A sampling of recent articles, videos, and images about space related science news:

** Ultima Thule grows from a dot to a world in this time lapse of images captured by the New Horizons probe as it approached the Kuiper Belt object: Approach to Ultima Thule – New Horizons

Ultima Thule is providing a plethora of clues to the early formation stages of the solar system: A Prehistoric Puzzle in the Kuiper Belt | NASA

This strange shape is the biggest surprise, so far, of the flyby. “We’ve never seen anything like this anywhere in the solar system,” said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute, Boulder, Colorado. “It is sending the planetary science community back to the drawing board to understand how planetesimals – the building blocks of the planets – form.”

Because it is so well preserved, Ultima Thule is offering our clearest look back to the era of planetesimal accretion and the earliest stages of planetary formation. Apparently Ultima Thule’s two lobes once orbited each other, like many so-called binary worlds in the Kuiper Belt, until something brought them together in a “gentle” merger.

“This fits with general ideas of the beginning of our solar system,” said William McKinnon, a New Horizons co-investigator from Washington University in St. Louis. “Much of the orbital momentum of the Ultima Thule binary must have been drained away for them to come together like this. But we don’t know yet what processes were most important in making that happen.”

**Asteroid Bennu is spewing out dust as seen in the latest images from the OSIRIS-REx probe, which reached the near earth object last December: Bennu Particle Ejection Event – Jan. 19, 2019 – OSIRIS-REx Mission

“This view of asteroid Bennu ejecting particles from its surface on January 19 was created by combining two images taken by the NavCam 1 imager onboard NASA’s OSIRIS-REx spacecraft: a short exposure image (1.4 ms), which shows the asteroid clearly, and a long exposure image (5 sec), which shows the particles clearly. Other image processing techniques were also applied, such as cropping and adjusting the brightness and contrast of each layer. Date Taken: Jan. 19, 2019” – Credit: NASA/Goddard/University of Arizona/Lockheed Martin

This behavior was not expected: NASA Mission Reveals Asteroid Has Big Surprises | NASA

“The discovery of plumes is one of the biggest surprises of my scientific career,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson. “And the rugged terrain went against all of our predictions. Bennu is already surprising us, and our exciting journey there is just getting started.”

Shortly after the discovery of the particle plumes on Jan. 6, the mission science team increased the frequency of observations, and subsequently detected additional particle plumes during the following two months. Although many of the particles were ejected clear of Bennu, the team tracked some particles that orbited Bennu as satellites before returning to the asteroid’s surface.

The OSIRIS-REx team initially spotted the particle plumes in images while the spacecraft was orbiting Bennu at a distance of about one mile (1.61 kilometers). Following a safety assessment, the mission team concluded the particles did not pose a risk to the spacecraft. The team continues to analyze the particle plumes and their possible causes.

“The first three months of OSIRIS-REx’s up-close investigation of Bennu have reminded us what discovery is all about — surprises, quick thinking, and flexibility,” said Lori Glaze, acting director of the Planetary Science Division at NASA Headquarters in Washington. “We study asteroids like Bennu to learn about the origin of the solar system. OSIRIS-REx’s sample will help us answer some of the biggest questions about where we come from.”

The mission will go through several different phases of its investigation of the asteroid starting with the Baseball Diamond Phase:

The in-depth study of Bennu begins in earnest during Detailed Survey: Baseball Diamond Phase. OSIRIS-REx will make multiple passes around Bennu to produce the wide range of viewing angles necessary to fully observe the asteroid. The spacecraft will also use its OTES spectrometer to map the chemical composition of Bennu’s entire surface. Images obtained during this phase will be of high enough resolution to produce digital terrain maps and global image mosaics for proposed sample sites. Bennu’s terrain will be surveyed in bulk and sections will be classified as either “safe” or “unsafe,” with the results visualized on a hazard map.

The phase’s name comes from the early stage of mission design when the stations the spacecraft would traverse were arranged in the shape of a baseball diamond.  Although the mission design has since evolved, the original name for the phase remains.

In 2023 the spacecraft will return to earth with samples of the asteroid’s surface, some of which is seen in these detailed images: A Region of Bennu’s Northern Hemisphere Close Up | NASA

This trio of images acquired by NASA’s OSIRIS-REx spacecraft shows a wide shot and two close-ups of a region in asteroid Bennu’s northern hemisphere. The wide-angle image (left), obtained by the spacecraft’s MapCam camera, shows a 590-foot (180-meter) wide area with many rocks, including some large boulders, and a “pond” of regolith that is mostly devoid of large rocks. The two closer images, obtained by the high-resolution PolyCam camera, show details of areas in the MapCam image, specifically a 50-foot (15 meter) boulder (top) and the regolith pond (bottom). The PolyCam frames are 101 feet (31 meters) across and the boulder depicted is approximately the same size as a humpback whale.

