Space. The final frontier.
After three decades of travelling through the massive vacuum of space, Voyager 1 has left the solar system and Voyager 2 is relatively close behind.
The National Aeronautics and Space Administration (NASA) sent two unmanned space probes in 1977 to take advantage of a favourable alignment of the planets during the late 1970s. The Voyager probes both carry a golden record in the event that either spacecraft is ever found by intelligent life forms from other planetary systems. These discs carry photos of Earth and its lifeforms, a range of scientific information, spoken greetings from people such as the President of the United states and a medley of sounds from Earth such as whale songs and Mozart. Voyager 1 and Voyager 2 were sent to study Jupiter and Saturn but they continued on their mission even after they passed it. Now both Voyagers are in the Heliosheath, the outermost layer of the heliosphere where the solar wind is slowed by the pressure of interstellar gas. Voyager 1 used Saturn to help slingshot its way past Pluto and Voyager 2 travelled past Uranus and Neptune.
Now after 36 years, travelling through space at a velocity of 17 kilometres per second, NASA’s Voyager 1 probe has left our solar system. This plutonium-powered probe has entered interstellar space and has travelled farther than anyone or anything Earth has ever sent. Voyager 1 has travelled beyond the reach of the sun’s solar winds, and as of writing this article, 18.8 billion kilometres from Earth.
The probe carries cameras, magnetometers, and other instruments that send data and photographs back via radio waves in the form of 0’s and 1’s which take 17 hours to reach Earth. Voyager 1 is now sending back data from the boundary range between solar winds and interstellar wind, passing the debris of thousands of exploded stars in the Milky Way Galaxy.
The instruments on Voyager 1 that are for directly detecting the transition zone between where the solar winds end and where interstellar space begins died in 1980 and researchers have been relying on indirect measures of magnetic and electrical activity from other instruments on board to find the answer.
One of the key identifiers of the boundary between our solar system and interstellar space is the difference in the density of charged particles between the solar wind and the interstellar space. This is because the density is about 50 times greater in interstellar space than in the region with solar winds. Scientists still believe that the telltale sign that Voyager 1 has left the solar system would be a change in direction of magnetic field lines. Last year, scientists monitoring Voyager 1 noticed strange events that meant the spacecraft was broken. Charged particles streaming from the sun had vanished but at the same time, there was a spike in galactic cosmic rays. Since there was also no change in the magnetic field line direction, scientists believed that the probe was still in the heliosphere. Many are still waiting for the direction of the magnetic field lines to change as it might still be too early to judge.
One of the most iconic pictures the Voyager probe has taken is the Pale Blue Dot from Valentine’s Day, 1990. The cameras on the probe have since been turned off to save memory and power and even if they were turned back on, they would mostly not work after years of being exposed to very cold conditions. Voyager 1 is escaping the solar system at a speed of about 3.6 AU per year, 35 degrees out of the ecliptic plane to the north, in the general direction of the Solar Apex, and in the year 40,272 AD, Voyager will come within 1.7 light years of an obscure star in the constellation Ursa Minor.
Much like in Star Trek: Voyager, Voyager 1 is the first man made object to enter an unknown region of space and has very weak line of communication with Earth. Unlike Star Trek: Voyager, this spacecraft is unmanned and will not be coming home. Voyager 1’s first mission outside of our solar system will be to explore interstellar space. Voyager 1 will now study exotic particles and other phenomena in an unexplored part of the universe and radio data back to Earth. Meanwhile, Voyager 2 has travelled 15.3 billion kilometres from Earth and is expected to reach interstellar space in 2016, but the amount of power available to the probe has been decreasing since its launch and is expected to be unable to power any of its instruments by 2025.
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