[X] My Assistant

[ljk4-1]

Proof that ground-based observations continue to have a major role to
play in Sol system studies:

Radio observations of comet 9P/Tempel 1 with the Australia Telescope facilities during the Deep Impact encounter

http://arxiv.org/abs/astro-ph/0604489

[ljk4-1]

Astrophysics, abstract
astro-ph/0604608

From: John Robert Brucato [view email]

Date: Fri, 28 Apr 2006 13:27:24 GMT (260kb)

An IR study of pure and ion irradiated frozen formamide

Authors: John R. Brucato, Giuseppa A. Baratta, Giovanni Strazzulla

Comments: 6 pages, 3 figures. Accepted for publication in A&A

Context. The chemical evolution of formamide (HCONH2), a molecule of astrobiological interest that has been tentatively identified in interstellar ices and in cometary coma, has been studied in laboratory under simulated astrophysical conditions such as ion irradiation at low temperature.

Aims. To evaluate the abundances of formamide observed in space or in laboratory, the integrated absorbances for all the principal IR features of frozen amorphous pure formamide deposited at 20 K were measured. Further evidence that energetic processing of ices occurring in space is extremely relevant both to astrochemistry and to astrobiology has been found, showing that new molecular species are synthesized by ion irradiation at a low temperature.

Methods. Pure formamide were deposited at 20 K and IR transmission spectra measured for different ice thicknesses. The ice thickness was derived by looking at the interference pattern (intensity versus time) of a He-Ne laser beam reflected at an angle of 45 deg by the vacuum-film and film-substrate interfaces. Samples of formamide ice were irradiated with 200 keV H+ ions and IR spectra recorded at different ion fluences.

Results. New molecules were synthesized among which are CO, CO2, N2O, isocyanic acid (HNCO), and ammonium cyanate (NH4+OCN-). Some of these species remain stable after warming up to room temperature.

http://arxiv.org/abs/astro-ph/0604608

[ljk4-1]

Astrophysics, abstract
astro-ph/0605389

From: Edward M. Drobyshevski [view email]

Date: Tue, 16 May 2006 14:20:11 GMT (280kb)

Deep Impact Mission to Tempel 1 Favours New Explosive Cosmogony of Comets

Authors: E.M.Drobyshevski, E.A.Kumzerova, A.A.Schmidt

Comments: 21 pages incluging 3 figures

The assumption that short-period (SP) comets are fragments of massive icy envelopes of Ganymede-like bodies saturated by products of ice electrolysis that underwent global explosions provides a plausible explanation of all known manifestations of comets, including the jet character of outflows, the presence of ions in the vicinity of the nucleus, the bursts and splitting of cometary nuclei, etc., with solar radiation initiating burning of the products of electrolysis in the nucleus. As shown persuasively by numerical simulation carried out in hydrodynamic approximation, the shock wave initiated by the Deep Impact (DI) impactor in the cometary ice saturated originally by the electrolysis products 2H2 + O2 is capable of activating under certain conditions exothermal reactions (of the type O2 + H2 + organics = H2O + CO + HCN + other products of incomplete burning of organics including its light and heavy pyrolyzed compounds, soot, etc.), which will slow down shock wave damping (forced detonation) and increase many times the energy release. As a result, the measured energetics of ejections and outflows from the crater have to exceed the DI energetics. Analysis of different clusters of the DI experiment data confirms these conclusions and expectations and thus it favours the planetary origin of comets.

http://arxiv.org/abs/astro-ph/0605389

[ljk4-1]

Astrophysics, abstract
astro-ph/0606045

From: Frank Bensch [view email]

Date: Fri, 2 Jun 2006 09:29:31 GMT (168kb)

Submillimeter Wave Astronomy Satellite observations of comet 9P/Tempel 1 and Deep Impact

Authors: F. Bensch, G.J. Melnick, D.A. Neufeld, M. Harwit, R.L. Snell, B.M. Patten, V. Tolls

