On December 10th, NASA announced that Voyager 2 has left the sun’s protective bubble and is now flying in interstellar space. It is now 11 billion miles away from Earth! The bubble it passed through, known as the heliopause, is the boundary between the protective bubble of the sun’s particles and magnetic field, and the interstellar medium. Scientists were able to tell that Voyager 2 was approaching heliopause on November 5th when their instruments read a sharp decrease in solar winds and an increase in galactic cosmic rays. On December 10th, scientists confirmed that Voyager 2 has joined its twin, Voyager 1, beyond the reaches of our solar system.
Voyager 1 entered interstellar space back in 2012, however, each spacecraft had very different crossings. Voyager 1 and 2 passed through the heliopause in different hemispheres and at different points in the solar cycle, so naturally the information transmitted by Voyager 1 is different than the information transmitted by Voyager 2. Both spacecrafts are true explorers in uncharted territory and will hopefully continue transmitting data to scientists back on Earth for many years to come, ushering in a new era of heliophysic science.
Voyager 2 has had a long journey up to this point. It has been flying through space since 1977, when it was launched within weeks of Voyager 1. Since leaving our planet, Voyager 2 has visited 4 planets; Saturn, Jupiter, Neptune, and Uranus, and has traveled over 18.5 billion miles. At the speed of 34,191 miles per hour, Voyager 2 is able to travel 290 million miles every year. At this point Voyager 2 is so distant that it takes transmitted data about 17 hours to reach scientists here on Earth, traveling at the speed of light. By comparison, it takes light from the sun about 8 minutes to reach us on Earth.
Although the spacecraft is a senior citizen, scientists are hopeful that Voyager 2 will continue to transmit data for another 10 years, making the Voyager mission an impressive 50-year mission. As an older piece of technology, keeping the spacecraft going is not without its struggles. Scientists monitor the spacecraft’s heat and energy reserves. As the spacecraft ages, it generates less heat year after year and the power produced by the Voyager 2 is declining gradually. Eventually, to save power, scientists will have difficult decision of deciding which of Voyager’s instruments to turn off, one by one. Until then, there is a lot still to learn about interstellar space and scientists are excited to see what the Voyager spacecrafts can tell us about the space between the stars.
If you want to keep up with Voyager 1 and 2, you can check out NASA’s live feed of their mission status at https://voyager.jpl.nasa.gov/mission/status/