2023-10-25 12:20:44
NASA Voyager team focuses on software fix and thrusters
These efforts should help extend the life of NASA’s interstellar explorers.
Engineers on NASA’s Voyager mission are taking steps to ensure that the two spacecraft, launched in 1977, continue to explore interstellar space for years to come.
One such measurement concerns fuel residue that appears to be accumulating inside the narrow tubes of some of the spacecraft’s thrusters. Thrusters are used to keep each spacecraft’s antenna pointed toward Earth. This type of accumulation has been observed in a handful of other spacecraft.
The team is also downloading a software patch to prevent a repeat of a problem that occurred on Voyager 1 last year. Engineers have resolved the issue, and the fix aims to prevent it from recurring on Voyager 1 or its twin, Voyager 2.
Accumulation of propellants
The thrusters of Voyager 1 and Voyager 2 are primarily used to keep spacecraft antennas pointed toward Earth in order to communicate. Spaceships can rotate in three directions: up and down, left right and around the central axis, like a wheel. As it does so, the thrusters automatically turn on and reorient the spacecraft so that its antennas remain pointed toward Earth.
The propellant is delivered to the thrusters through fuel lines, then passes through smaller lines inside the thrusters, called propellant inlet tubes, which are 25 times narrower than the external fuel lines. Each propellant firing adds tiny amounts of propellant residue, resulting in a gradual buildup of material over decades. In some propellant inlet tubes, buildup becomes significant. To slow this buildup, the mission began letting both spacecraft rotate slightly farther in each direction before igniting the thrusters. This will reduce the frequency of thruster firings.
Adjustments to the thrusters’ rotation range were made by commands sent in September and October, and they allow the spacecraft to move nearly one degree more in each direction than in the past. The mission is also conducting fewer and longer firings, which will further reduce the total number of firings performed by each spacecraft.
The adjustments have been carefully designed to minimize impact on the mission. Although more spacecraft rotations might result in the occasional loss of scientific data – much like on a phone call where the person on the other end of the line cuts out from time to time – the team concluded that the plan will allow the Voyagers to send back more data over time.
Engineers can’t know for sure when the thruster inlet tubes will be completely blocked, but they think that with these precautions it won’t happen for at least five years, if not much longer.
The team can take additional steps in the coming years to further extend the life of the thrusters.
“At this point in the mission, the engineering team faces many challenges that we don’t have a recipe for,” said Linda Spilker, mission scientist at NASA’s Jet Propulsion Laboratory in California. South.”But they continue to find creative solutions.”
Making up for lost time In 2022, the onboard computer that points the Voyager 1 probe toward Earth began sending back garbled status reports, although it continued to function normally. It took mission engineers months to identify the problem. The Articulation and Attitude Control System (AACS) was sending erroneous commands, writing them to computer memory instead of executing them. One of these missed commands garbled the flight status report. the AACS before it reaches engineers on the ground.
The team determined that the AACS had entered an incorrect mode; however, she was unable to determine the cause and is therefore not sure if the problem might recur. The software fix should prevent this.
“This patch is like an insurance policy that will protect us in the future and help us keep these probes active for as long as possible,” said Suzanne Dodd, Voyager project manager at JPL.
They are the only spacecraft to ever operate in interstellar space, and the data they return is invaluable to our understanding of our local universe.
Voyager 1 and Voyager 2 traveled more than 15 billion and 12 billion kilometers respectively from Earth.
These distances, the patch instructions will take more than 18 hours to reach the spacecraft. Due to the age of the ship and communication time, there is a risk that the patch might overwrite critical code or have other unintended effects on the ship. To reduce these risks, the team spent months writing, reviewing and verifying the code. As an added security measure, Voyager 2 will receive the patch first and serve as a test bed for its twin. Voyager 1 is further away from Earth than all other spacecraft, making its data more valuable.
The team will download the patch and perform an AACS memory read to ensure it is in the correct location on Friday, October 20. If there are no immediate issues, the team will issue a command on Saturday, October 28 to verify that the patch is working as it should.
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