Construction Tips from a Type 2 Engineer: Collaboration with Isaac Arthur

Fraser Cain and Isaac Arthur team up again to bring you another epic collaboration. This time, it’s construction tips from an engineer from a Type 2 Civilization.

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Weekly Space Hangout – February 10, 2017: Weekend Eclipse, Occultation and Comet 45P!

Host: Fraser Cain (@fcain) Guests: Paul M. Sutter ( / @PaulMattSutter) Morgan Rehnberg ( / @MorganRehnberg) Dave Dickinson ( / @astroguyz) Their stories this week: Comet 45P Flies Past Earth A new “kind” of black hole A Penumbral Lunar Eclipse The Moon Occults Regulus Mars didn’t have enough CO2 to sustain liquid water ISS is […]

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Colonizing the Inner Solar System

In this epic, 2-part episode, we team up with Isaac Arthur to imagine how humans will colonize the inner Solar System, becoming a true spacefaring civilization.

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Pure Metal Asteroid Has Mysterious Water Deposits

Water has been showing up in all sorts of unexpected places in our Solar System, such as the Moon, Mercury and Saturn’s moon Ganymede. Add one more place to the list: Asteroid 16 Psyche. This metal-rich asteroid may have traces of water molecules on its surface that shouldn’t be there, researchers say.

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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.
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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First Detection of Water Clouds Outside Our Solar System

Artist's conception of how WISE 0855 might appear if viewed close-up in infrared light. Artwork by Joy Pollard, Gemini Observatory/AURA.

Brown dwarfs – those not-quite-a-planet and not-quite-a-star objects – are intriguing oddities that are too low in mass to burn hydrogen, but are more massive than planets. They only emit a faint amount of light, so they are hard to detect, making scientists unsure of how many of them might be out there in our galaxy.

But astronomers have been keeping an eye one particular brown dwarf known called WISE 0855. Just 7.2 light-years from Earth, it is the coldest known object outside of our Solar System and is just barely visible at infrared wavelengths. But with some crafty spectroscopic observing techniques, astronomers have now determined this object has some exciting characteristics: its atmosphere is full of clouds of water vapor. This is the first time water clouds have been detected outside of our Solar System.

“It’s five times fainter than any other object detected with ground-based spectroscopy at this wavelength,” said Andrew Skemer, assistant professor of astronomy and astrophysics at UC Santa Cruz and the first author on a paper on WISE 0855 published in Astrophysical Journal Letters (paper is available on arXiv here). “Now that we have a spectrum, we can really start thinking about what’s going on in this object. Our spectrum shows that WISE 0855 is dominated by water vapor and clouds, with an overall appearance that is strikingly similar to Jupiter.”

This brown dwarf’s full name is WISE J085510.83-071442.5, but we’re among friends, so it’s W0855 for short. It has about five times the mass of Jupiter and is the coldest brown dwarf ever detected, with an average temperature of about 250 degrees Kelvin, or minus 10 degrees F, minus 20 C. That makes it nearly as cold as Jupiter, which is 130 degrees Kelvin.

“WISE 0855 is our first opportunity to study an extrasolar planetary-mass object that is nearly as cold as our own gas giants,” Skemer said.

Skemer and his team used the Gemini-North telescope in Hawaii and the Gemini Near Infrared Spectrograph to observe WISE 0855 over 13 nights for a total of about 14 hours. Skemer was part of a team that studied this object in 2014 found tentative indications of water clouds based on very limited photometric data. Skemer said obtaining a spectrum (which separates the light from an object into its component wavelengths) was the only way to detect this object’s molecular composition.

A video about the 2014 discovery and study of WISE 0855:

WISE 0855 is too faint for conventional spectroscopy at optical or near-infrared wavelengths, but the team took up a challenge and looked at the thermal emissions from the object at wavelengths in a narrow window around 5 microns.

“I think everyone on the research team really believed that we were dreaming to think we could obtain a spectrum of this brown dwarf because its thermal glow is so feeble,” said Skemer. WISE 0855, is so cool and faint that many astronomers thought it would be years before a spectrum could be obtained. “I thought we’d have to wait until the James Webb Space Telescope was operating to do this,” Skemer said.

This spectroscopic view provided a glimpse into the environment of WISE 0855’s atmosphere. With the data in hand, the researchers then developed atmospheric models of the equilibrium chemistry for a brown dwarf at 250 degrees Kelvin and calculated the resulting spectra under different assumptions, including cloudy and cloud-free models. The models predicted a spectrum dominated by features resulting from water vapor, and the cloudy model yielded the best fit to the features in the spectrum of WISE 0855.

While the spectra of this object are strikingly similar to Jupiter, WISE 0855 appears to have a less turbulent atmosphere.

“The spectrum allows us to investigate dynamical and chemical properties that have long been studied in Jupiter’s atmosphere, but this time on an extrasolar world,” Skemer said.

The scientists say WISE 0855 looks more similar to Jupiter than any exoplanet yet discovered, which is especially intriguing since the Juno mission has just begun its exploration at the giant world. Jupiter, along with the other gas planets in our Solar System, all have clouds and storms, although Jupiter’s clouds are mainly made of ammonia with lower level clouds perhaps containing water. One of Juno’s goals is to determine the global water abundance at Jupiter.

