# NASA has Figured Out How to Extend the Lives of the Voyagers Even Longer



## micropage7 (Jul 14, 2019)

*NASA has Figured Out How to Extend the Lives of the Voyagers Even Longer*
Voyagers 1 and 2 have the distinction of being in space for 42 years and still operating. And even though they’re 18 billion km (11 billion miles) from the Sun, they’re still valuable scientifically. But they’re running out of energy, and if NASA wants them to continue on much longer, they have some decisions to make.

*The Energy Problem*
The energy issue is becoming more and more critical over time for the Voyagers. Not only do their scientific instruments require energy, but the spacecraft need to keep themselves warm in the frigid environment of space. The pair of spacecraft aren’t solar powered: that wouldn’t be possible so far from the Sun. They rely on radioisotope thermoelectric generators (RTG) for their energy.
Each of the Voyager probes has three RTGs, and they use plutonium 238 for their fuel source. As that isotope decays, it produces heat which is converted to electrical energy. Each Voyager launched generating 470 watts at 30 volts DC, but over time that degrades. Not only is the fuel steadily depleted, but the thermocouples used in the system degrade over time. As of 2011, both Voyagers were generating just under 270 watts, which is about 76% of the power they started out with.

While that 270 watts is better than predicted when the probes were designed and launched, it still means that inevitable decisions need to be made about which spacecraft systems need to be turned off.
First off, you’ve gotta give NASA credit for keeping the probes going this long. It’s amazing in its own right. Some parts of the probes have already had their power turned off, and remarkably, they’re still performing.
In response to energy concerns, in 2011 NASA turned off the heater for Voyager 1’s ultraviolet spectrometer. That instrument was designed to operate at temperatures as low as -35 degrees Celsius (-31 degrees Fahrenheit), but after its heater was turned off, it kept working at -79 degrees Celsius (-110 degrees Fahrenheit.)

But that was in 2011, and since then the RTGs have lost even more power. In fact, they lose about .8% of their power output each year. Now, NASA engineers are sharpening their slide rules and putting a new energy management plan in place to keep the probes going even longer.

*Turning The Heat Off To Keep The Voyagers Going*
Recently, NASA decided to turn off the heater for another instrument, this time on Voyager 2. They’ve turned off the heat for Voyager 2’s Cosmic Ray Subsystem (CRS). That’s too bad, because back in November 2018, the CRS instrument was key in determining that Voyager 2 had left the heliosphere and entered interstellar space. Ever since the probes left the heliosphere, they’ve been sending us unique and important information about how the heliosphere interacts with the interstellar wind. No other spacecraft can do that, and to put another one in place would take decades.

But even though the instrument heater for Voyager 2’s Cosmic Ray Subsystem (CRS) has been turned off, engineers confirmed that the instrument is still working at -59 Celsius (-74 F), even though they were only tested down to -45 C (-49F.) 

“It’s incredible that Voyagers’ instruments have proved so hardy,” said Voyager Project Manager Suzanne Dodd, who is based at NASA’s Jet Propulsion Laboratory in Pasadena, California. “We’re proud they’ve withstood the test of time. The long lifetimes of the spacecraft mean we’re dealing with scenarios we never thought we’d encounter. We will continue to explore every option we have in order to keep the Voyagers doing the best science possible.”
As it stands now, Voyager 2 is still returning data from five instruments, even though the CRS had its heat turned off. In particular, it’s still heating the Low-Energy Charged particle instrument. That’s because it can return data on the transition out of the heliosphere in much the same way that CRS can. The CRS is uni-directional, while the Low-Energy instrument is omni-directional, which is one of the reasons the CRS had its heat turned off.





Voyager 1 and 2 have both left the heliosphere behind, and are the first spacecraft to do so. Image Credit: By NASA/JPL-Caltech –  

*Delaying the Inevitable*
Generating heat is an energy intensive activity. As the power in the probes runs down, eventually more heaters will have to be turned off to allow the remaining instruments to operate. There’s no way around it. But the shrinking energy budget on the probes also affects other systems besides scientific instruments.

