Space Friday: Mars, Neptune, Pluto, and More!

A Mystery Mineral on Mars

Landing inside Gale Crater on Mars in 2012, NASA’s Curiosity rover has been slowly working its way up the slopes of five-kilometer (three-mile) high Mount Sharp at the crater’s center. Along the way it has drilled into the rocks, analyzing samples and detecting sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon, essential building blocks for life.

A paper recently published in the Proceedings of the National Academy of Sciences reports that last year, Curiosity drilled into a site dubbed “Buckskin” and found a mineral scientists hadn’t expected. Not unobtanium, kryptonite, or anything not found on Earth, the material is a silica called tridymite, which is typically formed at high temperatures in a process known as silicic volcanism. One familiar example of silicic volcanism in the U.S. is Mount St. Helens in Washington state, which exploded violently in 1980, with devastating results for the area.

“The combination of high silica content and extremely high temperatures in the volcanoes creates tridymite,” says Richard Morris, lead author of the paper.

Co-author Doug Ming adds, "The discovery of tridymite was completely unexpected. This discovery now begs the question of whether Mars experienced a much more violent and explosive volcanic history during the early evolution of the planet than previously thought."–Bing Quock

A Dark Vortex on Neptune

This week scientists confirmed the presence of a dark vortex on the planet Neptune. Dark vortices are high-pressure systems where the flow of ambient air is perturbed and diverted upward over the vortex, very similar to the high-pressure regions that periodically bring dry, warm weather here to the west coast. While the dark vortices are difficult to spot, they’re often associated with bright patches of high-altitude clouds, which had been recently spotted on the distant planet.

Dark vortices aren’t too unusual on Neptune—the first was observed by NASA’s Voyager 2 spacecraft in 1989—and seem to persist for years before disappearing. This is a much shorter time span compared to similar anticyclones on Jupiter—such as the familiar Great Red Spot—which evolve over decades.

Many questions remain as to how these dark vortices originate, what controls their drift and oscillation, how they interact with the environment and how they eventually dissipate, according to UC Berkeley’s Joshua Tollefson. Tollefson and his colleagues hope that by measuring the evolution of the new dark vortex, scientists will extend their knowledge of both the dark vortices themselves and the structure and dynamics of the surrounding atmosphere.–Molly Michelson

A Hidden Ocean on Pluto?

Out in the boondocks of the Solar System, billions of miles from the warming rays of the Sun, the dwarf planet Pluto may be defying scientists’ expectations by concealing an ocean of liquid water beneath its crust. That’s the conclusion of a new study from Brown University’s Department of Earth, Environmental, and Planetary Sciences, led by Noah Hammond.

A year ago, when NASA’s New Horizons spacecraft flew past the diminutive world, it managed to snap high-resolution images of bizarre features on its surface, including nitrogen glaciers apparently flowing slowly into the flat expanse of Sputnik Planum, ringed by towering mountains of rock-hard water ice, with enormous, super-sluggish convection cells of nitrogen slush bubbling up from beneath the crust like a giant lava lamp. There were plenty of signs that Pluto may at one time have had water on its surface, and as with many other solid bodies in the outer solar system, there are indications that a mantle of water ice underlies the crust of more volatile ices such as nitrogen, methane, and carbon dioxide. Scientists had thought that the water would long have frozen solid, transforming under the high subsurface pressures and low temperatures into ice II, which has a denser, more compact crystalline structure than the ice you get out of the freezer (there are 17 forms of ice, by the way—find out what they are here). Ice II takes up less volume, so planetologists expected to see signs of shrinkage and compression on Pluto. They didn’t, which suggests that Pluto’s water may be only partly frozen and would still be expanding.

Certain surface features, such as great systems of cracks, indicate internal pressures, perhaps caused by the expansion of the mantle. One particularly interesting radial pattern is dubbed the “spider,” due to its appearance. The convergence of the cracks forming this feature seem to indicate that the spider is the focus of stresses pushing up from beneath the crust.

“Our model shows that recent geological activity on Pluto can be driven just from phase changes in the ice—no tides or exotic materials or unusual processes are required,” says study co-author Amy C. Barr. “This lends support to the idea that oceans may be common among large Kuiper Belt objects, just as they are common among the satellites of the outer planets.” –Bing Quock

A Peek at the Center of the Galaxy

The black hole at the center of our galaxy is four million times as massive as the Sun, but by its nature, unobservable. Astronomers say they got a little closer, however, by making observations of a star known as S2 that orbits the black hole every 16 years with the GRAVITY instrument. GRAVITY is part of the Very Large Telescope (VLT) Interferometer in the Chilean Atacama desert. By combining light from four telescopes it achieves the same spatial resolution and precision in measuring positions as a telescope of up to 130 metres in diameter, allowing ultra-precise measurements of S2 and other stars close to the black hole.

These results provide a taste of the groundbreaking science that scientists hope GRAVITY will produce as it probes the extremely strong gravitational fields close to the central supermassive black hole, testing Einstein’s theory of general relativity. The team hopes that this latest observation will set the stage for when S2 comes closest to the black hole in 2018, at just 17 light-hours away and travelling at almost 30 million kilometers per hour, or 2.5 percent of the speed of light. At this distance the effects due to general relativity will be most pronounced and GRAVITY observations will yield their most important results. –Molly Michelson

Hubble’s 5-Year Extension

The Hubble Space Telescope (HST), launched in 1990 and once ridiculed as a symbol of failure because of its improperly-curved mirror, then rescued and restored to full operation by spacewalking astronauts—THAT Hubble Space Telescope—has been given yet another lease on life. Following its final servicing by a Space Shuttle crew in 2009, NASA officials stated that the orbiting observatory could continue operations through at least 2015 and perhaps beyond. NASA has a pretty good record for over-engineering spacecraft so that they last well beyond life expectancy estimates (just look at the Opportunity rover and the International Space Station), but the main issue is continued funding, which is typically reevaluated every two years.

On Thursday, the space agency took care of that by awarding a contract extension to the Association of Universities for Research in Astronomy (AURA), which manages the Space Telescope Science Institute (STSci), which in turn runs HST. This extension allows AURA to continue operating the telescope through June 2021. In the 26 years since its deployment, the instrument named after American astronomer Edwin Hubble has become one of the most productive scientific devices ever built, enabling scientists to study out-of-this-world phenomena as black holes, gravitational lenses, stellar nurseries, colliding galaxies, and extrasolar planets, providing the scientific world and the public with dazzling views of the cosmos.

The extension overlaps the planned launch of Hubble’s successor, the James Webb Space Telescope. Barring any delays in JWST’s timeline, the two could be operating simultaneously, complementing each other and providing the most detailed views of the Universe ever seen.

The next Benjamin Dean Astronomy Lecture at Morrison Planetarium on July 18 will feature Zoltan Levay, Senior Image Processing Specialist at STSci. –Bing Quock

​Image: NASA, ESA, and M.H. Wong and J. Tollefson (UC Berkeley)