[meteorite-list] Deep Impact Captured by Gemini Telescope

[Ron Baalke]

Gemini Observatory
Hilo, Hawaii

Tuesday, 5 July 2005

Deep Impact Captured by Gemini
	
The Gemini North telescope on Mauna Kea successfully captured the dramatic 
fireworks display produced by the collision of NASA's Deep Impact probe 
with Comet 9P/Tempel 1. Researchers in two control rooms on Hawaii¹s Big 
Island (on the Mauna Kea and in Hilo) were able to keep enough composure 
amid an almost giddy excitement to perform a preliminary analysis of the 
data. They concluded from the mid-infrared spectroscopic observations that 
there was strong evidence for silicates or rocky material exposed by the 
impact. Little doubt remains that the unprecedented quality of the Gemini 
data will keep astronomers busy for years.

"The properties of the mid-infrared light were completely transformed 
after impact," said David Harker of the University of San Diego, 
co-investigator for the research team. "In addition to brightening by a 
factor of about 4, the characteristics of the mid-infrared light was like 
a chameleon and within five minutes of the collision it looked like an 
entirely new object." Harker¹s research partner Chick Woodward of the 
University of Minnesota speculated further, "We are possibly seeing 
crystalline silicates which might even be similar to the beach sand here 
in Hawaii! This data will keep us busy trying to figure out the size and 
composition of these grains to better understand the similarities and 
differences between the material contained within comets and other bodies 
in the solar system."

In addition to the spectroscopic observations, before-and-after images 
were also obtained by the Gemini telescope in thermal infrared light and 
can be seen in Figure 1.  Gemini monitored the comet for several weeks 
prior to the impact and will continue to watch it through the end of July.

The Gemini observations were part of a coordinated effort between the W.M. 
Keck, Subaru and Gemini Observatories so that each could concentrate on 
different observations and provide a complete, complementary "picture" of 
the impact. Astronomers anticipate that the data gathered from the largest 
and most sophisticated set of telescopes positioned to see the impact will 
add considerably to our understanding of comets as dynamic probes of our 
solar system¹s early evolution some 4.5-5 billion years ago.

The Gemini observations were made using Michelle, the facility 
mid-infrared imager/spectrograph built at the Royal Observatory of 
Edinburgh (ROE) in the UK. The instrument has unique capabilities in the 
mid-infrared especially at Gemini which uses protected silver coatings on 
main mirrors to provide exceptional performance in the "thermal" or 
mid-infrared part of the spectrum.

Gemini is an international partnership managed by the Association of 
Universities for Research in Astronomy under a cooperative agreement with 
the National Science Foundation.

The Gemini Observatory provides the astronomical communities in each 
partner country with state-of-the-art astronomical facilities that 
allocate observing time in proportion to each country's contribution. In 
addition to financial support, each country also contributes significant 
scientific and technical resources. The national research agencies that 
form the Gemini partnership include: the US National Science Foundation 
(NSF), the UK Particle Physics and Astronomy Research Council (PPARC), the 
Canadian National Research Council (NRC), the Chilean Comisión Nacional de 
Investigación Cientifica y Tecnológica (CONICYT), the Australian Research 
Council (ARC), the Argentinean Consejo Nacional de Investigaciones 
Científicas y Técnicas (CONICET) and the Brazilian Conselho Nacional de 
Desenvolvimento Científico e Tecnológico (CNPq). The Observatory is 
managed by the Association of Universities for Research in Astronomy, Inc. 
(AURA) under a cooperative agreement with the NSF. The NSF also serves as 
the executive agency for the international partnership.

IMAGE CAPTION:
[Figure 1:
http://www.gemini.edu/images/stories/websplash/websplash2005-12/fig1_hi.jpg 
(174KB)]
Gemini North Michelle mid-infrared (11.6 micron) false-color images of 
9P/Temple 10 minutes before impact (left), 3 hours after (center) and 24 
hours after impact (right). Scale and orientation are the same for all 
images. Note: the middle image represents a physical expanse about that of 
the Big Island of Hawaii.