NRAO Very Long Baseline Array takes radio image of Voyager 1

Credit: NRAO/AUI/NSF

The image above is a radio image of Voyager 1.

It was taken from NRAO's Very Long Baseline Array (VLBA), which is a collection of 10 radio telescopes scattered from Hawaii to the Virgin Islands.

It captures the faint radio signal of the distant probe. That pale blue dot is the most distant object made by humans.

The radio strength of Voyager 1 is about 23 watts. That signal is directed toward Earth, but Voyager is about 15 billion kilometers from Earth, so by the time the probe's signal reaches us its power is less than an attowatt, or a billionth of a billionth of a watt.

That faint signal is the only information we have from a probe that left our planet 36 years ago.

Of course it isn't enough to simply detect the signal from Voyager 1, we must receive the signal the way you might receive a radio signal, or a mobile phone call.

That requires even greater sensitivity, which is why it requires large radio telescopes to communicate with Voyager.

We have to be able to hear Voyager's faint messages, and we have to send radio responses that are powerful enough and focused enough for Voyager to receive.

Voyager 1 has, arguably, entered interstellar space, but has only begun its journey to the edge of our solar system.

It will eventually leave our Sun's grasp, since it has enough speed to escape the Sun's gravity, but it will become silent long before then.

In another 5 – 10 years it won't have enough power to operate its instruments.

That's part of what makes this current milestone so significant. Voyager 1 has not only reached interstellar space, but it has communicated the fact to us and we have gained knowledge and insight from it.

That pale blue dot, a radio blip in a radio dark sky, is a part of us.

It is an 800 kg, car sized, nuclear-powered computer that we launched into space to explore the solar system.

Our curiosity and quest for knowledge drove us to create it, and our developing intelligence allowed us to build it.

After a 36 year journey towards the harshness of interstellar space, it continues to communicate with its creators.

Looking out from one pale blue dot towards another one.

(Taken from an article by Brian Koberlein)

NASA's Stardust Comet Probe Catches Dust from Interstellar Space

This false colour image shows a diffraction pattern from the first interstellar dust candidate Orion, collected by NASA's Stardust spacecraft in 2004. 

Credit: Zack Gainsforth

Seven tiny grains of rock captured by NASA's comet-chasing Stardust probe in 2004 may be visitors from the vast reaches of interstellar space, researchers say.

These interstellar dust motes from Stardust are fluffier and more diverse than expected, findings that could one day shed light on the origins of the solar system, scientists added.

Interstellar dust motes are bits of rock that permeate the enormous spaces between the stars.

NASA's comet-chasing Stardust probe

Supernovas and ancient stars produce interstellar dust, which contains elements such as carbon, nitrogen and oxygen that are necessary for life.

"By analyzing interstellar dust, we can understand our own origins," said lead study author Andrew Westphal, a planetary scientist at the University of California at Berkeley.

"Just as people go to Africa to look for fossil hominids, say, 4.5 million years old, trying to understand the origins of humanity, we want to look at stuff that helped form the solar system 4.5 billion years ago."



NASA launched the Stardust spacecraft in 1999 on a mission to collect dust from the wake of Comet Wild-2 (pronounced "Vilt-2").

Stardust rendezvoused with the comet in 2004 and, in 2006, returned its sample container back to Earth via parachute.

This image shows a top-down view of a dust particle impact on NASA's Stardust spacecraft Al foil collector. 

Credit: Stardust ISPE/ NRL

But while Stardust captured samples of Comet Wild-2 on one side of the craft's collector tray, the other side was pointed away from the comet to catch bits of interstellar dust in a stream emanating from about the direction of the constellation Ophiuchus.

These 12 images are a good representation of the closest images of comet Wild 2. 

The temporal sequence starts at the upper left and continues left to right on the first three rows. 

The overexposed and out-of-sequence images at the bottom are long exposures taken for autonomous tracking and yield the best jet images. 

All images were scaled to a constant image scale.

Credit: NASA Stardust

The tray was exposed to space for 195 days to capture particles in tiles of silica aerogel, a porous material resembling frozen smoke, which possesses a sponge-like structure that is 99.8 percent air.

