Voyager Anniversary Celebration: 40 Years in Space

The Voyage Out of the Solar System

The USSR's 86 kg Sputnik 1 satellite launched in October of 1957 and orbited for three months. The only sensors aboard were thermometers for measuring the internal and external temperature of the satellite.
120 days later, the United States of America’s 13.4 kg Explorer 1 launched and carried cosmic-ray detectors, five temperature sensors, acoustic impact detectors, and wire grid micrometeorite impact detectors. The final transmission of Explorer 1 came 105 days later, and it eventually burned up in the Earth’s atmosphere some 12 years later. These advancements were major milestones in the space race and gave us GPS technology along the way.
Scientists from the two countries continued to loft men and satellites with increasingly complex sensors into the skies above.

Image of the Voyager 2 launch. Image courtesy of NASA.

Rocket engineers developed propulsion systems capable of generating the thrust needed to lift heavy payloads and learned how to reach the speeds necessary to escape Earth permanently. Giving an object the speed necessary to escape the solar system

6.5×106ms

is a Herculean task, and engineers used carefully planned gravitational slingshot techniques coupled with carefully calculated course corrections to steal momentum from the outer planets.
But to create a probe that can leave our lonely Earth and then our solar system to visit what lies beyond, while still collecting and transmitting useful scientific data, is a task worthy of Zeus himself. But this feat wasn’t accomplished by mythical gods—it was accomplished by scientists and engineers who set out to solve a problem, and solved it brilliantly.

Image of scientists testing Voyager 2. Image courtesy of NASA.

The two Voyager spacecraft launched twenty years after the very first satellites. Each spacecraft had a launch mass of 825.5 kg (1820 lbs) and carried a variety of scientific instruments that allowed them to unlock the secrets of the planets and moons in our solar system. By studying the space in between the planets, they also hoped to unlock the secrets of our sun. The Voyager mission taught us that there are active volcanoes on Jupiter’s moon Io and gave us a baseline to determine that Jupiter’s giant red spot is slowly shrinking away. We learned that Jupiter’s moon Europa is an icy planet that might contain life. We learned about the composition of Saturn’s rings.
They accomplished all of this without microprocessors and with only 68 kilobytes of memory.
But four decades is far too long to operate on battery power and the two spacecraft are too far away from the sun for solar panels, so diminishing Radioisotope Thermoelectric Generators provide the available power.
The Voyager missions also challenged some of the brightest minds to create a cohesive representation of our planet and species in the Golden Record.

Image of Voyager test model. Image courtesy of NASA.

All About Circuits has been featuring different Voyager scientific instruments each Sunday of these past ten weeks in celebration of the Voyager missions 40th anniversary. Today, we invite you to take a look back at our previous articles and learn a bit more about the missions that amazed humankind all those years ago.

Voyager Articles at All About Circuits

Below, you will find the Voyager series here on All About Circuits. Explore the sensors, experiments, and engineering that have made this feat of space exploration possible and meaningful.

• The Voyager Mission Anniversary Celebration Series: Introduction, by Mark Hughes—provides an overview of the spacecraft background, trajectory, scientific experiments, and the gravitational assist methods used to achieve escape velocity from the solar system.
• Powering the Voyager Spacecraft with Radiation: The Radioisotope Thermoelectric Generator, by Robin Mitchell—discusses the power system used by the spacecraft
• Communicating Over Billions of Miles:  Long Distance Communications in the Voyager Spacecraft, by Mark Hughes—tells readers about the radio communications system on Earth and aboard the spacecraft that allow mankind's longest yet bi-directional communication.
• The Brains of the Voyager Spacecraft: Command, Data, and Attitude Control Computers, by Chantelle Dubois—introduces the redundant and fault-tolerant computer system that guided Voyager on its journey while collecting data from the various scientific experiments.
• Exploring the Solar System with the Voyager Spacecraft’s Cameras, Polarimeters, and Magnetometers, by Mark Hughes—details how the video cameras took pictures of the planets and moons, discovered a component of the molecular composition of atmospheres, as well as how we detected the magnetic field orientation and intensity.
• The Infrared Interferometer, Spectrometer, and Radio Astronomy of the Voyager Spacecraft, by Mark Hughes—provides information about how the spacecraft determine the energy balance of planets and moons as well as the composition of the planetary rings.
• How the Voyager Missions’ Plasma Science Investigations Teach Us About Solar Winds, by Mark Hughes—interviews an active Voyager Project scientist and explains the active Plasma experiments that are currently returning data.
• The Low Energy Particle Instruments on the Voyager Spacecraft, by Chantelle Dubois—explains the plasma spectrometer, cosmic ray system, and low-energy charged particle system aboard the spacecraft
• The Voyager Mission: Insight into Our Solar System, by Chantelle Dubois—provides links to the data archives for the Voyager spacecraft.

Going Further

The Voyager Spacecraft will continue to transmit scientific data until 2025, and we can track their position for an additional 10 years after that. If you would like to know more about the Voyager spacecraft, here are some resources that we used while writing these articles.
The Voyager Backgrounder document provides an overview of the spacecraft, its mission, and the various scientific experiments aboard the spacecraft.
The Design and Performance Summary Series (DESCANSO) provided by the Deep Space Communications and Navigation Center of Excellence, provides thoroughly detailed information about communication with deep space spacecraft.

Image of scientist inspecting Voyager 2 antenna. Image courtesy of NASA.

The Jet Propulsion Laboratory's Photojournal provides images and animations of spacecraft and the solar system.
The Scientific and Technical Information Program is a collection of scientific and technical papers about all of NASA's missions.

Conclusion

We hope that you have enjoyed this series and that it'll inspire you to take a moment to think about all of the incredibly hard work that went into making the Voyager spacecraft possible.
The spacecraft designers meticulously designed every aspect of the spacecraft and devoted 11,000 man-years to take the spacecraft from inception to Neptune.

Happy 40 years in space, Voyager!