Engineers Extend Power Supply for NASA Voyager 2 Probe

More than four decades after leaving Earth, NASA's Voyager 2 spacecraft is still sending valuable information back from interstellar space. But keeping the aging probe alive has become an increasingly difficult engineering challenge.

Voyager 2 launched in August 1977, and its radioisotope power system has been steadily losing electrical output as the plutonium inside its generators naturally decays. NASA says the spacecraft's available power decreases by roughly 4 watts every year.

Now, engineers at NASA's Jet Propulsion Laboratory are using increasingly creative power-management techniques to squeeze more life out of the spacecraft.

The goal is simple: keep Voyager 2 collecting science for as long as possible.

Voyager 2 Is Running Out of Power

Voyager 2 does not have solar panels. At its enormous distance from the Sun, sunlight is far too weak to provide practical power.

Instead, the spacecraft relies on radioisotope thermoelectric generators (RTGs). These generators convert heat produced by the natural radioactive decay of plutonium-238 into electricity.

When Voyager 2 launched in 1977, its three generators produced substantially more power than the spacecraft needed. Almost 49 years later, that electrical budget has become extremely tight.

NASA's radioisotope power information says Voyager 2's RTGs originally produced about 158 watts each, while the spacecraft's power was measured at about 225 electrical watts in April 2024.

That decline means engineers have to make difficult decisions about what stays powered.

Engineers Are Saving Power by Turning Things Off

One of the most remarkable parts of the Voyager mission is that extending its life doesn't necessarily mean adding more power.

Instead, engineers are removing power consumption wherever possible.

Over the years, NASA has switched off systems and scientific instruments that are no longer essential. In September 2024, engineers shut down Voyager 2's plasma science instrument because its scientific usefulness had declined while its power requirements remained important. Four other science instruments continued operating at that time.

In March 2025, NASA also shut down Voyager 2's Low-Energy Charged Particles instrument, another step designed to preserve the remaining power for the spacecraft's most important scientific and engineering systems.

This is essentially an engineering version of living with a shrinking battery: keep the most valuable functions running and eliminate everything that can be sacrificed.

The “Big Bang” Plan

NASA engineers have been developing a more ambitious energy-saving strategy known informally as “the Big Bang.”

The plan involves changing multiple powered systems at once, switching off some equipment and replacing or reconfiguring functions with lower-power alternatives.

NASA said in April 2026 that Voyager 2 would be the first spacecraft to receive the experimental power-saving approach because it has slightly more available power than Voyager 1 and is closer to Earth, making it the safer spacecraft on which to test the strategy. Testing was planned for May and June 2026.

The idea isn't to magically increase the amount of electricity Voyager 2's aging generators produce.

Instead, engineers are trying to make every remaining watt count.

Why Temperature Is Just as Important as Electricity

Keeping Voyager 2 alive isn't simply a matter of turning off electronics.

The spacecraft is operating in an extremely cold environment, and some components need to remain warm enough to function.

For example, NASA has previously explained that spacecraft fuel lines must be protected from freezing because a failure there could prevent Voyager from maintaining the correct antenna orientation toward Earth. Engineers therefore have to balance electrical consumption against thermal requirements.

That creates a difficult engineering puzzle:

Turn off too much, and the spacecraft can become too cold.

Keep too much running, and the limited power supply disappears sooner.

The Voyager team has spent decades finding ways to maintain that balance.

Voyager 2 Is Still Doing Science

Despite its age, Voyager 2 remains scientifically valuable.

The spacecraft crossed the heliopause and entered interstellar space in November 2018. It is now exploring an environment that no other spacecraft has been able to study from such a distant location.

NASA's current instrument-status information shows that Voyager 2's magnetometer and plasma-wave subsystem remain operational, while several other instruments have already been shut down over the years.

These remaining instruments help scientists study the magnetic fields and particles surrounding the spacecraft.

And because Voyager 2 is traveling through interstellar space, even relatively small measurements can provide information about a region that is otherwise extremely difficult to investigate.

Why Voyager 2 Still Matters

It can be easy to think of Voyager as an old spacecraft that has simply survived far beyond expectations.

But the mission is much more than that.

Voyager 2 visited Jupiter, Saturn, Uranus and Neptune before heading toward interstellar space. It remains the only spacecraft to have flown past Uranus and Neptune.

Its observations transformed our understanding of the outer solar system and later gave scientists a rare opportunity to study the boundary between the Sun's influence and interstellar space.

Today, the mission is also becoming a lesson in something different: how to operate technology long after its original design assumptions have expired.

The engineers managing Voyager 2 cannot physically repair the spacecraft. They cannot replace its generators. They cannot send someone to service it.

Every solution has to be designed on Earth and transmitted across billions of kilometers.

Commands Take Hours to Reach Voyager 2

Distance makes even routine engineering work remarkably difficult.

Voyager 2 is now more than 13 billion miles (21 billion kilometers) from Earth, according to NASA's current mission information.

A command sent from Earth therefore takes many hours to reach the spacecraft, and engineers must wait for the spacecraft's response before knowing whether the command worked as expected.

NASA has previously noted that communications with Voyager 2 can require roughly 19 hours in each direction, depending on the spacecraft's distance.

That means engineers cannot simply make a change and immediately check the result.

A small mistake can become a very long wait.

The Mission Could Continue Into the 2030s

The Voyager mission is already operating far beyond its original expectations.

NASA previously estimated that, after the latest power-conservation measures, the spacecraft could potentially continue operating with at least one science instrument into the 2030s, although the exact lifetime depends on the spacecraft's health and its shrinking power supply.

NASA also notes that even after science operations eventually end, engineering data could potentially continue to be transmitted for several more years, with the Deep Space Network potentially remaining capable of receiving signals from the spacecraft into the mid-2030s depending on available power.

That is not a guarantee.

Voyager 2 was designed nearly half a century ago, and unexpected failures could shorten its remaining operational life.

A Different Kind of Space Technology

Modern spacecraft are often associated with powerful computers, advanced sensors and sophisticated autonomous systems.

Voyager 2 represents something very different.

Its technology was designed in an era when computers were dramatically less powerful than today's smartphones. Yet the spacecraft continues to operate because generations of engineers have learned how to work around its limitations.

The current power-saving effort is another example of that philosophy.

Instead of asking how to make an almost 50-year-old spacecraft perform like a modern probe, engineers are asking a much more practical question:

What is the most valuable science we can still get from the power we have left?

That approach may ultimately be Voyager 2's greatest engineering legacy.

Voyager 2 Keeps Going

Voyager 2 has traveled farther than almost any machine humanity has ever built, and it continues to explore an environment that remains largely unknown.

Its declining power supply is an unavoidable consequence of time. But engineers have repeatedly found ways to stretch the spacecraft's remaining resources.

From shutting down unused systems to carefully managing heaters and scientific instruments, every decision is now about extending the mission a little further.

The spacecraft may eventually fall silent.

But for now, NASA's engineers are doing what they have done for decades: finding another way to keep Voyager moving forward.

And somewhere billions of kilometers away, a spacecraft launched in 1977 is still answering the call.

Key Takeaway

NASA's Voyager 2 is facing a steadily declining power supply because its plutonium-powered RTGs lose electrical output over time. Engineers are responding with aggressive power conservation, including shutting down nonessential instruments and developing the “Big Bang” energy-saving strategy. NASA expects the mission could continue returning science from interstellar space into the 2030s, although the exact lifetime remains uncertain.

Sources

NASA Science — Voyager Mission

NASA JPL — Voyager Power Strategy

NASA — Voyager 2 Power Conservation