In December 2018, the spacecraft NASA Voyager 2 reached interstellar space, following the example of his sister Voyager 1. At present, only five spacecraft have been launched to make such a spectacular trip, including the Voyagers. The remaining three are pioneers 10 and 11 and New Horizons. Which one will be the next one to be a great escape?
This milestone – the interstellar space – can be considered as leaving the solar system with a certain definition. Make sure what it means. In the 1990s, the New York Times reported that Pioneer was reportedly leaving the solar system as he flew past Neptune's orbit. This was not what the scientists of Voyager 2 had made. Instead, the newer measurement considers the transition of solar heliopause, the theoretical boundary of its heliosphere, as the decisive factor for the entry of interstellar space. The heliosphere is a bubble of charged particles that originates and flows through the sun. Scientists use it to mark the place where interstellar space begins.
But the heliosphere is difficult and it changes with the 22-year solar cycle of the sun, which decreases and grows with the sun's wind and decomposes to the sun in the direction of the star's path. This is not something that is easy to measure from Earth. NASA's Interstellar Border Survey (IBEX) mission works to remotely define the edges of the bubble. (Heliosphere is a bubble, heliopause is its edge.) [What’s Next for NASA’s Voyager 2 in Interstellar Space?]
Observation of Voyager's probes shows that this bubble has been pierced. However, because scientists think that the sun is also surrounded by Oort Cloud, an area of icy bodies estimated at 1,000 to 100,000 astronomical units – far beyond heliopause – the Voyager can not be considered completely out of the solar system. (One astronomical unit or AU is the distance between the Earth and the Sun – 93 million miles or 150 million kilometers).
When Voyager 1 and 2 crossed the heliopause, their ever-functioning particles showed historical events. Heliososphere acts as a shield that keeps many particles with higher energy generated by cosmic rays produced by other stars. By tracking some of the low-energy particles inside the solar system and high-energy particles from outside, the devices could reveal a sudden increase in cosmic rays to warn scientists that the space probe had left the solar system.
Which spacecraft will then pass through interstellar space?
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Changing the heliosphere makes it impossible to find out when Pioneer 10 and 11 will enter the interstellar space. In fact, it is possible that one of them can already.
According to a NASA survey "Beyond the Earth: Chronicle of Deep Space Exploration" on November 5, 2017, Pioneer 10 was about 118,824 AUs from Earth, than any craft except Voyager 1. However, while Pioneer 11 and Voyager Twins were heading toward the apparent Sun travel, Pioneer 10 faces towards the back. According to the 2017 research, the heliosphere tail is about 220 AU from the sun. As Pioneer 10 travels around 2.5 AU / yr, Pioneer will take up to about 2057-40 years – to experience a change in boundaries.
Pioneer 11 is estimated at about 97.6 AU from Earth on November 5, 2017, according to the same e-book. Unlike his twin, the spacecraft moves in approximately the same direction as the Voyagers. Voyager 2 switched to interstellar media approximately 120 AU. Given that Pioneer 11 travels at 2.3 AU / year, it should get into interstellar space in the next decade around 2027 – assuming the boundaries do not change, which is likely to be.
And the latest spacecraft between the three new horizons? On January 1, 2019, the spacecraft appeared with the latest solar system object and began much later than the other four. During his ride, New Horizons was 43 AU from the sun. Alan Stern, mission chief investigator, told Space.com that the spacecraft travels about 3.1 AU per year, or 31 AU in ten years. For the next 20 years, the spaceship has a good chance to move into interstellar space. If New Horizons reached the same Voyager 2 boundary (it will not, but is considered as the default), the route would be in less than 24 years in 2043. However, it is possible that the ISM line will move inward, the transition. [NASA’s 10 Greatest Science Missions]
While we will not have direct confirmation of crossing heliopause using the Pioneer space probe, it is possible that the new horizons will still work and provide a detailed study of interstellar space. The particle detectors it carries are far more powerful than the Voyager detectors, Stern said. In addition, New Horizons carry a dust detector that would give a view of the area behind the heliosphere.
"Putting a dust detector into interstellar media would be a very valuable experience," he said.
But it will be tight, whether they work or not. According to Stern, it is a limiting factor. New horizons are exhausted from decomposing plutonium oxide. Right now the spaceship has enough power to work until the late 1930s, Stern said, and is currently in good shape.
If the ever-changing heliosphere stays static – the unlikely event – Pioneer 11 will be overcoming heliopaus next in 2027, followed by New Horizons in 2043. Pioneer 10, the first of five spacecraft to be launched, will last leave the heliosphere in 2057. this assumes an extremely unrealistic possibility that heliopause will remain static for the next 40 years.
Execution of passage
If you are interested in when the spacecraft "will go" in the long distance race, David Cranor has calculated the numbers in his blog, nothing more powerful. Cranor, working in the space industry, never worked on any of the five missions. To make it clear that the spacecraft travels in different ways, they will not cross each other as if they were traveling on the road. Instead, which one is the furthest and closest to Earth will change over time.
"I've always been really interested in Voyager and pioneers, and I just curious to know when they will meet when someone mentions that New Horizons goes faster than pioneers," said Cranor Space.com.
Limited data work has revealed that Voyager 1 has gone through Pioneer 11 between 1982 and 1983. He estimated that Voyager 2 surpassed Pioneer 11 around March 1988, although changes in speed and direction suggest that it was probably earlier.
As the New Horizons Pioneer 10 and 11 pass through the future is enormous, Cranor has warned that numbers will have a significantly high error rate. However, using the speeds that each vessel traveled to December 2017, it calculated that New Horizons would pass through Pioneer 11 in 2113 and would not pass Pioneer 10 until 2187.
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