This other control has just caused every instrument on this ship, and
all the others in the task force, to make permanent records on magnetic
tape of all their readings.

"If a collision occurs and the probe missile falls into the sea," Tom
went on, "there's only one hope of recovery--to plot the exact
geographical position and then get to the spot before the enemy does!"

"Roger!" Bud agreed.

It was obvious that Tom's fears about the missiles colliding were well
founded. The mystery blip had veered as the recovery missile speeded up.
Within seconds, the three blips met on the screen and fused into a
single spot of light.

"The probe missile's no longer responding to control!" one of the
telemetering scientists called out.

Admiral Walter, grim-faced, flashed a questioning look at Tom. "Then
recovery has failed?"

"I'm afraid so, sir."

The fused blip was still visible on screen as the radar dishes tracked
it, moving in a way that indicated a steep downward plunge.

For a moment Tom felt numb with despair. But he set his jaw firmly and
turned to the admiral.

"Sir, I'd like helicopters readied for take-off immediately," Tom said.
"As soon as the tracking instruments lose contact, have the recording
tapes picked up from every ship in the task force and brought here to
the _Recoverer_."

Admiral Walter nodded tersely. "Very well. Then what?"

"I'll get to work right now," Tom replied, "and lay out a computer
program to process the readings."

The data--consisting of millions of information "bits" from the
shipboard instrument tapes--would be fed to an electronic brain. The
brain would then calculate the probable location in latitude and
longitude of the sunken missile.

As the admiral snapped out orders, Tom exchanged a brief worried glance
with his father. Each was pondering the same thought.

_Could Tom find the lost Jupiter probe missile? Or would their enemy
locate it first?_

CHAPTER II

UNDERSEA SURVEY

With an effort, Tom forced all thoughts of failure out of his mind and
concentrated on the job at hand. In an hour he had the computer program
blocked out.

Mr. Swift and several of the other scientists checked his work. Each
nodded approval. By this time, the fused blip had long since disappeared
from the radarscopes, indicating that the Jupiter probe missile--or what
was left of it--had plunged to the ocean bottom.

"What's your next move, Tom?" Admiral Walter asked.

"No point