Horions/APL

Posted on by Nancy Atkinson

Hubble Detects A Planet Around Binary Star System

This artist's illustration shows a planet circling a pair of distant red dwarf stars, representing the the system OGLE-2007-BLG-349 system, about 8,000 lightyears from Earth. Credit: NASA, ESA, and G. Bacon (STScI).

Binary stars are common throughout the galaxy, as it has been estimated about half the stars in our sky consist of two stars orbiting each other. Therefore, it’s also thought that about half of all exoplanet host stars are binaries as well. However, only about 10 of these so called circumbinary planets have been found so far in the 3,000-plus confirmed extrasolar planets that have been discovered.

But chalk up one more circumbinary planet, and this one bodes well for a technique that could help scientists find planets that orbit far away from their stars. Astronomers using the Hubble Space Telescope have confirmed a very interesting “three-body” system where two very close stars have a planet that orbits them both at a rather large distance.

The two red dwarf stars are just 7 million miles apart, or about 14 times the diameter of the Moon’s orbit around Earth. The planet orbits roughly 300 million miles from the stellar duo, about the distance of the asteroid belt from the Sun. The planet completes an orbit around both stars roughly every seven years.

Will China's new space telescope out-perform the Hubble? Image:
The Hubble Space Telescope. Image: NASA

Hubble used the a technique called gravitational microlensing, where the gravity of a foreground star bends and amplifies the light of a background star that momentarily aligns with it. The light magnification can reveal clues to the nature of the foreground star and any associated planets.

The system, called OGLE-2007-BLG-349, was originally detected in 2007 by the Optical Gravitational Lensing Experiment (OGLE), a telescope at the Las Campanas Observatory in Chile that searches for and observes microlensing effects from small distortions of spacetime, caused by stars and exoplanets.

However, the original OGLE observations could not confirm the details of the OGLE-2007-BLG-349 system. OGLE and several other ground-based observations determined there was a star and a planet in this system, but they couldn’t positively identify what the observed third body was.

“The ground-based observations suggested two possible scenarios for the three-body system: a Saturn-mass planet orbiting a close binary star pair or a Saturn-mass and an Earth-mass planet orbiting a single star,” said David Bennett, from NASA’s Goddard Space Flight Center, who is the first author in a new paper about the system, to be published in the Astrophysical Journal.

With Hubble’s sharp eyesight, the research team was able to separate the background source star and the lensing star from their neighbors in the very crowded star field. The Hubble observations revealed that the starlight from the foreground lens system was too faint to be a single star, but it had the brightness expected for two closely orbiting red dwarf stars, which are fainter and less massive than our sun.

“So, the model with two stars and one planet is the only one consistent with the Hubble data,” Bennett said.
“OGLE has detected over 17,000 microlensing events, but this is the first time such an event has been caused by a circumbinary planetary system,” explains Andrzej Udalski from the University of Warsaw, Poland, co-author of the study and leader of the OGLE project.

The team said this first-ever confirmation of an exoplanet system using the gravitational microlensing technique suggests some intriguing possibilities. While data from the Kepler Space Telescope is more likely to reveal planets that orbit close to their stars, microlensing allows planets to be found at distances far from their host stars.

“This discovery, suggests we need to rethink our observing strategy when it comes to stellar binary lensing events,” said Yiannis Tsapras, another member of the team, from the Astronomisches Recheninstitut in Heidelberg, Germany. “This is an exciting new discovery for microlensing”.

The team said that since this observation has shown that microlensing can successfully detect circumbinary planets, Hubble could provide an essential new role in the continued search for exoplanets.

OGLE-2007-BLG-349 is located 8,000 light-years away, towards the center of our galaxy.

(And, you’re welcome… I didn’t mention Tatooine in this article, until now!)

Further reading: Hubblesite, ESA Hubble,

Posted on by Nancy Atkinson

How To See the Doomed Tiangong-1 Chinese Space Station

Artist's illustration of China's 8-ton Tiangong-1 space station, which is expected to fall to Earth in late 2017. Credit: CMSE.

