The Voyager 2 spacecraft has been away from Earth for more than 43 years and is now 125 astronomical units away from our planet. That is 125 times the distance between the Earth and the Sun.
Understandably, this distance makes it quite difficult for NASA to communicate with distant spacecraft – there is a delay of more than 17 hours. With Voyager 2, however, there’s another problem with talking to the spaceship.
After flying by Jupiter, Saturn and Uranus, Voyager 2 made its last planetary flight in August 1989 over Neptune. Scientists are also interested in flying over Neptune’s fascinating moon Triton, so they commanded Voyager 2 to do so on its way out of Neptune, past Triton’s north pole. This orbit sends it along a path south from the plane of the Solar System, and it continues to place it south.
This has consequences for communication with NASA’s Deep Space Network on Earth, which includes three major radio antenna facilities around the world, in California, Spain and Australia. Typically, this geographic range allows all still operational NASA spacecraft to communicate with at least one of these facilities at all times.
But since Voyager 2 had dived so far south of the Solar System’s plane, it can now only communicate by line of sight with its 70-meter-wide antenna in Canberra, Australia. Since this facility is around 5 decades old, it needs to undergo refurbishment and upgrading work starting in March, and it has been running offline ever since. This work is expected to end in February, so NASA has been unable to send a signal to Voyager 2 since then.
Last week, to test recently installed hardware on a large disk, Voyager mission managers were able to send a series of signals to the spacecraft for the first time since March. The space agency said cruise ship 2 responded that it had received the signals and executed NASA’s orders.
That’s good for NASA and science in general, as Voyager 2 (along with Voyager 1) is currently venturing beyond the Solar System, into interstellar space. In addition to the great black region, Voyager 2 will continue to return data about the speeds, density, temperature and pressure of charged particles in interstellar medium.