The Voyager 1 spacecraft, located nearly 25 billion kilometers from Earth, continues to face challenges due to its dwindling power supply.
Nasa engineers have successfully restored communication with Voyager 1, and the spacecraft is operating normally after a prolonged signal loss caused by its decreasing power. The issue began in October when the aging probe automatically switched from its X-band transmitter to the much weaker S-band transmitter to communicate with the mission team on Earth. As the most distant spacecraft from Earth, Voyager 1 is currently exploring interstellar space at a distance of 24.9 billion kilometers, according to CNN.
Voyager 1 traveling through interstellar space. (Photo: Sci Tech Daily).
The probe switched its transmitter when the onboard computer determined that Voyager 1 had too little power after the mission team sent a command to turn on one of the heaters. This unexpected change prevented engineers from receiving information about the status of Voyager 1, as well as the scientific data collected by the spacecraft’s instruments, for nearly a month. With some clever solutions to address the issue, the team successfully switched Voyager 1 back to the X-band transmitter and resumed daily data transmissions from mid-November.
“The duo of probes was never really designed to operate like this, and the whole team learns new things every day,” said Kareem Badaruddin, Voyager mission manager at NASA’s Jet Propulsion Laboratory in Pasadena, California. “We’re fortunate they were able to fix this problem.”
This is just one of many challenges that the mission team has faced in recent years as Voyager 1 and its twin, Voyager 2, continue to explore space more than 47 years after launch. The duo of probes, launched weeks apart in 1977, has far outlasted their original mission, which was designed to fly by the largest planets in the Solar System over four years. They are now traveling through interstellar space and are the only operational spacecraft beyond the heliopause, the boundary of the Sun’s magnetic field and charged particle bubble that extends past the orbit of Pluto.
Both spacecraft operate using heat from decaying plutonium converted into electricity. Each year, the probes lose about 4 watts of power, according to NASA, equivalent to a small energy-saving light bulb. The team began shutting down any systems that were not critical to the probes’ flight five years ago. Some of these systems include heaters that help the scientific instruments operate at appropriate temperatures. However, engineers were surprised that all contact instruments still functioned, even at temperatures significantly lower than those they were tested at decades earlier.
Occasionally, the engineering team sends commands to Voyager 1 to turn on some heaters and warm components that have been damaged by radiation after decades in space, according to Bruce Waggoner, Voyager mission assurance manager. The heat may help reverse damage caused by radiation, a factor that affects the performance of the spacecraft’s components. However, the command sent to the heaters on November 16 triggered the spacecraft’s automatic fault protection system. If a spacecraft uses more power than is available, it automatically shuts down non-essential systems to conserve energy. The team detected the latest issue when they received no response from the spacecraft on October 18.
The two Voyager probes had turned off all non-essential systems except for the scientific instruments, causing the fault protection system to deactivate the X-band transmitter and switch to the S-band, which uses much less power. Voyager 1 had been using the X-band transmitter for decades, but the S-band had not been used since 1981 due to its much weaker signal. The team had to search for the extremely weak S-band signal before they could restore communication with the spacecraft.
On November 7, engineers successfully sent commands to Voyager 1 to switch back to the X-band transmitter and began collecting scientific data on November 18. They are actively reinstalling the system used to synchronize Voyager’s three computers. This is one of the final tasks aimed at ensuring Voyager returns to its previous operational state before the signal transmitter issue arose.
The transmitter change is just one of several initiatives NASA has used to overcome communication challenges with the aging spacecraft this year, including firing thrusters to help keep Voyager’s antenna pointed toward Earth and developing solutions for computer glitches that interrupted the flow of scientific data from the probe for several months.
The Voyager team uses a computer model to help predict how much power the heaters and instruments onboard the spacecraft use. However, the incident of turning on the heaters triggering the fault protection system signals that this probe has reached the end of its lifespan and faces a more uncertain future.
