Engineers Working to Resolve Issue With Voyager 1 Computer

Editor’s note: A previous version of this post identified the TMU as the telecommunications unit. It is the telemetry modulation unit.

An illustration of a spacecraft against a blue space-like background
Artist’s illustration of one of the Voyager spacecraft. Credit: Caltech/NASA-JPL

Engineers are working to resolve an issue with one of Voyager 1’s three onboard computers, called the flight data system (FDS). The spacecraft is receiving and executing commands sent from Earth; however, the FDS is not communicating properly with one of the probe’s subsystems, called the telemetry modulation unit (TMU). As a result, no science or engineering data is being sent back to Earth.

Among other things, the FDS is designed to collect data from the science instruments as well as engineering data about the health and status of the spacecraft. It then combines that information into a single data “package” to be sent back to Earth by the TMU. The data is in the form of ones and zeros, or binary code. Varying combinations of the two numbers are the basis of all computer language.

Recently, the TMU began transmitting a repeating pattern of ones and zeros as if it were “stuck.” After ruling out other possibilities, the Voyager team determined that the source of the issue is the FDS. This past weekend the team tried to restart the FDS and return it to the state it was in before the issue began, but the spacecraft still isn’t returning useable data.

It could take several weeks for engineers to develop a new plan to remedy the issue. Launched in 1977, the spacecraft and its twin, Voyager 2, are the two longest-operating spacecraft in history. Finding solutions to challenges the probes encounter often entails consulting original, decades-old documents written by engineers who didn’t anticipate the issues that are arising today. As a result, it takes time for the team to understand how a new command will affect the spacecraft’s operations in order to avoid unintended consequences.

In addition, commands from mission controllers on Earth take 22.5 hours to reach Voyager 1, which is exploring the outer regions of our solar system more than 15 billion miles (24 billion kilometers) from Earth. That means the engineering team has to wait 45 hours to get a response from Voyager 1 and determine whether a command had the intended outcome.

News Media Contact
Calla Cofield
Jet Propulsion Laboratory, Pasadena, Calif.

HelioCloud Leads Heliophysics Research into the Cloud Computing Revolution

Announcing HelioCloud – a new, collaborative, cloud-based tool for heliophysics scientists and students to rapidly access and analyze high-volume datasets from a web browser. With an easy-to-navigate interface and generous data storage, HelioCloud offers a streamlined approach to conduct research.HelioCloud Logo

Work in the Cloud, Download Results

This free and open-source platform offers a virtual software environment with high performance computing capabilities to run code and plot, visualize, and analyze data without needing to download any software. HelioCloud holds up to ten thousand times the data storage of most laptops – it’s like having big data on demand. This allows users to expedite research by working with large datasets stored in the cloud and then downloading only the results. HelioCloud’s searchable registry includes 600 terabytes of data from NASA’s Heliophysics Digital Resource Library (HDRL), the data ingest and archive for heliophysics missions. 

An Image of the Sun, showing bright loops of yellow plasma, taken by NASA's Solar Dynamics Observatory
Access data from SDO AIA (pictured), SDO HMI, MMS, and all of CDAWeb rapidly via HelioCloud. Credit: NASA/SDO

Easy Local Access

Researchers who prefer to work with software stored on their own computer can download and install HelioCloud as a virtualized operating system container that includes a reusable software stack with all of the components needed to replicate and run the program locally. This container includes heliophysics software applications written in Python programming languages, like SunPy and PySPEDAS, as well as integrated development environments including Daskhub and Jupyter Notebooks. 

Built for Collaboration

HelioCloud provides an open science framework that breaks down barriers to collaboration by enabling multipoint access to shared data, code, and analysis tools in a secure environment. Users can automatically access data made public by NASA and other HelioCloud communities, and safely store, modify, and share code with stable runtime environments. 

This community-based project is supported by NASA and led by a development team at Johns Hopkins University Applied Physics Laboratory. HelioCloud invites heliophysics researchers from NASA and other research labs as well as universities to join the project as users or developers and take part in the game-changing evolution of big-data analysis. 

Visit for more info.
Mailing list:

By Rose Brunning
Communications Lead
NASA Heliophysics Digital Resource Library (HDRL)