Rocketing Into the Northern Lights

February 9, 2013

Auroras are a visible reminder of our planet’s connection to space. The “northern lights” and “southern lights,” as they are more commonly known, are like a rain of highly energized particles from the space around Earth. Provoked by storms and winds from the Sun, electrons trapped inside Earth’s magnetic field (magnetosphere) accelerate down toward the upper atmosphere (ionosphere), where they smash into oxygen and nitrogen molecules and release photons of green, red, and blue light. The light shows can take the shape of waving curtains or rays or diffuse clouds.

At the same time that particles are raining down from space, others are leaving. The “auroral wind” is a strong but intermittent stream of oxygen atoms that flow from the atmosphere into outer space during northern lights shows. Scientists from NASA’s Goddard Space Flight Center and The Aerospace Corporation, together with the support team from the University of Alaska’s Geophysical Institute, launched a rocket from the Poker Flat Research Range to study this little-understood emission from the atmosphere. The NASA-sponsored VISIONS campaign—VISualizing Ion Outflow via Neutral atom imaging during a Substorm—was designed to fly instruments into the aurora for a fifteen-minute close-up examination.

The photo above was taken by Sebastian Saarloos, an amateur photographer who was watching the launch from Delta Junction, Alaska, about 120 miles (195 kilometers) southeast from Poker Flat. He captured the image of the rocket streaking into the aurora at 11:21 p.m. local time on February 6, 2013.

Most of the atmosphere is bound by Earth’s gravity, but a small portion gets heated enough by the aurora that it can break free and flow outwards into near-Earth space. The atoms that form this wind initially travel at just 300 miles per hour—only one percent of the speed needed to overcome gravity and leave Earth's atmosphere.

“This oxygen would normally never gain enough energy to leave the atmosphere,” said Doug Rowland, principal investigator for VISIONS and a member of NASA’s Space Weather Laboratory. “On the other hand, at very high altitudes, satellite experiments have measured oxygen atoms moving faster than 50 miles per second. These experiments have shown that if oxygen can reach these high altitudes, there are plenty of ways for it to gain even more energy and escape near-Earth space entirely. What we don’t know is how the oxygen gets enough energy to fight against gravity and reach the higher altitudes where these slingshots are active.”

You can observe a short video of the launch by clicking here.

·      Related Reading

·      Carlowicz, M.J. and Hill, S. (2002) NASA Poster: Aurora—Fabled Glowing Lights of the Sun-Earth Connection. (PDF) Accessed February 8, 2013.

·      Geophysical Institute, University of Alaska–Fairbanks (2013, February 7) Successful Launch From Poker Flat Research Range. Accessed February 8, 2013.

·      NASA (2013, January 31) VISIONS: Seeing the Aurora in a New Light. Accessed February 8, 2013.

·      NASA (2013, February 7) VISIONS: A Successful Launch. Accessed February 8, 2013.

Photograph copyright Sebastian Saarloos. Caption by Mike Carlowicz, Earth Observatory, and Claire De Saravia, NASA-GSFC, with reporting from Amy Hartley, University of Alaska Geophysical Institute.

Instrument: 

Photograph

Saving Siding Spring Observatory

February 7, 2013

On the afternoon of January 14, 2013, a fierce bushfire swept across the campus of Siding Spring Observatory, a world-class astronomy facility on a ridge in Australia’s Warrumbungle National Park. The observatory is home to some of the most powerful sky-mapping telescopes in the world.

Ten years earlier, a brush fire devastated one of Australia’s other top observatories, so the staff of Siding Spring feared that history was repeating itself. As the fire reached the observatory’s campus, cameras and telescopes sent back disturbing images of flames lapping at the doorsteps of buildings and smoke billowing overhead.

By nightfall on January 14, the situation looked dire to the scientists and staff who had evacuated and were left to monitor the situation online. A handful of buildings on the campus were on fire. At one point, a thermometer on campus recorded a spike in air temperatures to 100 degrees Celsius (212 degrees Fahrenheit).

The next day, however, brought relief. The fire subsided, and only three buildings at Siding Spring—including theresidence of a Siding Spring astronomer—were destroyed. Aside from minor smoke damage, the major telescopes were fine.

