Does Mars Have Rings? Not Right Now, But Maybe One Day

NASA - Mars Science Laboratory (MSL) patch.

March 20, 2017

As children, we learned about our solar system's planets by certain characteristics -- Jupiter is the largest, Saturn has rings, Mercury is closest to the sun. Mars is red, but it's possible that one of our closest neighbors also had rings at one point and may have them again someday.

That's the theory put forth by NASA-funded scientists at Purdue University, Lafayette, Indiana, whose findings were published in the journal Nature Geoscience. David Minton and Andrew Hesselbrock developed a model that suggests that debris that was pushed into space from an asteroid or other body slamming into Mars around 4.3 billion years ago alternates between becoming a planetary ring and clumping together to form a moon.

One theory suggests that Mars' large North Polar Basin or Borealis Basin -- which covers about 40 percent of the planet in its northern hemisphere -- was created by that impact, sending debris into space.

"That large impact would have blasted enough material off the surface of Mars to form a ring," Hesselbrock said.

Hesselbrock and Minton's model suggests that as the ring formed, and the debris slowly moved away from the Red Planet and spread out, it began to clump and eventually formed a moon. Over time, Mars' gravitational pull would have pulled that moon toward the planet until it reached the Roche limit, the distance within which a planet's tidal forces will break apart a celestial body that is held together only by gravity.

Image above: The image from NASA's Curiosity Mars rover shows one of Mars' two moons, Phobos, passing directly in front of the other, Deimos, in 2013. New research suggests the moons consolidated long ago from dust rings around the planet and, in the distant future, may disintegrate into new rings. Image Credits: NASA/JPL-Caltech/Malin Space Science Systems/Texas A&M Univ.

Phobos, one of Mars' moons, is getting closer to the planet. According to the model, Phobos will break apart upon reaching the Roche limit, and become a set of rings in roughly 70 million years. Depending on where the Roche limit is, Minton and Hesselbrock believe this cycle may have repeated between three and seven times over billions of years. Each time a moon broke apart and reformed from the resulting ring, its successor moon would be five times smaller than the last, according to the model, and debris would have rained down on the planet, possibly explaining enigmatic sedimentary deposits found near Mars' equator.

"You could have had kilometer-thick piles of moon sediment raining down on Mars in the early parts of the planet's history, and there are enigmatic sedimentary deposits on Mars with no explanation as to how they got there," Minton said. "And now it's possible to study that material."

Other theories suggest that the impact with Mars that created the North Polar Basin led to the formation of Phobos 4.3 billion years ago, but Minton said it's unlikely the moon could have lasted all that time. Also, Phobos would have had to form far from Mars and would have had to cross through the resonance of Deimos, the outer of Mars' two moons. Resonance occurs when two moons exert gravitational influence on each other in a repeated periodic basis, as major moons of Jupiter do. By passing through its resonance, Phobos would have altered Deimos' orbit. But Deimos' orbit is within one degree of Mars' equator, suggesting Phobos has had no effect on Deimos.

"Not much has happened to Deimos' orbit since it formed," Minton said. "Phobos passing through these resonances would have changed that."

"This research highlights even more ways that major impacts can affect a planetary body," said Richard Zurek of NASA's Jet Propulsion Laboratory, Pasadena, California. He is the project scientist for NASA's Mars Reconnaissance Orbiter, whose gravity mapping provided support for the hypothesis that the northern lowlands were formed by a massive impact.

Minton and Hesselbrock will now focus their work on either the dynamics of the first set of rings that formed or the materials that have rained down on Mars from disintegration of moons.

Curiosity is part of NASA's ongoing Mars research and preparation for a human mission to Mars in the 2030s. Caltech manages JPL, and JPL manages the Curiosity mission for NASA's Science Mission Directorate in Washington. For more about Curiosity, visit: http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl/

For more information about NASA missions investigating Mars, visit: https://mars.nasa.gov/

Image (mentioned), Text, Credits: NASA/Laurie Cantillo/Dwayne Brown/JPL/Guy Webster/Purdue University/Steve Tally/Emil Venere/Writer: Brian Wallheimer.

