How did the probes get there?

Left behind, book 4;

Buck tiptoed downstairs and flipped on the television, finding an all-news station.
As soon as he saw what was going on, he woke up everyone in the house except
Hattie. He told Chloe, Tsion, and Ken, “It's almost noon in New Babylon, and I've
just heard from Rayford. Follow me.”
Newscasters told the story of what astronomers had discovered just two hours
before—a brand-new comet on a collision course with Earth. Global Community
scientists analyzed data transmitted from hastily launched probes that circled the
object. They said meteor was the wrong term for the hurtling rock formation, which
was the consistency of chalk or perhaps sandstone.
Pictures from the probes showed an irregularly shaped projectile, light in color. The
anchorman reported, “Ladies and gentlemen, I urge you to put this in perspective.
This object is about to enter Earth's atmosphere. Scientists have not determined its
makeup, but if—as it appears—it is less dense than granite, the friction resulting
from entry will make it burst into flames.
“Once subject to Earth's gravitational pull, it will accelerate at thirty-two feet per
second squared. As you can see from these pictures, it is immense. But until you
realize its size, you cannot fathom the potential destruction on the way. GC
astronomers estimate it at no less than the mass of the entire Appalachian Mountain
range. It has the potential to split the earth or to knock it from its orbit.
“The Global Community Aeronautics and Space Administration projects the
collision at approximately 9:00 A.M. Central Standard Time. They anticipate the
best possible scenario, that it will take place in the middle of the Atlantic Ocean.
“Tidal waves are expected to engulf coasts on both sides of the Atlantic for up to
fifty miles inland. Coastal areas are being evacuated as we speak. Crews of
oceangoing vessels are being plucked from their ships by helicopters, though it is
unknown how many can be moved to safety in time. Experts agree the impact on
marine life will be inestimable.

I'd really love to have heard Hoyle on that.

`