China’s first space station, Tiangong-1, is expected to fall to Earth sometime in late 2017. We’ve known for several months that the orbital demise of the 8-metric ton space station was only a matter of time. But Chinese space agency officials recently confirmed that they have lost telemetry with the space station and can no longer control its orbit. This means its re-entry through Earth’s atmosphere will be uncontrolled.

Despite sensational headlines this past week (and earlier this year) about Tiangong-1 exploding and raining down molten metal, the risk is quite low that people on Earth will be in danger. Any remaining debris that doesn’t burn up in the atmosphere has a high chance of falling into an ocean, since two-thirds of Earth’s surface is covered by water.

Artist's illustration of China's 8-ton Tiangong-1 space space station. Credit: CMSE.
Artist’s illustration of China’s 8-ton Tiangong-1 space space station. Credit: CMSE.

While NASA and other space agencies say it’s very hard to compute the overall risk to any individual, it’s been estimated that the odds that you, personally, will be hit by a specific piece of debris are about 1 in several trillion.
But numerically, the chance that one person anywhere in the world might be struck by a any piece of space debris comes out to a chance of 1-in-3,200, said Nick Johnson, chief scientist with NASA’s Orbital Debris during a media teleconference in 2011 when the 6-ton UARS satellite was about to make an uncontrolled reentry.

Johnson also reminded everyone that throughout the entire history of the space age, there have been no reports of anybody in the world being injured or struck by any re-entering debris. Something of this size re-enters the atmosphere every few years, and many are uncontrolled entries. For example, there were the UARS and ROSAT satellites in 2011, GOCE in 2013 and Kosmos 1315 in 2015. All of those re-entered without incident, with some returning so remotely there was no visual evidence of their fall.

Wu Ping, deputy director of China’s Manned Space Engineering (CMSE) office, said at a press conference before the launch of the Tiangong-2 space station last week (September 15, 2016) that based on their calculations and analysis, most parts of the space lab will burn up during its fall through the atmosphere. She added that China has always highly valued the management of space debris, and will continue to monitor Tiangong-1, and will release a forecast of its falling and report it internationally.

Tiangong-1 as seen in a a composite of three separate exposures taken on May 25, 2013. Credit and copyright: David Murr.
Tiangong-1 as seen in a a composite of three separate exposures taken on May 25, 2013. Credit and copyright: David Murr.

So, all that can be done now is to monitor its position over time to be able to predict when and where it might come down.

Without telemetry, how can we monitor its orbital position?

“Although Tiangong-1 is no longer functioning, keeping track of where it is not a problem,” said Chris Peat, who developed and maintains Heavens-Above.com, a site that provides orbital information to help people observe and track satellites orbiting the Earth.

“Like all other satellites, it is being tracked by the world-wide network of radar installations operated by the US Department of Defense,” Peat explained via email to Universe Today. “They make the orbital elements available to the public via the Space-Track web site and this is where we get the orbital data from in order to make our predictions.”

Peat says they check for new data every 4 hours, and Space-Track updates the orbits of most large objects about once per day.

Since Tiangong-1 is such a large object, Peat said there is no chance that it will be lost by Space-Track before re-entry. Additionally, amateur/hobby observers also make observations of the position of some satellites and calculate their own orbits for them. This is mostly done for classified satellites for which Space-Track does not publish data, and is not really necessary in the case of Tiangong-1, Peat said.

But with uncertainties of when and where this 8-ton (7.3 metric tons) vehicle will come back to Earth, you can bet that the amateur observing community will keep an eye on it.

First image of a solar transit of Tiangong-1, the first module of the Chinese space station, taken from Southern France on May 11th 2012. Credit: Thierry Legault. Used by permission.
First image of a solar transit of Tiangong-1, the first module of the Chinese space station, taken from Southern France on May 11th 2012. Credit: Thierry Legault. Used by permission.

“As it gets lower and enters the denser atmosphere, it will be subject to greater perturbations, but I do not expect Space-Track to lose it because it is so large,” Peat said. “It will actually become brighter and easier to see as it gets lower.”

