从旅行者二号经历的高能粒子宇宙射线，到低能粒子，再到几乎没有，表明旅行者二号已经穿越了日冕层的“光顶”。旅行者一号和二号这两次旅行最大的不同，是穿越日冕层时感受到的粒子变化，和日冕层不同的形状。这说明日冕层是随太阳风变化的，是动态的。
NASA engineers have turned off a heater on Voyager 2 because of the continually shrinking power supply facing each of the spacecraft on their odysseys. The heater in question is paired with an instrument called the cosmic-ray subsystem instrument, which is still sending data back to Earth even at its new ambient temperature of minus 74 Fahrenheit (minus 59 Celsius). Engineers have also fired up a long-dormant thruster system on the aging spacecraft.
The long lifetimes of the spacecraft mean we're dealing with scenarios we never thought we'd encounter," Suzanne Dodd, project manager for the Voyager mission at NASA's Jet Propulsion Laboratory in California, said in a statement. "We will continue to explore every option we have in order to keep the Voyagers doing the best science possible."
