At 47 years old, the pair of Voyager probes are the oldest currently operational deep space mission, and in their time they have traveled all the way through our solar system and out into the interstellar space that lies beyond the influence of our sun. At a distance of around 15.4 billion miles away from Earth, and with hardware constructed in the 1970s, the pair have faced their share of technical difficulties.
Voyager 1 in particular had a serious issue with its communications system this year that prevented it from transmitting science data for months. But now, following some very careful fixes, Voyager 1 is back online again, having resumed its science operations and continuing its long, lonely mission.
The communication problem was announced in December last year, when a system called the telemetry modulation unit stopped communicating with the probe’s computer system, called the flight data system. That issue was fixed in April this year, by engineers cleverly divvying up the work of a broken chip and distributing it throughout the functioning computer system. In June, Voyager 1 could power its science instruments back on and return to its observations.
That wasn’t the end of the probe’s problems though. In October, the spacecraft turned off one of its radio transmitters for no obvious reason, in what seemed to be an automatic response when the spacecraft detects a fault. Non-essential systems are designed to turn themselves off when an anomalous events occurs to prevent damage, such as from drawing too much power. But this meant that part of the communications system called the X-band radio transmitter was no longer working properly, and the spacecraft could only communicate using a weaker transmission system called the S-band.
It wasn’t clear if the S-band signal would even be strong enough to be picked up from Earth, but engineers were able to locate the signal and keep in touch with the spacecraft. This meant they weren’t able to get science data though, due to communication limitations.
Before they could turn the X-band transmitter back on, engineers had to figure out what had triggered the fault detection in the first place. It turns out to have been turning on a radiator that caused the fault, as the spacecraft is operating on such a tiny amount of power. Though its power generators output around 470 watts on launch, the spacecraft loses 4 watts of power each year, so power is a constant concern. The spacecraft currently uses four of its 10 original science instruments.
Engineers reactivated the X-band transmitter earlier this month, and has been collecting data again since last week. With a few final tasks like resetting a system that synchronizes the spacecraft’s three onboard computers, it will be back to full operations once again.