sign in sign up
<<
Home , Deep Impact (spacecraft)

Other Astronomical News

Report on the Workshop on Deep Impact as a World Observatory Event held in Brussels, Belgium, 7–10 August 2006

Hans Ulrich Käufl1 One of the spectacular deconvolved images from the Christiaan Sterken2 Deep Impact High Resolution Imager shown in the conference (courtesy Mike A’Hearn and the Deep Impact Team). This is a colour composite of an , a green and a violet filter forced to av- 1 ESO erage grey. Note the blueish areas on the surface 2 Vrije Universiteit Brussel, Belgium close to the crater-like structure. Those were entirely unexpected. It is highly interesting to find out if those structures can be correlated with the jets which were meticulously monitored from ground-based ob- In the context of NASA’s Deep Impact servers worldwide. This aspect in the picture – en- space mission, 9P/Tempel1 tirely unrelated to the impact plume – illustrates very well how comet research, apart from the impact has been at the focus of an unprece- experiment, will profit from the synergy of spacecraft dented worldwide long-term multi- data and the unprecedented worldwide coordinated wavelength observation campaign. The observing campaign. comet has been studied through its perihelion passage by various spacecraft including the Deep Impact mission it- self, HST, Spitzer, , XMM and all To make full use of the global data set, a To inspire new ideas, it was very helpful major ground-based observatories in workshop bringing together observers and interesting to have Roberta Olson basically all wavelength bands used in across the electromagnetic spectrum and from the New York Historical Society, astronomy, i.e. from radio cm-waves from different sites and projects was author of the book Fire in the sky (Olson to X-rays. For some ‘glossy-print’ infor- considered of great value. Synergy be- and Pasachoff 1999), at the workshop mation please have a look to e.g. ESO’s tween the different data sets can only be delivering a lecture titled , Charis- dedicated web-pages (deepimpact. achieved if observers share their data ma, and Celebrity: Reflections on Their eso.org). Due to the dynamical and other and arrive at a coherent interpretation. Deep Impact. Comets, like no other class technical constraints of the space mis- Therefore the participating of celestial objects, have spurred in- sion, ESO’s could not observe in the ESO campaign took the lead to tense attention of mankind to watch the the moment of impact – the comet was organise this workshop on a rather short skies and to wonder about the under- indeed exactly setting on the western notice. The workshop was held in Brus- lying principles and messages. For many horizon. However, the ESO observatory sels, Belgium from 7 to 10 August. More participants, however, it was new how sites, La Silla and Paranal were more than 70 colleagues presented 50 oral far reaching the impact of apparitions of or less the worldwide hub of the mid- and papers and 18 posters. The proceedings bright comets on the general public are long-term ground-based observations for will be published in the ESO Springer and how this manifests itself in many di- monitoring. Predictions for cometary conference series. verse pieces of art. activity induced by the experiment made before the impact ranged from ‘very little’ At the Brussels workshop – 12 months As with any good research project, the to the instantaneous release of material after Deep Impact – all participants had Deep Impact experiment and the associ- equivalent to ~ 10 days of normal activity progressed sufficiently in the analysis ated observation campaign have an- of the comet close to perihelion. In sum- and understanding of their data sets. The swered a fair set of questions about mary, Mike A’Hearn, the PI of Deep Im- coherent presentation of many diverse comets, but there are still open questions pact, confirmed in his review talk, that the results allowed for a synthesis. Thanks to and there is now a full set of new ques- release was at the lower end of expec- the Deep Impact campaign, many prop- tions. On the other hand, the next gen- tations and that there was no activity of erties from thermal inertia to tensile eration of spacecraft, especially the ESA- the impact site induced after the crater strength of the cometary nuclear surface mission ROSETTA, to land in August had formed. Especially as the long-term are now well constrained. Already at 2014 on Comet 67P/Churyumov-Gerasi- signatures after impact were rather sub- the workshop an intense discussion to menko and the next generation of opti- tle, the use of the world’s best facilities arrive at synergies – which will be tran- cal and radio telescopes, e.g. ALMA and to document the event was well warranted scribed for the proceedings – took place. the ELT, will be the keys to solve at in retrospect. Particularly interesting and exciting, least some of the truly enigmatic aspects however, are the open questions such as: of comets (and create new questions). The ground-based observing campaign the chemical composition of the ejecta; has been described in a recent Science the correlation of the complex observed publication by 209 authors from 85 aca- dust fans reported from many weeks Acknowledgements demic institutions all around the world of ground-based monitoring of nuclear Our special thanks go to the sponsoring organisa- (Meech et al. 2005). Some early results surface features, as imaged by the tions, ESO, the FWO Research Foundation – from the ESO observations have been spacecraft; and the absence of long-term Flanders, the Brussels Hoofdstedelijk Gewest, the reported earlier in The Messenger (Käufl effects from the impact site. Indeed Ministerie van de Vlaamse Gemeenschap and et al. 2005). the nature and physics of jets and active the host for the workshop, the Royal Academies for Science and the Arts of Belgium. zones of comets appears more enigmatic than ever.