Best regards, Orbiter.ch

Mars Volcano, Earth’s Dinosaurs Went Extinct About the Same Time

NASA Goddard Space Flight Center logo.

March 20, 2017

New NASA research reveals that the giant Martian shield volcano Arsia Mons produced one new lava flow at its summit every 1 to 3 million years during the final peak of activity. The last volcanic activity there ceased about 50 million years ago—around the time of Earth’s Cretaceous–Paleogene extinction, when large numbers of our planet’s plant and animal species (including dinosaurs) went extinct.

Located just south of Mars’ equator, Arsia Mons is the southernmost member of a trio of broad, gently sloping shield volcanoes collectively known as Tharsis Montes. Arsia Mons was built up over billions of years, though the details of its lifecycle are still being worked out. The most recent volcanic activity is thought to have taken place in the caldera—the bowl-shaped depression at the top—where 29 volcanic vents have been identified. Until now, it’s been difficult to make a precise estimate of when this volcanic field was active.

Image above: This digital-image mosaic of Mars' Tharsis plateau shows the extinct volcano Arsia Mons. It was assembled from images that the Viking 1 Orbiter took during its 1976-1980 working life at Mars. Image Credits: NASA/JPL/USGS.

“We estimate that the peak activity for the volcanic field at the summit of Arsia Mons probably occurred approximately 150 million years ago—the late Jurassic period on Earth—and then died out around the same time as Earth’s dinosaurs,” said Jacob Richardson, a postdoctoral researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It’s possible, though, that the last volcanic vent or two might have been active in the past 50 million years, which is very recent in geological terms.”

Richardson is presenting the findings on March 20, 2017, at the Lunar and Planetary Science Conference in The Woodlands, Texas. The study also is published in Earth and Planetary Science Letters.

Measuring about 68 miles (110 kilometers) across, the caldera is deep enough to hold the entire volume of water in Lake Huron, and then some. Examining the volcanic features within the caldera required high-resolution imaging, which the researchers obtained from the Context Camera on NASA’s Mars Reconnaissance Orbiter.

The team mapped the boundaries of the lava flows from each of the 29 volcanic vents and determined the stratigraphy, or layering, of the flows. The researchers also performed a technique called crater counting—tallying up the number of craters at least 330 feet (100 meters) in diameter—to estimate the ages of the flows.

Artist's view of erupting volcano on Mars. Image Credit: NASA

Using a new computer model developed by Richardson and his colleagues at the University of South Florida, the two types of information were combined to determine the volcanic equivalent of a batting lineup for Arsia Mons’ 29 vents. The oldest flows date back about 200 million years. The youngest flows probably occurred 10 to 90 million years ago—most likely around 50 million years ago.

The modeling also yielded estimates of the volume flux for each lava flow. At their peak about 150 million years ago, the vents in the Arsia Mons’ caldera probably collectively produced about 1 to 8 cubic kilometers of magma every million years, slowly adding to the volcano’s size.

“Think of it like a slow, leaky faucet of magma,” said Richardson. “Arsia Mons was creating about one volcanic vent every 1 to 3 million years at the peak, compared to one every 10,000 years or so in similar regions on Earth.”

A better understanding of when volcanic activity on Mars took place is important because it helps researchers understand the Red Planet’s history and interior structure.

“A major goal of the Mars volcanology community is to understand the anatomy and lifecycle of the planet’s volcanoes. Mars’ volcanoes show evidence for activity over a larger time span than those on Earth, but their histories of magma production might be quite different,” said Jacob Bleacher, a planetary geologist at Goddard and a co-author on the study. “This study gives us another clue about how activity at Arsia Mons tailed off and the huge volcano became quiet.”

