HISTORY – SCIENCE – For the second time in history a human object has reached the space between the stars. NASA's Voyager 2 has already emerged from the heliosphere – the bubble of particles and magnetic fields created by the Sun.
The members of the NASA Voyager team will discuss the results at a press conference at 11 am at 8 am at the meeting of the American Geophysical Union in Washington DC. The press conference will be released live on the agency's website.
By comparing the data from various instruments on board the spacecraft, mission scientists found that the probe had crossed the outer edge of the heliosphere on November 5th. This limit, called heliopause, is the place where the complex, hot, sunny wind meets the cold, dense interstellar environment. His twin "Voyager 1" crossed this border in 2012, but Voyager 2 brings a working tool that will provide the first of his natural observations of the nature of this entry into the interstellar space.
Voyager 2 is now a little over 11 billion miles (18 billion kilometers) from Earth. The mission operators can still communicate with Voyager 2 when entering this new phase of their journey, but information moving at the speed of light takes about 16.5 hours to travel from a space ship on Earth. For comparison, the light that travels from the Sun takes about eight minutes to reach the Earth.
The most convincing proof of leaving the Voyager 2 heliosphere comes from the Plasma Science Experiment (PLS), a tool that stopped working on Voyager 1 in 1980, long before the probe crossed the heliopause. Until recently, the space around Voyager 2 was mostly filled with plasma from our Sun. This spill, called the solar wind, creates a balloon – the heliosphere – that envelops the planets in our solar system. PLS uses the plasma current to detect the velocity, density, temperature, pressure and flow of the solar wind. PLS aboard Voyager 2 marked a sharp drop in the particle speed of the solar wind on November 5. Since that date, the plasma instrument has not observed a stream of solar wind in the environment around Voyager 2, which makes the mission scientists sure that the probe has left the heliosphere.
"Work on Voyager makes me feel like a researcher because everything we see is new," says John Richardson, chief PLS tool researcher and senior researcher at the Massachusetts Institute of Technology in Cambridge. "Although Voyager 1 crossed the heliopasis in 2012, he did so in a different place and time and without PLS data, so we still see things that nobody has seen before."
In addition to plasma data, members of Voyager's team of scientists see evidence from three other on-board instruments, the cosmic rays subsystem, the low energy particle tool, and the magnetometer, which is consistent with the conclusion that Voyager 2 has passed the heliopause. The members of the Voyager team tend to continue studying the data from these other on-board tools to get a clearer picture of the environment Voyager 2 travels to.
"There is still much to learn about the area of interstellar space just after heliopause," said Ed Stone, a Vocabulary scientist based in Caltec in Pasadena, California.
Together, the two warriors provide a detailed insight into how our heliosphere interacts with the constant interstellar wind that flows beyond. Their observations are complemented by data from NASA's Space Border Interceptor (IBEX), a mission that remotely captures this limit. NASA is also preparing an additional mission – the forthcoming Interstellar Mapping and Acceleration Study (IMAP), which will begin in 2024 to benefit from the voyagers' observations.
"Voyager has a very special place for us in our helofish fleet," said Nicolas Fox, director of the Heliophysics Division at NASA's headquarters. "Our research begins from the sun and extends to everything the sun's wind touches." Making Voyagers send information about the edge of the Sun's influence gives us an unprecedented idea of a truly uncharted territory.
As the probes left the heliosphere, Voyager 1 and Voyager 2 have not left the solar system yet and will not leave soon. The boundary of the solar system is considered to be outside the outer edge of the Oort cloud – a collection of small objects still under the influence of Sun's gravity. The width of the Oort Cloud is not known exactly, but is expected to start from about 1,000 astronomical units (UA) from the Sun and expand to about 100,000 UA. An AU is the distance from the Sun to Earth. It will take about 300 years until the Voyager 2 reaches the inner edge of the Oort Cloud and probably 30,000 years to go beyond it.
The Voyager probes are powered by heat from the decomposition of radioactive materials contained in a device called radioisotope thermal generation (RTG). The output power of the RTG decreases by about four watts per year, which means that different parts of the voyagers, including the cameras of the two spaceships, have been shut down over time to power.
"I think we are all happy and relieved that Voyager's probes have worked long enough to cross this cornerstone," said Susanne Dodd, head of the Voyager project at NASA's Jet Propulsion Laboratory in Pasadena, California. "That's what we all have been waiting for, and now we look forward to what we can learn from the presence of the two probes outside the heliopause."
Voyager 2 started in 1977, 16 days before Voyager 1, and they both traveled far beyond their original destinations. Spacecrafts have been built for the past five years, and have conducted close research on Jupiter and Saturn. However, as the mission continued, it was possible to fly further on the two furthest giant planets – Uranus and Neptune. As the spacecraft flew through the solar system, reprogramming of the remote control was used to give the soldiers greater opportunities than they had when they left the Earth. Their two-plane mission became four planetary missions. Their five years of life have lasted 41 years, making Voyager 2 the longest mission of NASA.
Voyager's story has affected not only generations of current and future scientists and engineers, but also the Earth's culture, including films, art and music. Each spacecraft carries a golden record of Earth sounds, pictures and messages. Since the spacecraft can last for billions of years, these circular time capsules can one day be the only traces of human civilization.
Voyager's military controllers communicate with the probes using NASA's Deep Space Network (DSN), a global interplanetary spacecraft communication system. The DSN consists of three cluster antennas in Goldstone, California; Madrid, Spain; and Canberra, Australia.
Star Wars Voyager is part of NASA's Heliophysical Observatory, sponsored by NASA's Heliophysics Division in Washington, DC. JPL builds and manages the Voyager double spacecraft. NASA's DSN, run by JPL, is an international network of antennas that support interplanetary missions of spacecraft and radio astronomy and radar observations for the study of the solar system and the universe. The network also supports selected missions in orbit around the Earth. The Organization for Scientific and Industrial Research of National Science and Industrial Science, the Australian National Research Agency, works both in the DSN Communication Deep Space Communication and the Parkes Observatory, which NASA has been using since November 8 to transmit data from Voyager 2.
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