“It Came From Outer Space” –NASA’s NEOWISE Spacecraft Discovers 28 Previously Unknown Near Earth Objects

 

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Sixty-five-million years ago the Chicxulub Asteroid smashed into Earth releasing the equivalent of 10 Billion Hiroshima bombs. This week, NASA’s Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) mission has released its third year of survey data, with the spacecraft discovering 97 previously unknown celestial objects in the last year. Of those, 28 were near-Earth objects, 64 were main belt asteroids and five were comets. Earth is struck by an asteroid 60 meters wide approximately once every 1500 years, whereas an asteroid 400 meters across is likely to strike the planet every 100,000 years.


The spacecraft has now characterized a total of 693 near-Earth objects since the mission was re-started in December 2013. Of these, 114 are new. The NEOWISE team has released an animation depicting this solar system survey’s discoveries and characterizations for its third year of operations.

“NEOWISE is not only discovering previously uncharted asteroids and comets, but it is providing excellent data on many of those already in our catalog,” said Amy Mainzer, NEOWISE principal investigator from NASA’s Jet Propulsion Laboratory in Pasadena, California. “It is also proving to be an invaluable tool in in the refining and perfecting of techniques for near-Earth object discovery and characterization by a space-based infrared observatory.”

Near-Earth objects (NEOs) are comets and asteroids that have been nudged by the gravitational attraction of the planets in our solar system into orbits that allow them to enter Earth’s neighborhood. Ten of the objects discovered by NEOWISE in the past year have been classified as potentially hazardous asteroids, based on their size and their orbits.

If the past is prelude, there’s bound to be a massive collision event from a rogue asteroid at some point in the near future unless we successfully intervene.The impact map above shows most of the 160 impact craters that have been identified since 1950. The bulk of the terrestrial impact craters that were ever formed, however, have been obliterated by eons of geological processes.

Study the map at a glance you’ll see major impacts in the major population centers of the U.S., Europe, Africa, and Australia.

 

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Astrophysicist Sir Martin Rees of Cambridge University has famously speculated that the asteroid risk is just one of many reasons why humankind has only a 50/50 chance of making it into the next century. Even so, he says comets are more frightening of a doomsday prospect.

Comets are much more dangerous than asteroids, which have nonetheless gotten more media attention. Comets travel a lot faster through space than asteroids, which travel at about 25-30 km per second. The speed of a comet approaches a much faster 70 km per second. A relatively small object of just one and a half km in diameter hitting the Earth would release more energy than all the atomic bombs ever detonated and then some. An object of 20 km or more would likely cause mass extinction.

More than 2.6 million infrared images of the sky were collected in the third year of operations by NEOWISE. These data are combined with the Year 1 and 2 NEOWISE data into a single archive that contains approximately 7.7 million sets of images and a database of more than 57.7 billion source detections extracted from those images.

 

 

 

The NEOWISE images also contain glimpses of rare objects, like comet C/2010 L5 WISE. A new technique of modeling comet behavior called tail-fitting showed that this particular comet experienced a brief outburst as it swept through the inner-solar system.

“Comets that have abrupt outbursts are not commonly found, but this may be due more to the sudden nature of the activity rather than their inherent rarity,” said Emily Kramer, a NASA Postdoctoral Program Fellow at JPL and lead author of paper on the NEOWISE study. “It is great for astronomers to view and collect cometary data when they find an outburst, but since the activity is so short-lived, we may simply miss them most of the time.”

The tail-fitting technique identifies the size and quantity of dust particles in the vicinity of the comet, and when they were ejected from the comet’s nucleus, revealing the history of the comet’s activity. With tail-fitting, future all-sky surveys may be able to find and collect data on more cometary outburst activity when it happens. A paper detailing the tail-fitting technique and other results of the study was published in the March 20 volume of the Astrophysical Journal.

Originally called the Wide-field Infrared Survey Explorer (WISE), the spacecraft was launched in December 2009. It was placed in hibernation in 2011 after its primary astrophysics mission was completed. In September 2013, it was reactivated, renamed NEOWISE and assigned a new mission: to assist NASA’s efforts to identify the population of potentially hazardous near-Earth objects. NEOWISE also is characterizing more distant populations of asteroids and comets to provide information about their sizes and compositions.

The Daily Galaxy via NASA Neowise  and NASA Asteroid Watch

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