Keller, H. U. and Küppers, Michael and Fornasier, S. and Gutierrez, P. J. and Hviid, S.F. and Jorda, L. and Knollenberg, Jörg and Lowry, Stephen C. and Rengel, Miriam and Bertini, Ivano and Cremose, Gabriele and Ip, Wing and Koschny, Detlef and Kramm, Rainer and Kürth, Ekkehard and Lara, L.M. and Sierks, H. and Thomas, N. and Barbieri, C. and Lamy, P. and Rickman, H. and Rodrigo, Rafael and A'Hearn, Michael F. and Angrilli, F. and Barucci, M.A. and Bertaux, J. L. and da Deppo, Vania de and Davidsson, Björn J.R. and Cecco, Mariolino and Debei, S. and Fulle, M. and Gliem, F. and Groussin, Olivier and López Moreno, José Luis and Marzari, Francesco and Naletto, G. and Sabau, L. and Sanz Andres, Angel Pedro and Wenzel, K. P.
Observations of Comet 9P/Tempel 1 around the Deep Impact event by the OSIRIS cameras onboard Rosetta.
"Icarus", v. 187
The OSIRIS cameras on the Rosetta spacecraft observed Comet 9P/Tempel 1 from 5 days before to 10 days after it was hit by the Deep Impact projectile. The Narrow Angle Camera (NAC) monitored the cometary dust in 5 different filters. The Wide Angle Camera (WAC) observed through filters sensitive to emissions from OH, CN, Na, and OI together with the associated continuum. Before and after the impact the comet showed regular variations in intensity. The period of the brightness changes is consistent with the rotation period of Tempel 1. The overall brightness of Tempel 1 decreased by about 10% during the OSIRIS observations. The analysis of the impact ejecta shows that no new permanent coma structures were created by the impact. Most of the material moved with View the MathML source∼200ms−1. Much of it left the comet in the form of icy grains which sublimated and fragmented within the first hour after the impact. The light curve of the comet after the impact and the amount of material leaving the comet (View the MathML source4.5–9×106kg of water ice and a presumably larger amount of dust) suggest that the impact ejecta were quickly accelerated by collisions with gas molecules. Therefore, the motion of the bulk of the ejecta cannot be described by ballistic trajectories, and the validity of determinations of the density and tensile strength of the nucleus of Tempel 1 with models using ballistic ejection of particles is uncertain.