Voyager Spacecraft Face Fading Power, NASA Takes Steps to Extend Missions
After more than 47 years traversing the vast expanse of interstellar space, the iconic Voyager spacecraft are facing a critical challenge: dwindling power. These pioneering probes, humanity’s farthest-flung emissaries, have provided invaluable data about the cosmos, but their aging power systems are forcing NASA engineers to make difficult decisions to prolong their operational lifespan.
The Voyager missions, launched in 1977, have far exceeded their initial objectives of exploring the outer planets of our solar system. Now, as they journey through interstellar space, they continue to send back valuable information about the heliosphere – the protective bubble surrounding our solar system – and the interstellar medium beyond. However, the spacecraft’s power source, fueled by the decay of plutonium, is gradually diminishing, necessitating careful management of available energy.
To conserve power and keep the missions alive for as long as possible, NASA engineers at the Jet Propulsion Laboratory (JPL) have begun shutting down some of the science instruments on both Voyager probes. This strategy, while necessary, marks a somber chapter in the history of these groundbreaking missions.
On February 25th, Voyager 1’s cosmic ray subsystem experiment was deactivated. This instrument, comprised of three telescopes, was designed to study cosmic rays by measuring their energy and flux. The data collected by this subsystem was instrumental in determining when and where Voyager 1 crossed the boundary of the heliosphere and entered interstellar space in 2012.
Following suit, the low-energy charged particle instrument aboard Voyager 2 is scheduled to be shut off on March 24th. This instrument measures the various ions, electrons, and cosmic rays originating from our solar system and the galaxy, providing valuable insights into the composition and dynamics of the interstellar environment.
According to NASA’s announcement, without these power-saving measures, the twin probes would likely have exhausted their energy reserves within a few months, leading to the termination of the mission. By strategically deactivating selected instruments, engineers estimate that they can extend the operational lifespan of the Voyagers by another year or so before further instruments need to be shut down.
Suzanne Dodd, Voyager project manager at JPL, acknowledged the grim reality while emphasizing the importance of maximizing the missions’ longevity. "The Voyagers have been deep space rock stars since launch, and we want to keep it that way as long as possible," she stated. "But electrical power is running low. If we don’t turn off an instrument on each Voyager now, they would probably have only a few more months of power before we would need to declare end of mission."
The Voyagers are powered by radioisotope thermoelectric generators (RTGs), which convert the heat generated by the decaying plutonium into electricity. Each year, the spacecraft lose approximately 4 watts of power due to the decreasing heat output. To compensate for this gradual decline, the mission team has systematically turned off systems deemed non-essential for maintaining the core functions of the missions, including some science instruments.
Initially equipped with 10 science instruments each, the Voyager spacecraft now operate with only three instruments apiece. Some instruments were specifically designed for data collection during planetary flybys and were deactivated after the spacecraft completed their exploration of the solar system’s planets.
Voyager 1 officially entered interstellar space in 2012, followed by Voyager 2 in 2018. These milestones marked their passage beyond the heliosphere, the protective bubble created by the Sun’s magnetic field and solar wind, into the realm of interstellar space.
In October 2024, the team made the difficult decision to turn off Voyager 2’s plasma science instrument, which measured the density, temperature, and velocity of electrically charged particles, further conserving power.
Currently, Voyager 1 continues to utilize its magnetometer and plasma wave subsystem. However, its low-energy charged particle instrument is slated for deactivation next year. Voyager 2 will continue gathering data through its magnetic field and plasma wave instruments, while its cosmic ray subsystem is scheduled for shutdown in 2026.
Patrick Koehn, Voyager program scientist, emphasized the extraordinary achievements of the missions. "The Voyager spacecraft have far surpassed their original mission to study the outer planets," he said. "Every bit of additional data we have gathered since then is not only valuable bonus science for heliophysics, but also a testament to the exemplary engineering that has gone into the Voyagers – starting nearly 50 years ago and continuing to this day."
Voyager 1 was launched on September 5, 1977, shortly after its twin probe, Voyager 2, which began its journey on August 20, 1977. Voyager 1 followed a faster trajectory, exiting the asteroid belt sooner and conducting close encounters with Jupiter and Saturn. During these flybys, it made remarkable discoveries, including two new Jovian moons, Thebe and Metis, as well as five new moons and a new ring, known as the G-ring, around Saturn. Voyager 2 embarked on a trajectory that took it past the gas giants Jupiter and Saturn and subsequently allowed it to explore the icy giants Uranus and Neptune.
Voyager 1 is currently located more than 15 billion miles (25 billion kilometers) from Earth, while Voyager 2 is over 13 billion miles (21 billion kilometers) away. These immense distances underscore the remarkable journey undertaken by these spacecraft and the challenges associated with maintaining communication and power.
With the implementation of the current energy-conserving plan, NASA engineers believe that the twin spacecraft could potentially continue operating into the 2030s, albeit with only one instrument each. This extended operation would provide valuable opportunities to gather further data from the unexplored regions of interstellar space.
Linda Spilker, Voyager project scientist at JPL, emphasized the ongoing significance of the missions. "Every minute of every day, the Voyagers explore a region where no spacecraft has gone before," she said. "That also means every day could be our last." This sentiment captures the precarious nature of the missions and the constant possibility of unexpected failures, while also highlighting the immense scientific value of the data they continue to transmit. The Voyager missions represent a remarkable feat of engineering and a testament to human curiosity and our desire to explore the universe. Even as their power dwindles, their legacy will continue to inspire future generations of scientists and engineers to push the boundaries of space exploration.