Malin Space Science Systems, San Diego, built and operates the Context Camera. NASA’s Jet Propulsion Laboratory, Pasadena, manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate, Washington.

Related:

Earth and Planetary Science Letters: http://dx.doi.org/10.1016/j.epsl.2016.10.040

Journey to Mars: https://www.nasa.gov/topics/journeytomars/index.html

Goddard Space Flight Center: https://www.nasa.gov/centers/goddard/home/index.html

Jet Propulsion Laboratory: https://www.nasa.gov/centers/jpl/home/index.html

Images (mentioned), Text, Credits: NASA’s Goddard Space Flight Center, by Elizabeth Zubritsky/Karl Hille.

Greetings, Orbiter.ch

NASA's Swift Mission Maps a Star's 'Death Spiral' into a Black Hole

NASA - Swift Mission patch.

March 20, 2017

Some 290 million years ago, a star much like the sun wandered too close to the central black hole of its galaxy. Intense tides tore the star apart, which produced an eruption of optical, ultraviolet and X-ray light that first reached Earth in 2014. Now, a team of scientists using observations from NASA's Swift satellite have mapped out how and where these different wavelengths were produced in the event, named ASASSN-14li, as the shattered star's debris circled the black hole.

"We discovered brightness changes in X-rays that occurred about a month after similar changes were observed in visible and UV light," said Dheeraj Pasham, an astrophysicist at the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts, and the lead researcher of the study. "We think this means the optical and UV emission arose far from the black hole, where elliptical streams of orbiting matter crashed into each other."

Swift Charts a Star's 'Death Spiral' into Black Hole

Video above: This animation illustrates how debris from a tidally disrupted star collides with itself, creating shock waves that emit ultraviolet and optical light far from the black hole. According to Swift observations of ASASSN-14li, these clumps took about a month to fall back to the black hole, where they produced changes in the X-ray emission that correlated with the earlier UV and optical changes. Video Credits: NASA's Goddard Space Flight Center.

Astronomers think ASASSN-14li was produced when a sun-like star wandered too close to a 3-million-solar-mass black hole similar to the one at the center of our own galaxy. For comparison, the event horizon of a black hole like this is about 13 times bigger than the sun, and the accretion disk formed by the disrupted star could extend to more than twice Earth's distance from the sun.

When a star passes too close to a black hole with 10,000 or more times the sun's mass, tidal forces outstrip the star's own gravity, converting the star into a stream of debris. Astronomers call this a tidal disruption event. Matter falling toward a black hole collects into a spinning accretion disk, where it becomes compressed and heated before eventually spilling over the black hole's event horizon, the point beyond which nothing can escape and astronomers cannot observe. Tidal disruption flares carry important information about how this debris initially settles into an accretion disk.

Astronomers know the X-ray emission in these flares arises very close to the black hole. But the location of optical and UV light was unclear, even puzzling. In some of the best-studied events, this emission seems to be located much farther than where the black hole's tides could shatter the star. Additionally, the gas emitting the light seemed to remain at steady temperatures for much longer than expected.

ASASSN-14li was discovered Nov. 22, 2014, in images obtained by the All Sky Automated Survey for SuperNovae (ASASSN), which includes robotic telescopes in Hawaii and Chile. Follow-up observations with Swift's X-ray and Ultraviolet/Optical telescopes began eight days later and continued every few days for the next nine months. The researchers supplemented later Swift observations with optical data from the Las Cumbres Observatory headquartered in Goleta, California.

Image above: This artist’s rendering shows the tidal disruption event named ASASSN-14li, where a star wandering too close to a 3-million-solar-mass black hole was torn apart. The debris gathered into an accretion disk around the black hole. New data from NASA's Swift satellite show that the initial formation of the disk was shaped by interactions among incoming and outgoing streams of tidal debris. Image Credit: NASA's Goddard Space Flight Center. 

