Over the next day or so the press packed up and went home. The TV monitors showed the spacecraft’s parting glance at a crescent Jupiter, only hinting at the vastness of space Voyager 1 would travel until its encounter with Saturn in the autumn of 1980. Maybe now there would be a relative calm that would allow the scientists to begin analyzing that “decade’s worth of data.” But things were not to be calm just yet.
Fire and Brimstone
At about 5 a.m. on March 8, Voyager had taken a historic picture. Looking back at a crescent Io from a distance of 4.5 million kilometers, the camera had been used to obtain a long-exposure view for the spacecraft navigation team—one that showed the satellite against the field of background stars. During the day, Linda Morabito, an optical navigation engineer, began to work with this picture on her computer-controlled image display. She noted what appeared to be a crescent cloud, extending beyond the edge of Io. But Io has no atmosphere, so a cloud rising hundreds of kilometers above the surface did not seem to make sense.
The next day, working with her colleagues, Morabito eliminated all possibilities for the new feature on Io except the obvious—a cloud. If it were a cloud, it must be the result of an ongoing volcanic eruption of incredible violence. The picture was shown to members of the Imaging Team, who agreed with the identification. But it was Friday and Brad Smith and Larry Soderblom, along with most of the other team members, had left for the weekend to try to get some rest. The picture would have to wait two more days.
HIGHLIGHTS OF THE VOYAGER 1 SCIENTIFIC FINDINGS[2]
Atmosphere
Uniform wind speeds for cloud features with widely different size scales, suggesting that mass motion and not wave motion is being observed.
Rapid formation and spreading of bright cloud material, perhaps the result of disturbances that trigger convective activity.
A pattern of east-west winds in the polar regions, previously thought to have been dominated by convective upwelling and downwelling.
Anticyclonic motion of material associated with the Great Red Spot, with a rotational period of about six days.