Re: When I use my ham radio, are my transmissions going into space?

The answer depends for the most part on the band you are 
using. VHF easily penetrates to LEO (low earth orbit) and our local 
ham radio club at Johnson Space Center routinely makes contact on 2 
meters (142 MHz). VHF, UHF, and SHF (super high frequency) are used 
to communicate with satellites for commerical, TV, telephone, and 
hamsats.
Longer frequency HF transmissions will have a portion reflected back 
from the ionsphere, a portion absorbed, and a portion propagated thru 
to space. The ratios vary with the frequency, time of year, and 
sunspot cycle. There are good diagrams of the various atmospheric 
layers in the ARRL (Ham Radio) training materials and books, and 
possibly on their web site.  A full discussion would consume a book, 
but if you are a VHF (2 meter or 440) operator, you can count on your 
signal being 'out there'.

de KE5IQ