Comments: 38 pages, 2 tables, 7 figures; Icarus, in press

On 4 July 2005 at 5:52 UT the Deep Impact mission successfully completed its goal to hit the nucleus of 9P/Tempel 1 with an impactor, forming a crater on the nucleus and ejecting material into the coma of the comet. NASA's Submillimeter Wave Astronomy Satellite (SWAS) observed the 1(10)-1(01) ortho-water ground-state rotational transition in comet 9P/Tempel 1 before, during, and after the impact. No excess emission from the impact was detected by SWAS and we derive an upper limit of 1.8e7 kg on the water ice evaporated by the impact. However, the water production rate of the comet showed large natural variations of more than a factor of three during the weeks before and after the impact. Episodes of increased activity with Q(H2O)~1e28 molecule/s alternated with periods with low outgassing (Q(H2O)<~5e27 molecule/s). We estimate that 9P/Tempel 1 vaporized a total of N~4.5e34 water molecules (~1.3e9 kg) during June-September 2005. Our observations indicate that only a small fraction of the nucleus of Tempel 1 appears to be covered with active areas. Water vapor is expected to emanate predominantly from topographic features periodically facing the Sun as the comet rotates. We calculate that appreciable asymmetries of these features could lead to a spin-down or spin-up of the nucleus at observable rates.

http://arxiv.org/abs/astro-ph/0606045

[Guest_AlexBlackwell_*]

Published online today, July 13, 2006, in Science Express:

Spitzer Spectral Observations of the Deep Impact Ejecta
C. M. Lisse, et al.
Published online July 13, 2006; 10.1126/science.1124694 (Science Express Research Articles)
Abstract
Supporting Online Material

[Comga]

The Deep Impact team wants to go back to Comet Tempel 1 with the surviving flyby bus and a new spacecraft. ....

To quote:

"The proposed new missions are called DeepR and DIXI. DeepR (Deep-Rosetta) would clone the Deep Impact mission, building identical flyby and impactor spacecraft and targeting comet 67P/Churyumov-Gerasimenko (C-G)..."

"DIXI, which stands for Deep Impact eXtended Investigation, would use the surviving Deep Impact spacecraft and its three working instruments (two color cameras and an IR spectrometer) for a flyby of Comet Boethin in December 2008."

You didn't read your own quote. DeepR is to target comet 67P/C-G with a "clone" spacecraft. DIXI would have the existing spacecraft fly by Comet Boethin. Neither is to planned to go back to Comet Tempel 1.

Note that a new flyby of Temple 1 would have <50% chance of seeing the crater. Only half the nucleus is sunlit, and as the approach would not straight down the line from the sun, not all of the sunlit surface can be observed. Even less of the surface can be imaged if the spacecraft "turns tail" and goes into a self protecton orientation like the Deep Impact flyby spacecraft did.

[Guest_AlexBlackwell_*]

Published online today, July 13, 2006, in Science Express:

Spitzer Spectral Observations of the Deep Impact Ejecta
C. M. Lisse, et al.
Published online July 13, 2006; 10.1126/science.1124694 (Science Express Research Articles)
Abstract
Supporting Online Material

Some related press releases:

Scientists Gaining Clearer Picture of Comet Makeup and Origin
The Johns Hopkins University Applied Physics Laboratory
Office of Communications and Public Affairs
July 17, 2006

Deep Impact Reveals Comet's Components
Scientific American
SCIENCE NEWS
July 14, 2006

[Guest_AlexBlackwell_*]

Interesting paper in press with Icarus:

Submillimeter Wave Astronomy Satellite observations of Comet 9P/Tempel 1 and Deep Impact
Icarus, In Press, Corrected Proof, Available online 21 July 2006
Frank Bensch, Gary J. Melnick, David A. Neufeld, Martin Harwit, Ronald L. Snell, Brian M. Patten and Volker Tolls
Abstract
Preprint

[Phil Stooke]

It's Stardust which is proposed to revisit Tempel-1.

Phil