NASA's Voyager 1 spacecraft, which is 47 years old, recently reconnected with Earth after a short period of silence. This was made possible by a radio transmitter that had not been used since 1981. Engineers at NASA's Jet Propulsion Laboratory (JPL) in California successfully restored contact with Voyager 1 on October 24.

On October 16, a transmitter malfunctioned, causing a momentary communication lapse for the spacecraft, which is positioned more than 15 billion miles away in interstellar space. This shutdown was probably caused by the spacecraft's fault protection system, which cuts off some systems when too much power is used. The journey of a message from Earth to Voyager 1 and back takes around 23 hours, according to NASA. 

When NASA engineers delivered a command to the spacecraft on October 16, they were unable to detect the response until October 18. Communications with Voyager 1 ceased entirely a day later. The space agency team looked into the matter and found that Voyager 1 had shifted to a second, lower-power transmitter due to a malfunction in its fault protection mechanism.

Despite having two radio transmitters, Voyager 1 has only been using the "X-band" for years. But the "S-band," the other transmitter, uses a different frequency that hasn't been used since 1981. NASA decided not to return to the X-band transmitter at this time until they can figure out what triggered the fault protection system, which might take weeks.

"Engineers are being cautious because they want to determine whether there are any potential risks to turning on the X-band. In the meantime, engineers sent a message to Voyager 1 on October 22 to check that the S-band transmitter was working and received confirmation on October 24. But it's not a fix the team wants to rely on for too long," Voyager mission assurance manager, Bruce Waggoner told CNN. Voyager 1 was launched after Voyager 2, but it took a quicker path, allowing it to leave the asteroid belt before Voyager 2 did. As a result, Voyager 1 passed Voyager 2 on December 15, 1977. It is the first human-made object to enter interstellar space.

Voyager 1 was also the first spacecraft to cross the heliosphere, which is the point where the effects from beyond our solar system become stronger than those from the Sun. Two additional Jovian moons, Thebe and Metis, as well as a thin ring around Jupiter, have been found thus far by Voyager 1. The 'G-Ring' was discovered at Saturn, along with five new moons.