Voyager 2 enters interstellar space

Image: This illustration shows the position of NASA’s Voyager 1 and Voyager 2 probes, outside of the heliosphere, a protective bubble created by the Sun that extends well past the orbit of Pluto. Credits: NASA/JPL-Caltech
This illustration shows the position of NASA’s Voyager 1 and Voyager 2 probes, outside of the heliosphere, a protective bubble created by the Sun that extends well past the orbit of Pluto. Credits: NASA/JPL-Caltech

For the second time in history, a human-made object has reached the space between the stars. NASA’s Voyager 2 probe now has exited the heliosphere – the protective bubble of particles and magnetic fields created by the Sun.

Comparing data from different instruments aboard the trailblazing spacecraft, mission scientists determined the probe crossed the outer edge of the heliosphere on Nov. 5. This boundary, called the heliopause, is where the tenuous, hot solar wind meets the cold, dense interstellar medium. Its twin, Voyager 1, crossed this boundary in 2012, but Voyager 2 carries a working instrument that will provide first-of-its-kind observations of the nature of this gateway into interstellar space.

Voyager 2 now is slightly more than 11 billion miles (18 billion kilometers) from Earth. Mission operators still can communicate with Voyager 2 as it enters this new phase of its journey, but information – moving at the speed of light – takes about 16.5 hours to travel from the spacecraft to Earth. By comparison, light traveling from the Sun takes about eight minutes to reach Earth.

The most compelling evidence of Voyager 2’s exit from the heliosphere came from its onboard Plasma Science Experiment (PLS), an instrument that stopped working on Voyager 1 in 1980, long before that probe crossed the heliopause. Until recently, the space surrounding Voyager 2 was filled predominantly with plasma flowing out from our Sun. This outflow, called the solar wind, creates a bubble – the heliosphere – that envelopes the planets in our solar system. The PLS uses the electrical current of the plasma to detect the speed, density, temperature, pressure and flux of the solar wind. The PLS aboard Voyager 2 observed a steep decline in the speed of the solar wind particles on Nov. 5. Since that date, the plasma instrument has observed no solar wind flow in the environment around Voyager 2, which makes mission scientists confident the probe has left the heliosphere.

“Working on Voyager makes me feel like an explorer, because everything we’re seeing is new,” said John Richardson, principal investigator for the PLS instrument and a principal research scientist at the Massachusetts Institute of Technology in Cambridge. “Even though Voyager 1 crossed the heliopause in 2012, it did so at a different place and a different time, and without the PLS data. So we’re still seeing things that no one has seen before.”

In addition to the plasma data, Voyager’s science team members have seen evidence from three other onboard instruments – the cosmic ray subsystem, the low energy charged particle instrument and the magnetometer – that is consistent with the conclusion that Voyager 2 has crossed the heliopause. Voyager’s team members are eager to continue to study the data from these other onboard instruments to get a clearer picture of the environment through which Voyager 2 is traveling.

“There is still a lot to learn about the region of interstellar space immediately beyond the heliopause,” said Ed Stone, Voyager project scientist based at Caltech in Pasadena, California.

“Voyager has a very special place for us in our heliophysics fleet,” said Nicola Fox, director of the Heliophysics Division at NASA Headquarters. “Our studies start at the Sun and extend out to everything the solar wind touches. To have the Voyagers sending back information about the edge of the Sun’s influence gives us an unprecedented glimpse of truly uncharted territory.”

While the probes have left the heliosphere, Voyager 1 and Voyager 2 have not yet left the solar system, and won’t be leaving anytime soon. The boundary of the solar system is considered to be beyond the outer edge of the Oort Cloud, a collection of small objects that are still under the influence of the Sun’s gravity. The width of the Oort Cloud is not known precisely, but it is estimated to begin at about 1,000 astronomical units (AU) from the Sun and to extend to about 100,000 AU. One AU is the distance from the Sun to Earth. It will take about 300 years for Voyager 2 to reach the inner edge of the Oort Cloud and possibly 30,000 years to fly beyond it.

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

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).

At Monday, August 13 meeting: Crewed American space missions: 2018

The program for the August 13 General Membership Meeting will cover American Crewed Space Missions: 2018. The talk will be delivered by Tom Benson, a retired NASA aerospace engineer.

