On August 20, 1977, NASA’s Voyager 2 spacecraft was launched into space. Its twin, Voyager 1, was released 16 days later. Today, they are not only the furthest man-made objects — 12 billion and 14.5 billion miles (19.3 billion and 23.3 billion kilometers) from Earth, respectively — but also NASA’s longest operating mission, which continues to send data from interstellar flights. Towards the edge of the solar system as it approaches its forty-fifth birthday.
but all Voyager spacecraft It is powered by a limited nuclear power source, and both sources are dwindling to dangerously low levels. Each spacecraft carries a store of the radioactive isotope plutonium-238. When the isotope decays, it releases energy that is converted into electricity by three radioisotope thermoelectric generators (RTGs). At launch, RTGs supplied each spacecraft with 450 watts of power. Now, they produce less than half that amount and their electrical output is decreasing by four watts each year.
“It takes about 200 watts, roughly, to power the transmitter on the spacecraft, to be able to send the signals back to a landAnd we’re at an energy level right now where we only have about five to six watts of power margin per spacecraft,” Susan Dodd, director of the Voyager Interstellar Mission, who also serves as director of the Interplanetary Network Directorate at NASA Jet Propulsion Laboratory (JPL) in California, for Space.com.
Related: 40 photos from NASA’s epic ‘Grand Tour’ mission
But the offer is not over yet. Voyager teams are strategically conserving energy by turning off certain subsystems on both spacecraft, such as some heaters, allowing others to run for longer.
Miraculously, the remaining scientific instruments are performing well so far even in cold temperatures. “It’s great that we’re getting data that’s far beyond what we thought we could run on cold,” Dodd said.
Between the anniversaries of each launch this summer, the Voyager instrument teams will hold a meeting to discuss their latest findings. The collected data becomes the basis for a new model that will guide future plans for the two spacecraft, including shutting down any instrument, and using conservation methods, Dodd estimates that the spacecraft could operate for another five years, if its operation was solely based on energy. “If we’re really lucky, maybe we do some operations without some thresholds, we might be able to go to 2030,” she said.
But the spacecraft’s advanced age poses another problem: general hardware and software failures. For example, just a few months ago, the Voyager 1 Expression and Attitude Control System (AACS), which directs the spacecraft and its communications antenna, began Send bad telemetry data back to Earth. However, mission personnel know that the AACS system is already working fine because the signal from its antenna has remained stable – and appears to be confused about where to locate it.
“We can drive the spacecraft and the spacecraft can return the science data to us, so it’s running as usual,” Dodd said. “It’s just one computer system that can’t tell us it’s running as usual.”
Such anomalies are expected to appear with age in Voyagers, and the malfunction could eventually lead to the loss of the spacecraft, even if it was still powerful. But however Voyager 1 and 2 continue to operate, the Voyager mission has already been a huge success. The original mission was to fly out of the solar system gaseous planets their satellites and sending data back to Earth – tasks that both spacecraft had completed by 1989.
Then the secondary Voyager Interstellar Mission began, tasking the Voyager spacecraft with obtaining information about the space secrets behind the Sun’s influence. “How do things change as you get further and further away from the sun?” Dodd said. “And how does the interaction of the magnetic field with interstellar space change as we go further and further? How does the density of the plasma change as we go further and further?”
She noted that there was only one way to answer these questions. “The key here is to keep the spacecraft operational and to return the data for as long as possible.”
#NASAs #twin #Voyager #probes #years #theyre #facing #tough #decisions