If you want to watch for it yourself, Heavens-Above provides tracking information anywhere around the world. Just input your specific location and click on “Tiangong-1,” listed under “Satellites.” Heavens-Above (they also have an app) is great for being able to see satellites like the International Space Station and Hubble, as well as seeing astronomical objects like planets and asteroids. Heavens-Above also has an interactive sky chart.

Additionally, Marco Di Lorenzo on the Alive Universe website is monitoring Tiangong-1’s orbit, showing the orbital decay over time. He will be updating its status up through re-entry.

But despite being able to track Tiangong-1, as well as knowing its location and orbit is not the same as being able to say exactly when and where it will fall to Earth.

“This is a notoriously difficult task,” Peat said and even a day before re-entry, the estimated re-entry point will still be uncertain by many thousands of kilometers. The Russian Mir space station was brought down in a controlled manner using its propulsion system to re-enter over the South Pacific, but Tiangong-1 is no longer functioning so the re-entry point cannot be influenced by ground controllers.”

Graphic shows the procedure of Shenzhou-8 spacecraft docking with Tiangong-1 space lab module on Nov. 3, 2011. (Xinhua/Lu Zhe)
Graphic shows the procedure of Shenzhou-8 spacecraft docking with Tiangong-1 space lab module on Nov. 3, 2011. (Xinhua/Lu Zhe)

Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics who also monitors objects in orbit, said via Twitter that Tiangong-1’s reentry could be anywhere between the latitudes of 43 degrees North and 43 degrees South, which is a rather large area on our planet and are the latitudes where a majority of Earth’s population resides. That’s not especially comforting, but remember, the odds are in your favor.

This plot shows the orbital height of the Chinese space station Tiangong-1 over the last year. It's orbit was boosted in mid-December 2015. Credit: Chris Peat/Heavens-Above.com.
This plot shows the orbital height of the Chinese space station Tiangong-1 over the last year. It’s orbit was boosted in mid-December 2015. Credit: Chris Peat/Heavens-Above.com.

Peat now has a page on Heavens-Above showing the orbital height of Tiangong-1 and you can see how the height is reducing as a function of time. It shows there was an orbital boost in December 2015.

Tiangong-1 was launched in September 2011 and ended its functional life in March this year, when it had “comprehensively fulfilled its historical mission,” Chinese officials said. It was operational for four and a half years, which is two and a half years longer than its designed life. It was visited by the un-crewed Shenzhou-8 in 2011, and the crewed missions of Shenzhou-9 in 2012 and Shenzhou-10 in 2013. It also was used for Earth observation and studying the space environment, according to CMSE.

If you happen to capture an image of Tiangong-1, please add it to Universe Today’s Flickr pool page.

Posted on by Nancy Atkinson

Incredible Images of Mars from Earth

Mars as seen from Earth on June 13, 2016. Credit and copyright: Damian Peach.

What did you do during your summer this year? Award-winning astrophotographer Damian Peach spent much of his 2016 summer capturing incredibly clear images of Mars during opposition, when the Red Planet was closest to Earth. Peach has now compiled a wonderful “rotating planet” movie of images taken between June 4th – 18th, 2016, showing amazing detail of the planet.


At its closest point this year, Mars was about 46.8 million miles (75.3 million kilometers) from Earth.

Peach’s astrophotography truly sets “a new standard” as one commenter said, and Peach just won another prize in the “Planets, Comets & Asteroids” division of the Insight Astronomy Photographer of the Year 2016, awarded at the Royal Observatory in Greenwich, England last night.

Peach has said this summer held “excellent seeing,” both from his home in the UK and from a photography trip to Barbados. He even captured a fleeting localized dust storm on Mars during mid-June over Mare Erythraeum, one of the prominent dark areas on the planet that were once thought to be seas. In the image below of the dust storm, Peach also pointed out the “linear cloud streak in the southern hemisphere – clearly those Martian flying saucer pilots have been having fun!”

