Weekly Space Hangout -Sept 13, 2017: Dr. Claudia Lagos from ICRAR

Hosts: Fraser Cain (universetoday.com / @fcain) Dr. Paul M. Sutter (pmsutter.com / @PaulMattSutter) Dr. Kimberly Cartier ( KimberlyCartier.org / @AstroKimCartier ) Dr. Morgan Rehnberg (MorganRehnberg.com / @MorganRehnberg ChartYourWorld.org) Special Guest: This week’s guest is Dr. Claudia Lagos (@CDPLagos). Claudia is the Research Assistant at the International Centre for Radio Astronomy Research, in the University of […]

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Confirmed: Ceres Has a Transient Atmosphere

Sometimes they see it, sometimes they don’t. That’s why scientists have never been completely sure if Ceres has an atmosphere or not. But now data from the Dawn spacecraft — in orbit of Ceres — confirms the dwarf planet really does have a very weak atmosphere, but it comes and goes. The on-again-off-again nature of […]

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Brightest ‘Spot’ on Ceres is Likely a Cryovolcano

The bright regions on the dwarf planet Ceres have been some of the most talked about features in planetary science in recent years. While data from the Dawn spacecraft has shown these bright areas are salt deposits (alas, not lights of an alien city), the question remained of how these salts reached the surface. Researchers […]

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Soar Over Ceres With New Images From the Dawn Spacecraft

There’s one thing that could mean the end the Dawn mission: if the hydrazine fuel for its maneuvering thruster system runs out. Now, engineers for the Dawn mission have figured out a way to save on this fuel while still sending Dawn to a new science orbit around the dwarf planet Ceres. They are effectively […]

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Phenomenal New View of Ceres ‘Lonely Mountain’ Reveals Signs of Volcanic Activity

Ahuna Mons towers over the Cerean landscape in this photo taken by the Dawn spacecraft. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

An isolated 3-mile-high (5 km) mountain Ahuna Mons on Ceres is likely volcanic in origin, and the dwarf planet may have a weak, temporary atmosphere. These are just two of many new insights about Ceres from NASA’s Dawn mission published this week in six papers in the journal Science.

“Dawn has revealed that Ceres is a diverse world that clearly had geological activity in its recent past,” said Chris Russell, principal investigator of the Dawn mission, based at the University of California, Los Angeles.

Ahuna Mons is a volcanic dome similar to earthly and lunar volcanic domes but unique in the solar system, according to a new analysis led by Ottaviano Ruesch of NASA’s Goddard Space Flight Center and the Universities Space Research Association. While those on Earth erupt with molten rock, Ceres’ grandest peak likely formed as a salty-mud volcano. Instead of molten rock, salty-mud volcanoes, or “cryovolcanoes,” release frigid, salty water sometimes mixed with mud.

https://www.youtube.com/watch?v=-6nxKqPIUkE&list=PLv6Y2ySiZO7I5kvnkj4ZQiHKQO4Q-njIJ
Learn more about Ahuna Mons

“This is the only known example of a cryovolcano that potentially formed from a salty mud mix, and that formed in the geologically recent past,” Ruesch said. Estimates place the mountain formation within the past billion years.

Dawn may also have detected a weak, temporary atmosphere; the probe’s gamma ray and neutron (GRaND) detector observed evidence that Ceres had accelerated electrons from the solar wind to very high energies over a period of about six days. In theory, the interaction between the solar wind’s energetic particles and atmospheric molecules could explain the GRaND observations.

A temporary atmosphere would confirm the water vapor the Herschel Space Observatory detected at Ceres in 2012-2013. The electrons that GRaND detected could have been produced by the solar wind hitting the water molecules that Herschel observed, but scientists are also looking into alternative explanations.

While Ahuna Mons may have erupted liquid water in the not-too-distant past, Dawn found probable water ice right now in the mid-latitude Oxo Crater using its visible and infrared mapping spectrometer (VIR).

