Striking the solar shock wave

摘要

Next week, NASA will call out one last time to Earth's most remote explorer. After 25 years in space, Pioneer 10 is now 10 billion kilometres from the Sun, a distance so great that data from the spacecraft take a little over 9 hours to travel home at the speed of light. Sadly, NASA can no longer afford to listen to Pioneer's swan song. Fred Wirth, who as project manager has devoted most of his career to the Pioneer mission, says, "The volume and scientific importance of the data was not judged to warrant NASA spending $500 000 a year to staff the control centre and operate the spacecraft." In any case, Pioneer 10's power levels are dropping. By the end of next year it will have died, just like its sister spacecraft, Pio-neer 11, which fell silent two years ago.