Deep Impact Update - August 11, 2005

http://deepimpact.jpl.nasa.gov/mission/update.html

Deep Impact Science Team retreat
Lucy McFadden
August 11, 2005

The Deep Impact science team gathered in Hilo, Hawaii the last week of
July for a working retreat to examine the results from Deep Impact's
encounter on July 4th. Collaborating astronomers from around the world
joined them both in person and via videoconference. The impact of comet
Tempel 1 was scheduled to be observable from the ground while the comet
was above the horizon in Hawaii, the location of some of the darkest
and
driest skies in the world. Many of the astronomers who used telescopes
at Mauna Kea attended the workshop to learn about the impact from the
Deep Impact science team's perspective, which would enable them to
better interpret their own data. It was truly a collaborative effort,
as
the science team is interested in ground-based and space-based results
to give us perspective on the Deep Impact spacecraft data. While about
50 people were present at the workshop, we had colleagues attending by
videoconference in Germany, and Maryland, USA. We spanned 12 time
zones,
and didn't know whether to say "Good morning" or "Good Night". We
settled on "Aloha" and appreciated our distant colleagues wearing their
Hawaiian shirts to feel closer to the pulse of the meeting.

Our tasks involved reviewing some of the most interesting data that we
collected, reporting on the calibration, checking it and crosschecking,
and discussing possible interpretations. We also defined additional
questions we need to have answered in order to arrive at robust
interpretations of the nature of the comet before impact, the
phenomenon
of the impact itself, and the effects of the impact afterwards.

From the images posted on the web pages, it is known that the Deep
Impact spacecraft returned spectacular data from the collision. Bright
dust glowed and illuminated space shortly after impact. The comet
zipped
by and the spacecraft looked back to see what effects had been made. So
much dust was kicked up by the impact, that the science team is still
analyzing the images to measure the size of the crater. This analysis
continues.

The spectrometer showed spectral signatures of water, hydrocarbons, CO
and CO2. We continue the analysis of the spectra to determine how hot
the water was (between 1000 and 2000 K) and how long it remained hot.
The interpretation is a challenge, because the spacecraft and the comet
were in motion. That is both an advantage and a challenge. We continue
to put together the story of what we saw, when, and how fast the
spacecraft was moving.

Initial reports from ground-based and space-based observers are varied.
Some telescopes saw dramatic changes as a result of the impact, while
others did not. One has to recall that the results depend not only on
how large a telescope is being used, and its sensitivity, but also at
what region of the spectrum the data are acquired. The physics of the
impact is not active in all spectral regions. There is a lot of
information to be gleaned from both positive and negative results from
ground-based and space-based data. Combining those results with that of
the Deep Impact spacecraft, that was right there when it happened, but
carried only two types of instruments (visible imagers and an IR
spectrometer) will provide an interesting scientific story when we get
it all sorted out.

At week's end we had compiled contributions to a manuscript to be
submitted to Science magazine that is scheduled for publication in
September 2005. The full set of raw and calibrated data are scheduled
to
be delivered to the Planetary Data System in January 2006. The
Planetary
Data System releases the data to the public.