Exposed water-ice is rare on the dwarf planet, but the low density of Ceres — 2.08 grams/cm3 vs. 5.5 for Earth — the impact-generated ice detection and the the existence of Ahuna Mons suggest that Ceres’ crust does contain a significant amount of water ice.

Impact craters are clearly the most abundant geological feature on Ceres, and their different shapes help tell the complex story of Ceres’ past. Craters that are roughly polygonal — shapes bounded by straight lines — hint that Ceres’ crust is heavily fractured. In addition, several Cerean craters display fractures on their floors. There are craters with flow-like features. Bright areas are peppered across Ceres, with the most reflective ones in Occator Crater. Some crater shapes could indicate water-ice in the subsurface.

All these crater forms imply an outer shell for Ceres that is not purely ice or rock, but rather a mixture of both. Scientists also calculated the ratio of various craters’ depths to diameters, and found that some amount of crater relaxation must have occurred as icy walls gradually slump.

“The uneven distribution of craters indicates that the crust is not uniform, and that Ceres has gone through a complex geological evolution,” Hiesinger said.

Ceres’ crust also appears loaded with clay-forming minerals called phyllosilicates. These phyllosilicates are rich in magnesium and also have some ammonium embedded in their crystalline structure. Their distribution throughout the dwarf planet’s crust indicates Ceres’ surface material has been altered by a global process involving water.

Now in its extended mission, the Dawn spacecraft has been increasing its altitude since Sept. 2 as scientists stand back once again for a broader look at Ceres under different lighting conditions now compared to earlier in the mission.

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Large Impact Craters on Ceres Have Gone Missing

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

Scientists have found a bit of a mystery at the dwarf planet Ceres. Yes, there are those intriguing bright spots inside numerous craters, the mystery that has mostly been solved, as being made of bright salts, likely leftover from a briny solution of sodium carbonate and ammonium chloride. But a new puzzle involves the craters themselves. In the rough and tumble environment of the asteroid belt, ancient Ceres was certainly pummeled by numerous large asteroids during its 4.5 billion-year lifetime. But yet, there are just a few large craters on Ceres.

How could that be?

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

Ceres has lots of little craters, but the Dawn spacecraft, orbiting Ceres since early 2015, has found only 16 craters larger than 100 km, and none larger than 280 km (175 miles) across. Scientists who model asteroid collisions in our Solar System predicted Ceres should have amassed up to 10 to 15 craters larger than 400 kilometers (250 miles) wide, and at least 40 craters larger than 100 km (62 miles) wide. By comparison, Dawn’s other target of study, the smaller asteroid Vesta, has several large craters, including one 500 kilometers (300 miles) in diameter, covering almost the entire south pole region.

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

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

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

There are a few reasons why the big craters have been erased, and the scientists now have to figure out which reason or combination of reasons best explains their findings. One reason could be because large amounts of water or ice in Ceres’ interior, which has long been suspected. Because ice is less dense than rock, the topography could “relax” over time — just like what happens if you push on your skin, then take the pressure off, and it relaxes back to its original shape. The scientists said that over geological timescales of several million years the water or ice would slowly flow and the craters would smooth out.

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

Another reason could be hydrothermal activity, such as geysers or cryovolcanoes, which could have flowed across the surface, possibly burying pre-existing large craters. Smaller impacts would have then created new craters on the resurfaced area.

And then, all the smaller, later impacts could have erased the bigger older impact basins. But if that were the case, the older basins would seemingly be more visible than they are now.

“Regardless of the specific mechanism(s) for crater removal, our result requires that large crater obliteration was active well after the late heavy bombardment era, or about 4 billion year ago. This conclusion reveals that Ceres’ cratering record is inextricably linked to its peculiar composition and internal evolution,” Marchi said.

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

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

Sources: SwRI, JPL

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NASA Approves New Horizons Extended KBO Mission, Keeps Dawn at Ceres

New Horizons trajectory and the orbits of Pluto and 2014 MU69.

