But the moment of closest encounter did not have the same impact a landing would have had. Although the champagne would flow later for those who had worked so long and hard on this successful mission, there was none now. In the press room there were just four coffeepots working overtime to help keep the press alert. In the science areas, focus had shifted to the satellite encounters, which would stretch over the next 24 hours; meanwhile, a few persons tried to catch a little sleep at their desks before the first closeups of Io came in. The instant of encounter came ... and went ... with no screams, no New Year’s noisemakers. All the excitement of the mission lay both behind ... and ahead. Thursday, February 22. The encounter activity was kicked off in Washington, D.C., by a press conference at NASA Headquarters. After introductory statements by NASA and JPL officials, some of the scientific results from the observatory and far encounter phases were presented. Both the plasma wave and the planetary radio astronomy instruments had detected very-low-frequency radio emission that generally increased in intensity whenever either the north or south magnetic pole of Jupiter tipped toward the spacecraft. The plasma wave experiment had also detected radiation that seemed to come from a region either near or beyond the orbit of Io—perhaps even as far as the outer magnetosphere. In addition, Frederick L. Scarf, Principal Investigator for the plasma wave instrument, released a recording of the ion sound waves created by 5 to 10 kilovolt energy protons traveling upstream from Jupiter. James Warwick, Principal Investigator of the radio astronomy investigation, enthusiastically reported the detection of a striking new low-frequency radiation from Jupiter, at wavelengths of tens of kilometers. Such radio waves cannot penetrate the ionosphere of the Earth, and thus had never been detected before. Because of their huge scale, these bursts probably did not originate at Jupiter itself, but in magnetospheric regions above the planet—perhaps in association with the high-density plasma torus associated with Io. Warwick commented that “only from the magnificent perspective of the Voyager as it approaches Jupiter have we been able to get this complete picture.” [Illustration: The Voyager 1 encounter with Jupiter took place during a little more than 48 hours, from the inbound to the outbound crossing of the orbit of Callisto. This figure shows the spacecraft path as it would be seen from above the north pole of Jupiter. Closest approach to Jupiter was 350 000 kilometers. The close flybys of Io, Ganymede, and Callisto all took place as the spacecraft was outbound.] Voyager 1 trajectory Launch date = 9/5/77 Jupiter arrival date = 3/5/79 Satellite closest approach Sun occultation Earth occultation Io Ganymede Periapsis Callisto Amalthea Europa