The images were taken on February 25 while the spacecraft was in orbit around Bennu, approximately 1.1 miles (1.8 km) from the asteroid’s surface. The observation plan for this day provided for one MapCam and two PolyCam images every 10 minutes, allowing for this combination of context and detail of Bennu’s surface.

** Lunar sample containers unopened since Apollo astronauts filled them during EVAs on the surface will soon be examined by teams of researchers who will take advantage of modern instruments to attain better insights into what the materials say about the formation and subsequent development of the Moon: NASA Selects Teams to Study Untouched Moon Samples | NASA

NASA has selected nine teams to continue the science legacy of the Apollo missions by studying pieces of the Moon that have been carefully stored and untouched for nearly 50 years. A total of $8 million has been awarded to the teams.

“By studying these precious lunar samples for the first time, a new generation of scientists will help advance our understanding of our lunar neighbor and prepare for the next era of exploration of the Moon and beyond, “ said Thomas Zurbuchen, Associate Administrator for NASA’s Science Mission Directorate in Washington, DC. “This exploration will bring with it new and unique samples into the best labs right here on Earth.”

** Mars:

**** Opportunity rover’s last shot. While Opportunity has now gone quiet, it left an enormous legacy of data and images including a beautiful final parting panorama: Opportunity’s Parting Shot Was a Beautiful Panorama – NASA’s Mars Exploration Program

Opportunity’s final panorama with notations.

**** Huge caves on Mars appear more likely with the latest findings: New evidence for many large and extensive Martian cave systems | Behind The Black.

The second important implication of this finding, and the one that is possibly more important, is that this research suggests that there are many many many underground voids on Mars, formed by water, that could be found in many places. Some might be easily accessible. Some might require drilling into. In either case, they would provide ample locations for building habitable colonies.

And they would likely still have that water, now frozen into the underground ice table.

The possibilities are mind-boggling. They suggest that everyone studying Mars must rethink the surface features. The alienness of Mars means they might resemble Earth geology, but might have formed in ways we have not previously imagined. And the consequences of that alien formation might make future human colonization far easier.

****  Caves appear common on rocky worlds throughout our solar system: “The Planets Under Our Feet: Caves on Earth, Mars, and Beyond” –

Dr. Penelope Boston, NASA Ames Research Center New exploration indicates that caves may be more common on rocky and icy worlds in our Solar System than we have thought in the past. Caves below the Earth show us a very different planet than the familiar one we experience on the surface. Each dark cave system has its own micro-organisms and distinctive mineral and chemical properties. Dr. Boston takes us on a tour of the some of the most spectacular caves under the Earth and the unusual life-forms they harbor, and considers how the lessons they teach us can be applied to the exploration of the Solar System, especially the icy moons of the giant planets.

**** More Mars geology findings are highlighted by Bob Zimmerman who closely monitors the latest image releases from the orbiters:

The image shows numerous evidence of avalanches and erosion, both at its base and at its rim. None of these avalanches likely occurred during those catastrophic floods, but long afterward.

Signs of “landslides on the face of the mesa north of Hydraotes Chaos”. Mars Reconnaissance Orbiter HiRISE camera via Bob Zimmerman.

The top inset is shown to the left. Here very large sections of the the cliff face at the rim have broken off, dropping giant blocks downward. This material piles up to create an alluvial slope heading down to the floor of the canyon. On the upper cliff and on this slope the dark streaks indicate both past landslides as well as possible seeps of water coming out of the cliff face.

The bottom inset is shown next to the left. It focuses on the head of the largest landslide, and shows a flow at its base that resembles a gravitational collapse as shown in this science paper about Martian ground water.

You are staring at one of the unsolved mysteries on Mars. This surface texture of interconnected ridges and troughs, referred to as “brain terrain” is found throughout the mid-latitude regions of Mars. (This image is in Protonilus Mensae.)

This bizarrely textured terrain may be directly related to the water-ice that lies beneath the surface. One hypothesis is that when the buried water-ice sublimates (changes from a solid to a gas), it forms the troughs in the ice. The formation of these features might be an active process that is slowly occurring since HiRISE [MRO’s high resolution camera] has yet to detect significant changes in these terrains.

A section of a MRO HiRISE image showing a Mars region with an appearance named “Brain Terrain”. (Via Bob Zimmerman)

At today’s presentations at the 50th Lunar and Planetary Science Conference in Texas, scientists showed images and data [pdf] suggesting that many of the Martian gullies found on cliff faces are formed when the dust layer protecting underlying snow gets blown away and the exposed snow/ice then melts.

The image [below] was taken by the high resolution camera of Mars Reconnaissance Orbiter (MRO) in 2009, and has been cropped to post here. The white streaks are what they suggest is exposed ice/snow.

A section of a MRO HiRISE image that appears to show white streaks of water ice in a cliff gully.

** The locations of science spacecraft in our solar system are shown in this video from the Planetary Society:

Emily Lakdawalla takes us on a tour of the spacecraft currently exploring from within our solar system. All planets and spacecraft locations are shown at their location for April 1st, 2019.

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