Sep 23 2015

From The Space Library

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Revision as of 08:26, 25 September 2015

NASA Scientists Use Jet to Measure Air Quality Data From California Wildfires

On Aug. 19, 2015, a team of scientists from NASA’s Ames Research Center organized the flight of an Alpha Jet to collect environmental data from two recent wildfires in California’s Southern Sierra Nevada mountain range.

As part of the ongoing Alpha Jet Atmospheric eXperiment (AJAX) project, pilots of H211, LLC, a NASA partner, flew through plumes of smoke from the “Cabin Fire” and “Rough Fire” in Sequoia National Forest, California, measuring ozone and greenhouse gases from the fires to understand their effects on air quality.

“It gives us a more complete picture of wildfires,” said Warren Gore, chief of the Atmospheric Science Branch at Ames, based in Moffett Field, California. “It gives information on what is burned and what pollution is produced. Ozone can cause respiratory distress when people breathe it in, whether they have respiratory problems or not. It could affect their health, and it could have a long term effect.”

The California Department of Forestry and Fire Protection (CAL Fire) believes lightning ignited the “Cabin Fire,” which has consumed approximately 7,000 acres in the Golden Trout Wilderness, north of Glendora, since July 19. The “Rough Fire,” which started on July 31, also a result of lightning, has burned more than 100,000 acres in Kings Canyon, near Hume Lake. Twenty-five hundred people from the Hume Lake Christian Camp and surrounding area were evacuated.

“Smoke from wildfires can be lifted high into the atmosphere and transported long distances. It affects not only local air quality but can also have regional and even global impacts”, said Laura Iraci, AJAX Principal Investigator and research scientist at Ames. “For example, the smoke from these fires is impacting large areas of California and Nevada.”

“We’ve seen more methane for every molecule of carbon dioxide emitted from these particular fires than we’ve seen with previous fires,” said Emma Yates, a research scientist at NASA Ames. “We don’t know what’s causing this. Interactions between urban pollution and forest fires is a big challenge, the difficulty being how to identify how much each source contributes to measured concentrations within a mixed wildfire-urban plume. Some researchers speculate that could be playing a role.”

This flight was the 167th AJAX mission in the past five years, using onboard equipment to make measurements of the atmosphere. Results gathered from the 2013 Rim Fire in Stanislaus National Forest are being prepared for publication. Similarly data from this year's fires will be analyzed and shared with the science community and other stakeholders, like the California Air Resources Board and the San Joaquin Valley Air Pollution Control District. Information provided by AJAX can supplement the decision process of these regulatory agencies.

NASA enables studies that unravel the complexities of our planet from the highest reaches of Earth’s atmosphere to its core. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as weather forecasting and natural resource management. Scientists worldwide use NASA data to tackle some of the biggest questions about how our planet is changing. Earth science research at Ames features basic and applied research in atmospheric and biospheric sciences, and conducts airborne science campaigns.

Milky Way’s Black Hole Shows Signs of Increased Chatter

Three orbiting X-ray space telescopes have detected an increased rate of X-ray flares from the usually quiet giant black hole at the center of our Milky Way galaxy after new long-term monitoring. Scientists are trying to learn whether this is normal behavior that was unnoticed due to limited monitoring, or these flares are triggered by the recent close passage of a mysterious, dusty object.

By combining information from long monitoring campaigns by NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton, with observations by the Swift satellite, astronomers were able to carefully trace the activity of the Milky Way’s supermassive black hole over the last 15 years. The supermassive black hole, a.k.a. Sagittarius A*, weighs in at slightly more than 4 million times the mass of the Sun. X-rays are produced by hot gas flowing toward the black hole.

The new study reveals that Sagittarius A* (Sgr A* for short) has been producing one bright X-ray flare about every ten days. However, within the past year, there has been a ten-fold increase in the rate of bright flares from Sgr A*, at about one every day. This increase happened soon after the close approach to Sgr A* by a mysterious object called G2.

“For several years, we’ve been tracking the X-ray emission from Sgr A*. This includes also the close passage of this dusty object” said Gabriele Ponti of the Max Planck Institute for Extraterrestrial Physics in Germany. “A year or so ago, we thought it had absolutely no effect on Sgr A*, but our new data raise the possibility that that might not be the case."

Originally, astronomers thought G2 was an extended cloud of gas and dust. However, after passing close to Sgr A* in late 2013, its appearance did not change much, apart from being slightly stretched by the gravity of the black hole. This led to new theories that G2 was not simply a gas cloud, but instead a star swathed in an extended dusty cocoon.

“There isn’t universal agreement on what G2 is,” said Mark Morris of the University of California at Los Angeles. “However, the fact that Sgr A* became more active not long after G2 passed by suggests that the matter coming off of G2 might have caused an increase in the black hole’s feeding rate.”

While the timing of G2’s passage with the surge in X-rays from Sgr A* is intriguing astronomers see other black holes that seem to behave like Sgr A*. Therefore, it’s possible this increased chatter from Sgr A* may be a common trait among black holes and unrelated to G2. For example, the increased X-ray activity could be due to a change in the strength of winds from nearby massive stars that are feeding material to the black hole.

“It’s too soon to say for sure, but we will be keeping X-ray eyes on Sgr A* in the coming months,” said co-author Barbara De Marco, also of Max Planck. “Hopefully, new observations will tell us whether G2 is responsible for the changed behavior or if the new flaring is just part of how the black hole behaves.”

The analysis included 150 Chandra and XMM-Newton observations pointed at the center of the Milky Way over the last 15 years, extending from September 1999 to November 2014. An increase in the rate and brightness of bright flares from Sgr A* occurred after mid-2014, several months after the closest approach of G2 to the huge black hole.

If the G2 explanation is correct, the spike in bright X-ray flares would be the first sign of excess material falling onto the black hole because of the cloud’s close passage. Some gas would likely have been stripped off the cloud, and captured by the gravity of Sgr A*. It then could have started interacting with hot material flowing towards the black hole, funneling more gas toward the black hole that could later be consumed by Sgr A*.

A paper on these findings has been accepted by the Monthly Notices of the Royal Astronomical Society. A preprint is available online. NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.