Images of Mars from Earth on Jun 15, 2016. Credit and copyright: Damian Peach.
Images of Mars from Earth on Jun 15, 2016. Credit and copyright: Damian Peach.

See more of Peach’s excellent astrophotography work at his website , or on Twitter. See a larger version of the lead image here.

Mars is still visible in the night sky, but if you missed seeing this planet at its brightest in 2016, the next time Mars will be at opposition will be in 2018, with close approach on July 31, 2018.

Posted on by Nancy Atkinson

30-Ton Chunk Of 4,500 Year-Old Meteorite Unearthed In Argentina

The Campo del Cielo meteorite was found in outside the small Argentinian town of Gancedo. Credit: Ministerio de Gobierno Facebook page.

Holy iron meteorite, Batman! A gigantic 30-ton chunk of the famous Campo del Cielo meteorite fall has been found outside of a small town in Argentina. The Gancedo meteorite was found on September 10, 2016 by a team of meteorite hunters from the Astronomy Association of the Chaco. This is the second largest piece ever found in the Campo del Cielo region.

Gancedo is the name of the town and Chaco is the province in Argentina where the meteorite was found.

A 30-ton Campo del Cielo meteorite being extracted from the ground in Argentina. Credit: Ministerio de Gobierno Facebook page.
A 30-ton Campo del Cielo meteorite being extracted from the ground in Argentina. Credit: Ministerio de Gobierno Facebook page.

Scientists estimate about 4,500 years ago, a 600 ton space rock entered Earth’s atmosphere and broke apart, sending a shower of metallic meteorites across a 1,350 square km region northwest of Buenos Aires. The region has at least 26 craters.

A spokesman from the Chaco Astronomy Association said they will have the meteorite re-weighed to verify its weight.

The Ministerio de Gobierno Facbook page shared images and a video of the extraction.

While some media outlets have reported this is the second largest meteorite ever found, it actually is only the second largest meteorite from the Campo del Cielo site. The largest meteorite found on Earth is the Hoba meteorite, discovered in Namibia, Africa and is estimated to weigh more than 132,000 pounds (66 tons), and the second largest is the El Chaco, also part of the Campo del Cielo meteorite fall, which weighs an estimated 37,000 kilograms (37 tons).

Meteorites from Campo del Cielo are widely available, but if you are interested in getting a piece, buy only from reputable dealers.

Campo del Cielo meteorites are described as a polycrystalline coarse octahedrite, the most common kind of nickel-iron meteorites.

Sources and further reading: Facebook, ABC News, Scientific American, Meteorite Market.

Posted on by Nancy Atkinson

At ISO 400,000, This 6-Minute Film Shows Why We Love the Night Sky

The pursuit of the night sky is ongoing for amateur astronomers. Credit and copyright: Ben Canales.

Obviously, you’ve seen timelapse videos of the night sky because we share them here on Universe Today all the time. But you’ve probably not seen a video like this one before. This one isn’t a timelapse, and you’ll see the night sky in all its splendor, in real time.

“I think this one may be the beginning of something damn interesting,” said filmmaker Ben Canales, who along with cohort John Waller of Uncage The Soul Productions, shot this video with new low-light technology. Using the new Canon MH20f-SH, which has the capability of shooting at 400,000 ISO, they were able to “film in the quiet moments that have been impossible to capture until now.”

“Since 2013, I’ve been tinkering with all sorts of camera/lens/software combinations trying to move beyond a long exposure still to real time video of the stars,” Canales said on Facebook. “Sooner or later, we have to move beyond a frozen photo of the stars to hear, see, feel what it is really like being out there!”

In addition to showcasing this wonderful new low-light shooting, Infinity² really captures the emotional side of amateur astronomy and the beauty of being under the night sky. He took a group of high school students out to witness the Perseid Meteor Shower in Oregon, and the students got together with the Oregon Star Party. Together, they answer the simple question “What do you feel?”

As Canales says, “Something internal and personal draws us out to the night sky.”

Check out more on Uncage The Soul Productions, Canales’ astrophoto website and Facebook.