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite offers a unique perspective on how close the observatory came to destruction. The satellite acquired these false-color views of the burn scar on February 4, 2013, three weeks after the fire. The images combine measurements from both the visible and the infrared portions of the electromagnetic spectrum; unburned forest vegetation appears dark red, unburned grasslands are pink, and burned vegetation is brown. The observatory’s buildings and telescope domes are white. The fire burned a large swath of Warrumbungle National Park severely—except for a small patch of unburned forest around and just north of the observatory.

Years of preparation, combined with the heroic efforts of 30 firefighters, explain why only that small patch of forest survived. A decade earlier, after fire devastated Mount Stromlo Observatory, Siding Spring took steps to strengthen its defenses against bushfire. Mesh nets were installed over many of the observatory’s structures to repel flying embers. And controlled fires were occasionally set around the observatory grounds to rid the forests of underbrush.

Amanda Bauer, an Australian Astronomical Observatory fellow who wrote about the fire and its aftermath on a blog (Astropixie) summed up the sentiments of the staff: “[I was] overjoyed that the measures taken to save Siding Spring Observatory against the fire (when combined with a bit of luck) were enough in this case!”

·      References

·      Astropixie (2013, Jan. 13 - Feb. 1) Siding Spring Observatory Fire. Accessed Feb. 5, 2013.

·      Australian Geographic (2013, Jan. 16) Bushfire hits Australia’s largest observatory. Accessed Feb. 5, 2013.

·      Gizmodo (2013, Jan. 17) How The Fire Fight For Australia’s Greatest Observatory Was Won. Accessed Feb. 5, 2013.

·      Physics World (2013, Jan. 16) Fires Ravage Siding Spring Observatory. Accessed Feb. 5, 2013.

·      Sky & Telescope (2013, Jan. 13) Fire Damages Siding Spring Observatory. Accessed Feb. 5, 2013.

·      Sydney Morning Herald (2013, Jan. 14) ‘It looked like an atom bomb’: telescope saved but ‘dangerous’ bushfire destroys homes. Accessed Feb. 5, 2013.

NASA Earth Observatory image by Jesse Allen, using data from NASA/GSFC/METI/ERSDAC/JAROS, and U.S./JapanASTER Science Team. Caption by Adam Voiland.

Instrument: 

Terra - ASTER

A Satellite’s View of Ship Pollution

February 8, 2013

For more than a decade, scientists have observed “ship tracks” in natural-color satellite imagery of the ocean. These bright, linear trails amidst the cloud layers are created by particles and gases from ships. They are a visible manifestation of pollution from ship exhaust, and scientists can now see that ships have a more subtle, almost invisible, signature as well.

Data from the Dutch and Finnish-built Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite show long tracks of elevated nitrogen dioxide (NO₂) levels along certain shipping routes. NO₂, is among a group of highly-reactiveoxides of nitrogen, known as NO_x, that can lead to the production of fine particles and ozone that damage the human cardiovascular and respiratory systems. Combustion engines, such as those that propel ships and motor vehicles, are a major source of NO₂ pollution.

The map above is based on OMI measurements acquired between 2005 and 2012. The NO₂ signal is most prominent in an Indian Ocean shipping lane between Sri Lanka and Singapore, appearing as a distinct orange line against (lighter) background levels of NO₂. Other shipping lanes that run through the Gulf of Aden, the Red Sea, and the Mediterranean Sea also show elevated NO₂ levels, as do routes from Singapore to points in China. These aren’t the only busy shipping lanes in the world, but they are the most apparent because ship traffic is concentrated along narrow, well-established lanes.

The Atlantic and Pacific Oceans also have heavy ship traffic, but OMI doesn’t pick up NO₂ pollution tracks because the shipping routes are less consistent. The shapes of landmasses force ships into narrow paths in the Indian Ocean, while ships in the Atlantic and Pacific tend to spread out over a broad areas as they navigate around storms.

In addition, the air over the northeastern Indian Ocean is relatively pristine. Heavy NO₂ pollution (dark red in the map) from cities and off-shore drilling activity along the coasts of China, Europe, and the United States obscures the ship tracks that might otherwise be visible to OMI. In the map, the Arctic is gray because the lack of light during the winter and frequent cloudiness during the summer prevented OMI from collecting usable data in the area.

Urban areas and industrialization aren’t the only source of NO₂ in the map. Agricultural burning in southern Africa and persistent westerly winds make an elevated band of NO₂ that stretches from southern Africa to Australia. (In central Africa, easterly winds push pollutants from fires toward the Atlantic, keeping NO₂ levels comparatively low over the northern Indian Ocean.) Lightning, which produces NO_x, also contributes to background NO₂ levels.