SpaceX Falcon 9 - Credit: SpaceX

On July 8, 2011, the final Space Shuttle mission was launched from Cape Canaveral.

For the last six years, the United States has paid the Russian Space Agency to deliver crew members to the International Space Station (ISS). That process is about to end as Americans will once again ride on American spacecraft launched from U.S. soil!

The Commercial Crew Program of NASA has contracted with SpaceX and Boeing to each develop a spacecraft which can deliver and return astronauts to the ISS. The first flights are scheduled for this year. Tom Benson, retired from NASA Glenn Research Center, will report on these missions and share with us any breaking news from the “high frontier!”

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.

Illustration: Falcon 9 booster with Dragon crewed spacecraft. Credit: SpaceX

Ancient organic material, mysterious methane on Mars

This low-angle self-portrait of NASA's Curiosity Mars rover shows the vehicle at the site from which it reached down to drill into a rock target called "Buckskin" on lower Mount Sharp. Image Credit: NASA/JPL-Caltech/MSSS
This low-angle self-portrait of NASA’s Curiosity Mars rover shows the vehicle at the site from which it reached down to drill into a rock target called “Buckskin” on lower Mount Sharp. Image Credit: NASA/JPL-Caltech/MSSS

From a NASA News Release

NASA’s Curiosity rover has found new evidence preserved in rocks on Mars that suggests the planet could have supported ancient life, as well as new evidence in the Martian atmosphere that relates to the search for current life on the Red Planet. While not necessarily evidence of life itself, these findings are a good sign for future missions exploring the planet’s surface and subsurface.

The new findings – “tough” organic molecules in three-billion-year-old sedimentary rocks near the surface, as well as seasonal variations in the levels of methane in the atmosphere – appear in the June 8 edition of the journal Science.

Organic molecules contain carbon and hydrogen, and also may include oxygen, nitrogen and other elements. While commonly associated with life, organic molecules also can be created by non-biological processes and are not necessarily indicators of life.

“With these new findings, Mars is telling us to stay the course and keep searching for evidence of life,” said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters, in Washington. “I’m confident that our ongoing and planned missions will unlock even more breathtaking discoveries on the Red Planet.”

“Curiosity has not determined the source of the organic molecules,” said Jen Eigenbrode of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who is lead author of one of the two new Science papers. “Whether it holds a record of ancient life, was food for life, or has existed in the absence of life, organic matter in Martian materials holds chemical clues to planetary conditions and processes.”

Although the surface of Mars is inhospitable today, there is clear evidence that in the distant past, the Martian climate allowed liquid water – an essential ingredient for life as we know it – to pool at the surface. Data from Curiosity reveal that billions of years ago, a water lake inside Gale Crater held all the ingredients necessary for life, including chemical building blocks and energy sources.

“The Martian surface is exposed to radiation from space. Both radiation and harsh chemicals break down organic matter,” said Eigenbrode. “Finding ancient organic molecules in the top five centimeters of rock that was deposited when Mars may have been habitable, bodes well for us to learn the story of organic molecules on Mars with future missions that will drill deeper.”

Seasonal Methane Releases

In the second paper, scientists describe the discovery of seasonal variations in methane in the Martian atmosphere over the course of nearly three Mars years, which is almost six Earth years. This variation was detected by Curiosity’s Sample Analysis at Mars (SAM) instrument suite.

Water-rock chemistry might have generated the methane, but scientists cannot rule out the possibility of biological origins. Methane previously had been detected in Mars’ atmosphere in large, unpredictable plumes. This new result shows that low levels of methane within Gale Crater repeatedly peak in warm, summer months and drop in the winter every year.

“This is the first time we’ve seen something repeatable in the methane story, so it offers us a handle in understanding it,” said Chris Webster of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, lead author of the second paper. “This is all possible because of Curiosity’s longevity. The long duration has allowed us to see the patterns in this seasonal ‘breathing.'”

Finding Organic Molecules

To identify organic material in the Martian soil, Curiosity drilled into sedimentary rocks known as mudstone from four areas in Gale Crater. This mudstone gradually formed billions of years ago from silt that accumulated at the bottom of the ancient lake. The rock samples were analyzed by SAM, which uses an oven to heat the samples (in excess of 900 degrees Fahrenheit, or 500 degrees Celsius) to release organic molecules from the powdered rock.

