The functioning instruments aboard the Voyager spacecraft

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Winston

Lorenzo von Matterhorn
Joined
Jan 31, 2009
Messages
9,560
Reaction score
1,749
Forty years and still going strong
The functioning instruments aboard the Voyager spacecraft
2 Jul 2018

https://www.astronomy.com/news/2018/07/forty-years-and-still-going-strong

Currently operating instruments aboard the Voyagers include:

Plasma Spectrometer (PLS):
Functioning only on Voyager 2

This instrument consists of two metal devices (known as Faraday cups) placed at right angles to each other. The one pointed along the Earth-spacecraft line records data regarding the velocity, density, and pressure of plasma ions. The other off-axis device measures electrons within certain energy parameters. The PLS system was critical to studying the solar wind (the stream of charged particles flowing out of the Sun), determining how the solar wind interacts with planets, evaluating plasma in the magnetosphere of Jupiter and how it is affected by its moons, and studying ions both within and outside of the solar system.

Cosmic Ray System (CRS):
Functioning on Voyager 1 and 2

As its name implies, the CRS detects cosmic rays (high-energy particles that originate outside of our solar system). The CRS can identify both electrons and protons around the spacecraft and has been used to study the solar wind as well as the electrical flow around planets such as Saturn. As the spacecraft approached the edge of the solar system, the CRS was vital to determining when Voyager 1 crossed the termination shock, where solar wind markedly slows, and when the spacecraft later detected a sharp rise in cosmic rays it was felt to be one of the confirmatory pieces of evidence that it had indeed crossed into true interstellar space.

Magnetometer (MAG):
Functioning on Voyager 1 and 2

The Voyager magnetometers are used to measure changes in the Sun's magnetic field with regard to both distance and time, as well as to study the magnetic fields around the outer planets and how they interact with their respective moons. Each Voyager carries several magnetometers that are spaced out along a deployable “boom” that minimizes interference from the spacecraft itself; some are near the base of the spacecraft, one magnetometer is 23 feet (7 meters) from the boom base, and the farthest nearly an astonishing 43 feet (13 m) from the base. Currently, the magnetometers are generating data regarding the magnetic field at the edge of the solar system and in interstellar space.

Almost as amazing as the magnetometers themselves, rarely given any credit, and worth mentioning is the magnetometer boom itself, which allowed the entire MAG experiment to succeed. The delicate 43-foot-long (13 m) arm that attaches the magnetometers to the space probes had to be deployed after the Titan-Centaur rockets had released the Voyagers from their nosecones into space. During launch, the boom and the attached magnetometers were largely compressed into a canister only a few feet in length. Once safely freed of its launch vehicle, latch pins on the Voyagers were released and the boom deployed to its full length, allowing the magnetometers to function. The magnetometer boom is a true marvel of engineering.

Low Energy Charged Particle (LECP) Experiment:
Functioning on Voyager 1 and 2

The LECP looks for and measured electrons, protons, alpha particles, and other heavy elements both around planets and in interplanetary space. The LCEP is made of up two subsystems: the Low Energy Magnetospheric Particle Analyzer (LEMPA) and the Low Energy Particle Telescope (LEPT). The LECP was used to help identify the shape of the magnetospheres around Saturn and Uranus.

Plasma Wave Subsystem (PWS):
Functioning on Voyager 1 and 2

This device was used to analyze the plasma wave and low-frequency radio wave spectra in the magnetospheres of Jupiter, Saturn, Uranus, and Neptune. The PWS continues to take measurements both within and beyond the heliopause (the boundary where the solar wind is stopped by the interstellar medium).

All of the other instruments on both Voyager probes, including the cameras that took so many iconic images, have either failed or been disabled. Astronomers hope that the remaining working instruments will continue to operate for several more years and the Voyagers will continue to be a source of meaningful data.

Although technology on Earth has advanced dramatically since the Voyagers were launched, the two spacecraft are frozen, technologically speaking: They were sent on their missions with the best equipment available at the time (including an 8-track tape recorder for data storage, believe it or not) and they have stood the test of time. While time moves forward here on Earth, aboard the Voyager spacecraft it is always 1977.
 
Interstellar 8-track: The tape recorders of Voyager

https://hackaday.com/2018/11/29/interstellar-8-track-the-low-tech-data-recorders-of-voyager/

Voyager needed to save data and send it slowly back to earth. A NASA backgrounder on the Voyager missions shows that a data storage was specified that could buffer about 536 Mb, or the equivalent of 100 full-resolution photographs from the spacecraft’s camera.

The data tape recorder (DTR) system was subcontracted to Lockheed and manufactured by Odetics Corp. The specs show that the machine was a belt driven recorder that used a 1,076' (328 m) long reel of 1/2" (12.5 mm) wide magnetic tape which recorded data on eight separate tracks. The DTR could record at two different speeds – 115.2 kbps and 7.2 kbps. Playback topped out at a much slower 57.6 kbps, with 33.6, 21.6, and 7.2 kbps being options as well.

It appears that none of the non-flown DTRs exist in any museum collections anymore, and all we have is one picture of the mechanism.The Smithsonian has a DTR bay assembly in its collection, and lists the size as 24" high x 19" wide x 14" deep (56 cm x 48 cm x 36 cm). Given the arrangement of the connectors on the backplane, the DTR is probably about 24" tall and about 10" wide.

Exactly what the composition of the magnetic tape was, and what secrets were used to prevent it from degrading in the harsh environment of space, are unclear. Odetics, the manufacturer, claimed that the tape would travel through the mechanism a distance of 2,700 mi (4,400 km) before discernible wear.

It seems to have worked. The DTRs in both spacecraft performed flawlessly from their launch in 1977 and through the entire Grand Tour mission, as well as the extended mission that set both vehicles on a course out of the solar system. In 2007, the DTR in Voyager 1 was shut down for good, not due to any issues with the unit, but because of the dwindling supply of power coming from the craft’s radioisotope thermal generators. As of this writing, the DTR in Voyager 2 is still working, but is likely to be shut down as the power wanes in that vehicle.


main-qimg-7869f6e338a98b17cb525f685128c5a1
 
Back
Top