OSIRIS Cruise Science The OSIRIS cameras have demonstrated the capability to do competitive science as astronomical telescopes We should take advantage of this capability ! Keeping in mind lifetime issues Concentrating on a few promising projects Considering ESA’s “No cruise science, but exceptions are possible” policy Purpose of this talk: Show some examples that came up in discussions within the team Initiate discussion what should be done

1. Asteroid phase curves Many asteroids can be observed by OSIRIS with good Signal/Noise over a large range in phase angles Normally not achievable from Earth Asteroids with relatively close approaches to Rosetta would be preferred It is probably not feasible to get close enough to any asteroid (apart from Steins and Lutetia) to resolve it with the NAC

Asteroid phase curves Advantages Clearly defined scientific goal Effort and number of exposures controlled by number of target objects Disadvantages Science can partly be done by earth-based study of NEAs Operationally expensive for ESA

2. Observations of comets OSIRIS already observed 3 comets Linear 2002/T7 and Machholz 2004/Q2 during commissioning Tempel 1 during Deep impact Possible results Stereo-reconstruction of tail direction and structures Water production from OH CS (unobservable from Earth) in case of a very bright comet Special case of comets 22P/Kopff and 81P/Wild 2: Could be observed in OH and OI in support of H2O observations by Herschel

Example of images of bright comets ESA ©2004 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA Comet LINEAR ESA ©2005 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA Comet Machholz

Observations of bright comets Advantages Proven capability of the instrument Good PR opportunity Operationally relatively easy Disadvantages Added scientific value over earth-based observations is unclear in most cases Deep Impact was a special case Exception: Possibility of stereo observations Herschel support should be seriously considered

3. COROT follow-up COROT is currently looking for the photometric signal of extrasolar planets in transit of their stars OSIRIS is in principle capable of a similar transit search While we do not have the resources for a full search program, participation in the follow-up could be envisaged

COROT follow-up Advantages Touches a hot scientific topic Project in large international context High visibility Disadvantages Operationally demanding Lifetime issues ? Unrelated to Rosetta Science

4. Gravitational microlensing Gravitational microlensing shows a parallax effect on the scale of ~1 AU Can be observed with near-simultaneous observations of the galactic center with OSIRIS and ground-based telescopes

Gravitational microlensing Advantages First observation of its kind with strong scientific justification Good outreach perspective Can be done with relatively few exposures Disadvantages Capability of photometry in relatively crowded field still to be demonstrated Science is remote from Rosetta science Difficult to sell to ESA

5. Interstellar Extinction in the UV The OSIRIS filters below 300 nm operate in a relatively unexplored wavelength range The WAC with its large field of view may provide new information about interstellar extinction Extinction peaks at around 250 nm

Interstellar Extinction Advantages Explores unique capability of OSIRIS Operationally simple Data may already be found in existing data sets Disadvantages May require a large data volume Unrelated to Rosetta Science

Issues We need to decide if we want to go for Cruise science If the answer is yes, we need to prioritize and try to get our suggestions into the program Watch out for serendipitous science opportunities that may be in existing data sets