NASA plans to disable more systems on the two Voyager spacecraft later this year, giving the rest enough power until around 2030. This is reported by the American magazine Scientific American, citing several researchers who have worked with the probes for decades. They were launched in 1977 and provided surprising glimpses and impressive images of the outer solar system. With the farewell to other instruments, the slow farewell to by far the longest active probes is beginning. Four science instruments are still functioning on Voyager 1 and five on Voyager 2. The magnetometers and the plasma science instrument (on Voyager 2) will likely remain active the longest.
Active for 40 years longer than expected
Launched 16 days apart in 1977, the two Voyager probes took advantage of a rare constellation in which the four largest planets in the solar system came particularly close together. Both first visited Jupiter and gained momentum to Saturn, where they separated: Voyager catapulted itself out of the plane of the solar system there, Voyager 2 to Uranus and Neptune. Originally only a four-year mission was planned, but now they have been on the road for almost 45 years and are still active. The Voyager program has long been one of NASA’s greatest successes. More recently, the Voyager twins – because there were so many failures with space probes at the time, there were two of each important – had reached interstellar space.
Although there is still enough fuel to correct the alignment of the probes, the power is slowly draining on both. The radionuclide batteries carried for this purpose produce about four watts less each year and the first heaters had to be turned off earlier, writes Scientific American. Contrary to expectations, this did not cause the cosmic ray detector to fail, even though its temperature had dropped by more than 60 degrees Celsius. If all goes well, the probes could send data into the 2030s, but that depends on the power supply, says Linda Spilker, who has worked on the mission since 1977.
The two Voyager probes are more than 19 billion kilometers from Earth, the signals need 18 (Voyager 2) and more than 21 (Voyager 1) hours, respectively, for this distance. It also complicates the analysis of a problem that exists on Voyager 1. NASA had made public a month ago that it had been sending data to Earth for some time that did not match what was happening on board. The probe is functioning normally and executing commands correctly, but data from the on-board computer responsible for alignment and orbit control was incorrect. Although we at NASA are sure we can solve the mystery. But it will take time, said NASA’s chief science officer. According to Space, Thomas Zurbuchen explained the difficulties in the following way: “Imagine that you are talking to someone and you can only say one word at a time. At the same time, he always hears the answer only two days later. That’s the type of conversation we have.”
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