In a paper describing the results published March 15 in The Astrophysical Journal Letters, Pasham, Cenko and their colleagues show how interactions among the infalling debris could create the observed optical and UV emission.

Tidal debris initially falls toward the black hole but overshoots, arcing back out along elliptical orbits and eventually colliding with the incoming stream.

"Returning clumps of debris strike the incoming stream, which results in shock waves that emit visible and ultraviolet light," said Goddard's Bradley Cenko, the acting Swift principal investigator and a member of the science team. "As these clumps fall down to the black hole, they also modulate the X-ray emission there."

Swift spacecraft. Image Credit: NASA

Future observations of other tidal disruption events will be needed to further clarify the origin of optical and ultraviolet light.

Goddard manages the Swift mission in collaboration with Pennsylvania State University in University Park, the Los Alamos National Laboratory in New Mexico and Orbital Sciences Corp. in Dulles, Virginia. Other partners include the University of Leicester and Mullard Space Science Laboratory in the United Kingdom, Brera Observatory and the Italian Space Agency in Italy, with additional collaborators in Germany and Japan.

Related:

Scientists Identify a Black Hole Choking on Stardust (MIT): http://news.mit.edu/2017/black-hole-choking-stardust-0315

ASASSN-14li: Destroyed Star Rains onto Black Hole, Winds Blow it Back: http://chandra.harvard.edu/photo/2015/tidal/

'Cry' of a Shredded Star Heralds a New Era for Testing Relativity: https://www.nasa.gov/mission_pages/swift/bursts/shredded-star.html

Researchers Detail How a Distant Black Hole Devoured a Star: https://www.nasa.gov/mission_pages/swift/bursts/devoured-star.html

All Sky Automated Survey for SuperNovae (ASASSN): http://www.astronomy.ohio-state.edu/~assassin/index.shtml

Las Cumbres Observatory: https://lco.global/

NASA's Swift: http://www.nasa.gov/mission_pages/swift/main/index.html

Images (mentioned), Video (mentioned), Text, Credits: NASA's Goddard Space Flight Center, by Francis Reddy/Karl Hille.

Greetings, Orbiter.ch

Stem Cells Seem Speedier in Space

ISS - International Space Station patch.

March 20, 2017

ISS - International Space Station. Image Credits: NASA

Growing significant numbers of human stem cells in a short time could lead to new treatments for stroke and other health issues. Scientists are sending stem cells to the International Space Station to test whether these cells proliferate faster in microgravity without suffering any side effects.

Therapeutic uses require hundreds of millions of stem cells and currently no efficient way exists to produce such quantities. Previous research suggests that microgravity could help, and the space station is home to the nation’s only national lab in microgravity.

Image above: Cultured stem cells. Image Credits: BioServe Inc., University of Colorado.

Some types of stem cells grow faster in simulated microgravity, according to Abba Zubair, a researcher at the Mayo Clinic in Jacksonville, Florida. Zubair is principal investigator for the Microgravity Expanded Stem Cells investigation, which is cultivating human stem cells aboard the space station for use in clinical trials back on Earth. He holds a doctor of medicine degree in transfusion medicine and cell therapy and a doctorate of philosophy in tumor immunology.

Human stem cells are cells that have not yet specialized in function and can divide into a spectrum of cell types, rejuvenating and repairing tissue throughout a person’s lifetime. Stem cells in every organ of the body, including skin and bones, maintain those organs and repair tissue by dividing and differentiating into specialized cells.

Harvesting a person’s stem cells and growing enough of them for use in therapies has proven difficult, though. Researchers have successfully grown mesenchymal stem cells, found in bone marrow, but growing sufficient quantities takes weeks. That could be too late for treatment of some conditions.

Image above: The Plate Habitat (PHAB) containing BioCell cassettes for the Expanded Stem Cell investigation aboard the space station. Image Credits: BioServe Inc., University of Colorado.