The probes have small thrusters and they are critical to the probes’ operation. The spacecraft have to be oriented so that their antennae face Earth for them to receive commands and return data to Earth. Each spacecraft has a tank of hydrazine monopropellant fuel used to power their small thrusters, which operate in tiny bursts or puffs to orient the spacecraft. 

If the lines feeding the fuel to the thrusters froze, then engineers would be unable to aim the spacecrafts’ antennae or instruments. At that point, the spacecraft would likely be useless. So they require heat as well.
However, there’s another problem with the thrusters. Inevitably, systems like those break down over time, and in 2017 engineers noticed a problem. Some of the thrusters on Voyager 1 were having to work harder to maintain the correct orientation toward Earth. So they turned to some long-unused thrusters to see if they could get the job done.

Believe it or not, this secondary set of thrusters hadn’t been used for 37 years. But they were fired up and they did their job. That’s got to be some kind of record in itself.

Now, the main thrusters on Voyager 2 are starting to show problems. With the success they had with Voyager 1’s old, unused thrusters, engineers have decided to fire up the old backup thrusters on Voyager 2 as well. But these ones haven’t been dormant as long as Voyager 1’s were. They were last used when Voyager 1 encountered Neptune in 1989 30 years ago, and NASA plans to turn them on later this month.
With clever engineering, careful planning, and judicious use of both Voyagers’ remaining energy, the inevitable end for the spacecraft is being delayed. As a result, their ongoing scientific contributions can continue into the future for a while yet.

Engineers and mission planners think that there’s still a few years of operational capability left. That’s important, because everything we’re learning about the region of space they’re in is because of their unique position to observe it. That can’t be understated, because new papers are still being written based on Voyager data, not only from where they are now, but from where they were years, even decades, ago.
In 2017, NASA former chair of NASA’s Outer Planet Assessment Group Fran Bagenal was interviewed in Nautilus. In that interview she said, “I’m still analyzing Voyager data, believe it or not. We’ve just published three papers on Voyager data that was taken 33 years ago, at the same time that we’re all celebrating the 40th anniversary of the launch. It was fun. I realized that some of the data I had done my thesis on, from 1979, had not been reanalyzed.”
It begs the question, how many future papers based on current data might be written decades from now?

*Nothing Lasts Forever*
The Voyager program’s most famous photos is the Pale Blue Dotphoto (actually a series of photos.) We no longer receive any photos from the Voyager cameras. There’s nothing to take pictures of way out there. But it’s almost uncanny how those spacecraft are still delivering data, unique data, so many decades after they were designed, built, and launched. In an odd way, they’re like time capsules of early space exploration technology.

“Both Voyager probes are exploring regions never before visited, so every day is a day of discovery,” said Voyager Project Scientist Ed Stone, who is based at Caltech. “Voyager is going to keep surprising us with new insights about deep space.”
Nothing lasts forever and one day that’ll be it for the Voyager spacecraft. For people knowledgeable about the missions, and who have an inkling of what they’ve contributed to humanity’s knowledge, that’ll be a sad day. It’s strange to think of all that’s gone on here on Earth while the two spacecraft have been making their journey.

The good news is that future spacecraft will build on the work done by the Voyager program. 

NASA is launching the Interstellar Mapping and Acceleration Probe (IMAP) in 2024, and it will capitalize on the Voyagers’ observations. Their Interstellar Boundary Explorer (IBEX) is already building on the work of Voyager 1 and 2 and giving us more detailed info on the heliosphere.

In the same Nautilus interview, Fran Bagenal said, “I would predict that we’ll cease to be able to communicate with it somewhere around another 15 years time or so.” She’s not an official spokesperson for the Voyager program, but if she’s accurate, that means that communications may end by 2032.

https://www.universetoday.com/14280...extend-the-lives-of-the-voyagers-even-longer/


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## Solaris17 (Jul 14, 2019)

This is massively cool


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## R-T-B (Jul 15, 2019)

The Voyager probes have always fascinated me.  Want to visit them in Elite Dangerous someday for fun...


