Meteor crater discovered hidden by polar ice

Animated GIF: Credit: NASA's Goddard Space Flight Center/Cindy Starr

Two views of the Hiawatha crater region: one covered by the Greenland Ice Sheet, and the second showing the topography of the rock beneath the ice sheet, including the crater. Credit: NASA’s Goddard Space Flight Center/Cindy Starr

An international team of researchers that includes a NASA glaciologist has discovered a 19-mile-wide meteorite impact crater hiding beneath more than half a mile of ice in northwest Greenland. This is the first impact crater of any size ever found under the polar ice sheets.

The group, led by researchers from the Centre for GeoGenetics at the Natural History Museum of Denmark, University of Copenhagen, worked for the past three years to verify their discovery, which was initially made in 2015 using NASA data. The researchers first spotted the crater in July 2015, while they were inspecting a new map of the topography beneath Greenland’s ice sheet that used ice-penetrating radar data primarily from NASA’s Operation IceBridge — a multi-year airborne mission to track changes in polar ice — and earlier NASA airborne missions in Greenland. The scientists noticed an enormous, previously unexamined circular depression under Hiawatha Glacier, sitting at the very edge of the ice sheet in northwestern Greenland.

Their finding is described in a study published on Nov. 14 in the journal Science Advances. The crater is roughly 1,000 feet deep and more than 19 miles in diameter, encompassing an area slightly larger than that comprised inside the Capital Beltway around Washington, D.C. Its dimensions place it among the 25 largest impact craters on Earth.

The crater formed when an iron meteorite more than half a mile wide smashed into northwest Greenland – but the timing of when the event happened remains a key question and one the researchers want to answer next. The authors put the range between less than three million years ago and as recently as less than 13,000 years ago. The resulting depression has since been covered by ice.

A narrated video outlines the discovery and includes data visualizations which can be found here: https://svs.gsfc.nasa.gov/4572

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November 12: Final membership meeting of 2018

Artist's Concept: Kepler-186f was the first rocky planet to be found within the habitable zone -- the region around the host star where the temperature is right for liquid water. This planet is also very close in size to Earth. Even though we may not find out what's going on at the surface of this planet anytime soon, it's a strong reminder of why new technologies are being developed that will enable scientists to get a closer look at distant worlds.

Artist’s Concept: Kepler-186f was the first rocky planet to be found within the habitable zone — the region around the host star where the temperature is right for liquid water.
Credits: NASA Ames/SETI Institute/JPL-Caltech

The Monday, November 12 meeting of the Cuyahoga Astronomical Association (CAA), at Rocky River Nature Center, will be the last for the year and will feature the election of officers and at-large board members for the next two-year term. Annual dues will also be due at that time.

The evening’s program, which is open to the public, is titled, “Discovering New Worlds”
presented by CAA member Lydia Bindal. Ms. Bindal will take us on a metaphorical expedition to explore exoplanets: planets which aren’t a part of our solar system! How do we detect them? What have we found so far? What are their properties? What can they tell us about our own solar system? And could they possess life?

The CAA’s monthly meetings are held on the second Monday of every month (except December) at 7:30 PM at the Rocky River Nature Center; 24000 Valley Parkway; North Olmsted, Ohio, in the Cleveland Metroparks.

Following the presentation and a brief social break, the club will conduct its membership business meeting.

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Hubble Space Telescope is not doomed; gyroscope issues being addressed

The Hubble Space Telescope (HST) photographed by astronauts on a servicing mission in 1997. Credit: NASA/ESA

The Hubble Space Telescope (HST) photographed by astronauts on a servicing mission in 1997. Credit: NASA/ESA

You may have heard that the Hubble Space Telescope recently had some issues that were resolved by a good old fashioned “reboot.” No, that’s not what happened.

Over the last week, NASA has made great strides towards solving the problem with a backup gyroscope on the NASA/ESA Hubble Space Telescope. The backup gyroscope was turned on after the spacecraft entered safe mode following a gyroscope failure on Friday, 5 October. However, when it was turned on the backup gyroscope incorrectly returned  extremely high rotation rates. These high rotation rates have since reduced and are now within the expected range. Additional tests will be performed to ensure Hubble can return to science operations using this gyroscope.

