In 1977, two probes launched less than a month apart on a mission to the great beyond.
The Voyagers are powered by heat from decaying plutonium, which is converted into electricity.
Each year, the aging spacecraft lose about 4 watts of power.
An artist’s depiction of the Voyager spacecraft.NASA/JPL-Caltech
Each Voyager spacecraft began with 10 instruments, but now have just three each.
This interview has been lightly edited for clarity and length.
Passant Rabie, Gizmodo: How long have you worked on the Voyager mission?
Spilker explains the tradition of lucky peanuts, which date back to the Ranger Project in the 1960’s, at a gathering in Von Karman Auditorium at NASA’s Jet Propulsion Laboratory in Pasadena, California. Credit: NASA/JPL-Caltech
I, of course, hadnt heard of Voyager.
So I said, wheres Voyager going?
Gizmodo: How has the mission evolved over the years?
Weve turned off a lot of instruments on Voyager.
As the instruments turned off, the mission got smaller.
The challenge was, can we reach the heliopause?
We didnt know where it was, we had no idea how far away it was.
If you think about that, thats like 21 years after the start of the mission.
Gizmodo: Is it an emotional decision to turn off Voyagers instruments?
He helped build the instrument in the early 1970s.
And he said, it was hard to think about turning it off for the whole team.
Gizmodo: What are the challenges that come with operating a mission for this long?
So the challenge with these aging components is, how long until a key piece fails?
Were well past the warranty of four years.
So, thats where were at.
Then, of course, if you have less power, the temperature goes down inside.
Theres something called a bus that has all the electronics inside, and thats getting colder and colder.
How cold can the lines get before they freeze?
How cold can some of these other components get before they stop working?
So thats another challenge.
Thats another challenge that were going through to balance.
But were hopeful that we can get one, possibly two, spacecraft to the 50th anniversary in 2027.
Voyagers golden anniversary, and perhaps even into the early 2030s with one, maybe two, science instruments.
Gizmodo: What about the language that the spacecraft use?
And it was like a detective story, you know, what can we do?
And they figured it out, and it worked.
You have no information coming back from Voyager.
But in bringing in those people, where do you start?
In the 70s, we didnt have the computers we do today.
A lot of Voyager material is in memos, and sometimes the memos are scanned in a PDF file.
And they just stuck sticky notes all over as they were figuring it out.
Meanwhile, the scientists are patiently waiting for their data to come back.
Gizmodo: Youmentioned that the team has gotten smaller over the years.
Spilker:As it’s possible for you to imagine, most of the people are new.
Retirees are very happy to come back and help us.
Spilker:Voyager left breadcrumbs, clues for future missions to come.
One of Voyagers goals was to see through to the surface of Saturns Moon, Titan.
We didnt know if it could have liquid oceans on the surface, or what the surface looked like.
It looked like a bad day in a smoggy city.
I had a chance to go work on Cassini.
I got in very early, and helped formulate the mission concept.
I spent around 30 years on Cassini, and then the mission ended in 2017.
I went home and I told my husband, I dont think Im going to retire.
Gizmodo: How does it feel now that the mission is approaching its end?
Im just really, really happy to have been a part of it.
Gizmodo:Theres always this debate of whether we should launch another interstellar probe.
Im wondering how you feel about that?
Spilker:I think it would be a great idea, it could even go further than Voyager.
But there are other bubbles.
How far do you have to keep going to reach another bubble?
And what is it like to get farther and farther away from the Sun?
Were still working and thinking about an interstellar probe that would go much, much farther than Voyager.
Youre talking about a multi-generation mission.
Gizmodo: Should we have already launched one?
Spilker:Theres so many interesting places to go.
Prior to Voyager, we had no idea what the heliopause was like.
Then getting this sort of taste of interstellar space makes us want to go back.
Spilker:Were entering a new and interesting era.
You have the private industry wanting to play a bigger role in getting us to space.
Theres just been sort of a blossoming of scientific missions and our understanding of our place in the universe.
So Im hopeful, theres always tough times to weather.
Weve been through tough times before, and I think well weather this one.
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