Or, more appropriately, Voyager 1 is cooling its instruments. To help conserve power, the mission managers at NASA have decided to cut the electricity to a heating element – one that’s part of the nearby infrared spectrometer that’s not been in operation for some 14 years. This power cut will lower the temperature of the ultraviolet spectrometer by about 23 degrees Celsius (41 degrees Fahrenheit)… a temperature that’s mild compared to the below minus 79 degrees Celsius (minus 110 degrees Fahrenheit) that the instrument has dropped to in previous times. It’s not a drastic measure, however, but all part of a crucial plan to manage electrical power to keep the spacecraft operational and transmitting data for another 13 years.
Just because the power is cut back doesn’t mean the instrument quit working. At the present, the spectrometer is continuing to gather and transmit data. The resilient system was designed to work in temperatures as frosty as minus 35 degrees Celsius (minus 31 degrees Fahrenheit) and has even operated beyond the call of duty when heaters were switched off over the last 17 years. While it was taking a chance that the equipment might malfunction, the engineering team was confident since the spectrometer has worked at minus 56 degrees Celsius (minus 69 degrees Fahrenheit.) since 2005. “The spectrometer is likely operating at a temperature somewhat lower than minus 79 degrees Celsius, or minus 110 degrees Fahrenheit,” says the team. “But the temperature detector does not go any lower.”
While it has been awhile since Voyager 1’s encounter with Jupiter and Saturn which made the spectrometer busy, that doesn’t mean its data will be disregarded. Both scientists and mission management specialists will continue to monitor performance levels and an international team of scientists will further review spectrometer data.
I remember, some time after Voyager 1 flew past Jupiter, of seeing a television show that played a movie of Jupiter’s bands of rolling clouds. I was mesmerized. Now, UnmannedSpaceflight.com member Bjorn Jonsson has re-mastered that data into a crisp, clear video. I find it just as mesmerizing! In his description, Jonsson says, “The movie is based on 58 orange-green-blue color composites obtained on every Jovian rotation from January 6 to January 29, 1979. Over this period Voyager 1’s distance from Jupiter dropped from 58 to 36 million km so the resolution and sharpness of the frames increases from start to finish. The 58 frames were tweened, increasing the number of frames by a factor of 8 (that is, 7 synthetic frames are inserted between each real frame).”
You can see more of Jonsson’s work at his website.
After 33 years, NASA’s twin Voyager spacecraft are still actively working – gathering information, communicating with Earth, (and Tweeting!), and they are about to go where no space probe has gone before: into interstellar space. Because of the unfamiliar nature of the heliosphere, and especially its outermost layer, the heliosheath, it is not known exactly when the Voyagers will actually reach the “great beyond.”
“The heliosheath is 3 to 4 billion miles (4.8 to 6 billion km) in thickness,” said Voyager Project Scientist, Ed Stone. “That means we’ll be out within five years or so.” The V’ger’s Plutonium 238 heat source will keep the critical subsystems running through at least 2020, but after that, Stone says, “Voyager will become our silent ambassador to the stars.”
This video features highlights of the Voyager journeys to the outer planets and the discoveries they have made, and shows where they are now and where they are headed.
She might be old, but she’s still got it where it counts. The 33-year old Voyager 1 probe, flying out near the edge of the solar system conducted a roll program, spinning 70 degrees counterclockwise, and held the position by spinning gyroscopes for two hours, 33 minutes. Voyager performed its in-flight gymnastics on March 7, 2011 and scientists hope the maneuver will help answer the question of which direction is the sun’s stream of charged particles turns when it nears the edge of the solar system.
“Even though Voyager 1 has been traveling through the solar system for 33 years, it is still a limber enough gymnast to do acrobatics we haven’t asked it to do in 21 years,” said Suzanne Dodd, Voyager project manager, based at NASA’s Jet Propulsion Laboratory. “It executed the maneuver without a hitch, and we look forward to doing it a few more times to allow the scientists to gather the data they need.”
Voyager needed to get in the right orientation to enable its Low Energy Charged Particle instrument to gather data.
The last time either of the two Voyager spacecraft rolled and stopped in a gyro-controlled orientation was Feb. 14, 1990, when Voyager 1 snapped a family portrait of the planets. See the image here.
The two Voyager spacecraft are traveling through a turbulent area known as the heliosheath,the outer shell of a bubble around our solar system created by the solar wind. The solar wind is traveling outward from the sun at a million miles per hour. Scientists think the wind must turn as it approaches the heliosheath where it makes contact with the interstellar wind — , which originates in the region between stars.
In June 2010, when Voyager 1 was about 17 billion kilometers (about 11 billion miles) away from the sun, data from the Low Energy Charged Particle instrument began to show that the net outward flow of the solar wind was zero. That zero reading has continued since. The Voyager science team doesn’t think the wind has disappeared in that area, but perhaps has just turned a corner. But where does it go from there: up, down or to the side?
