NASA reports that the Voyager I spacecraft now cruising through interstellar space is returning bizarre spacetime data and is, in effect, lost.
The craft is now 14.5 billion miles from Earth, so that NASA's commands, traveling at the speed of light, take almost a day to reach the probe. It takes another day for Voyager's automated response, sent from the mystery-laden interstellar medium, to reach Earth.
Readouts from the probe's steering system don't reflect what scientists deduce must actually be happening. The data show strings of zeroes, random numbers or the number 377 (which has 13 and 29 as its prime factors). None of these data are consistent with feedback that would say the probe's high-gain antenna is pointed toward Earth. Yet, because there is no detectable drop in the antenna's signal, it seems that it must nevertheless be pointing to Earth.
Further, all systems aboard the spacecraft seem to be operating normally.
But, there is no certainty that the antenna is still pointing to Earth, meaning it could be traveling in an unknown direction. Is there something in the interstellar medium that might boost the signal, even though it is pointing the wrong way? Probabilities would suggest that that is quite unlikely. If the craft has reversed direction, that reversal would eventually be detected because, presumably, the signal would become stronger.
The prevailing idea is that age-related diminishing power and wear and tear might have something to do with the telemetry data going awry, but there is no particular process that has become a suspect. That is, no plausible scenario has emerged as to what might be going on.
Few would expect that spacetime outside the solar system would be significantly different from the spacetime within the Sun's system, though a free-floating black hole could yield confusing effects. Einstein's general theory of relativity is thought to apply uniformly throughout the cosmos.
Yet, once Voyager crossed the heliosphere -- the barrier at the outer limits of the solar system where solar winds pile up into a fiercely hot, but attenuated, plasma -- it entered the Deep Unknown. There have been numerous apparent spacetime anomalies that show up when interstellar space is viewed from Earth. Yet, even so, most scientists believe general relativity always applies, though a few are suspicious of that assumption.
NASA statement
The craft is now 14.5 billion miles from Earth, so that NASA's commands, traveling at the speed of light, take almost a day to reach the probe. It takes another day for Voyager's automated response, sent from the mystery-laden interstellar medium, to reach Earth.
Readouts from the probe's steering system don't reflect what scientists deduce must actually be happening. The data show strings of zeroes, random numbers or the number 377 (which has 13 and 29 as its prime factors). None of these data are consistent with feedback that would say the probe's high-gain antenna is pointed toward Earth. Yet, because there is no detectable drop in the antenna's signal, it seems that it must nevertheless be pointing to Earth.
Further, all systems aboard the spacecraft seem to be operating normally.
But, there is no certainty that the antenna is still pointing to Earth, meaning it could be traveling in an unknown direction. Is there something in the interstellar medium that might boost the signal, even though it is pointing the wrong way? Probabilities would suggest that that is quite unlikely. If the craft has reversed direction, that reversal would eventually be detected because, presumably, the signal would become stronger.
The prevailing idea is that age-related diminishing power and wear and tear might have something to do with the telemetry data going awry, but there is no particular process that has become a suspect. That is, no plausible scenario has emerged as to what might be going on.
Few would expect that spacetime outside the solar system would be significantly different from the spacetime within the Sun's system, though a free-floating black hole could yield confusing effects. Einstein's general theory of relativity is thought to apply uniformly throughout the cosmos.
Yet, once Voyager crossed the heliosphere -- the barrier at the outer limits of the solar system where solar winds pile up into a fiercely hot, but attenuated, plasma -- it entered the Deep Unknown. There have been numerous apparent spacetime anomalies that show up when interstellar space is viewed from Earth. Yet, even so, most scientists believe general relativity always applies, though a few are suspicious of that assumption.
NASA statement
While the spacecraft continues to return science data and otherwise operate as normal, the mission team is searching for the source of a system data issue.
The engineering team with NASA’s Voyager 1 spacecraft is trying to solve a mystery: The interstellar explorer is operating normally, receiving and executing commands from Earth, along with gathering and returning science data. But readouts from the probe’s attitude articulation and control system (AACS) don’t reflect what’s actually happening onboard.
The AACS controls the 45-year-old spacecraft’s orientation. Among other tasks, it keeps Voyager 1’s high-gain antenna pointed precisely at Earth, enabling it to send data home. All signs suggest the AACS is still working, but the telemetry data it’s returning is invalid. For instance, the data may appear to be randomly generated, or does not reflect any possible state the AACS could be in.
PROBE FINDS NO FAULT
The issue hasn’t triggered any onboard fault protection systems, which are designed to put the spacecraft into “safe mode” – a state where only essential operations are carried out, giving engineers time to diagnose an issue. Voyager 1’s signal hasn’t weakened, either, which suggests the high-gain antenna remains in its prescribed orientation with Earth.
The team will continue to monitor the signal closely as they continue to determine whether the invalid data is coming directly from the AACS or another system involved in producing and sending telemetry data. Until the nature of the issue is better understood, the team cannot anticipate whether this might affect how long the spacecraft can collect and transmit science data.
Voyager 1 is currently 14.5 billion miles (23.3 billion kilometers) from Earth, and it takes light 20 hours and 33 minutes to travel that difference. That means it takes roughly two days to send a message to Voyager 1 and get a response – a delay the mission team is well accustomed to. “A mystery like this is sort of par for the course at this stage of the Voyager mission,” said Suzanne Dodd, project manager for Voyager 1 and 2 at NASA’s Jet Propulsion Laboratory in Southern California. “The spacecraft are both almost 45 years old, which is far beyond what the mission planners anticipated. We’re also in interstellar space – a high-radiation environment that no spacecraft have flown in before. So there are some big challenges for the engineering team. But I think if there’s a way to solve this issue with the AACS, our team will find it.”
JUST GET USED TO IT?
It’s possible the team may not find the source of the anomaly and will instead adapt to it, Dodd said. If they do find the source, they may be able to solve the issue through software changes or potentially by using one of the spacecraft’s redundant hardware systems.
It wouldn’t be the first time the Voyager team has relied on backup hardware: In 2017, Voyager 1’s primary thrusters showed signs of degradation, so engineers switched to another set of thrusters that had originally been used during the spacecraft’s planetary encounters. Those thrusters worked, despite having been unused for 37 years.
Voyager 1’s twin, Voyager 2 (currently 12.1 billion miles, or 19.5 billion kilometers, from Earth), continues to operate normally.
Launched in 1977, both Voyagers have operated far longer than mission planners expected, and are the only spacecraft to collect data in interstellar space. The information they provide from this region has helped drive a deeper understanding of the heliosphere, the diffuse barrier the Sun creates around the planets in our solar system.
WEAKENING STRENGTH
Each spacecraft produces about 4 fewer watts of electrical power a year, limiting the number of systems the craft can run. The mission engineering team has switched off various subsystems and heaters in order to reserve power for science instruments and critical systems. No science instruments have been turned off yet as a result of the diminishing power, and the Voyager team is working to keep the two spacecraft operating and returning unique science beyond 2025.
While the engineers continue to work at solving the mystery that Voyager 1 has presented them, the mission’s scientists will continue to make the most of the data coming down from the spacecraft’s unique vantage point.
The Voyager spacecraft were built by JPL, which continues to operate both. JPL is a division of Caltech in Pasadena. The Voyager missions are a part of the NASA Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate in Washington.
No comments:
Post a Comment