Engineers have decided why NASA’s Voyager 1 probe has been transmitting gibberish for almost 5 months, elevating hopes of recovering humanity’s most distant spacecraft.
Voyager 1, touring outbound some 15 billion miles (24 billion km) from Earth, began beaming unreadable information down to floor controllers on November 14. For almost 4 months, NASA knew Voyager 1 was nonetheless alive—it continued to broadcast a regular sign—but couldn’t decipher something it was saying.
Confirming their speculation, engineers at NASA’s Jet Propulsion Laboratory (JPL) in California confirmed a small portion of corrupted reminiscence triggered the issue. The defective reminiscence financial institution is situated in Voyager 1’s Flight Data System (FDS), considered one of three computer systems on the spacecraft. The FDS operates alongside a command-and-control central pc and one other gadget overseeing perspective management and pointing.
The FDS duties embrace packaging Voyager 1’s science and engineering information for relay to Earth by means of the craft’s Telemetry Modulation Unit and radio transmitter. According to NASA, about 3 p.c of the FDS reminiscence has been corrupted, stopping the pc from finishing up regular operations.
Optimism rising
Suzanne Dodd, NASA’s undertaking supervisor for the dual Voyager probes, informed Ars in February that this was one of the vital critical issues the mission has ever confronted. That is saying one thing as a result of Voyager 1 and a pair of are NASA’s longest-lived spacecraft. They launched 16 days aside in 1977, and after flying by Jupiter and Saturn, Voyager 1 is flying farther from Earth than any spacecraft in historical past. Voyager 2 is trailing Voyager 1 by about 2.5 billion miles, though the probes are heading out of the Solar System in numerous instructions.
Normally, engineers would attempt to diagnose a spacecraft malfunction by analyzing information it despatched again to Earth. They could not try this on this case as a result of Voyager 1 has been transmitting information packages manifesting a repeating sample of ones and zeros. Still, Voyager 1’s floor group recognized the FDS because the possible supply of the issue.
The Flight Data Subsystem was an innovation in computing when it was developed 5 many years in the past. It was the primary pc on a spacecraft to use unstable reminiscence. Most of NASA’s missions function with redundancy, so every Voyager spacecraft launched with two FDS computer systems. But the backup FDS on Voyager 1 failed in 1982.
Due to the Voyagers’ age, engineers had to reference paper paperwork, memos, and blueprints to assist perceive the spacecraft’s design particulars. After months of brainstorming and planning, groups at JPL uplinked a command in early March to immediate the spacecraft to ship again a readout of the FDS reminiscence.
The command labored, and Voyager.1 responded with a sign completely different from the code the spacecraft had been transmitting since November. After a number of weeks of meticulous examination of the brand new code, engineers pinpointed the areas of the unhealthy reminiscence.
“The group suspects that a single chip liable for storing a part of the affected portion of the FDS reminiscence isn’t working,” NASA mentioned in an replace posted Thursday. “Engineers can’t decide with certainty what triggered the difficulty. Two potentialities are that the chip might have been hit by an lively particle from area or that it merely might have worn out after 46 years.”
Voyager 1’s distance from Earth complicates the troubleshooting effort. The one-way journey time for a radio sign to attain Voyager 1 from Earth is about 22.5 hours, which means it takes roughly 45 hours for engineers on the bottom to find out how the spacecraft responded to their instructions.
NASA additionally should use its largest communications antennas to contact Voyager 1. These 230-foot-diameter (70-meter) antennas are in excessive demand by many different NASA spacecraft, so the Voyager group has to compete with different missions to safe time for troubleshooting. This means it will take time to get Voyager 1 again to regular operations.
“Although it might take weeks or months, engineers are optimistic they will discover a means for the FDS to function usually with out the unusable reminiscence {hardware}, which might allow Voyager 1 to start returning science and engineering information once more,” NASA mentioned.