In an ‘Independence Day’ gift to a slew of US planetary research scientists, NASA has granted approval to nine ongoing missions to continue for another two years this holiday weekend.

The biggest news is that NASA green lighted a mission extension for the New Horizons probe to fly deeper into the Kuiper Belt and decided to keep the Dawn probe at Ceres forever, rather than dispatching it to a record breaking third main belt asteroid.

And the exciting extension news comes just as the agency’s Juno probe is about to ignite a July 4 fireworks display on July 4 to achieve orbit at Jupiter – detailed here.

“Mission approved!” the researchers gleefully reported on the probes Facebook and Twitter social media pages.

“Our extended mission into the #KuiperBelt has been approved. Thanks to everyone for following along & hopefully the best is yet to come.

The New Horizons spacecraft will now continue on course in the Kuiper Belt towards an small object known as 2014 MU69, to carry out the most distant close encounter with a celestial object in human history.

“Here’s to continued success!”

The spacecraft will rendezvous with the ancient rock on New Year’s Day 2019.

Researchers say that 2014 MU69 is considered as one of the early building blocks of the solar system and as such will be invaluable to scientists studying the origin of our solar system how it evolved.

It was almost exactly one year ago on July 14, 2015 that New Horizons conducted Earth’s first ever up close flyby and science reconnaissance of Pluto – the most distant planet in our solar system and the last of the nine planets to be explored.

The immense volume of data gathered continues to stream back to Earth every day.

“The New Horizons mission to Pluto exceeded our expectations and even today the data from the spacecraft continue to surprise,” said NASA’s Director of Planetary Science Jim Green at NASA HQ in Washington, D.C.

“We’re excited to continue onward into the dark depths of the outer solar system to a science target that wasn’t even discovered when the spacecraft launched.”

While waiting for news on whether NASA would approve an extended mission, the New Horizons engineering and science team already ignited the main engine four times to carry out four course changes in October and November 2015, in order to preserve the option of the flyby past 2014 MU69 on Jan 1, 2019.

Green noted that mission extensions into fiscal years 2017 and 2018 are not final until Congress actually passes sufficient appropriation to fund NASA’s Planetary Science Division.

“Final decisions on mission extensions are contingent on the outcome of the annual budget process.”

NASA’s Dawn asteroid orbiter just completed its primary mission at dwarf planet Ceres on June 30, just in time for the global celebration known as Asteroid Day.

“The mission exceeded all expectations originally set for its exploration of protoplanet Vesta and dwarf planet Ceres,” said NASA officials.

The Dawn science team had recently submitted a proposal to break out of orbit around the middle of this month in order to this conduct a flyby of the main belt asteroid Adeona.

Green declined to approve the Dawn proposal, citing additional valuable science to be gathered at Ceres.

The long-term monitoring of Ceres, particularly as it gets closer to perihelion – the part of its orbit with the shortest distance to the sun — has the potential to provide more significant science discoveries than a flyby of Adeona,” he said.

Dawn is Earth’s first probe in human history to explore any dwarf planet, the first to explore Ceres up close and the first to orbit two celestial bodies.

The asteroid Vesta was Dawn’s first orbital target where it conducted extensive observations of the bizarre world for over a year in 2011 and 2012.

The mission is expected to last until at least later into 2016, and possibly longer, depending upon fuel reserves.

Dawn will remain at its current altitude at LAMO for the rest of its mission, and indefinitely afterward, even when no further communications are possible.

Green based his decision on the mission extensions on the biannual peer review scientific assessment by the Senior Review Panel.

The other mission extension – contingent on available resources – are: the Mars Reconnaissance Orbiter (MRO), Mars Atmosphere and Volatile EvolutioN (MAVEN), the Opportunity and Curiosity Mars rovers, the Mars Odyssey orbiter, the Lunar Reconnaissance Orbiter (LRO), and NASA’s support for the European Space Agency’s Mars Express mission.

Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.

Ken Kremer

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