Still image from the film Infinity ². Image Courtesy Ben Canales.
Still image from the film Infinity². Image Courtesy Ben Canales.
Still image from the film Infinity ². Image Courtesy Ben Canales.
Still image from the film Infinity ². Image Courtesy Ben Canales.

Infinity ² from Uncage the Soul Productions on Vimeo.

Posted on by Nancy Atkinson

Newly Discovered Asteroid Has a Close Encounter with Earth

Orbit diagram for asteroid 2016 RB1's close approach to Earth on September 7, 2016. Credit: NASA/JPL Small Body Database.

As NASA prepares to send a spacecraft to a distant asteroid, another space rock made a surprise visit to Earth’s vicinity. The newly discovered small asteroid, named 2016 RB1, passed safely by Earth, coming within approximately 23,900 miles (38,463 km) of our planet, or just outside the orbit of many communications satellites.

The asteroid passed by Earth at 1:28 p.m. Eastern Time (1728 UT).

An animation of asteroid 2016 RB1 from images obtained by the Virtual Telescope Project on September 6, 2016. Credit: Gianluca Masi/Virtual Telescope Project.
An animation of asteroid 2016 RB1 from images obtained by the Virtual Telescope Project on September 6, 2016. Credit: Gianluca Masi/Virtual Telescope Project.

Click on the image if it is not animating in your browser.

The asteroid was discovered on Monday, September 5 by the Mt. Lemmon Survey telescope in Tucson, Arizona. 2016 RB1 is estimated to be between 24 to 52 feet (7.3 – 16 meters) across, which is just a bit smaller than the Chelyabinsk meteor that exploded over northern Russian in February 2013, which was estimated to be around 56 ft (17 meters) wide.

On Thursday, September 8, NASA hopes to launch its OSIRIS-ReX mission to study asteroid Bennu and conduct a sample return, with the sample coming back to Earth by 2023. With the mission, scientists hope to learn more about the formation and evolution asteroids and of the Solar System as a whole.

Here’s a graphic comparing the small asteroid 2016 RB1 to other objects, compiled by Mikko Tuomela and Massimo Orgiazzi.

Objects on Earth and in space compared to the newly found asteroid 2016 RB1 (center of graphic). Compiled by Mikko Tuomela and Massimo Orgiazzi. Used by permission.
Objects on Earth and in space compared to the newly found asteroid 2016 RB1 (center of graphic). Compiled by Mikko Tuomela and Massimo Orgiazzi. Used by permission.

A few observers were able to track the asteroid, including Gianluac Masi of the Virtual Telescope project, and Ernesto Guido of the Remanzacco Observatory.

An image of 2016 RB1 taken on September 7, 2016, remotely from the Q62 iTelescope network (Siding Spring, Australia). Credit: Ernesto Guido.
An image of 2016 RB1 taken on September 7, 2016, remotely from the Q62 iTelescope network (Siding Spring, Australia). Credit: Ernesto Guido.

2016 RB1 is the third asteroid so far in September 2016 that traveled between the Earth and the Moon. Asteroid 2016 RR1 passed by at 0.32 lunar distances on September 2, and just a few hours later, asteroid 2016 RS1 passed by at 0.48 times the Earth-moon distance. But this latest asteroid pass is the closest, at 0.10 lunar distances.

From its orbit, astronomers have determined 2016 RB1 is likely an Aten asteroid, a group of Near-Earth Objects that cross the orbits of Earth, Venus and even Mercury.

Sources and further reading: Remanzacco Observatory
Virtual Telescope Project
JPL’s Small Body Database
Earth-Sky.org
Ian O’Neill at Discovery Space News/Seeker

Posted on by Nancy Atkinson

There It Is! Philae Lander Found

Philae has been found! Credit: Main image and lander inset: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA; context: ESA/Rosetta/ NavCam.

The search is over, and looking at these images, no wonder it was so hard to find the little Philae lander!

