November 22, 2013

Satellite Stereo A picks up Comet Ison and NASA looked at in Infrared for Debris Size - Nov 22, 2013

Because NASA's twin STEREO probes are designed to observe the sun, they can see sundiving comets even when the glare becomes intense.

Yesterday, Comet ISON joined Earth, Mercury, and Comet Encke in the field of view of STEREO-A's Heliospheric Imager.



Meanwhile, NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) embarked on a “target of opportunity” flight recently that included study of Comet ISON.

The observatory’s flight path saw NASA’s highly modified 747SP that carries a high-tech German-built 2.5 meter infrared telescope depart its home base at Palmdale, Calif., the evening of Oct. 24, 2013.

The comet ISON observations began south of the Canadian border, above the border of Idaho and Montana while SOFIA was flying at 43,000 feet altitude. The entire non-stop flight took nearly 10 hours to complete.

Principal investigator Diane Wooden of NASA's Ames Research Center, who had proposed that Comet ISON be studied at three infrared wavelengths – 11.1, 19.7, and 31.5 microns, was aboard the Oct. 24 SOFIA flight.

"Studying the dust’s thermal emission from SOFIA enables us to derive the grain size, its distribution, and the mass of the amount of dust coming from the comet," she said. "This is a critical complement to studying the gases that are released.

“We learned that the comet is dust-poor not only for small grains, as already known by the weak scattered light at visible wavelengths, but also for larger grains detectable at these mid-IR wavelengths from SOFIA,” Wooden concluded.

Although, according to Wooden, the comet is dust-poor for small grains and larger grains, it seems that they have some concern about the size of the debris and at what rate.

Furthermore, according to NASA, the comet has a diameter of 3,5 km. According to BPearthwatch the comet has a diameter of 20 km! nasa.gov , spaceweather , bpearthwatch


 

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