The frequency bit was just a wild guess.
It very well may be something else entirely. I have heard no real good explanations though and I think many folks instinctively know it's some sort of 'barrier' or change in the fundamental underpinnings of space.

It may be that certain types of matter can only travel beyond a certain point with even more force and momentum than the probes have - a sort of 'solar' breakaway speed?

However, if it were true - or something similar - that might also explain the lack of "et's" landing on the Whitehouse lawn.

Space travel between solar systems may be even more difficult than we thought and require even greater technological leaps.

It's a crying shame we don't have a fleet of ships exploring the solar system and getting first hand data on all this stuff - I have "feeling" this phenomenon, when understood, may explain a lot of things.

Best wishes,

SDAI-Tech1