Prologue - Freeman and Hume verify the signal.

It had been three days since the Joint Chiefs had met.  Fritz Hume
had been friendly enough, but Freeman was still uncertain of the
mathematician's source of amusement.  With three hours remaining
before the "verification" event was expected, the two men had
positioned themselves in the Grissom Observatory's control room. 
Freeman decided it couldn't hurt to ask.  Anyway, nobody else was
around who had anything less than Top Secret clearance.

"This talk of aliens, or E.T.s .. you seem like you're taking it
seriously."

Hume arched an eyebrow at his colleague's question, then smiled that
maddeningly complacent smile of his.  "Transformative D was.. an
extremely difficult cipher," he conceded.  "It would have taken
our own computers, working full time, thousands of years to break
it.  If the message was authentic, and assuming they didn't just
intercept our key, then it follows that our hypothetical visitors have
computing power several thousand times better than we can muster. 
Millions of times, maybe.  Imagine a culture resting on that sort
of computing power, Dr. Haight."

Freeman shook his head, smiling.  "I'm an aerospace engineer, not
a computer scientist," he replied ruefully.  "Still, I think I see
your point.. you could find the cure for cancer, or things like it, in
trivial amounts of time, right?  Solve society's problems?"

Hume chuckled.  "You could solve the problems solvable by
computation, yes.  Computers are excellent at finding facts, but
not at enforcing decisions based on those facts.  Of course, our
visitors might also have mastered artificial intelligence, and that
A.I. may have superceded its creators in political leadership. 
Either way, there's no predicting what meeting such beings would be
like.  I'm quite excited, actually."

"At least someone is," murmured Freeman.

The high-speed fiber-optic network that connected the Observatory with
other such sites was up and running.  The team had backup
land-lines for calling out, and in a pinch, their phones.

Nobody breathed as the second-hand swung round.  11:59.

The clock struck twelve.  Somewhere, somebody's watch began to
beep.  It was drowned out seconds later by automated alarms and
excited cries:  "We're getting data!"  "Confirmed, binary
message flashing from the indicated coordinates!"  "... Verify
with Arecibo..."  "... Arecibo standing by,
confirms
receipt."  "... Confirmation two..."

Freeman had been on his feet, a cup of coffee in his hand.  Now he
almost forgot to hold onto it as he rushed forward to the computer
console, where a visual image was being displayed on the
foreground.  He narrowed his eyes.  There!  Pulses of
light, delicate like twinkling stars, but clearly visible.

".. Triangulation figures coming in now," a technician reported. 
"Estimated distance 495,421 miles."  Freeman mentally calculated,
then glanced at Dr. Hume.  "About twice as far as the Moon is from
us," he clarified.  Hume just nodded, staring raptly at the binary
translation of the flashes.  "Probably sufficiently far to rule
out the possibility of a satellite, yes?  Well... smart fellows."

Freeman heard more chatter from the technicians.  All he could do was
reach for the telephone handset.  We've
got to let everyone know, he thought.