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Asteroids and Comets

All the Little Things in the Solar System, and the Things They Can Do to Earth

Is there an asteroid or comet out there that poses a risk to life on Earth? The answer is certainly "yes," but we don't yet know where the next major impactor will come from or when it will crash. The best way to reduce this uncertainty is to search the skies for these crumbs of the solar system. The Planetary Society has a long history of supporting amateur and underfunded professional astronomers in their efforts to discover and track potentially hazardous near-Earth objects. This is useful not only for planetary defense, but also for learning about the solar system's origin and evolution.

A fortuitous byproduct of our increasing ability to detect fainter objects is that, for the first time, we now stand a chance of discovering smaller, five- to ten-meter-sized rocks while they are still in space before they burn up in our atmosphere and scatter meteorites along the ground. We are now beginning to link meteorites that we can study in our labs with the data on orbits and compositions that we amass with astronomical observations. Every meteorite, every tiny asteroid has a story, and we can combine these stories together to answer fundamental questions about how the solar system formed and evolved. What were the ingredients that made Earth and the other planets? How are those constituents different now? How have asteroid and comet impacts shaped the origin and evolution of life on Earth (and, potentially, on other planets)? Can asteroids serve as stepping-stones for human travel to farther destinations?

Blogs About Asteroids, Comets, and the Impact Threat

Rosetta spacecraft may be dying, but Rosetta science will go on

Posted by Emily Lakdawalla on 2016/09/29 12:47 CDT | 3 comments

The Rosetta mission will end tomorrow when the spacecraft impacts the comet. ESA took advantage of the presence of hundreds of members of the media to put on a showcase of Rosetta science. If there’s one thing I learned today from all the science presentations, it’s this: Rosetta data will be informing scientific work for decades to come.

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Dawn Journal: 9th Anniversary

Posted by Marc Rayman on 2016/09/29 12:05 CDT | 2 comments

Nine years ago today, Dawn set sail on an epic journey of discovery and adventure. The intrepid explorer has sailed the cosmic seas and collected treasures that far exceeded anything anticipated or even hoped for.

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Rosetta end-of-mission update

Posted by Emily Lakdawalla on 2016/09/09 12:40 CDT | 5 comments

The European Space Agency has shared plans for the end of the Rosetta mission scheduled for September 30, just three weeks from now. The landing site will be located on the "head" of the comet, next to a prominent pit now named Deir el-Medina.

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Asteroids, Comets, and the Threat

Asteroids and Comets Visited by Spacecraft

A comparison of all the asteroids and comets ever visited by spacecraft, up to date as of November 10 (when Deep Impact flew past Hartley 2). Vesta is not included.

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Sizing Up the Threat from Near-Earth Objects (NEOs)

Scientifically, it is useful to divide the impact hazard into two types of events: those with local consequences and those with global consequences. Global events, while much less likely, actually pose a greater risk.

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The Torino Scale

The Torino scale is a color-coded advisory system that enables near-Earth object (NEO) researchers to place objects within a potential threat range from zero -- where there is virtually no chance of collision, to 10 -- where global catastrophe is certain.

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