Now, nearly a decade after Stardust's samples reached Earth, a preliminary analysis of the material suggests that seven of the dust motes the probe caught may have origins outside the solar system.

If that is confirmed, these tiny flecks of rock will represent the first specks of interstellar dust a spacecraft has ever returned to Earth.

"These are the very first contemporary samples of solid material from outside the solar system that we've identified," Westphal told reporters.

"Instead of looking at interstellar dust with telescopes, now we get to look at samples we collected from space with microscopes."

The keystoning apparatus cuts a picokeystone out of NASA's Stardust spacecraft interstellar dust collector at the Johnson Space Center in Houston. 

Credit: ESA /Rosetta /NAVCAM

Voyager 1 spacecraft might not have reached interstellar space

The heliosphere, in which the Sun and planets reside, is a large bubble inflated from the inside by the high-speed solar wind blowing out from the Sun. 

Pressure from the solar wind, along with pressure from the surrounding interstellar medium, determines the size and shape of the heliosphere. 

The supersonic flow of solar wind abruptly slows at the termination shock, the innermost boundary of the solar system. 

The edge of the solar system is the heliopause. 

The bow shock pushes ahead through the interstellar medium as the heliosphere plows through the galaxy. 

Credit: Southwest Research Institute

In 2012, the Voyager mission team announced that the Voyager 1 spacecraft had passed into interstellar space, traveling further from Earth than any other manmade object.

But, in the nearly two years since that historic announcement, and despite subsequent observations backing it up, uncertainty about whether Voyager 1 really crossed the threshold continues.

There are some scientists who say that the spacecraft is still within the heliosphere, the region of space dominated by the Sun and its wind of energetic particles, and has not yet reached the space between the stars.

Now, two Voyager team scientists have developed a test that they say could prove once and for all if Voyager 1 has crossed the boundary.

The new test is outlined in a study accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union (AGU).

The scientists predict that, in the next two years, Voyager 1 will cross the current sheet, the sprawling surface within the heliosphere where the polarity of the sun's magnetic field changes from plus to minus.

The spacecraft will detect a reversal in the magnetic field, proving that it is still within the heliosphere but, if the magnetic field reversal doesn't happen in the next year or two as expected, that is confirmation that Voyager 1 has already passed into interstellar space.

"The proof is in the pudding," said George Gloeckler, a professor in atmospheric, oceanic and space sciences at the University of Michigan in Ann Arbor and lead author of the new study.

Gloeckler has worked on the Voyager mission since 1972 and has been a vocal opponent of the view that Voyager 1 has entered interstellar space.

He said that, although the spacecraft has observed many of the signs indicating it may have reached interstellar space, like cosmic rays, Voyager 1 did not see a change in magnetic field that many were expecting.

"This controversy will continue until it is resolved by measurements," Gloeckler said.

This artist’s concept shows the Voyager 1 spacecraft entering the space between stars. 

The Voyager mission team announced in 2012 that the Voyager 1 spacecraft had passed into interstellar space, but some scientists say it is still within the heliosphere, the region of space domininated by the Sun and its wind of energetic particles. 

In a new study, two Voyager team scientists are proposing a test that they say could prove once and for all of Voyager 1 has crossed the boundary. 

Credit: NASA/JPL-Caltech

If the new prediction is right, "this will be the highlight of my life," he said. "There is nothing more gratifying than when you have a vision or an idea and you make a prediction and it comes true."

The Voyager 1 and 2 spacecraft were launched in 1977 to study Jupiter and Saturn. The mission has since been extended to explore the outermost limits of the Sun's influence and beyond.

Voyager 2, which also flew by Uranus and Neptune, is on its way to interstellar space.

More information: Geophysical Research Letters DOI: 10.1002/2014GL060781

Sun sends more 'shock waves' to Voyager 1 - Video

Credit: NASA/JPL-Caltech

NASA's Voyager 1 spacecraft has experienced a new "shock wave" from the sun as it sails through interstellar space.

Such waves are what led scientists to the conclusion, in the fall of 2013, that Voyager had indeed left our sun's bubble, entering a new frontier.