Sources: UC Santa Cruz, Gemini

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Enceladus’ Jets Selectively Power-Up Farther From Saturn

Icy water vapor geysers erupting from fissures on Enceladus. Credit: NASA/JPL

A crowning achievement of the Cassini mission to Saturn is the discovery of water vapor jets spraying out from Enceladus‘ southern pole. First witnessed by the spacecraft in 2005, these icy geysers propelled the little 515-kilometer-wide moon into the scientific spotlight and literally rewrote the mission’s objectives. After 22 flybys of Enceladus during its nearly twelve years in orbit around Saturn, Cassini has gathered enough data to determine that there is a global subsurface ocean of salty liquid water beneath Enceladus’ frozen crust—an ocean that gets sprayed into space from long “tiger stripe” fissures running across the moon’s southern pole.  Now, new research has shown that at least some of the vapor jets get a boost in activity when Enceladus is farther from Saturn.

By measuring the changes in brightness of a distant background star as Enceladus’ plumes passed in front of it in March 2016, Cassini observed a significant increase in the amount of icy particles being ejected by one particular jet source.

Named “Baghdad 1,” the jet went from contributing 2% of the total vapor content of the entire plume area to 8% when Enceladus was at the farthest point in its slightly-eccentric orbit around Saturn. This small yet significant discovery indicates that, although Enceladus’ plumes are reacting to morphological changes to the moon’s crust due to tidal flexing, it’s select small-scale jets that are exhibiting the most variation in output (rather than a simple, general increase in outgassing across the full plumes.)

“How do the tiger stripe fissures respond to the push and pull of tidal forces as Enceladus goes around its orbit to explain this difference? We now have new clues!” said Candice Hansen, senior scientist at the Planetary Science Institute and lead planner of the study. “It may be that the individual jet sources along the tiger stripes have a particular shape or width that responds most strongly to the tidal forcing each orbit to boost more ice grains at this orbital longitude.”

The confirmation that Enceladus shows an increase in overall plume output at farther points from Saturn was first made in 2013.

Whether this new finding means that the internal structure of the fissures is different than what scientists have suspected or some other process is at work either within Enceladus or in its orbit around Saturn still remains to be determined.

“Since we can only see what’s going on above the surface, at the end of the day, it’s up to the modelers to take this data and figure out what’s going on underground,” said Hansen.

Sources: Planetary Science Institute and NASA/JPL

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Spotlight On Pluto’s Frozen Polar Canyons

This enhanced color view Long canyons run vertically across the polar area—part of the informally named Lowell Regio, named for Percival Lowell, who founded Lowell Observatory and initiated the search that led to Pluto’s discovery. The widest of the canyons is about 45 miles (75 kilometers) wide and runs close to the north pole. Roughly parallel subsidiary canyons to the east and west are approximately 6 miles (10 kilometers) wide.

Pluto’s frozen nitrogen custard “heart” has certainly received its share of attention. Dozens of wide and close-up photos homing on this fascinating region rimmed by mountains and badlands have been relayed back to Earth by NASA’s New Horizons probe after last July’s flyby. For being only 1,473 miles (2,370 km) in diameter, Pluto displays an incredible diversity of landscapes.

This week, the New Horizons team shifted its focus northward, re-releasing an enhanced color image of the north polar area that was originally part of a high-resolution full-disk photograph of Pluto. Inside of the widest canyon, you can trace the sinuous outline of a narrower valley similar in outward appearance to the Moon’s Alpine Valleycut by a narrow, curvy rill that once served as a conduit for lava.

We see multiple canyons in Pluto’s polar region, their walls broken and degraded compared to canyons seen elsewhere on the planet. Signs that they may be older and made of weaker materials and likely formed in ancient times when Pluto was more tectonically active. Perhaps they’re related to that long-ago dance between Pluto and its largest moon Charon as the two transitioned into their current tidally-locked embrace.

In the lower right corner of the image, check out those funky-shaped pits that resemble the melting outlines of boot prints in the snow. They reach 45 miles (70 km) across and 2.5 miles (4 km) deep and may indicate locations where subsurface ice has melted or sublimated (vaporized) from below, causing the ground to collapse.

Notice the variation in color across the landscape from yellow-orange to pale blue. High elevations show up in a distinctive yellow, not seen elsewhere on Pluto, with lower elevations and latitudes a bluish gray. New Horizons’ infrared measurements show abundant methane ice across the Lowell Region, with relatively little nitrogen ice. The yellow terrains may be older methane deposits that have been more processed by solar UV light than the bluer terrain. The color variations are especially striking in the area of the collapse pits.

Pluto’s icy riches include not only methane and nitrogen but also water, which forms the planet’s bedrock. NASA poetically refers to the water ice as “the canvas on which (Pluto’s) more volatile ices paint their seasonally changing patterns”. Recent images made in infrared light shows little or no water ice in the informally named places called Sputnik Planum (the left or western region of Pluto’s “heart”) and Lowell Regio. This indicates that at least in these regions, Pluto’s bedrock remains well hidden beneath a thick blanket of other ices such as methane, nitrogen and carbon monoxide.

To delve more deeply into Pluto, visit the NASA’s photojournal archive, where you’ll find 130 photos (and counting!) of the dwarf planet and its satellites.

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Weekly Space Hangout – Oct. 9, 2015: Nobel Prizes, Private Moon Launches & Water on Pluto!

Host: Fraser Cain (@fcain) Guests: Paul Sutter ( / @PaulMattSutter) Morgan Rehnberg ( / @MorganRehnberg ) Kimberly Cartier (@AstroKimCartier ) Brian Koberlein (@briankoberlein / (…)Read the rest of Weekly Space Hangout – Oct. 9, 2015: Nobel Prizes, Private Moon Launches & Water on Pluto! (325 words) © Fraser for Universe Today, 2015. | Permalink […]