22August2017

Voyager 1 is out of the Solar System

  1. Launched in 1977, Voyager was sent initially to study the outer planets but it kept on going.
  2. Voyager 1 flies out of Solar System – on less power than an iPhone 5
  3. Around August 25, 2012, more than 19 billion kilometers from the Sun, the Voyager 1 space probe became the first human-made object to cross out of the Solar System and into interstellar space.
  4. It has drifted beyond the bubble of hot gas from our Sun and now moving in the space between the stars
  5. Scientists have confirmed that the 35-year old probe, launched to study the Jovian system, has crossed into a region of space that shows all the signs of it being the interstellar medium.
  6. It is so far away that it takes around 17 hours for its radio signals to reach Earth.

A NASA probe has become the first man-made object to travel beyond the Solar System, the American space agency revealed last night.

Scientists said that Voyager 1’s instruments indicate it has drifted beyond the bubble of hot gas from our Sun and was now moving in the space between the stars.

And it’s incredible feat was achieved on less power than an iPhone. The Voyager has reportedly less than 40KB of memory, whilst a 16GB iPhone 5 has 240,000 times that.

Professor Ed Stone, chief scientist on the mission, said: “This is really a key milestone that we’d been hoping we would reach when we started this project over 40 years ago – that we would get a spacecraft into interstellar space.”

Scientists have been debating for more than a year whether NASA’s 36-year-old Voyager 1 spacecraft has left the solar system and become the first human-made object to reach interstellar space.

By a fluke measurement, they now know definitively it has.

“We made it,” lead Voyager scientist Edward Stone, from the California Institute of Technology, told reporters on Thursday.

The key piece of evidence came by chance when a pair of solar flares blasted charged particles in Voyager’s direction in 2011 and 2012. It took a year for the particles to reach the spacecraft, providing information that could be used to determine how dense the plasma was in Voyager’s location.

Plasma consists of charged particles and is more prevalent in the extreme cold of interstellar space than in the hot bubble of solar wind that permeates the solar system.

Voyager 1, now 13 billion miles from Earth, could not make the measurement directly because its plasma detector stopped working more than 30 years ago.

“This was basically a lucky gift from the sun,” Stone said.

Professor Stone added: “This is historic – one of those journeys of exploration like circumnavigating the globe for the first time or having a footprint on the Moon for the first time. “This is the first time we’ve begun to explore the space between the stars.”

Extrapolating from the measurements, scientists believe Voyager actually left the solar system in August 2012. That summer, the spacecraft radioed back another tantalizing piece of information, showing a huge spike in the number of galactic cosmic rays from outside the solar system and a corresponding decrease in particles emanating from the sun.

Scientists had been reluctant to conclude last year that Voyager had reached interstellar space because it was still picking up magnetic field measurements that were very similar to the sun’s magnetic field.

Computer models had predicted a significant shift in the interstellar magnetic field’s alignment.

“The magnetic field is still something that puzzles us considerably,” said physicist Gary Zank, with the University of Alabama in Huntsville.

Scientists now believe the interstellar magnetic field is somehow draped around and twisted by the heliosphere, the bubble of space under the sun’s influence.

Understanding how that happens is just one of the questions the Voyager team will attempt to figure out while the probe still has power. Voyager 1, and a sister spacecraft Voyager 2, use heat released by the natural decay of radioactive plutonium to generate electrical power for their instruments.
‘Alien environment’

After 2020, scientists expect they will have to start turning off instruments, and in 2025, the probes will be completely out of power and fall silent.

Voyager 2, which is heading out of the solar system in another direction, has five to seven more years before it reaches interstellar space, said Donald Gurnett, a longtime Voyager scientist at the University of Iowa.

“We’re in a truly alien environment,” Zank said. “What Voyager is going to discover truly beggars the imagination.”

The two Voyager probes, which were both launched in 1977 to study the outer planets of the solar system, contain gold phonographic records etched with music, greetings, sounds and images from Earth. The project was spearheaded by astronomer Carl Sagan, who died in 1996.

With Voyager 1 having left the solar system, the next time it will encounter a star is in 40,000 years, when it flies about 1.7 light years away from a star in the constellation Camelopardalis called AC +79 3888. The spacecraft is traveling nearly 1 million miles a day.

“Voyager has once again joined the ranks of the great human journeys of exploration,” Gurnett said. “This is the first journey into interstellar space.”

“We expect the fields and particles science instruments on Voyager will continue to send back data through at least 2020. We can’t wait to see what the Voyager instruments show us next about deep space.” – Suzanne Dodd, Voyager project manager

NASA’s twin Pioneer spacecraft, launched in the 1970s, also are leaving the solar system, but they have run out of power to relay information back to Earth.

The solar system and The Voyager 1

Know more of Voyager

Voyager is powered by an RTG (Radioisotope Thermal Generator) – a nuclear battery. It becomes a little weaker each day. Sometime after 2020, maybe as late as 2025, the power will become too little to transmit the 23 watt signal towards Earth, and we will lose track of Voyager I. It will continue to travel through the Milky Way – now fully independent of our sun, it may outlast our own solar system.

Voyager I and Voyager II have provided us with mountains of information about our solar system and beautiful images. The total cost of the program, now operating for 36 years, is still less than $1 billion dollars.

NASA photograph of one of the two identical Voyager space probes Voyager 1 and Voyager 2 launched in 1977.  (Wikimedia Commons)

Know more of their journey

Voyager 1, a testament to durable engineering, was launched by NASA in 1977 alongside its identical sister probe Voyager 2 to study the outer Solar System and the interstellar medium – whatever occupies the gigantic chasms between stars in the universe.

Voyager 1 flew by Jupiter in 1979 and Saturn in 1980, concluding its primary mission. It was the first probe to provide detailed images of the two planets and their moons. In 1990, 9.6 billion km from Earth, it turned around and photographed the entire Solar System.

Ever since, it has been drifting toward its edge at some 17 km/s, surrounded by a hot ‘sea’ of charged particles called plasma. To detect the crossover, which isn’t at an exact boundary, scientists were looking for some telltale signs: the plasma’s density would increase, its temperature decrease, and the direction of the surrounding magnetic field would change.

What Next?

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