The high-resolution camera on board the Rosetta spacecraft has finally spotted Philae “wedged into a dark crack on Comet 67P/Churyumov-Gerasimenko,” the ESA team said. They also said that now, seeing the lander’s orientation, it’s clear why establishing communications was so difficult following its landing on November 12, 2014.

Close-up of the Philae lander. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Close-up of the Philae lander. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Rosetta, orbiting the comet and getting ready for its own demise/touchdown on 67P, focused its OSIRIS narrow-angle camera towards a few candidate sites on September 2, 2016 as the orbiter came just 2.7 km of the comet’s surface. Clearly visible in the zoomed in versions are the main body of the lander, along with two of its three legs.

“With only a month left of the Rosetta mission, we are so happy to have finally imaged Philae, and to see it in such amazing detail,” says Cecilia Tubiana of the OSIRIS camera team, the first person to see the images when they were downlinked from Rosetta on September 4.

Tubiana told Universe Today via email that Philae wasn’t too hard to find in the images. “Philae was in hiding in shadow, and as soon as we stretched the brightness to ‘see’ into the shadow, Philae was there!”

She added that nothing else about Philae’s condition has been revealed from the images so far.

The Philae lander was last seen after it first touched down at a region called Agilkia on the odd-shaped, two-lobed comet 67P. During its dramatic touchdown, the lander flew, landed, bounced and then repeated that process for more than two hours across the surface, with three or maybe four touchdowns. 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 comet. After three days, Philae’s primary battery ran out of power and the lander went into hibernation, only to wake up again and communicate briefly with Rosetta in June and July 2015 as the comet came closer to the Sun and more power was available.

But after more than a year of silence, the Rosetta team announced in mid-August 2016 that they would no longer attempt communications with Philae.

Philae’s final location had been plotted but until yesterday, never actually seen by Rosetta’s cameras. Radio ranging data was used to narrow down the search to an area spanning a few tens of meters, and a number of potential candidate objects were identified in relatively low-resolution images taken from larger distances.

Philae close-up, labelled. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
Philae close-up, labelled. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.

Compare some of the features of the cliff in the image above to this image taken by Philae of its surroundings:

The Philae lander captured a picture of a nearby cliff, nicknamed “Perihelion Cliff”, on the nucleus of Comet 67P/Churyumov-Gerasimenko. Credit: ESA/Rosetta/Philae/CIVA.
The Philae lander captured a picture of a nearby cliff, nicknamed “Perihelion Cliff”, on the nucleus of Comet 67P/Churyumov-Gerasimenko. Credit: ESA/Rosetta/Philae/CIVA.

“After months of work, with the focus and the evidence pointing more and more to this lander candidate, I’m very excited and thrilled that we finally have this all-important picture of Philae sitting in Abydos,” said ESA’s Laurence O’Rourke, who has been coordinating the search efforts over the last months at ESA, with the OSIRIS and SONC/CNES teams.

At 2.7 km, the resolution of the OSIRIS narrow-angle camera is about 5 cm/pixel, which is sufficient to reveal features of Philae’s 1 m-sized body and its legs.

“This wonderful news means that we now have the missing ‘ground-truth’ information needed to put Philae’s three days of science into proper context, now that we know where that ground actually is!” says Matt Taylor, ESA’s Rosetta project scientist.

An OSIRIS narrow-angle camera image taken on 2 September 2016 from a distance of 2.7 km in which Philae was definitively identified. The image has been processed to adjust the dynamic range in order to see Philae while maintaining the details of the comet's surface. Philae is located at the far right of the image, just above center. The image scale is about 5 cm/pixel. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
An OSIRIS narrow-angle camera image taken on 2 September 2016 from a distance of 2.7 km in which Philae was definitively identified. The image has been processed to adjust the dynamic range in order to see Philae while maintaining the details of the comet’s surface. Philae is located at the far right of the image, just above center. The image scale is about 5 cm/pixel. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.

The discovery comes less than a month before Rosetta descends to the comet’s surface. On September 30, the orbiter will be sent on a final one-way mission to investigate the comet from close up, including the open pits in a region called Ma’at, where it is hoped that critical observations will help to reveal secrets of the body’s interior structure.

