Data from the spacecraft’s orientation system do not reflect what is actually happening aboard a distant spacecraft, for reasons that NASA cannot explain, writes The Independent.
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If the probe’s orientation data were true, the probe would send it out to Earth. In other words, we could not receive this data at all.
Jakub Rozehnal, director of the Prague Planetarium
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While the probe as such operates normally, receiving and executing commands from Earth along with collecting and sending scientific data, a team of scientists is looking for the source of the system data problem, web space agencies.
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“Such a mystery is quite expected at this stage of the mission,” said Suzanne Dodd, project manager for Voyager 1 and 2 at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.
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“The probes are almost 45 years old, working so much longer than expected. (Originally, their lifespan was planned for only five years – editor’s note.) In addition, they are located in interstellar space – in an environment with high radiation, in which no spaceship has flown so far. The team of engineers thus faces great challenges. But I think if there is a way to solve the problem, then our team will find it, “she is convinced.
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The probe did not switch to emergency mode
There are some difficulties with the attitude articulation and control system (AACS), which controls the orientation of the probe, in particular keeping Voyager 1’s antenna pointed precisely at Earth, allowing the satellite to send data “home”.
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According to NASA, everything suggests that AACS is still working, but the telemetry data it returns is untrue – therefore meaningless. It appears as if the data were generated randomly or do not reflect any possible state in which AACS could be.
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In addition, the probe is equipped with automatic systems that have it switched to “safe mode” in the event of a similar problem, in which it performs only the operations necessary for survival. This will give technicians on Earth time to solve the problem. But that didn’t happen and Voyager is still in normal mode.
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The fact that the signal from the probe continues to come, however, confirms that the antenna is in fact pointed correctly towards the Earth – except that, paradoxically, the probe probably does not know.
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The need for precise orientation due to the huge distance
“To understand why data from Voyager 1 is considered meaningless by scientists, we need to know how they communicate with the probe. The spacecraft is now located at a distance of 23.3 billion kilometers, the signal from it flies to Earth in 20 hours and 33 minutes, “said astronomer and astrophysicist Jakub Rozehnal, director of the Planetum organization, which associates the Observatory and Planetarium of the Capital City of Prague. Prague, Štefánik Observatory and Ďáblice Observatory.
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It takes about two days to send a message to Voyager 1 and receive a response. According to Rozehnal, the appropriate distance requires a very precise orientation of the probe, which transmits data using a parabolic antenna with a diameter of 3.7 meters.
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The orientation of the probe is controlled by the aforementioned AACS system, which uses a sensor of the Sun and bright stars to maintain the orientation of the antenna so that it always points to the Earth. Here we receive signals through the Deep Space Network (DSN), which has a network of antennas with a diameter of 30 to 70 meters, which at all times cover the entire Earth.
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“Along with scientific data, the probe also sends data about its orientation to the Earth – and this is where the snag is,” recalls Rozehnal.
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“If the probe’s orientation data were true, the probe would send it out to Earth, in other words, we would not be able to receive that data at all. The fact that we hear the probe signal suggests that the AACS probe orientation system is working properly, but the systems that take care of writing and reading data from the memory registers are somehow ‘confused’, “the expert continued.
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“At this point, all we have to do is listen to the probe carefully and try to find some clue in the seemingly random data that would lead us to discover the faulty part of the broadcast chain,” he explained.
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The “completely unexpected” data is “only” systemic, but it is not known whether the problem is in the critical AACS system itself or comes from some other affiliate. Until we better understand the nature of the problem, we cannot predict how long the machine will still be able to collect and transmit scientific data, NASA warns.
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Rozehnal added that a number of important systems are duplicated on board, including AACS, so one option would be to switch to a backup system if it was eventually confirmed that the defect was indeed in it. However, according to him, this is not probable.
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“If there is a fault in the broadcast chain, there is a certain possibility that the faulty member can be bypassed by software, but if that fails, it is simply possible not to look at the confusing data and get ‘used’ to the error,” he said.
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Buzzing and density beyond the Solar System
In terms of scientific data, Voyager 1, for example, sent data revealing the “hum” of interstellar gas from a distance of more than 22.5 billion kilometers last June. The researchers studied the data and were able to identify something of it as a “persistent buzz.” But the signal from the camera was too weak to be heard.
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Voyager 1, now the most man-made object in space, has been in operation for almost 45 years. It now operates on the edge of the solar system and flies through the so-called interstellar medium. (Interstellar medium means superheated plasma present in the center of a cluster of galaxies, this gas is heated to a temperature of the order of 10 to 100 megakelvin and consists mainly of ionized hydrogen and helium – ed. Note.)
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The Voyager 1 apparatus itself set off in September 1977 (its “twin”, Voyager 2, already in August 1977), flew at a speed of approximately 61,152 km / h, in 1979 whizzed around Jupiter, then around Saturn in the late 1980s and had already passed the so-called heliopause, the border of the solar system with interstellar space. The spacecraft entered it in 2012, Voyager 2 in 2018.
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Both Voyagers are the only probes that collect data in interstellar space. The information they provide in this area has helped to gain a deeper understanding of the heliosphere, the barrier that the Sun creates around the planets of our solar system.
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| Heliosphere is the envelope of particles surrounding the Sun. It is a kind of “bubble” created by the solar wind, which extends far beyond Pluto’s orbit. The heliosphere ends where the pressure of the solar wind balances with the pressure of the surrounding stars. |
| Its helium mantle is the space in which the Sun’s magnetic field acts and where the solar wind moves at supersonic speeds. The edge of the helium mantle is called the heliopause – beyond this limit, the solar wind slows below the speed of sound. The Sun’s magnetic field ceases to act there, so the heliopause can be described as the imaginary boundary of the solar system. This theoretical limit is 18 billion kilometers away. |
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Voyager 2 is currently about 19.5 billion kilometers from Earth, remains in standard operation and has no problems.
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In addition, the “two” may have already helped determine that as it moves further away from the solar system, the density of outer space increases.
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