Anything below 30 meters [100 feet in diameter] wouldn't cause any damage. |
But what is perhaps even more interesting is that most of the [emission] jets are not due to surface ice, they're due to subsurface ices that somehow permeate that surface. |
Comets are far more than an intellectual interest. These things affect us, and may have even enabled us [to exist]. |
Goodness, no. The closest fragment will be about six million miles away--or twenty-five times farther than the Moon. |
It looks as though some of the fragments are themselves forming their own sub-fragments. |
It takes 7 1/2 minutes for a signal to get from Earth to the spacecraft and another 7 1/2 minutes to get back. So, we can't joystick this spacecraft like a video game. |
It's an interesting object and it's raised some interesting issues, but a worrisome threat? No. We've got plenty of time. |
It's not gonna knock your socks off, and it certainly won't be the brightest object in the sky, but it'll be easily observable with the naked eye . |
Sometimes, when the fragments break off, they flare up temporarily, but it usually doesn't last very long. |
The spacecraft has to be smart enough on its own to observe the comet, determine whether it's headed in the right direction, if not, make its own course correction, and then fire its thrusters to achieve that course correction. |
There's a certain amount of nervousness at present. ... It's a harsh environment out there and this is not easy. We don't really know what to expect, frankly. ... It could be anything from a crater the size of a football stadium to something that's far more modest. Or the spacecraft could simply bury itself into the comet. |
They could be the watering holes and fuel stations for future interplanetary exploration. |
This is a rare opportunity to watch a comet in its death throes ? from very close range. |
We hope to get 15 centimeters resolution. That's unprecedented resolution. |
We're trying to understand the structure of a comet and also its composition. Once we hit it, we will open up surface areas that are exposed to the sunlight and see new subsurface ices for the first time. |