48 The Messenger 126 – December 2006 References

Meech K. et al. 2005, Science 310, 265 Käufl H. U. et al. 2005, The Messenger 121, 11 Olson R. and Pasachoff J. M., “Fire in the Sky”, Photo: Tuvikene T. ISBN 0521663598. Cambridge, UK: Cambridge University Press, November 1999

The participants to this workshop, in the great hall of the magnificent palace of the Royal Academies for Science and the Arts of Belgium. The very special atmosphere of this historical building was very inspiring for this workshop. During the worldwide ground-based Deep Impact follow-up observing campaign, all observatories were basically linked and exchanging data, views and strategies quasi in real-time. This unique prevailed also during this dedicated workshop.

Around and about “Europe’s Quest for the Universe”

Jean-Pierre Swings developing innovative and sophisticat- (Institut d’Astrophysique et de Géo- ed telescopes and their auxiliary instru- physique, Liège University, Belgium) ments.

Professor Woltjer, ESO’s Director General Before even starting a review of “Europe’s for 13 years, was also instrumental in Quest for the Universe”, I think one should initiating studies towards conceiving and say a few words about its author. A tru- building a European Very Large Tele- ly impressive characteristic of Professor scope (the VLT), and getting the VLT con- Lodewijk Woltjer is indeed his vision to- struction started. Having been deeply wards excellence, in particular towards involved in the VLT advisory structure excellence in observational astrophys- (which he kindly mentions in his book!) I ics in (and for) Europe. One example: al- can testify that Lo Woltjer’s role was thirty years ago, he ‘forced’ some incredible: from a European vision to a fairly conventional European observers to remarkable ground-based astronomy start working on extragalactic astrophys- machine. ics on the occasion of the erection of So, in addition to his skills in theoretical ESO’s 3.6-metre , and even In parallel to this, he also had another astrophysics, a very interesting char- more so when the 3.5-m New Technol- vision, this one about interesting objects acteristic of Lo Woltjer concerns the two ogy Telescope became available. As far to observe, and at which wave-bands. complementary facets: ground-based as my own research group was concern- Here again his role in chairing the groups and space-borne astrophysics. In both ed, this led to the discovery, via these defining the future of European space cases, as briefly outlined above, he ESO telescopes, of several gravitational astrophysics was really fundamental, so played a pivotal role. He is therefore high- lenses. This type of research was in that ESA’s Horizon 2000+ objectives be- ly qualified to have written the recent fact made possible because Lo Woltjer came fantastic challenges. 300-page book about the origins and put together excellent teams of engi- evolution of the European Southern Ob- neers and scientists at ESO dedicated to servatory (ESO) and of the science pro-

The Messenger 126 – December 2006 49