The Voyager mission's critical moment

The future of NASA's aging Voyager spacecraft, which over the last 45 years have collected data no human-made probes have ever gathered, is starting to come into sharper focus.

Why it matters: Voyager 1 and Voyager 2 are the only functional human-made spacecraft currently in interstellar space.

• Both spacecraft — which launched to space in August (Voyager 2) and September (Voyager 1) 1977 — are not only scientific tools, but emissaries of humanity, carrying golden records that contain images, music and even a map for an alien civilization that may run across it to find us.
• "No spacecraft is going to get back to where Voyager 1 and 2 are for decades," Suzanne Dodd, Voyager's project manager, tells Axios.

Driving the news: Next month, the Voyager science team will meet to discuss the science that the spacecraft have been beaming back and talk about the future of the mission before making recommendations to NASA on how to proceed to get the best science from the aging probes.

• The Voyager team is also putting together a proposal to NASA asking the agency to again extend its mission so it can continue to gather information about this mysterious part of space. A final decision on a mission extension is expected this spring.
• Even as the Voyagers age and encounter technical difficulties, keeping them functioning remains a high priority because their data is unique.
• Mission controllers have turned off instruments on Voyager 1 and Voyager 2 that weren't deemed essential to their interstellar mission in the past, but now, as the spacecraft age, it's possible the team will need to start turning off functional instruments that are sending home important science to conserve power.

The intrigue: Complicating the August meeting — and the mission's future — is the fact that Voyager 1 is in the midst of a somewhat confounding anomaly involving how it communicates with its controllers back on Earth.

• When NASA sends a command for Voyager 1 to point in a certain direction, the probe isn't able to tell them it understood and is executing on the order, even though it follows the direction.
• "Its talking ability is garbled, but its actions are fine," Dodd said.

Between the lines: Troubleshooting the problem is complicated by the fact that it takes more than 21 hours to send a command to Voyager 1 and then another 21 hours to receive a message back because of its extreme distance from Earth.

• The mission's long life also works against current mission managers in another way: Many of the people who used to work with Voyager — particularly those who were around before launch and during construction — are no longer working with the mission.
• Today, NASA has processes for making sure that the technical specifications of any given spacecraft set for launch are digitized and available to the right people, but when the Voyagers were being built, that wasn't the case, further complicating attempts to fix the spacecraft.
• "I think we may never get to the root cause, and I think that we more than likely will live around it, which is pretty typical of extended missions," Dodd said.

In spite of all that, mission managers have devised a way to potentially keep the probes — which were designed for a five-year primary mission — functioning through the 2030s, if everything goes exceedingly well in the meantime.

• Instead of just allowing the spacecraft's power supplies to slowly deplete, the mission managers may be able to manage voltage in a way that would allow the spacecraft's power to exceed current expectations.
• "In the very most optimistic case, we get out around 2038, 2040. I feel good about 2030, but 2035 is scary and 2040 would be miraculous. But it's Voyager. Nobody thought we'd be here in 2022," Bruce Waggoner, the Voyager mission assurance manager, tells Axios.

The big picture: Both of the spacecraft are currently flying through interstellar space, but they're on different trajectories, allowing scientists on Earth to learn more about that part of space from two perspectives.

• Voyager 1 and Voyager 2 also have complementary instruments that are still functioning. Voyager 1 currently has four working instruments, Voyager 2 has five, and four of the five are the same instruments as Voyager 1.
• Having multiple, complementary data points from each spacecraft allows scientists to build more robust models of the interstellar medium and its nature.
• The probes have revealed the complex ways that the Sun interacts with the interstellar medium, showing that the Sun does influence the space between stars.