“Now that the lander search is finished we feel ready for Rosetta’s landing, and look forward to capturing even closer images of Rosetta’s touchdown site,” adds Holger Sierks, principal investigator of the OSIRIS camera.

The Rosetta team said they would be providing more details about the search as well as more images in the near future.

Source: ESA

Posted on by Nancy Atkinson

Talk About A Crowded Neighborhood: Closest Binary Stars With Multiple Planets Found

Artist’s conception of the binary system with three giant planets discovered in this study. One star hosts two planets and the other hosts the third. The system represents the smallest-separation binary in which both stars host planets that has ever been observed. Image courtesy of Robin Dienel/Carnegie.

The more we look, the more we see the great diversity in planetary systems around other stars. And curiously, planet hunters are finding that most star systems are very different from our own.

An example is a recently discovered system that is extremely crowded. It consists of a three giant planets in a binary (two stars) system. One star hosts two planets and the other hosts the third. The system represents the smallest-separation binary in which both stars host planets that has ever been observed.

“The probability of finding a system with all these components was extremely small,” said Johanna Teske from the Carnegie Institution for Science, “so these results will serve as an important benchmark for understanding planet formation, especially in binary systems.”

An illustration of this highly unusual system, which features the smallest-separation binary stars that both host planets ever discovered. Only six other metal-poor binary star systems with exoplanets have ever been found. Illustration courtesy of Timothy Rodigas/Carnegie.
An illustration of this highly unusual system, which features the smallest-separation binary stars that both host planets ever discovered. Only six other metal-poor binary star systems with exoplanets have ever been found. Illustration courtesy of Timothy Rodigas/Carnegie.

Teske and her team said this busy system might help explain the influence that giant planets like Jupiter have over a solar system’s architecture.

“We are trying to figure out if giant planets like Jupiter often have long and, or eccentric orbits,” Teske explained. “If this is the case, it would be an important clue to figuring out the process by which our Solar System formed, and might help us understand where habitable planets are likely to be found.”

The twin stars are named HD 133131A and HD 133131B. The former hosts two Jupiter-sized worlds and the latter a planet with a mass at least 2.5 times Jupiter’s. All three planets have “eccentric” or highly elliptical orbits. So far no smaller, rocky worlds have been detected but the team said those type of planets could be part of the system, or may have been part of the system in the past.

The two stars themselves are separated by only 360 astronomical units (AU – the distance between the Earth and the Sun, approximately 150,000,000 km or 93,000,000 miles). This is extremely close for twin stars with detected planets orbiting the individual stars. The next-closest known binary star system with planets has stars about 1,000 AU apart.

The two stars are more like fraternal twins rather than identical because they have slight different chemical compositions. The team said this could indicate that one star swallowed some baby planets early in its life, changing its composition slightly. Or another option is that the gravitational forces of the detected giant planets may have had a strong effect on fully-formed small planets, flinging them in towards the star or out into space.

But both stars are “metal poor,” meaning that most of their mass is hydrogen and helium, as opposed to other elements like iron or oxygen. This is another curious thing about this system, as most stars that host giant planets are “metal rich.”

The system was found using the Planet Finder Spectrograph, an instrument developed by Carnegie scientists and mounted on the Magellan Clay Telescopes at Carnegie’s Las Campanas Observatory. This finding represents the first exoplanet detection made based solely on data from the. PFS is able to find large planets with long-duration orbits or orbits that are very elliptical rather than circular.

This video tells more about the PFS:

You can read the team’s paper here. It has been accepted for publication in the Astronomical Journal.

Posted on by Nancy Atkinson

New Horizons Spies Pluto’s Neighbor Quaoar

Artist view of New Horizons passing Pluto and three of its moons.. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Now more than a year after its historic flyby of Pluto, the New Horizons spacecraft continues to speed through the Kuiper Belt. It’s currently on a beeline towards its next target of exploration, a KBO called 2014 MU69. But during its travels, New Horizons spotted another KBO, one of Pluto’s pals, Quaoar.

