VOYAGER: The Mission for Interstellar Space
Image of Saturn by Voyager 2, obtained Aug 11, 1981.
Interstellar space—the region between stars where no person has ever been, filled with material ejected by the death of adjacent stars millions of years ago. This is where the Voyager 1 spacecraft and its twin Voyager 2 have been journeying for the past decade, relaying scientific information regarding their surroundings back to Earth through the Deep Space Network (DSN).
Seven months ago, in November 2023, Voyager 1 stopped sending coherent information to mission control. Instead, it started sending unintelligible data—an indecipherable repeating pattern of code—instead of its usual binary information. Of course, this was not a completely unexpected event, as the spacecraft has been in space for over forty years and is currently in uncharted territory among the stars, around 24 billion kilometers from Earth. Voyager 1’s team worked to find not just the cause of the issue, but a way to fix it.
With time, the team identified the root cause of the problem: an issue with the telemetry modulation unit in the flight data subsystem (FDS), which is used to “package” data to be sent to Earth. Through a creative fix, they were able to work around the issue to restore communication. Consequently, on April 20th, 2024, they were able to resume receiving intelligible data from two of Voyager 1’s four scientific instruments, informing Earth of its operational status. Finally, two months later, all four instruments are up and running, successfully continuing the spacecraft’s effective communication with mission control. Voyager 1, it seems, will valiantly carry on with its interstellar mission.
So, what is this mission exactly? Voyager 1 and 2 were first launched in 1977. Their primary mission was to explore Jupiter and Saturn, in which they were successful. They made a wide range of discoveries that contributed to our scientific knowledge of these planets, such as the intricacies of Saturn’s rings or the active volcanoes on Io, one of Jupiter’s moons. Voyager 2 went on to complete close flybys of Uranus and Neptune, the remaining two gas giants. After this success, the spacecrafts’ missions were extended. Their current mission is called the Voyager Interstellar Mission (VIM), whose objective is “to extend the NASA exploration of the solar system beyond the neighborhood of the outer planets to the outer limits of the Sun's sphere of influence, and possibly beyond.” Scientists hope to locate the heliopause boundary, the outer bounds of the Sun’s magnetic field and solar wind, and to discover more about the environment of the outer solar system.
Both Voyagers are currently escaping the solar system at a rate of 3.6 AU (Astronomical Unit, around 150 million kilometers) and 3.3 AU respectively. Voyager 1 crossed the outer boundary of the heliosphere and entered interstellar space on August 25, 2012. Voyager 2 flew into interstellar space in 2018. From their respective locations in space, these adventurers have been continuously collecting and returning data to Earth. Voyager 1 is expected to transmit its findings until at least 2025. Depending on how much power remains for the spacecrafts to send a signal to Earth, they could remain in the range of the Deep Space Network until 2036. This sort of interstellar exploration is one ultimate goal that the Voyagers carry as they travel farther into the depths of the unknown.
Even having inhabited our planet for 300,000 years in hominid form, we are far from the oldest or greatest bodies in the universe. We have yet to discover so much about the world beyond our own. Voyager 1 and 2, as the first objects from Earth to venture into interstellar space, will continue to expand our knowledge of space for as long as they can. It’s one small step for spacecraft, one giant leap for space exploration in the history of humankind.