Opening a Window of Discovery on the Dynamic Universe

Near-Earth Objects (NEOs)

This Hubble Space Telescope image shows the odd-shaped debris that likely came from a collision between two asteroids.

Identifying objects in the outer solar system has proven difficult despite some recent successes. Finding objects much closer to Earth provides different challenges; at a given size, these objects are much brighter, but they are also moving much more rapidly across the sky. Scientifically, observing a sample of these near-Earth objects (NEOs) can tell us more about the primordial materials of our Solar System. However, given the small but definite chance of an asteroid impact, we are also motivated to gather a more complete catalog of these objects. Indeed, finding NEOs might be the most important contribution astronomy makes to life on Earth, given that, while the odds of a significant impact are slight, the consequences are grave. A strike by an asteroid 300 meters in diameter would be equivalent to 1600 megatons of TNT, and should it impact in an ocean basin, the resulting tsunami could devastate coastal margins. Ignoring the LSST's capabilities that enable us to learn more about the possibility with relatively modest effort would be negligence on our part.

Ground-based optical surveys are the most efficient tool for comprehensive NEO detection, determination of their orbits, and subsequent tracking, and the LSST is poised to make uniquely powerful contributions to the study of NEOs, which include both asteroids orbiting the Sun (near-Earth asteroids) and comets arriving from the outer solar system. Indeed, simply providing a comprehensive census of potentially hazardous asteroids (PHAs), which are NEOs with orbits having the highest probability of someday crossing Earth's, will transform the problem of forecasting an impact from a statistical one to a deterministic one.

The LSST's large mirror size, large field of view, and sophisticated data acquisition, processing and dissemination system will be uniquely suited to providing such a census. Its large mirror will be able to detect the faint, small objects in question, and its large field of view (about 10 square degrees), will enable frequent repeated observations of a significant fraction of the sky—producing tens of terabytes of imaging data per night. In order to recognize PHAs, determine their orbits and disseminate the results to the interested communities in a timely manner, a powerful and fully automated data system, such as is being created for the LSST, is mandatory.

The LSST system is located on Cerro Pachón in Chile, and will provide digital imaging of faint astronomical objects across the entire sky, night after night, in a relentless campaign of paired 15-second exposures of its 3,200 megapixel camera. The LSST will cover the entire available sky every few nights in two colors, finding objects as faint as 25th magnitude, with exquisitely accurate mapping and photometry. Over the proposed survey lifetime of 10 years, each sky location would be observed close to 1000 times. Equally important, due to frequent repeat visits LSST will effectively provide its own follow-up to derive orbits for detected moving objects. The latest LSST publication about LSST capabilities for enabling Solar System science is Jones et al. (2015)

Image Credit: 
NASA, ESA, and D. Jewitt (UCLA)

Financial support for LSST comes from the National Science Foundation (NSF) through Cooperative Agreement No. 1258333, the Department of Energy (DOE) Office of Science under Contract No. DE-AC02-76SF00515, and private funding raised by the LSST Corporation. The NSF-funded LSST Project Office for construction was established as an operating center under management of the Association of Universities for Research in Astronomy (AURA).  The DOE-funded effort to build the LSST camera is managed by the SLAC National Accelerator Laboratory (SLAC). 


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