Speed 2, Chance Encounter, space travel

The ship reached the ringed giant on schedule; by that time, the green beast had cleared the ring of pebbles on its way to the sixth planet. Since its discovery by the crew, the beast had gotten progressively faster, as its green jet appeared to have been functioning continuously, causing speculation as to how the beast was generating so much power. The doctor also noted that the beast gave off very little heat, though this was not unusual among known space beasts.

The itinerary had allotted ten dozen hours for guests to explore the ringed giant and its satellites, before heading to the inner planets, including the still highly-exothermic third planet. At its projected acceleration, the beast would have crossed the orbit of the great giant by then (though the fifth planet itself was on the other side of its star).