This animated sequence shows composite images of the Kuiper Belt object Quaoar, taken by New Horizons’ Long Range Reconnaissance Imager (LORRI). Click on the image to animate. Credit: NASA/JHUAPL/SwRI.
This animated sequence shows composite images of the Kuiper Belt object Quaoar, taken by New Horizons’ Long Range Reconnaissance Imager (LORRI). Click on the image to animate. Credit: NASA/JHUAPL/SwRI.

When these images were taken (in July 2016), Quaoar was approximately 4 billion miles (6.4 billion kilometers) from the Sun and 1.3 billion miles (2.1 billion kilometers) from New Horizons.

The animated sequence, above, (click the image if it isn’t animating in your browser) shows composite images taken by New Horizons’ Long Range Reconnaissance Imager (LORRI) at four different times over July 13-14: “A” on July 13 at 02:00 Universal Time; “B” on July 13 at 04:08 UT; “C” on July 14 at 00:06 UT; and “D” on July 14 at 02:18 UT. The New Horizons team explained that each composite includes 24 individual LORRI images, providing a total exposure time of 239 seconds and making the faint object easier to see.

Quaoar ( pronounced like “Kwa-war”) is about 690 miles or 1,100 kilometers in diameter, about half the size of Pluto. It was discovered on June 4, 2002 by astronomers Mike Brown and Chad Trujillo from Caltech, and at the time of its discovery, it was the largest object found in the Solar System since the discovery of Pluto. Quaoar’s discovery was one of the things that spurred the discussion of whether Pluto should continue to be classified as a planet or not.

But Quaoar is an interesting object in its own right and the New Horizons team said the oblique views of it that New Horizons can see – where LORRI sees only a portion of Quaoar’s illuminated surface — is very different from the nearly fully illuminated view of it that is visible from Earth. Comparing Quaoar from the two very different perspectives gives mission scientists a valuable opportunity to study the light-scattering properties of Quaoar’s surface.

If you’re thinking, “Why don’t we send a mission to Quaoar, or Sedna or Eris?” you aren’t alone. New Horizons team member Alex Parker has obviously been thinking about it. Parker tweeted that for a New Horizons-like mission it would take about 13 and a half years to reach Quaoar if it could be launched in December 2016. “Otherwise, we have to wait another 11 years for the next Jupiter assist window,” he said.

Um, NASA, can we put this on the schedule for 2027?

In the meantime, the images and data that New Horizons gathered during the Pluto flyby in July 2015 are still trickling back to Earth. The image below is a stunning view of Pluto’s methane snowcaps, visible at the terminator, showing the region north of Pluto’s dark equatorial band informally named Cthulhu Regio, and southwest of the vast nitrogen ice plains informally named Sputnik Planitia. This image was taken about 45 minutes before New Horizons’ closest approach to Pluto on July 14, 2015.

This area is south of Pluto's dark equatorial band informally named Cthulhu Regio, and southwest of the vast nitrogen ice plains informally named Sputnik Planitia. North is at the top; in the western portion of the image, a chain of bright mountains extends north into Cthulhu Regio. New Horizons compositional data indicate the bright snowcap material covering these mountains isn't water, but atmospheric methane that has condensed as frost onto these surfaces at high elevation. Between some mountains are sharply cut valleys – indicated by the white arrows. These valleys are each a few miles across and tens of miles long. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
This area is south of Pluto’s dark equatorial band informally named Cthulhu Regio, and southwest of the vast nitrogen ice plains informally named Sputnik Planitia. North is at the top; in the western portion of the image, a chain of bright mountains extends north into Cthulhu Regio. New Horizons compositional data indicate the bright snowcap material covering these mountains isn’t water, but atmospheric methane that has condensed as frost onto these surfaces at high elevation. Between some mountains are sharply cut valleys – indicated by the white arrows. These valleys are each a few miles across and tens of miles long. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

See all of the latest photos sent back from our robot in the outer reaches of our Solar System at the New Horizons website.