“Stem cells are inherently designed to remain at a constant number,” Zubair explains. “We need to grow them faster, but without changing their characteristics.”

The first phase of the investigation, he adds, is answering the question: “Do stem cells grow faster in space and can we grow them in such a manner that they are safe to use in patients?”

Investigators will examine the space-grown cells in an effort to understand the mechanism behind microgravity’s effects on them. The long-term goal is to learn how to mimic those effects and develop a safe and reliable way to produce stem cells in the quantities needed.

Image above: Abba Zubair in his lab at Mayo Clinic in Jacksonville, Florida. Image Credits: BioServe Inc., University of Colorado.

The second phase will involve testing clinical application of the cells in patients. Zubair has been studying treatment of stroke patients with lab-grown stem cells and plans to compare those results with use of the space-grown stem cells.

“What is unique about this investigation is that we are not only looking at the biology of the cells and how they grow, but focusing on application, how we can use them to treat patients,” he says.

The investigation expands existing knowledge of how microgravity affects stem cell growth and differentiation as well as advances future studies on how to produce large numbers of stem cells for treating stroke and other conditions.

The faster that happens, the better for those who could benefit from stem cell therapies.

Related links:

Human stem cells: https://www.youtube.com/watch?v=KTelwF805Os

Microgravity Expanded Stem Cells investigation: https://www.nasa.gov/mission_pages/station/research/experiments/1971.html

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Images (mentioned), Text, Credits: NASA Johnson Space Center/International Space Station Program Office/Melissa Gaskill/Kristine Rainey.

Best regards, Orbiter.ch

Hubble's Glittering Frisbee Galaxy

NASA - Hubble Space Telescope patch.

March 20, 2017

This image from Hubble’s Wide Field Camera 3 (WFC3) shows a section of NGC 1448, a spiral galaxy located about 50 million light-years from Earth in the little-known constellation of Horologium (The Pendulum Clock). We tend to think of spiral galaxies as massive and roughly circular celestial bodies, so this glittering oval does not immediately appear to fit the visual bill. What’s going on?

Imagine a spiral galaxy as a circular frisbee spinning gently in space. When we see it face on, our observations reveal a spectacular amount of detail and structure — a great example from Hubble is the telescope’s view of Messier 51, otherwise known as the Whirlpool Galaxy. However, the NGC 1448 frisbee is very nearly edge-on with respect to Earth, giving it an appearance that is more oval than circular. The spiral arms, which curve out from NGC 1448’s dense core, can just about be seen.

Although spiral galaxies might appear static with their picturesque shapes frozen in space, this is very far from the truth. The stars in these dramatic spiral configurations are constantly moving as they orbit around the galaxy’s core, with those on the inside making the orbit faster than those sitting further out.

This makes the formation and continued existence of a spiral galaxy’s arms something of a cosmic puzzle, because the arms wrapped around the spinning core should become wound tighter and tighter as time goes on — but this is not what we see. This is known as the winding problem.

For Hubble’s image of the Whirlpool Galaxy, visit:  

http://hubblesite.org/image/1677/news_release/2005-12

http://www.nasa.gov/hubble

http://www.spacetelescope.org/

Image Credits: ESA/Hubble & NASA/Text Credits: European Space Agency/NASA/Karl Hille.

Greetings, Orbiter.ch

Dragon Splashes Down in Pacific Ocean

SpaceX - CRS-10 Dragon Mission patch.

March 20, 2017

SpaceX’s Dragon cargo craft splashed down in the Pacific Ocean at 10:46 a.m. EDT, about 200 miles southwest of Long Beach, California, marking the end of the company’s tenth contracted cargo resupply mission to the International Space Station for NASA.

Expedition 50 astronauts Thomas Pesquet of ESA (European Space Agency) and Shane Kimbrough of NASA released the SpaceX Dragon cargo spacecraft from the International Space Station’s robotic arm right on schedule, at 5:11 a.m.