A wheel inside the gyroscope spins at a constant rate of 19,200 revolutions per minute. This wheel is mounted in a sealed cylinder, called a float, which is suspended in a thick fluid. Electricity is carried to the motor by thin wires, approximately the size of a human hair, that are immersed in the fluid. Electronics within the gyroscope detect very small movements of the axis of the wheel and communicate this information to Hubble’s central computer. The gyroscopes have two modes — high and low. High mode is a coarse mode used to measure large rotation rates when the spacecraft turns across the sky from one target to the next. Low mode is a precision mode used to measure finer rotations when the spacecraft locks onto a target and needs to stay very still.

On 18 October, the Hubble operations team commanded a series of turns in opposite directions in an attempt to clear any blockage that may have caused the float to be off-center and produce the exceedingly high rotation rates. During each turn the gyroscope was switched from high mode to low mode to dislodge any blockage that may have accumulated around the float.

Following these maneuvers, the team noticed a significant reduction in the high rotation rates, allowing the rates to be measured in low mode for brief periods of time. On 19 October, the operations team commanded Hubble to perform additional maneuvers and gyroscope mode switches, which appear to have cleared the issue. Gyroscope rates now appear to be normal in both high and low mode. Hubble then executed additional maneuvers to make sure that the gyroscope remained stable within operational limits as the spacecraft moved. The team saw no problems and continued to observe the gyroscopes through the weekend to ensure that it remained stable.

The Hubble operations team plans to execute a further series of tests to evaluate the performance of the gyroscopes under conditions similar to those encountered during routine science observations, including moving to targets, locking on to a target, and performing precision pointing. After these engineering tests have been completed, Hubble is expected to return to normal science operations.

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October 8: Monthly Membership Meeting

The October meeting of the Cuyahoga Astronomical Association (CAA) will take place Monday, October 8. Speaker for the evening will be CAA member and club secretary Trevor Braun on the topic, “Astronomical Tools.” There have been a variety of important astronomical tools dating from antiquity to the present. Trevor will give us an overview of the history of astronomical tools, show us how they have been and are being used, their impact on our knowledge of the Universe and ourselves, and best of all, how to make some of your own!

The CAA’s monthly meetings are held on the second Monday of every month (except December) at 7:30 PM at the Rocky River Nature Center; 24000 Valley Parkway; North Olmsted, Ohio, in the Cleveland Metroparks.

Following the presentation and a brief social break, the club will conduct its membership business meeting.

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Cassini: A parcel of papers published

The Cassini spacecraft ended its mission on Sept. 15, 2017. Image Credit: NASA/JPL-Caltech/Space Science Institute

This natural-color view is a composite of images taken in visible light with the Cassini spacecraft’s narrow-angle camera at a distance of approximately 1.4 million miles (2.3 million kilometers) from Saturn. The Cassini spacecraft ended its mission on Sept. 15, 2017. Image Credit: NASA/JPL-Caltech/Space Science Institute

October 4, 2018 — New research emerging from the final orbits of NASA’s Cassini spacecraft represents a huge leap forward in our understanding of the Saturn system — especially the mysterious, never-before-explored region between the planet and its rings. Some preconceived ideas are turning out to be wrong while new questions are being raised.

Six teams of researchers are publishing their work Oct. 5 in the journal Science, based on findings from Cassini’s Grand Finale. That’s when, as the spacecraft was running out of fuel, the mission team steered Cassini spectacularly close to Saturn in 22 orbits before deliberately vaporizing it in a final plunge into the atmosphere in September 2017.

Knowing Cassini’s days were numbered, its mission team went for gold. The spacecraft flew where it was never designed to fly. For the first time, it probed Saturn’s magnetized environment, flew through icy, rocky ring particles and sniffed the atmosphere in the 1,200-mile-wide (2,000-kilometer-wide) gap between the rings and the cloud tops. Not only did the flight path push the spacecraft to its limits, the new findings illustrate how powerful and agile the instruments were.