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## xkm1948 (Jul 15, 2019)

This makes me wonder how good today’s technology is capable of building a long lasting space probe. Should be releasing one every decade alternating between nations to lower the cost. That would be really cool.


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## Space Lynx (Jul 15, 2019)

xkm1948 said:


> This makes me wonder how good today’s technology is capable of building a long lasting space probe. Should be releasing one every decade alternating between nations to lower the cost. That would be really cool.



That requires world leaders who have excellent abilities to bring people together and next level rhetoric comparable to the ancient thinkers... current leaders are not capable, but there was someone who did bring 180 nations together physically in one room once upon time not that long ago.  Neat huh?


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## ToxicTaZ (Jul 15, 2019)

What will really Kool is when the new VX-200SS Impulse drive engine is finally finished developing with a new Solar Space craft can fly out there (20 light hours away) grab both Voyagers and bring them back to Earth and put them in a museum so all of us can glory apon the first two space craft that left our Solar System. Plus it would be a milestone in space travel to do such a feat.


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## 64K (Jul 15, 2019)

"_As of 2011, both Voyagers were generating just under 270 watts, which is about 76% of the power they started out with._"

How did they arrive at that percentage? If they launched with a capacity of 470 watts and they were down to 270 watts in 2011 then that would be 57% of the launch capacity.

It is amazing that they are still functioning and sending back data though.

I have wondered why it would not be possible to launch a vehicle traveling many times faster to reach where Voyager is much faster and perhaps a good bit larger with more power to transmit data well into interstellar space. Maybe something the size of the space shuttle. Too expensive with present NASA budget perhaps?


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## droopyRO (Jul 16, 2019)

It takes hours to make a command and receive the response, right ? If they decide to test the thrusts and push a button now, i guess it takes hours for them to actually receive the command and hours more to get a confirmation of them doing anything.


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## rtwjunkie (Jul 16, 2019)

droopyRO said:


> It takes hours to make a command and receive the response, right ? If they decide to test the thrusts and push a button now, i guess it takes hours for them to actually receive the command and hours more to get a confirmation of them doing anything.


You are correct. It is a huge margin for error.

“Voyager 1 data takes about 19 hours to reach Earth, and signals from Voyager 2 about 16 hours. (For comparison, it takes the rovers on Mars 20 minutes on average to call home.) The signals get picked up by NASA’s Deep Space Network, a collection of powerful antennae around the world that communicate with dozens of missions.”

That was as of 2017, so it’s worse now.









						When Will Voyager Stop Calling Home?
					

The twin spacecraft still send data back to the planet they left 40 years ago.




					www.theatlantic.com


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## micropage7 (Jul 16, 2019)

rtwjunkie said:


> You are correct. It is a huge margin for error.
> 
> “Voyager 1 data takes about 19 hours to reach Earth, and signals from Voyager 2 about 16 hours. (For comparison, it takes the rovers on Mars 20 minutes on average to call home.) The signals get picked up by NASA’s Deep Space Network, a collection of powerful antennae around the world that communicate with dozens of missions.”
> 
> ...


sometimes it's beyond you can imagine, man made satellite that still works far far away out from nowhere


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## Grog6 (Jul 16, 2019)

I remember watching the launches of these, and the Pioneer missions.

It's mindblowing that the electronics still work; these are all from the mid 70's, when TTL logic was being developed. 
IDK what family of electronics was used, but it's nothing like todays.

ASICs were rare, and the transmitters are TWT tubes. 

Awesome to see, all these years later.


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## robot zombie (Jul 16, 2019)

I'm just wondering why mobo manufacturers have never boasted "NASA grade" components. Seems like mil-spec has nothing on them.

Voyager LN2 board with gold foil accents 

Nah but I don't mean to take away from how cool that is. Those old parts are on a different level. But then they were probably over engineered to the max. I wonder what we'd be capable of now.


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## micropage7 (Jul 16, 2019)

robot zombie said:


> Nah but I don't mean to take away from how cool that is. Those old parts are on a different level. But then they were probably over engineered to the max. I wonder what we'd be capable of now.


maybe coz of it's from old architecture it lasts longer
it's like when you have CRT TV that last years before got err but it still works after years compared to newer LCD flat TV that in few years just got dead pixels and not fixable


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## AltCapwn (Jul 16, 2019)

Very interesting post, thank you very much for having took the time to write that.