"Normally, interstellar space is like a quiet lake," said Ed Stone of the California Institute of Technology in Pasadena, California, the mission's project scientist since 1972.

"But when our sun has a burst, it sends a shock wave outward that reaches Voyager about a year later. The wave causes the plasma surrounding the spacecraft to sing."

Data from this newest tsunami wave generated by our sun confirm that Voyager is in interstellar space, a region between the stars filled with a thin soup of charged particles, also known as plasma.

The mission has not left the solar system, it has yet to reach a final halo of comets surrounding our sun, but it broke through the wind-blown bubble, or heliosphere, encasing our sun.

Voyager is the farthest human-made probe from Earth, and the first to enter the vast sea between stars.

"All is not quiet around Voyager," said Don Gurnett of the University of Iowa, Iowa City, the principal investigator of the plasma wave instrument on Voyager, which collected the definitive evidence that Voyager 1 had left the sun's heliosphere.

"We're excited to analyze these new data. So far, we can say that it confirms we are in interstellar space."




The first two tsunami waves to reach Voyager 1 caused surrounding ionized matter to ring like a bell at frequencies expected in interstellar space. 

The third tsunami caused similar ringing, confirming that Voyager 1 continues it journey into interstellar space. 

Image Credit: NASA's Voyager 1 spacecraft

Our sun goes through periods of increased activity, where it explosively ejects material from its surface, flinging it outward. These events, called coronal mass ejections, generate shock, or pressure, waves.

Three such waves have reached Voyager 1 since it entered interstellar space in 2012. The first was too small to be noticed when it occurred and was only discovered later, but the second was clearly registered by the spacecraft's cosmic ray instrument in March of 2013.

Cosmic rays are energetic charged particles that come from nearby stars in the Milky Way galaxy. The sun's shock waves push these particles around like buoys in a tsunami.

Data from the cosmic ray instrument tell researchers that a shock wave from the sun has hit.

Meanwhile, another instrument on Voyager registers the shock waves, too. The plasma wave instrument can detect oscillations of the plasma electrons.

"The tsunami wave rings the plasma like a bell," said Stone. "While the plasma wave instrument lets us measure the frequency of this ringing, the cosmic ray instrument reveals what struck the bell—the shock wave from the sun."

This ringing of the plasma bell is what led to the key evidence showing Voyager had entered interstellar space. Because denser plasma oscillates faster, the team was able to figure out the density of the plasma.

In 2013, thanks to the second tsunami wave, the team acquired evidence that Voyager had been flying for more than a year through plasma that was 40 times denser than measured before, a telltale indicator of interstellar space.

Why is it denser out there? The sun's winds blow a bubble around it, pushing out against denser matter from other stars.

Now, the team has new readings from a third wave from the sun, first registered in March of this year.

These data show that the density of the plasma is similar to what was measured previously, confirming the spacecraft is in interstellar space.

Thanks to our sun's rumblings, Voyager has the opportunity to listen to the singing of interstellar space, an otherwise silent place.

Voyager 1 and its twin, Voyager 2, were launched 16 days apart in 1977. Both spacecraft flew by Jupiter and Saturn.

Voyager 2 also flew by Uranus and Neptune. Voyager 2, launched before Voyager 1, is the longest continuously operated spacecraft and is expected to enter interstellar space in a few years.

NASA Voyager-1 and Humankind set to cross the final frontier to Interstellar Space

It will be one of the most important milestones in human history as, for the first time, an ambassador for humankind moves beyond the confines and protection of our solar system.

NASA scientists are preparing for the moment, any day now, when the first of two spacecraft launched in the late 1970s crosses the invisible boundary that marks the start of "interstellar space".

Already they have passed some of the furthest planets of the solar system, transmitting spectacular images of the worlds that circle the sun.

This artist's concept by NASA/JPL-Caltech shows Voyager 1 and Voyager 2 at the edge of the solar system. 

The Voyager 1 probe, which is now about 17.7 billion kilometres from Earth, has entered a "transition zone" at the edge of the solar system, scientists say.  

Photo: AFP/NASA/JPL-Caltech

Voyager 1 is about 11 billion miles from Earth and hurtling away at a rate of 13 kilometres a second. Its sister craft, Voyager 2, is not far behind.

