Voyager Archives

October 8, 2012December 23, 2015 by Nancy Atkinson

Voyager 1 May Have Left the Solar System

Number of particles from the Sun hitting Voyager 1. Credit: NASA

While there’s no official word from NASA on this, the buzz around the blogosphere is that Voyager 1 has left the Solar System. The evidence comes from this graph, above, which shows the number of particles, mainly protons, from the Sun hitting Voyager 1 across time. A huge drop at the end of August hints that Voyager 1 may now be in interstellar space. The last we heard from the Voyager team was early August, and they indicated that on July 28, the level of lower-energy particles originating from inside our Solar System dropped by half. However, in three days, the levels had recovered to near their previous levels. But then the bottom dropped out at the end of August.

The Voyager team has said they have been seeing two of three key signs of changes expected to occur at the boundary of interstellar space. In addition to the drop in particles from the Sun, they’ve also seen a jump in the level of high-energy cosmic rays originating from outside our Solar System.

The third key sign would be the direction of the magnetic field. No word on that yet, but scientists are eagerly analyzing the data to see whether that has, indeed, changed direction. Scientists expect that all three of these signs will have changed when Voyager 1 has crossed into interstellar space.

“These are thrilling times for the Voyager team as we try to understand the quickening pace of changes as Voyager 1 approaches the edge of interstellar space,” said Edward Stone, the Voyager project scientist for the entire mission, who was quoted in early August. “We are certainly in a new region at the edge of the solar system where things are changing rapidly. But we are not yet able to say that Voyager 1 has entered interstellar space.”

Stone added that the data are changing in ways that the team didn’t expect, “but Voyager has always surprised us with new discoveries.”

Voyager 1 launched on Sept. 5, 1977, is approximately 18 billion kilometers (11 billion miles) from the Sun. Voyager 2, which launched on Aug. 20, 1977, is close behind, at 15 billion km (9.3 billion miles) from the Sun.

Sources: NASA, Eric Berger/ Houston Chronicle, Scientific American

September 18, 2012December 23, 2015 by Jason Major

35 Years Ago: Our First Family Portrait of the Earth and Moon

A crescent Earth and Moon as seen by Voyager 1 on September 18, 1977 (NASA)

35 years ago today, September 18, 1977, NASA’s Voyager 1 spacecraft turned its camera homeward just about two weeks after its launch, capturing the image above from a distance of 7.25 million miles (11.66 million km). It was the first time an image of its kind had ever been taken, showing the entire Earth and Moon together in a single frame, crescent-lit partners in space.

The view of Earth shows eastern Asia, the western Pacific Ocean and part of the Arctic. Voyager 1 was actually positioned directly above Mt. Everest when the images were taken (the final color image was made from three separate images taken through color filters.)

The Moon was brightened in the original NASA images by a factor of three, simply because Earth is so much brighter that it would have been overexposed in the images were they set to expose for the Moon. (Also I extended the sides of the image a bit above to fit better within a square format.)

Read the latest on Voyager 1: Winds of Change at the Edge of the Solar System

Previous images may have shown the Earth and Moon together, but they were taken from orbit around one or the other and as a result didn’t have both worlds fully — and in color! — within a single frame like this one does. In fact, it was only 11 years earlier that the very first image of Earth from the Moon was taken, acquired by NASA’s Lunar Orbiter I spacecraft on August 23, 1966.

It’s amazing to think what was happening in the world when Voyager took that image:
• World population was 4.23 billion (currently estimated to be 7.04 billion)
• The Space Shuttle Enterprise made its first test flight from a 747
• Star Wars, Close Encounters of the Third Kind and Saturday Night Fever were out in U.S. theaters
• Charlie Chaplin and Elvis Presley died
• U.S. federal debt was “only” $706 billion (now over $16 trillion!)
• And, of course, both Voyagers launched on their Grand Tour of the Solar System, ultimately becoming the most distant manmade objects in existence
(See more world stats and events here.)

Image: NASA/JPL

“Once a photograph of the Earth, taken from outside, is available – once the sheer isolation of the Earth becomes known – a new idea as powerful as any in history will be let loose.”
– Sir Fred Hoyle

September 7, 2012April 26, 2016 by Jason Major

Is Triton Hiding an Underground Ocean?

