Subject: How can you be SURE the Earth will never fall into the Sun?

I already read the answer that by virtue of its incredible speed, the Earth 
will not fall into the Sun. But the Earth, much like it's satellites, can only 
slow down, never speed up (without external intervention). And as we know, 
SkyLab came down in about 6 years. Sure the Earth is in no danger now, but how 
can you tell that 10,000 years from now, the Earth won't slow to a speed that 
puts it on an eventual path into the Sun.

Re: How can you be SURE the Earth will never fall into the Sun?