Voyager 1 Thrusters Fired Up After 37 Years of Deep Sleep

AdamSmith · December 2, 2017

Voyager 1 Thrusters Fired Up After 37 Years of Deep Sleep

By AKALib

Friday Dec 01, 2017 · 7:08 PM EST

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After 37 years of deep sleep, a set of thrusters aboard the Voyager 1 spacecraft, were successfully fired up on Wednesday, Nov 29. They will help augment the primary thrusters which are getting old and weak. The thrusters are used periodically to reorient the spacecraft and re-point its antenna to Earth, now 21 billion km away.

Voyager 1, launched in September 5, 1977, now flying in interstellar space, relies on thrusters that are fired for short millisecond periods to subtly rotate the spacecraft and point its communications antenna at Earth.

Since 2014, NASA engineers had noticed that Voyager’s "attitude control thrusters" have been degrading and losing efficiency.

The Voyager team assembled a group of propulsion experts to study the problem. The solution that came up with was to use the four Trajectory Correction Maneuver (TCM) thrusters, which were originally used for orientation control when Voyager flew by planets and moons during the first few years of its mission. The TCM thrusters are identical in size and functionality to the attitude control thrusters, and are located on the back side of the spacecraft. The TCM thrusters were last used on November 8, 1980, when Voyager 1 flew by Saturn. Back then, the TCM thrusters were used in a more continuous firing mode; they had never been used in the pulse mode necessary for its new role.

On Tuesday, Nov. 28, 2017, Voyager engineers sent instructions to fire up the four TCM thrusters. It took 19 hours and 35 minutes for the signal to reach Voyager 1 and another 19 hours and 35 minutes for the response to arrive. The received signals indicated that everything went according to plan — after 37 years of deep sleep in cold dark space, the thrusters worked perfectly!

Kudos to the designers of the spacecraft and the mission team, who pored through decades-old data and outdated assembler language software to figure out and implement the solution.

The plan going forward is to switch to the TCM thrusters in January. To make the change, Voyager has to turn on one heater per thruster, which requires power -- a limited resource for the aging mission. When there is no longer enough power to operate the heaters, the team will switch back to the attitude control thrusters.

The thruster test went so well, the team will likely do a similar test on the TCM thrusters for Voyager 2, the twin spacecraft of Voyager 1. The attitude control thrusters currently used for Voyager 2 are not yet as degraded as Voyager 1's.

More details at www.nasa.gov/...

Voyager 1

Voyager 1 was launched by NASA on September 5, 1977, to study the outer Solar System. Its twin Voyager 2 was launched 16 days earlier.

The Voyager 1 mission included flybys of Jupiter, Saturn and Saturn's large moon, Titan. It completed its primary mission with the flyby of Saturn on November 20, 1980.

It is now pursuing an extended mission to explore the regions and boundaries of the outer heliosphere. The mission is expected to continue until around 2025 when its radioisotope thermoelectric generators will no longer supply enough electric power to operate its scientific instruments.

A few vital statistics -

Parameter	Value
Distance	141 AU (2.11×10¹⁰ km) from Sun A AU = Earth-Sun distance = 150 million km
Speed	38,026 mph 520 million km per year
Communications Delay (one-way)	19 hours and 35 minutes
Launch Date	September 5, 1977
Power	3 radioisotope thermoelectric generators 470 W at launch time Plutonium-238 left = 72.76%. Will decline to 56.5% by 2050.

Here is a diagram of Voyager 1 and its instruments -

voyager.jpl.nasa.gov/...

Voyager 1 is in "Interstellar space" and Voyager 2 is currently in the "Heliosheath" -- the outermost layer of the heliosphere where the solar wind is slowed by the pressure of interstellar gas. See voyager.jpl.nasa.gov/… for some more fun facts of Voyager.

Here is an animation showing the trajectory of the two Voyager spacecraft -

The Golden Record

Each Voyager spacecraft carries a gold-plated audio-visual disc intended for any intelligent life forms out there. The disc carries encoded photographs, music, sounds and greetings in 55 languages.See diagram below for the record cover.

800px-The_Sounds_of_Earth_Record_Cover_-_GPN-2000-001978.jpg

voyager.jpl.nasa.gov/...

See voyager.jpl.nasa.gov/… for a fascinating description of the images and the playback instructions encoded in them. An excerpt is shown below -

In the upper left-hand corner is an easily recognized drawing of the phonograph record and the stylus carried with it. The stylus is in the correct position to play the record from the beginning. Written around it in binary arithmetic is the correct time of one rotation of the record, 3.6 seconds, expressed in time units of 0,70 billionths of a second, the time period associated with a fundamental transition of the hydrogen atom. The drawing indicates that the record should be played from the outside in. Below this drawing is a side view of the record and stylus, with a binary number giving the time to play one side of the record - about an hour.

Voyager 1 and 2 both carry this record. There are ten more on display at various NASA institutions. Even Carl Sagan, who chaired the committee that created the record, did not get a copy. The record was never made available to the general public.

Now we can get a copy (for $98), thanks to a Kickstarter-funded reissue of the Voyager Golden Record: 40th Anniversary Edition, issued as a 3 LP box set. Also, available as a 2 CD set at lightintheattic.net/… for $50. Both versions come with a hardcover illustrated book.

Ozma Records.

Here is video containing decoded information from the record -