Voyager 2 mosaic of Neptune’s largest moon, Triton (NASA)

At 1,680 miles (2,700 km) across, the frigid and wrinkled Triton is Neptune’s largest moon and the seventh largest in the Solar System. It orbits the planet backwards – that is, in the opposite direction that Neptune rotates – and is the only large moon to do so, leading astronomers to believe that Triton is actually a captured Kuiper Belt Object that fell into orbit around Neptune at some point in our solar system’s nearly 4.7-billion-year history.

Briefly visited by Voyager 2 in late August 1989, Triton was found to have a curiously mottled and rather reflective surface nearly half-covered with a bumpy “cantaloupe terrain” and a crust made up of mostly water ice, wrapped around a dense core of metallic rock. But researchers from the University of Maryland are suggesting that between the ice and rock may lie a hidden ocean of water, kept liquid despite estimated temperatures of -97°C (-143°F), making Triton yet another moon that could have a subsurface sea.

How could such a chilly world maintain an ocean of liquid water for any length of time? For one thing, the presence of ammonia inside Triton would help to significantly lower the freezing point of water, making for a very cold — not to mention nasty-tasting — subsurface ocean that refrains from freezing solid.

In addition to this, Triton may have a source of internal heat — if not several. When Triton was first captured by Neptune’s gravity its orbit would have initially been highly elliptical, subjecting the new moon to intense tidal flexing that would have generated quite a bit of heat due to friction (not unlike what happens on Jupiter’s volcanic moon Io.) Although over time Triton’s orbit has become very nearly circular around Neptune due to the energy loss caused by such tidal forces, the heat could have been enough to melt a considerable amount of water ice trapped beneath Triton’s crust.

Another possible source of heat is the decay of radioactive isotopes, an ongoing process which can heat a planet internally for billions of years. Although not alone enough to defrost an entire ocean, combine this radiogenic heating with tidal heating and Triton could very well have enough warmth to harbor a thin, ammonia-rich ocean beneath an insulating “blanket” of frozen crust for a very long time — although eventually it too will cool and freeze solid like the rest of the moon. Whether this has already happened or still has yet to happen remains to be seen, as several unknowns are still part of the equation.

“I think it is extremely likely that a subsurface ammonia-rich ocean exists in Triton,” said Saswata Hier-Majumder at the University of Maryland’s Department of Geology, whose team’s paper was recently published in the August edition of the journal Icarus. “[Yet] there are a number of uncertainties in our knowledge of Triton’s interior and past which makes it difficult to predict with absolute certainty.”

Still, any promise of liquid water existing elsewhere in large amounts should make us take notice, as it’s within such environments that scientists believe lie our best chances of locating any extraterrestrial life. Even in the farthest reaches of the Solar System, from the planets to their moons, into the Kuiper Belt and even beyond, if there’s heat, liquid water and the right elements — all of which seem to be popping up in the most surprising of places — the stage can be set for life to take hold.

Read more about this here on Astrobiology.net.

Inset image: Voyager 2 portrait of Neptune and Triton taken on August 28, 1989. (NASA)

August 7, 2012December 23, 2015 by Jason Major

Winds of Change at the Edge of the Solar System

As the venerable Voyager 1 spacecraft hurtles ever outward, breaking through the very borders of our solar system at staggering speeds upwards of 35,000 mph, it’s sending back information about the curious region of space where the Sun’s outward flow of energetic particles meets the more intense cosmic radiation beyond — a boundary called the heliosheath.

Voyager 1 has been traveling through this region for the past seven years, all the while its instruments registering gradually increasing levels of cosmic ray particles. But recently the levels have been jumping up and down, indicating something new is going on… perhaps Voyager 1 is finally busting through the breakers of our Sun’s cosmic bay into the open ocean of interstellar space?

Data sent from Voyager 1 — a trip that currently takes the information nearly 17 hours to make — have shown steadily increasing levels of cosmic radiation as the spacecraft moves farther from the Sun. But on July 28, the levels of high-energy cosmic particles detected by Voyager jumped by 5 percent, with levels of lower-energy radiation from the Sun dropping by nearly half later the same day. Within three days both levels had returned to their previous states.

The last time such a jump in levels occurred was in May — and that spike took a week to happen.

“The increase and the decrease are sharper than we’ve seen before, but that’s also what we said about the May data,” said Edward Stone, the Voyager project scientist based at the California Institute of Technology. “The data are changing in ways that we didn’t expect, but Voyager has always surprised us with new discoveries.”

The graph below shows the jump in cosmic particles detected starting May 2012.