Many more Grand Finale science results are to come, but here are some of today’s highlights:

  • Complex organic compounds embedded in water nanograins rain down from Saturn’s rings into its upper atmosphere. Scientists saw water and silicates, but they were surprised to see also methane, ammonia, carbon monoxide, nitrogen and carbon dioxide. The composition of the organics is different from that found on moon Enceladus — and also different from that on moon Titan, meaning there are at least three distinct reservoirs of organic molecules in the Saturn system.
  • For the first time, Cassini saw up close how rings interact with the planet and observed inner-ring particles and gases falling directly into the atmosphere. Some particles take on electric charges and spiral along magnetic-field lines, falling into Saturn at higher latitudes — a phenomenon known as “ring rain.” But scientists were surprised to see that others are dragged quickly into Saturn at the equator. And it’s all falling out of the rings faster than scientists thought — as much as 22,000 pounds (10,000 kilograms) of material per second.
  • Scientists were surprised to see what the material looks like in the gap between the rings and Saturn’s atmosphere. They knew that the particles throughout the rings ranged from large to small. But the sampling in the gap showed mostly tiny, nanometer-sized particles, like smoke, suggesting that some yet-unknown process is grinding up particles.
  • Saturn and its rings are even more interconnected than scientists thought. Cassini revealed a previously unknown electric-current system that connects the rings to the top of Saturn’s atmosphere.
  • Scientists discovered a new radiation belt around Saturn, close to the planet and composed of energetic particles. They found that while the belt actually intersects with the innermost ring, the ring is so tenuous that it doesn’t block the belt from forming.
  • Unlike every other planet with a magnetic field in our Solar System, Saturn’s magnetic field is almost completely aligned with its spin axis. The new data shows a magnetic-field tilt of less than 0.0095 degrees. (Earth’s magnetic field is tilted 11 degrees from its spin axis.) According to everything scientists know about how planetary magnetic fields are generated, Saturn should not have one. It’s a mystery that physicists will be working to solve.
  • Cassini flew above Saturn’s magnetic poles, directly sampling regions where radio emissions are generated. The findings more than doubled the number of direct measurements of radio sources from the planet, one of the few non-terrestrial locations where scientists have been able to study a radio-generation mechanism that is believed to operate throughout the universe.

For the Cassini mission, the science rolling out from Grand Finale orbits more than justifies the calculated risk of diving into the gap — skimming the upper atmosphere and skirting the edge of the inner rings, said Cassini Project Scientist Linda Spilker.

“Almost everything going on in that region turned out to be a surprise,” Spilker said. “That was the importance of going there, to explore a place we’d never been before. And the expedition really paid off — the data is tremendously exciting.”

Analysis of Cassini data from the spacecraft’s instruments will be ongoing for years to come, helping to paint a clearer picture of Saturn.

“Many mysteries remain, as we put together pieces of the puzzle,” Spilker said. “Results from Cassini’s final orbits turned out to be more interesting than we could have imagined.”

The papers published in Science are:

On Oct. 4, as the Science publication embargo lifts, articles describing research complementary to these findings will post online in Geophysical Research Letters (GRL), a journal of the American Geophysical Union (AGU).

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September 10 Meeting: Dancing on the Moon*

Image: Solar cells power a moon base and the surface mining operations. (Artist's concept by Pat Rawlings of SAIC for NASA/Lewis)

Solar cells power a moon base and the surface mining operations. (Artist’s concept by Pat Rawlings of SAIC for NASA/Lewis)

The September meeting of the Cuyahoga Astronomical Association (CAA) will take place Monday, September 10. Speaker for the evening will be NASA Engineer Bryan Palaszewski who will bring us close to home (astronomically) and discuss plans and ideas for humans to “live off the land”, establishing a permanent base on the surface of our nearest neighbor, the Moon!

The CAA’s monthly meetings are held on the second Monday of every month (except December) at 7:30 PM at the Rocky River Nature Center; 24000 Valley Parkway; North Olmsted, Ohio, in the Cleveland Metroparks.

Following the presentation and a brief social break, the club will conduct its membership business meeting.

* Okay, “Living on the Moon,” but we couldn’t resist a reference to an ancient Max Fleischer cartoon.

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Saving the Dark

Photo: An awe-inspiring night sky! The night sky could look like this in Northeastern Ohio if we would simply control our lighting. Image Credit: "Saving the Dark"

The night sky could look like this anywhere in Ohio if we would simply control our lighting. Image Credit: “Saving the Dark”

What do we lose when we lose sight of the stars? Excessive and improper lighting robs us of our night skies, disrupts our sleep patterns, and endangers nocturnal habitats. Saving the Dark explores the need to preserve or restore night skies and what we can all do to combat light pollution. This film will be shown October 5 & 6 at the Chagrin Documentary Film Festival

Click here for more information and to view the film’s trailer.

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