Each carries an array of instruments to gather information about outer space - and also a gold-plated copper disc with sounds and images intended to convey a sample of what life is like on Earth should they ever encounter other intelligent life.

Should an alien ever find one of the craft, the first human to whom they will be introduced - assuming they can decode the technology - will be Ann Druyan, now 63, an author and television producer who fell in love with the US astronomer Dr Carl Sagan while they were working on the Voyager mission.

A file photo released by NASA in 1970 shows the golden record on Voyager 1, launched on September 5, 1977, with a cartridge and a needle to play it.  

Photo: AFP/NASA

NASA Voyager 1: Data points to breakthrough into an interstellar future

This artist's concept shows NASA's two Voyager spacecraft exploring a turbulent region of space known as the heliosheath, the outer shell of the bubble of charged particles around our sun. Credit: NASA/JPL-Caltech

Data from NASA's Voyager 1 spacecraft indicate that the venerable deep-space explorer has encountered a region in space where the intensity of charged particles from beyond our solar system has markedly increased.

Voyager scientists looking at this rapid rise draw closer to an inevitable but historic conclusion - that humanity's first emissary to interstellar space is on the edge of our solar system.

Play the Video of Ed Stone Describing the status of Voyager 1&2

"The laws of physics say that someday Voyager will become the first human-made object to enter interstellar space, but we still do not know exactly when that someday will be," said Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena.

"The latest data indicate that we are clearly in a new region where things are changing more quickly. It is very exciting. We are approaching the solar system's frontier."

The data making the 16-hour-38 minute, 11.1-billion-mile (17.8-billion-kilometer), journey from Voyager 1 to antennas of NASA's Deep Space Network on Earth detail the number of charged particles measured by the two High Energy telescopes aboard the 34-year-old spacecraft.

These energetic particles were generated when stars in our cosmic neighborhood went supernova.

Artist's concept of NASA's Voyager spacecraft. Credit: NASA/JPL-Caltech

"From January 2009 to January 2012, there had been a gradual increase of about 25 percent in the amount of galactic cosmic rays Voyager was encountering," said Stone.

"More recently, we have seen very rapid escalation in that part of the energy spectrum.

Beginning on May 7, the cosmic ray hits have increased five percent in a week and nine percent in a month."

This marked increase is one of a triad of data sets which need to make significant swings of the needle to indicate a new era in space exploration.

The second important measure from the spacecraft's two telescopes is the intensity of energetic particles generated inside the heliosphere, the bubble of charged particles the sun blows around itself.

While there has been a slow decline in the measurements of these energetic particles, they have not dropped off precipitously, which could be expected when Voyager breaks through the solar boundary.

The final data set that Voyager scientists believe will reveal a major change is the measurement in the direction of the magnetic field lines surrounding the spacecraft.

While Voyager is still within the heliosphere, these field lines run east-west.

When it passes into interstellar space, the team expects Voyager will find that the magnetic field lines orient in a more north-south direction.

Such analysis will take weeks, and the Voyager team is currently crunching the numbers of its latest data set.

In 1972, Ed Stone became the Voyager Project Scientist. Twenty years later, both Voyager spacecraft were still operating, and this photo was taken in front of a full-scale model of the spacecraft, after Stone had been Director of JPL for about one year. 

"When the Voyagers launched in 1977, the space age was all of 20 years old," said Stone.

"Many of us on the team dreamed of reaching interstellar space, but we really had no way of knowing how long a journey it would be, or if these two vehicles that we invested so much time and energy in would operate long enough to reach it."

Launched in 1977, Voyager 1 and 2 are in good health. Voyager 2 is more than 9.1 billion miles (14.7 billion kilometers) away from the sun.

Both are operating as part of the Voyager Interstellar Mission, an extended mission to explore the solar system outside the neighborhood of the outer planets and beyond.

NASA's Voyagers are the two most distant active representatives of humanity and its desire to explore.

The Voyager spacecraft were built by NASA's Jet Propulsion Laboratory in Pasadena, Calif., which continues to operate both. JPL is a division of the California Institute of Technology.

The Voyager missions are a part of the NASA Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate in Washington.