NASA’s mission engineers have made a critical decision to disable the plasma science instrument on the Voyager 2 spacecraft. This move comes as the probe’s power supply gradually diminishes while it continues its journey over 12.8 billion miles (20.5 billion kilometers) from Earth.
Despite this setback, the spacecraft is still equipped with four other science instruments to study the outer region of our heliosphere, the protective bubble created by the Sun’s particles and magnetic fields.
While the Voyager 2 probe is expected to have enough power to continue its exploration with at least one operational science instrument into the 2030s, the team is working tirelessly to maximize its scientific capabilities. The data collected by the Voyager probes is truly unique, as no other human-made spacecraft has ventured into interstellar space, the region beyond the heliosphere.
The decision to deactivate the plasma science instrument underscores the team’s dedication to prolonging the mission’s scientific output. With the Voyager probes providing unprecedented insights into interstellar space, every effort is being made to ensure that this remarkable journey of discovery continues for as long as possible.
The plasma science instrument is a crucial tool, measuring the electrically charged atoms and their flow direction. However, its data collection has been limited in recent years due to its orientation relative to the flow of plasma in interstellar space.
Both spacecraft are powered by decaying plutonium, losing about 4 watts of power each year. After completing their exploration of the giant planets in the 1980s, the mission team disabled several non-essential science instruments to conserve power. This decision provided the spacecraft with extra power until a few years ago.
Subsequently, the team shut off all non-essential onboard systems, including some heaters, to ensure the probes keep working. Additionally, they modified how Voyager 2’s voltage is monitored to delay the shutdown of another science instrument.
On September 26, a team of brilliant engineers sent a command to power down the plasma science instrument on Voyager 2. This command traveled through space for 19 hours via NASA’s Deep Space Network before reaching the spacecraft, and it took another 19 hours for the return signal to reach Earth.
The mission engineers are always vigilant, carefully monitoring any changes made to the 47-year-old spacecraft to prevent any unintended side effects. Fortunately, they have confirmed that the switch-off command was executed flawlessly, and Voyager 2 is operating as expected.
In 2018, the plasma science instrument played a crucial role in confirming Voyager 2’s departure from the heliosphere. This boundary between our solar system and interstellar space is marked by distinct changes in atoms, particles, and magnetic fields, all of which Voyager’s instruments can detect. Inside the heliosphere, particles from the Sun flow outward, but as Voyager 2 ventured into interstellar space, it encountered a different flow of plasma, signaling its historic leap.
The plasma science instrument is an extraordinary piece of technology, with its four “cups” strategically placed to capture essential data. While three cups focus on observing the solar wind within the heliosphere, the fourth cup boldly ventures into interstellar space, providing crucial insights into planetary magnetospheres and the heliosphere.
When Voyager 2 ventured beyond the heliosphere, the plasma flow into the three cups facing the Sun dramatically declined. The fourth cup, however, continues to deliver invaluable data, albeit only once every three months when the spacecraft executes a 360-degree turn toward the Sun. This unique capability has played a pivotal role in the mission, influencing the decision to prioritize this instrument over others.
The plasma science instrument on Voyager 1 ceased operations in 1980 and was powered down in 2007 to conserve energy. However, aboard Voyager 2, the plasma wave subsystem remains active. It is capable of estimating plasma density during solar eruptions that generate shocks in the interstellar medium, producing fascinating plasma waves.
The Voyager team diligently monitors the spacecraft’s condition and available resources, making strategic engineering decisions to optimize the mission’s scientific output.