In 1977, two probes were launched less than a month apart on a mission to explore the unknown. The Voyager spacecraft twins were designed to journey beyond our solar system, venturing outside the protective bubble created by our sun. Voyager 1 reached interstellar space in 2012, followed by Voyager 2 in 2018. These spacecraft were the first to cross into this new frontier and have been collecting data for nearly 48 years. However, as they age, their power supply diminishes by about 4 watts each year, leading to the shutdown of unnecessary systems and instruments to conserve energy. The Voyager team, some of whom have been with the mission since its inception, face tough decisions to keep the mission alive and troubleshoot issues as the spacecraft endure the harsh conditions of space.
Linda Spilker, the project scientist for the Voyager mission, discussed the challenges of operating these aging spacecraft and passing down knowledge to new team members. With a smaller team and fewer instruments in operation, the mission has evolved over the years. Originally intended to last just a few years after reaching Neptune, Voyager surpassed expectations by crossing the heliopause and entering interstellar space. The emotional toll of turning off instruments that have been part of the mission for over 50 years is balanced by pride in the data they have collected. Operating a mission with 1970s technology brings its own set of challenges, as engineers work to prevent critical components from failing beyond the spacecraft’s warranty. Each year, we lose approximately 4 watts of power on the spacecraft, so we must identify ways to save 4 watts annually. The spacecraft was designed with a lot of redundancy, including duplicate computers and key components. We have managed to deactivate the backup units, but now we are left with no choice but to turn off some of the science instruments in order to conserve power. This is the current situation we are facing.
Additionally, the decreasing power supply is causing the temperature inside the spacecraft to drop. The electronics within the bus, which houses all the components, are gradually getting colder. This has raised concerns about the thermal limitations – how cold can the hydrazine lines outside the bus get before freezing, and how cold can other components become before malfunctioning. This presents another challenge that we are tackling.
Despite these obstacles, we are optimistic about the possibility of having one or even two spacecraft operational for the 50th anniversary in 2027. We are also aiming to extend their functionality into the early 2030s, possibly with one or two science instruments.
Regarding the spacecraft’s language, it operates on a unique machine language specific to the Voyager program. This includes three different computers for attitude control, commands, and data transmission. To address technical issues, we have enlisted experts familiar with the archaic machine language, as well as engineers who have had to learn it. This detective work has proven successful in troubleshooting and resolving problems.
The Voyager mission has taught us to anticipate and address unexpected challenges that arise, such as computer failures and communication disruptions. By collaborating with retired experts and subject matter specialists, we have managed to overcome various setbacks and keep the mission running efficiently.
The team has evolved over the years, with a mix of seasoned individuals who have been involved since the mission’s inception and newer members who bring fresh perspectives. Retirees have returned to contribute their expertise part-time, while younger recruits have brought new insights to the table. The transition of knowledge from experienced scientists to the next generation is crucial for the continuity and success of the mission.
From a scientific standpoint, the Voyager mission has provided invaluable insights and paved the way for future exploration. It has left a trail of clues and discoveries, particularly in uncovering the mysteries of Saturn’s moon, Titan. This legacy serves as a foundation for upcoming missions and scientific endeavors. Kami tidak tahu apakah Titan bisa memiliki samudra cair di permukaannya, atau seperti apa permukaannya. Selama terbang dekat Voyager di Titan, kami menemukan bahwa tidak satupun dari instrumen atau filter kamera yang dapat menembus kabut. Terlihat seperti hari buruk di kota berkabut.
Itu adalah penemuan Voyager, atau ketidakpenemuannya, tidak bisa melihat permukaan Titan, yang mengarah ke misi Cassini. Setelah terbang dekat Voyager, NASA dan European Space Agency berkumpul dan berkata, “kita perlu kembali.”
Saya punya kesempatan untuk bekerja di Cassini. Saya terlibat sangat awal, dan membantu merumuskan konsep misi. Saya menghabiskan sekitar 30 tahun di Cassini, dan kemudian misi berakhir pada tahun 2017. Pada titik itu, saya berpikir untuk pensiun tapi kemudian saya mendapat kesempatan untuk kembali ke Voyager dan bekerja dengan Edward Stone [yang menjabat sebagai ilmuwan proyek untuk Voyager dari 1972 hingga 2022] dan tim ilmu pengetahuan, dan kembali ke misi di mana saya memulai.
Saya pulang dan memberi tahu suami saya, “Saya rasa saya tidak akan pensiun.”