NASA Successfully Reactivates Voyager 1 Thrusters After Decades of Inactivity

In 2010 NASA engineers faced a major issue with Voyager 1, they had to wake up dormant thrusters on the spacecraft so that the craft remains capable of communicating with Earth. Operating at about 150 AU, or fifteen billion miles from Earth and far afield the Sun’s magnetic field, Voyager 1 was in jeopardy of losing signal to the broadening clogged fuel line. For the maneuver, NASAs Jet Propulsion lab came up with a complicated but effective strategy of warm up and switching to backup thrusters. Voyager 1 now has very little power, and it has almost reached the end of its lifetime; nevertheless, it is still functional and continues to provide data from the interstellar medium.

At the time it took to the space on September 5, 1977 Voyager 1 was not designed to keep working to this time. However, problems-coping in increasing, and now the aging spacecraft endures more difficulties in technical aspects as it progresses further in its journey into space. Scientists and engineers at Jet Propulsion Laboratory or JPL in Pasadena California are challenged with coming up with solutions while respecting the vulnerable state of the spacecraft.

Presently the space craft that is the most distant from the Earth, Voyager 1 is more than 15 billion miles (24 billion kilometers) away. It now floats in the interstellar space away from direct influence of the Sun’s magnetic field where it keeps on collecting data from this remote and hitherto virtually uncharted area.

In February this year, the engineers for the spacecraft noted a problem with thruster number 2 of Voyager 1 which they attributed to a blocked fuel line. This blockage endangered the orientating of the spaceship to communicate with the Earth that is vital for control and direction of the spacecraft. It helps to maintain Voyager’s orientation so that the antenna it used to transmit and receive signals.

“The mission would basically be over if the thrusters that are used for pointing the antenna at earth were to be blocked,” said Calla Cofield, A media specialist at JPL. To counter the situation, the team agreed to change the set of thrusters but performing the change was difficult.

A recurring problem

As mentioned earlier, Voyager has in recent years had to use a range of different sets of thrusters multiple times. Fortunately, the spacecraft is equipped with three sets: two engines are attitude control engines and one is used for trajectory correction. These thrusters were utilised during the planetary flybys for example the Jupiter in 1979 and Saturn in 1980.

Now Voyager 1 is going beyond the solar system and it only takes one set of thrusters to maintain the orientation of the antenna towards Earth. The thrusters work on the principle of decomposing liquid hydrazine into gas thrusters that fire in short pulses- about forty times a day to put solar wind forces into alignment.

From experience, the engineers realized that the fuel tubes in the thrusters were prone to blockage by silicon dioxide which is a product of the rubber diaphragm in the fuel tank. With the increasing number of blockages, the impact of thrusters reduce.

The first set of attitude thrusters started clogging in the year 2002, leading to replacement of the set by the second one. The second set of thrusters were also seen to have blockage in 2018 and hence, they had to switch to the trajectory correction thrusters.

However, in the recent inspection it was found that the next set of thrusters which correct the trajectory of the craft where even more clogged than the previous two sets.

When the switch to the trajectory correction thrusters was made six years ago, the fuel tube opening was 0. Its width is 01 inches, or 0. 25 millimeters, across. Now, clogging has decreased it to just 0. 0015 inches which is equal to 0. 035 millimeters, which is roughly half the thinners of human hair.

This led the team to restore one of the initial attitude thruster sets back into use The evaluation made by the assembled team was that the best course of action to be taken was to revert to one of the initial attitude thruster sets being used.

Making a challenging swap

Over the years, individual subsystems on both Voyager 1 and Voyager 2, the spacecraft twins, have begun to age, so the mission team has powered off anything that isn’t necessary for their survival and their science missions The heaters, specifically, have been turned off. This has made Voyager 1s components much colder in other words the team could not command a switch on the thruster without first warming it up.

But turns out, Voyager 1 doesn’t have enough power to turn on the heaters without flipping another system off. The team observed that switch off any of the scientific instruments would be unsafe since they may not turn on again.

After considering their options, the engineers found a solution: they were able to shut one of them main heaters on the spacecraft and swap them for about one hour the warmed up thrusters.

The plan worked and by August 27, Voyager 1 was maneuvering back and forth with one of its original thruster sets to reorient its antenna so as to be able to communicate with the mission control on Earth.

The team has cut back its use of the thruster to extend its life expectancy as this set should last another two to three years, Going said Todd Barber, a propulsion engineer for Voyager. Once this set of attitude thrusters is exhausted, there remains another set of the same, but half-choked attitude thrusters.

“Every single decision going forward in the Voyager mission will have to be even more guarded and largely analyz ed,” commented Suzanne Dodd, Voyager’s project manager.

Voyager 2’s thruster issues occurred in 1999 and 2018, however the spacecraft’s situation is less dire, Barber said. It should be noted that currently Voyager 2 is more than 12 light hours away from our planet, which means that it is located more than 12 billion miles (or 20 billion kilometers) away from it.

The data collected by these probes has been extremely important to scientists studying the form of heliosphere and how it protects earthly environment from cosmic rays and other energetic particles.

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