The mission of the Catalina Sky Survey is to contribute to the inventory of near-earth objects (NEOs), or more specifically, the potentially hazardous asteroids (PHAs) that pose an impact risk to Earth and it's inhabitants. The identification of the iridium anomaly at the Cretaceous-Tertiary boundary (Alvarez et al., 1980), associated Chicxulub impact crater (Hildebrand et al., 1991) and the Permian- Triassic "great dying" possibly being associated with Australian Bedout crater (Becker et al., 2004) strongly suggest that impacts by minor planets play an important role in the evolution of life.
Aside from the uncertainty of an asteroid impact, and whether there are means of mitigating them, we now have the technology to inventory the NEO population - the first element in assessing the threat. Given the catastrophic consequences of a collision with a large object, it would be irresponsible not to carry out an inventory now. The NEO Observations Program (NEOO) is a result of a 1998 congressional directive to NASA to conduct a program to identify 1 km. or larger bodies to an estimated 90 percent confidence level or better. Since then a further mandate (June, 2006) has been issued to identify 140 meter or larger bodies to the same confidence level.
There are numerous scientific benefits of surveying for NEOs. Those include improving the known population distribution in the main belt, finding the cometary distribution at larger perihelion distances, determining the distribution of NEOs as a product of collisional history and transport to the inner solar system, and identifying potential targets for flight projects.
The Catalina Sky Survey (CSS), Mt. Lemmon Survey and Siding Spring Survey (SSS) working together under the name of the first survey, are carrying out sustained, highly productive searches for NEOs, contributing to the Congressional mandates of obtaining an inventory of better than 90% of the previously mentioned NASA goal. Further, these surveys are operated in such a manner that same night follow up on newly discovered objects can usually be done facilitating the rapid determination of orbits and thus the specific hazard posed by the newly found objects.
Simply creating an inventory of NEOs is a necessary, but insufficient component of fully realizing the NEOO program goal. Assessing the threat posed by a PHA requires predictions of its impact energy. This requires knowing both the mass and velocity of the impacting object, or more precisely, its size, density, and velocity. Accurately determining size requires knowing the shape and albedo. Therefore, in parallel with deep survey activities the Mt. Lemmon 1.5-m telescope is used in characterization studies obtaining physical data of objects that will help complete our understanding of the threat posed by newly-discovered and multiple-return NEOs.
L. Alvarez et al., Science 208, 1095 (1980)
L. Becker et al., Science 304, 1469 (2004)
A. Hildebrand et al, Geology 19 (9): 867.871