Engineers adjust Voyagers 1 & 2 because of steadily dropping power
In recognition that the available power on both Voyager 1 and Voyager 2 continues to drop due to the age of the spacecraft, engineers have decided to make some major changes in how they operate both spacecraft.
For example, to save power on Voyager 2 they have turned off the heaters for the instrument that confirmed last year that the spacecraft had entered interstellar space. Even so, the instrument is still functioning and sending back data. It is expected it will continue to work for some time before finally succumbing to the cold of deep space.
They have also decided to reactivate the back-up thrusters on Voyager 2, just as they did with Voyager 1 in 2017.
Another challenge that engineers have faced is managing the degradation of some of the spacecraft thrusters, which fire in tiny pulses, or puffs, to subtly rotate the spacecraft. This became an issue in 2017, when mission controllers noticed that a set of thrusters on Voyager 1 needed to give off more puffs to keep the spacecraft’s antenna pointed at Earth. To make sure the spacecraft could continue to maintain proper orientation, the team fired up another set of thrusters on Voyager 1 that hadn’t been used in 37 years.
Voyager 2’s current thrusters have started to degrade, too. Mission managers have decided to make the same thruster switch on that probe this month. Voyager 2 last used these thrusters (known as trajectory correction maneuver thrusters) during its encounter with Neptune in 1989.
It is thirty years since those thusters on Voyager 2’s were used. If they work it will be an incredible testament to the engineers who designed both spacecraft.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
In recognition that the available power on both Voyager 1 and Voyager 2 continues to drop due to the age of the spacecraft, engineers have decided to make some major changes in how they operate both spacecraft.
For example, to save power on Voyager 2 they have turned off the heaters for the instrument that confirmed last year that the spacecraft had entered interstellar space. Even so, the instrument is still functioning and sending back data. It is expected it will continue to work for some time before finally succumbing to the cold of deep space.
They have also decided to reactivate the back-up thrusters on Voyager 2, just as they did with Voyager 1 in 2017.
Another challenge that engineers have faced is managing the degradation of some of the spacecraft thrusters, which fire in tiny pulses, or puffs, to subtly rotate the spacecraft. This became an issue in 2017, when mission controllers noticed that a set of thrusters on Voyager 1 needed to give off more puffs to keep the spacecraft’s antenna pointed at Earth. To make sure the spacecraft could continue to maintain proper orientation, the team fired up another set of thrusters on Voyager 1 that hadn’t been used in 37 years.
Voyager 2’s current thrusters have started to degrade, too. Mission managers have decided to make the same thruster switch on that probe this month. Voyager 2 last used these thrusters (known as trajectory correction maneuver thrusters) during its encounter with Neptune in 1989.
It is thirty years since those thusters on Voyager 2’s were used. If they work it will be an incredible testament to the engineers who designed both spacecraft.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Q:
(excuse, I did not follow the link)
–How many watts are being generated for each probe, right now?
From the article:
“Each of the probes is powered by three radioisotope thermoelectric generators, or RTGs, which produce heat via the natural decay of plutonium-238 radioisotopes and convert that heat into electrical power. Because the heat energy of the plutonium in the RTGs declines and their internal efficiency decreases over time, each spacecraft is producing about 4 fewer watts of electrical power each year. That means the generators produce about 40% less than what they did at launch nearly 42 years ago, limiting the number of systems that can run on the spacecraft.”
From the JPL site:
“Electrical power is supplied by three Radioisotope Thermoelectric Generators (RTGs). The current power levels are about 249 watts for each spacecraft.”
https://voyager.jpl.nasa.gov/mission/spacecraft/
My math got me 252 watts (down from 420 watts when new) from info in the first article. Pretty amazing power budget considering the lightbulbs on the front of my house (pre-LED) used 450 watts.
TL-
Thank you!
TL,
Good job with your numbers. Sorry this is a late post, I am catching up on the posts.
When I saw this post, I did some numbers but they came up higher, but I did not take in to account that the 312 SiGe unicouples in the MHW generators are breaking down over time.
One good book I used on research on the RTGs and the third Voyager spacecraft that was a test article was “Space Nuclear Radioisotope Systems” by David Buden. Good reference material, diagrams, and equations.
Jay–
good stuff, thank you.