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## toastem2004 (Jul 17, 2019)

For all our love of multi-gigahertz cpus and GB's of RAM, just goes to show newer is not always better.  I remember being enamored with the Voyager and Pioneer probes in grade school.  Amazing that such a thing built by man is still functional after all these years!  Between them and the twin Mars rovers that lived WAAYYY past their design times, probably the best things NASA & JPL ever made


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## Grog6 (Jul 19, 2019)

The Voyager Computers were TTL. 

"HYPACE added   transistor-transistor logic (TTL) medium-scale integrated circuits   to create a relatively fast (28-microsecond cycle) processor with   index registers for addressing. Byte-serial architecture was   possible because the TTL chips were designed for 4-bit parallel   operation, so the 18-bit words could be moved around in five   cycles instead of the 18 a serial machine would need, increasing   overall speed. Index registering meant that the same block of code   could be used for all three axes, reducing memory requirements. It   appeared that the attitude control systems of future spacecraft   would almost certainly benefit from such a computer. "

So, 18uS clocks on 4bit wide ttl chips, dual redundant architecture, reprogammable during flight, with SRAM memory driven directly from the RTG's, because if the RTG's failed, who cares about memory, lol.

This is similar to an 8085 uP simulator I built in 1984 from TTL gates; it was 20"x20" and all TTL logic. It drew 40A@5V.


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## 64K (Jul 19, 2019)

It's just wishful thinking on my part but I would like to see NASA's budget raised substantially. For 2020 they will receive 21 billion dollars of the 4.7 trillion dollar Federal Budget. 

Trump plans to increase funding by encouraging public-private partnerships with one of the goals being deep space exploration.









						NASA Budget: Current Funding, History, Economic Impact
					

The NASA budget is $25.2 billion, just 0.5% of the FY 2021 federal budget. Each dollar spent creates $8 of economic growth.




					www.thebalance.com


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## BorgOvermind (Jul 19, 2019)

"NASA has Figured Out How to Extend the Lives of the Voyagers Even Longer" and still not figured out how to make their own engines.


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## rtwjunkie (Jul 19, 2019)

BorgOvermind said:


> "NASA has Figured Out How to Extend the Lives of the Voyagers Even Longer" and still not figured out how to make their own engines.


If you are referring to the use of RD-180 engines from Russia, which are only used for heavy lift, good stewardship of taxpayer monies is the reason.  It has been available for cheap and the metallurgy involved would be prohibitive to manufacture ourselves.  It’s just cheaper to buy the best heavy engine there is.

If you are referring to NASA itself making other engines, they have contracted that to various US. companies who have considerable expertise.  Your statement is like asking why the Air Force has Pratt and Whitney and GE engines in it’s airplane fleet instead of making its own.

Not to fear. Every single engine used gets tested extensively at the Stennis Space Center near me. It is an extremely loud process, with a noise easement zone of about 125,000 acres around the center.









						Stennis Space Center: NASA's Largest Rocket Testing Site
					

Since 1961, the John C. Stennis Space Center has tested rockets that went to the moon and those that will carry humans even farther.




					www.space.com


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## EsaT (Jul 19, 2019)

xkm1948 said:


> This makes me wonder how good today’s technology is capable of building a long lasting space probe.


Actually modern integrated circuits with their tiny transistors and such would require lot more hardening to withstand various forms of radiation space probes are exposed to.
(similar to how modern electronics is lot more sensitive to EMP than some old tubes)


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## BorgOvermind (Jul 19, 2019)

There are many things, not only that.

The next project's engines are contracted to Aerojet Rocketdyne, which already spend 2 billion.

Let's take a reference, as example, to the $12 billion wasted on the SLS development which is still a drain in progress and has no chance of being nearly ready by 2024 (with President Trump picking on them on this as a bonus) after it was initially scheduled to be ready to go in 2017.


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