NASA Modis and Aqua images of Smog hazard over China

October 14, 2010

October 8, 2010

In early October 2010, a high-pressure weather system settled in over eastern China, and air pollution began to accumulate locally for nearly a week.

By October 9 and 10, China’s National Environmental Monitoring Center declared air quality “poor” to “hazardous” around Beijing and in 11 eastern provinces.

Citizens were advised to take measures to protect themselves, and visibility was reduced to 100 meters (330 feet) in some areas.

News outlets reported that at least 32 people died in traffic accidents caused by the poor visibility. Untold were the number of people suffering with asthma and other respiratory difficulties.


On October 8, 2010, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua and Terra satellites captured this natural color view of the smog event in China.

The milky white and gray covering the center of the image is smog and fog, while the brighter whites at the left and right edges are clouds.

The Ozone Monitoring Instrument on NASA’s Aura satellite detected extremely high levels of aerosol particles (lower left image) and sulfur dioxide (lower right) on October 8.

The sulfur dioxide typically comes from coal-burning power plants and smelters, and the peak concentrations—6 to 8 Dobson Units—were six to eight times the norm for China and 20 times the norm for the United States.

The Aerosol Index indicates the presence of ultraviolet light-absorbing aerosols, most likely smoke from fires and industrial processes. At an AI value of 4, aerosols are so dense that you would have difficulty seeing the midday sun.

The event was likely caused by a blend of increased emissions—from agricultural burning, factories, and vehicle emissions—and the stagnant weather system.

The relatively calm days did not bring enough wind to blow the pollution away from its sources. By October 11, a cold front brought cleansing rain and winds that cleared up the skies.

Pan-STARRS Discovers Potentially Hazardous Asteroid

The University of Hawaii's Pan-STARRS PS1 telescope on Haleakala has discovered an asteroid that will come within 4 million miles of Earth in mid-October. The object is about 150 feet in diameter and was discovered in images acquired on September 16, when it was about 20 million miles away.

It is the first "potentially hazardous object" (PHO) to be discovered by the Pan-STARRS survey and has been given the designation "2010 ST3."

"Although this particular object won't hit Earth in the immediate future, its discovery shows that Pan-STARRS is now the most sensitive system dedicated to discovering potentially dangerous asteroids," said Dr. Robert Jedicke, a University of Hawaii member of the PS1 Scientific Consortium (PS1SC), who is working on the asteroid data from the telescope.

"This object was discovered when it was too far away to be detected by other asteroid surveys," Jedicke noted.

Most of the largest PHOs have already been catalogued, but scientists suspect that there are many more under a mile across that have not yet been discovered. These could cause devastation on a regional scale if they ever hit our planet. Such impacts are estimated to occur once every few thousand years.

Volcanic Hazard Map Produced For Island Of Gran Canaria

Volcanic Hazard Map Produced For Island Of Gran Canaria

Spanish and French researchers have defined the age, location, size and geochemistry of the volcanoes of Gran Canaria during the Holocene, 11,000 years ago, in order to draw up a map of volcanic hazards for the island.

The research shows that the area of greatest volcanic activity is one of the most heavily populated areas in the north east of the island, which has suffered 24 eruptions over the period studied.

The team of French and Spanish scientists led by researchers from the University of Las Palmas de Gran Canaria (ULPGC) and the "Jaume Almera" Institute of Earth Sciences (CSIC, Barcelona) combined the data from previous studies with the results of analysis of 13 new radiocarbon ages in order to gain an understanding of the history of the island and predict the areas to be struck by future volcanic eruptions.

The result, which has been published recently in the Journal of Quaternary Science, is a map of volcanic hazards for Gran Canaria, describing risk scenarios.

"We have identified 24 volcanic eruptions that took place over the past 11,000 years on Gran Canaria. We know that volcanism was concentrated in the northern sector of the island and produced small monogenetic strombolian cones (eruptions that are not very violent and which release lava and pyroclastic flows) and, occasionally, phreatomagmatic calderas (which release ash), Alejandro Rodriguez-Gonzalez, lead author of the study and a researcher at the ULPGC, tells SINC.

In order to create the map, the researchers based themselves on detailed field work, which enabled them to define the limits of the various volcanic units (cone, lava and horizontal spread of pyroclastic flows) with a great degree of exactitude, using geomorphologiccal and stratigraphic criteria.

The data now made available by the scientists makes it possible to better evaluate the scale and type of future eruptions in this area. By working out the areas, before and after, of each eruption using Digital Land Models (DLM), the researchers have developed a novel and very detailed morphometric methodology for this kind of volcanic environment.

The study started with palaeotopographical reconstructions of areas affected by recent volcanic activity. "This allows our methodology to show geomorphological changes according to volcanic type and the periods of erosion involved", explains Rodriguez-Gonzalez.

Leonid Meteor Shower adds to Space Debris Hazards

Meteor showers produce gorgeous light shows. But the space debris responsible for them – usually dust cast off from comets – can seriously damage spacecraft, since it travels at relative speeds of up to 260,000 kilometres per hour.

This year, the Leonid shower peaks on 17 November and could produce a spectacular 300 meteors per hour during its peak.

This image of the 1999 Leonid shower was taken from an aircraft.

(Image: NASA-ARC/Shinsuke Abe and Hajime Yano/ISAS)


Satellites are not totally defenceless, however. When especially intense meteor showers are expected, they can orient their solar panels edge-on to the stream of impactors to minimise the chance of damage.

That was not possible for the European Space Agency's Olympus 1 satellite during the 1993 Perseid shower. An earlier meteoroid impact had disabled the pointing system on one of its solar arrays, leaving it exposed to the meteors, according to NASA's Bill Cooke.

Unfortunately for Olympus 1, the shower was especially intense that year because the comet responsible for the shower, Swift-Tuttle, had passed by Earth just the year before, leaving a fresh trail of debris.

During the shower, a Perseid impact seems to have led Olympus 1 to spin out of control. Efforts to regain control used up most of the spacecraft's fuel, leaving just enough to send it into a "graveyard" orbit, where it would not hit other satellites.

(Image: ESA)

Herschel & Planck: High Risk and High Stakes

Herschel & Planck sits ready in the cargo bay of the Ariane 5 launcher.

Separately, each is a major mission. Together, they constitute a landmark in astrophysics. The probes could revolutionise our understanding of the cosmos. If everything goes to plan, Herschel and Plank will dominate space science for at least five years. But if the launch goes wrong...

With science budgets shrinking, launching two such important missions on the same rocket smacks of madness, especially given that the launcher, an Ariane 5 rocket, has suffered a couple of high-profile and expensive failures. In 1996, a computer bug caused the loss of ESA's Cluster mission, which was rebuilt at a cost of €315 million. In 2002, a commercial launch exploded, forcing ESA to delay its Rosetta mission and costing it a further €100 million.

With the combined bill for Herschel and Planck coming in at more than €2 billion, it is near-inconceivable that they will be rebuilt if something goes wrong. Their loss would leave ESA reeling. The agency has other missions in the pipeline, including a mission to Mercury and a star-mapping project called Gaia. These have excellent scientific potential but they somehow seem small in comparison.

In short, if we lose Herschel and Planck, the heart of ESA's - and arguably the world's - space science programme would be ripped out. Let us all wish ESA the very best of luck.

Satellites collide - Space Debris animation