Just how much shipping contributes to overall NO_x emissions remains an open question for scientists. Research suggests that shipping accounts for 15 to 30 percent of global NO_x emissions; scientists are using satellite observations to reduce the uncertainty in such estimates.

OMI is not the only satellite instrument observing NO₂ levels in the atmosphere. The Global Ozone Monitoring Experiment (GOME) instruments on the European Space Agency’s ERS-2 and MetOp-A satellites, as well as theSCIAMACHY instrument on the Envisat satellite, have made similar measurements. In 2012, Dutch scientists publisheda study combining data from all four instruments to show that the NO₂ signal over major shipping increased steadily between 2003 and 2008, then dropped sharply due to the global recession and reduction in ship traffic.

·      References

·      deRuyter de Wildt, M., H. Eskes, and K. F. Boersma (2012, Jan. 5) The global economic cycle and satellite-derived NO₂trends over shipping lanes. Geophysical Research Letters.

·      Franke, K., Richter, A., Bovensmann, H., Eyring, V., Jöckel, P., Hoor, P., and Burrows, J. P. (2009) Ship emitted NO₂ in the Indian Ocean: comparison of model results with satellite data. Atmospheric Chemistry and Physics.

·      Vinken, G., Boersma F. (2011) From ship smokestack to global air pollution: bridging the scales to better constrain ship NO_x emissions from space. (PDF) Solas News.

·      Vinken, G., Boersma, F., Jacob, J., and Meijer, W. (2011) Accounting for non-linear chemistry of ship plumes in the GEOS-Chem global chemistry transport model. Atmospheric Chemistry and Physics.

·      Wang, C., Corbett, J., Firestone, J. (2008) Improving Spatial Representation of Global Ship Emissions Inventories.Environmental Science Technology.

NASA Earth Observatory image by Jesse Allen, using OMI NO2 data provided courtesy of Lok Lamsal, Aura Project Science Office. Caption by Adam Voiland, with information from Nickolay Krotkov, Anne Thompson, Geert Vinken, and Folkert Boersma.

Instrument: 

Aura – OMI

Moving Rock at Puyehue-Cordón Caulle

Obsidian—sharp-edged, translucent, and lustrous—is one of the most distinctive volcanic rocks. Its unique glassy properties result from a disordered structure: the atoms are irregular, like a liquid. Whereas crystalline materials like ice, diamonds, or granite have atoms arranged in repeating patterns, obsidian and other types of glass retain an irregular pattern because the atoms are frozen in place as the material solidifies. This can happen if a liquid is cooled very quickly (quenched in water, for example), or if it is so thick that the atoms have trouble moving through the fluid. Therefore extremely viscous, slow-moving lavas sometimes harden into obsidian.

From June 2011 until April 2012, Puyehue Cordón Caulle, a Chilean volcano, erupted a massive obsidian lava flow. The flow covered roughly 16 square kilometers (6.2 square miles) of land in lava about 30 meters (100 feet) thick. This natural-color satellite image shows the flow on January 13, 2013. It was collected by the Advanced Land Imager (ALI) on Earth Observing-1 (EO-1). The dark gray lava stands out against the light gray ash and lava bombs that cover surrounding areas.

A team of geologists visiting Puyehue in January 2013 discovered that the lava was still in motion even though the eruption had stopped. Unlike a crystalline rock, obsidian is not completely rigid: it can flow, even when solid. The higher the temperature, the faster a glass will deform, especially near its melting point. Volcanologist Hugh Tuffen describedhis experience approaching the flow: “The sound of advancing obsidian lava is quite fascinating and unlike anything I have ever heard—a succession of platey fracturing sounds, as if a bowl of rice crispies were made up of thousands of fragile plates that each broke, rather than the usual snap, crackle and pop.” The hot interior of the lava flow, insulated by a shell of solidified rock, allowed it to continue to ooze downhill.

More than 200 years after the science of geology was born, the Earth is still full of surprises.

1.  References

2.   Miller, Jim. (n.d.) Obsidian is Hot Stuff. Accessed February 1, 2013.

3.   Tuffen, Hugh. (2013, January) Cordón Caulle. Accessed February 1, 2013.

·         Further Reading

·         Puyehue Cordón Caulle, Eruptions Blog

·         Puyehue volcano in Chile erupts, BBC video