nounced himself as satisfied with their ability to
operate the ship under any normal conditions. With Turgan and Lura
watching and checking his calculations, he plotted a course which would
intercept Mars on its orbit.

"Luckily, Mars is approaching us now," he said, "and we won't have a
stern chase, which is always a long one. We will be able to reach Mars,
spend several days on it and return to Earth before ships can reach the
Earth from Jupiter, even if they are already on the way, which is highly
probable. I'll turn the ship a little."

Under his direction, the crew turned the ship in its course until it was
headed for the point in space where Damis planned to intercept the red
planet. With the course set to his satisfaction, he gave orders for the
stern motors to be operated at such a power as to give the highest
acceleration consistent with comfort for the crew. There were no windows
in the ship but two observers seated at instruments kept the entire
heavens under constant observation. Damis motioned one of them to stand
aside and told Lura to take his place. She sat down before a box in
which were set two lenses, eye-distance apart. She looked through the
lenses and gave a cry of astonishment. Before her appeared the heavens
in miniature with the entire galaxy of stars displayed to her gaze. In
the center of the screen was a large disk thickly marked with pocks.

"The moon," explained Damis. "We are headed directly toward it now but
we'll shift and go around it. We'll pass only a few hundred miles from
its surface, but unfortunately it will be between us and the sun and
you'll be able to see nothing. Look in the other observer."

* * * * *

Lura turned to the second instrument. A large part of the hemisphere was
blotted out by the Earth which was still only a few thousand miles away.
The sun showed to one side of the Earth, but a movable disk was arranged
in the instrument by means of which it could be shut off from the gaze
of the observer. Despite the presence of the sun, the stars shone
brilliantly in the intense black of space.

"How fast are we traveling?" asked Lura.

"It is impossible to tell exactly," he replied. "I can approximate our
speed by a study of the power consumed in our stern motors and again I
can approximate it by a series of celestial observations, provided we do
not have to change our course while I am doing so."

"Isn't there some sort of