A variety of technological and biological studies are returning in Dragon. The Microgravity Expanded Stem Cells investigation had crew members observe cell growth and other characteristics in microgravity. This information will provide insight into how human cancers start and spread, which aids in the development of prevention and treatment plans. Results from this investigation could lead to the treatment of disease and injury in space, as well as provide a way to improve stem cell production for human therapy on Earth.

Image above: The SpaceX Dragon is pictured seconds before splashing down in the Pacific Ocean. Image Credit: SpaceX.

Samples from the Tissue Regeneration-Bone Defect study, a U.S. National Laboratory investigation sponsored by the Center for the Advancement of Science in Space (CASIS) and the U.S. Army Medical Research and Materiel Command, studied what prevents vertebrates such as rodents and humans from re-growing lost bone and tissue, and how microgravity conditions affect the process. Results will provide a new understanding of the biological reasons behind a human’s inability to grow a lost limb at the wound site, and could lead to new treatment options for the more than 30 percent of the patient population who do not respond to current options for chronic non-healing wounds.

The Dragon spacecraft launched Feb. 19 on a SpaceX Falcon 9 rocket from historic Launch Complex 39A at NASA’s Kennedy Space Center in Florida, and arrived at the station Feb. 23.

Related links:

Center for the Advancement of Science in Space (CASIS): http://www.iss-casis.org/

Microgravity Expanded Stem Cells: https://www.nasa.gov/mission_pages/station/research/experiments/1971.html

Tissue Regeneration-Bone Defect: https://www.nasa.gov/mission_pages/station/research/experiments/2025.html

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS):  https://www.nasa.gov/mission_pages/station/main/index.html

Image (mentioned), Text, Credits: NASA/Mark Garcia.

Best regards, Orbiter.ch

SpaceX Dragon Spacecraft Departs Space Station

SpaceX - CRS-10 Dragon Mission patch.

March 19, 2017

Image above: The SpaceX Dragon spacecraft was released from space station at 5:11 a.m. ET on March 19 after delivering more than 5,500 pounds of cargo. Image Credit: NASA TV.

Expedition 50 astronauts Thomas Pesquet of ESA (European Space Agency) and Shane Kimbrough of NASA released the SpaceX Dragon cargo spacecraft from the International Space Station‘s robotic arm at 5:11 a.m. EDT.

U.S. Commercial Cargo Ship Departs the International Space Station

With the spacecraft a safe distance from the station, SpaceX flight controllers in Hawthorne, California, will command its deorbit burn around 10 a.m. The capsule will splash down at about 10:54 a.m. in the Pacific Ocean, where recovery forces will retrieve the capsule and its more than 5,400 pounds of cargo. The cargo includes science samples from human and animal research, external payloads, biology and biotechnology studies, physical science investigations and education activities.

The deorbit burn and splashdown will not be broadcast on NASA TV.

Image above: Image above: The SpaceX Dragon spacecraft released (Archive image). Image Credit: NASA.

NASA and the Center for the Advancement of Science in Space (CASIS), the non-profit organization that manages research aboard the U.S. national laboratory portion of the space station, will receive time-sensitive samples and begin working with researchers to process and distribute them within 48 hours of splashdown.

Dragon, the only space station resupply spacecraft able to return to Earth intact, launched Feb. 19 on a SpaceX Falcon 9 rocket from historic Launch Complex 39A at NASA’s Kennedy Space Center in Florida, and arrived at the station Feb. 23 for the company’s 10th NASA-contracted commercial resupply mission.

Related links:

Center for the Advancement of Science in Space (CASIS): http://www.iss-casis.org/

NASA TV: https://www.nasa.gov/multimedia/nasatv/index.html

SpaceX: https://www.nasa.gov/spacex

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Images (mentioned), Video (NASA TV), Text, Credits: NASA/Hayley Fick.

Best regards, Orbiter.ch