fe of the spaceship resumed, for the time being, without him. The
next port of call was Jupiter, and that presented problems of its own.
Between Mars and Jupiter was the great asteroid belt, a region of many
thousands of tiny planetoids, ranging in size from worldlets of two or
three hundred miles in diameter down to rocks the size of footballs.
"The debris of an exploded planet," was the comment Russ made to Burl.
"That's the most likely explanation. Anyway," he added, "there seems to
be no Sun-tap station on any of them. The next one is beyond the
asteroids, in Jupiter's orbit."

During the next few days, Lockhart and the two astrogators were busy
working out a rather complex maneuver, which consisted of having the
ship jump over the asteroid belt rather than travel directly through it.
While the orbits of thousands of the larger asteroids had been charted,
there were thousands more that consisted of just chunks of rock too
small to notice. They could not chance a collision with one of
these--yet to work out the whereabouts of all of them was impossibly
time-consuming.

What the _Magellan_ did was to depart from the plane of the ecliptic,
that level around the Sun to which all the planets generally adhere, and
to draw outward so as to avoid the path of the asteroids, then to come
back in onto the orbit and plane of Jupiter. This involved some tricky
work with the various gravitational lines, using Mars and the Sun for
repulsion and certain stars for attraction.

There were quite a number of gravity shifts, and during this period no
one could be quite sure what his weight would be from one moment to
another. There were several periods of zero gravity, when the crew
members would float and face the complex annoyances of a steady feeling
of free fall. Burl, after a couple of such sessions, got the hang of it
rather comfortably.

Lockhart looked at him oddly and smiled. "Glad to know it. I may have a
task for you soon, then."

Others found the weightless conditions not so bearable. One of the
engineering crew, Detmar, had to be hospitalized. What he had resembled
severe seasickness. Oberfield also experienced moments of acute upset.

Boulton's condition did not change. Once or twice he stirred slightly in
his sleep, and seemed to murmur something, but then he would lapse back
into his coma. Fortunately he did not resist food, and did swallow
liquids forced into his mouth.

Except for one or two rare intervals, com