SAM measured small organic molecules that came off the mudstone sample – fragments of larger organic molecules that don’t vaporize easily. Some of these fragments contain sulfur, which could have helped preserve them in the same way sulfur is used to make car tires more durable, according to Eigenbrode.

The results also indicate organic carbon concentrations on the order of 10 parts per million or more. This is close to the amount observed in Martian meteorites and about 100 times greater than prior detections of organic carbon on Mars’ surface. Some of the molecules identified include thiophenes, benzene, toluene, and small carbon chains, such as propane or butene.

In 2013, SAM detected some organic molecules containing chlorine in rocks at the deepest point in the crater. This new discovery builds on the inventory of molecules detected in the ancient lake sediments on Mars and helps explains why they were preserved.

Finding methane in the atmosphere and ancient carbon preserved on the surface gives scientists confidence that NASA’s Mars 2020 rover and ESA’s (European Space Agency’s) ExoMars rover will find even more organics, both on the surface and in the shallow subsurface.

These results also inform scientists’ decisions as they work to find answers to questions concerning the possibility of life on Mars.

“Are there signs of life on Mars?” said Michael Meyer, lead scientist for NASA’s Mars Exploration Program, at NASA Headquarters. “We don’t know, but these results tell us we are on the right track.”

This work was funded by NASA’s Mars Exploration Program for the agency’s Science Mission Directorate (SMD) in Washington. Goddard provided the SAM instrument. JPL built the rover and manages the project for SMD.

Want to see Wednesday’s total lunar eclipse? TV or online are best bet!

Photo: Umbral Shadow Crossing Moon by James Guilford
Umbral Shadow Crossing Moon by James Guilford

A total lunar eclipse will take place in the pre-dawn hours of January 31 but interested viewers in Northeastern Ohio are not well-favored! Weather conditions predicted for Wednesday morning are poor (mostly cloudy, at best) and the timing of the eclipse event itself works against us; at best we would see only a portion of the partial phase before our Moon sets!

Our best bet for watching this total lunar eclipse will be to view it on television or via streaming video. NASA Television and the agency’s website will provide live coverage of the celestial spectacle beginning at 5:30 a.m. EST. Weather permitting, the broadcast will feature views from the varying vantage points of telescopes at NASA’s Armstrong Flight Research Center in Edwards, California; Griffith Observatory in Los Angeles; and the University of Arizona’s Mt. Lemmon SkyCenter Observatory. You can access the live NASA broadcast via some cable television services, or online through NASA’s Moon webpages.

If skies do clear enough to see the Moon from our area, here’s a timetable for significant points in the upcoming eclipse as viewed from the city of Oberlin — the timing would be off only by a few seconds viewed from other areas of Northeastern Ohio.

Timetable of January 31, 2018 Total Lunar Eclipse. Credit: TimeAndDate.com
Timetable of January 31, 2018 Total Lunar Eclipse. Credit: TimeAndDate.com

This eclipse event is getting special attention because it offers the rare coincidence of three lunar events: A “supermoon,” a “blue moon” and a total lunar eclipse at the same time. A “supermoon” occurs when the Moon is closest to Earth in its orbit (at or near perigee) and appears about 14 percent brighter than usual. As the second Full Moon of the month, this Moon is also commonly called a Blue Moon, though it will not be blue in appearance. The “Super Blue Moon” will pass through Earth’s shadow and take on a reddish copper to deep-red tint. The eerie colors of totality seen during lunar eclipses frightened the ancients but delight us!

The last total lunar eclipse occurred Sept. 27-28, 2015. The next total lunar eclipse visible across North America will occur January 21, 2019.

The January 31 eclipse is the third in a series of supermoons in December 2017 and January 2018. Watch the Supermoon Trilogy video.

November 13: Monthly Membership Meeting

Artist's Concept: Nuclear Rocket at Mars. Credit: NASA
Artist’s Concept: Nuclear Rocket at Mars. Credit: NASA

The Cuyahoga Astronomical Association (CAA) will host its monthly meeting at 7:30 PM, Monday, November 13 in the Cleveland Metroparks’ Rocky River Nature Center, North Olmsted. Our speaker, Dr. Stanley Borowski, a Senior Engineer at NASA’s Glenn Research Center, Cleveland, will discuss the use of nuclear rocket engines in space exploration. The program is free and open to the public, no reservations required.

Following the program, the club’s monthly membership meeting will convene.