“Because the direction of the solar wind has changed and its radial speed has dropped to zero, we have to change the orientation of Voyager 1 so the Low Energy Charged Particle instrument can act like a kind of weather vane to see which way the wind is now blowing,” said Edward Stone, Voyager project manager. “Knowing the strength and direction of the wind is critical to understanding the shape of our solar bubble and estimating how much farther it is to the edge of interstellar space.”
Voyager engineers performed a test roll and hold back on Feb. 2, just to make sure the spacecraft was still capable. No problems for the old girl, and spacecraft had no problem in reorienting itself and locking back onto its guide star, Alpha Centauri.
There will be five more of these maneuvers over the next seven days, with the longest hold lasting three hours 50 minutes. The Voyager team plans to execute a series of weekly rolls for this purpose every three months.
Over the next few months, scientists will analyze the data.
“We do whatever we can to make sure the scientists get exactly the kinds of data they need, because only the Voyager spacecraft are still active in this exotic region of space,” said Jefferson Hall, Voyager mission operations manager at JPL. “We were delighted to see Voyager still has the capability to acquire unique science data in an area that won’t likely be traveled by other spacecraft for decades to come.”
Voyager 2 was launched on Aug. 20, 1977. Voyager 1 was launched on Sept. 5, 1977. On March 7, Voyager 1 was 17.4 billion kilometers (10.8 billion miles) away from the sun. Voyager 2 was 14.2 billion kilometers (8.8 billion miles) away from the sun, on a different trajectory.
The solar wind’s outward flow has not yet diminished to zero where Voyager 2 is exploring, but that may happen as the spacecraft approaches the edge of the bubble in the years ahead.
The venerable Voyager spacecraft are truly going where no one has gone before. Voyager 1 has now reached a distant point at the edge of our solar system where it is no longer detecting the solar wind. At a distance of about 17.3 billion km (10.8 billion miles) from the Sun, Voyager 1 has crossed into an area where the velocity of the hot ionized gas, or plasma, emanating directly outward from the sun has slowed to zero. Scientists suspect the solar wind has been turned sideways by the pressure from the interstellar wind in the region between stars.
“The solar wind has turned the corner,” said Ed Stone, Voyager project scientist based at the California Institute of Technology in Pasadena, Calif. “Voyager 1 is getting close to interstellar space.”
The event is a major milestone in Voyager 1’s passage through the heliosheath, the turbulent outer shell of the sun’s sphere of influence, and the spacecraft’s upcoming departure from our solar system.
Since its launch on Sept. 5, 1977, Voyager 1’s Low-Energy Charged Particle Instrument has been used to measure the solar wind’s velocity.
When the speed of the charged particles hitting the outward face of Voyager 1 matched the spacecraft’s speed, researchers knew that the net outward speed of the solar wind was zero. This occurred in June, when Voyager 1 was about 10.6 billion miles from the sun.
However, velocities can fluctuate, so the scientists watched four more monthly readings before they were convinced the solar wind’s outward speed actually had slowed to zero. Analysis of the data shows the velocity of the solar wind has steadily slowed at a rate of about 45,000 mph each year since August 2007, when the solar wind was speeding outward at about 130,000 mph. The outward speed has remained at zero since June.
“When I realized that we were getting solid zeroes, I was amazed,” said Rob Decker, a Voyager Low-Energy Charged Particle Instrument co-investigator and senior staff scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. “Here was Voyager, a spacecraft that has been a workhorse for 33 years, showing us something completely new again.”
Scientists believe Voyager 1 has not crossed the heliosheath into interstellar space. Crossing into interstellar space would mean a sudden drop in the density of hot particles and an increase in the density of cold particles. Scientists are putting the data into their models of the heliosphere’s structure and should be able to better estimate when Voyager 1 will reach interstellar space. Researchers currently estimate Voyager 1 will cross that frontier in about four years.
Our sun gives off a stream of charged particles that form a bubble known as the heliosphere around our solar system. The solar wind travels at supersonic speed until it crosses a shockwave called the termination shock. At this point, the solar wind dramatically slows down and heats up in the heliosheath.
A sister spacecraft, Voyager 2, was launched in Aug. 20, 1977 and has reached a position 8.8 billion miles from the sun. Both spacecraft have been traveling along different trajectories and at different speeds. Voyager 1 is traveling faster, at a speed of about 38,000 mph, compared to Voyager 2’s velocity of 35,000 mph. In the next few years, scientists expect Voyager 2 to encounter the same kind of phenomenon as Voyager 1.
The results were presented at the American Geophysical Union meeting in San Francisco.