Over 11 billion miles (18 billion km) from home, Voyager 1 has been cruising through space since its launch on September 5, 1977. Its twin, Voyager 2, was launched two weeks earlier and is currently 9.3 billion miles (15 billion km) away. Both spacecraft are healthy and continue to communicate with Earth, and will both eventually break through the borders of our solar system and enter true interstellar space. If they are still operational when that happens — and there’s no reason that they shouldn’t be — we will finally get a sense of what conditions are like “out there”.

Although Voyager 1 is registering intriguing fluctuations in radiation from both inside and outside the Solar System, it’s not quite there yet.

“Our two veteran Voyager spacecraft are hale and healthy as they near the 35th anniversary of their launch,” said Suzanne Dodd, Voyager project manager based at JPL in Pasadena. “We know they will cross into interstellar space. It’s just a question of when.”

Read more about Voyager’s ongoing breakout here.

“We are certainly in a new region at the edge of the solar system where things are changing rapidly. But we are not yet able to say that Voyager 1 has entered interstellar space.”

– Edward Stone, Voyager project scientist, Caltech

Images: NASA/JPL-Caltech

June 15, 2012December 23, 2015 by Jason Major

Voyager 1 Breaking Through the Borders of the Solar System

After almost 35 years traveling at over 35,000 mph, the venerable (and still operational!) Voyager 1 spacecraft is truly breaking through to the other side, crossing the outermost boundaries of our solar system into interstellar space — over 11 billion miles from home.

Data received from Voyager 1 — a trip that currently takes the information 16 hours and 38 minutes to make — reveal steadily increasing levels of cosmic radiation, indicating that the spacecraft is leaving the relatively protected bubble of the Sun’s influence and venturing into the wild and wooly space beyond.

From the JPL press release:

“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.

“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.

“When the Voyagers launched in 1977, the space age was all of 20 years old. 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.”

– Ed Stone, Voyager project scientist, Caltech

Voyager 1 Spacecraft Enters New Region of Solar System

The Voyager 1 spacecraft has started to transverse what JPL has dubbed as a "cosmic purgatory" between our solar system - and interstellar space. Image Credit: NASA/JPL

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Voyager 1 is in uncharted territory. The long-lived spacecraft has entered a new region of space that lies between where our solar system ends and where interstellar space begins. This area is not a place of sightseeing however, as a NASA press release referred to it as a kind of “cosmic purgatory.”

Here, the solar winds ebb somewhat, the magnetic field increases and charged particles from within our solar system – is leaking out into interstellar space. This data has been compiled from information received from Voyager 1 over the course of the last year.

“Voyager tells us now that we’re in a stagnation region in the outermost layer of the bubble around our solar system,” said Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena. “Voyager is showing that what is outside is pushing back. We shouldn’t have long to wait to find out what the space between stars is really like.”

Despite the fact that Voyager 1 is approximately 11 billion miles (18 billion kilometers) distant from the sun – it still has not encounter interstellar space. The information that scientists have gleaned from the Voyager 1 spacecraft indicates that the spacecraft is still located within the heliosphere. The heliosphere is a “bubble” of charged particles that the sun blows around itself and its retinue of planets.

voyager_t607 — Voyager 1 has traveled far past the realm of the gas or even ice giants and is now in uncharted territory where scientists are learning more and more about the dynamic environment at the far-flung edges of our solar system. Image Credit: NASA/JPL - Caltech

The latest findings were made using Voyager’s Low Energy Charged Particle instrument, Cosmic Ray Subsystem and Magnetometer.

Experts are not certain how long it will take the Voyager 1 spacecraft to finally breach this bubble and head out into interstellar space. Best estimates place the length of time when this could happen anywhere from the next few months – to years. These findings counter findings announced in April of 2010 that showed that Voyager 1 had essentially crossed the heliosphere boundary. The discoveries made during the past year hint that this region of space is far more dynamic than previously thought.

607895main_voyager20111205-673 — Voyager 1 has entered into a region of space between the sun's influence and the beginning of interstellar space that NASA has dubbed the "stagnation region." Image Credit: NASA/JPL - Caltech

The magnetometer aboard Voyager 1 has picked up an increase in the intensity of the magnetic field located within this “stagnation field.” Essentially the inward pressure from interstellar space is compressing the magnetic field to twice its original density. The spacecraft has also detected a 100-fold increase in the intensity of high-energy electrons diffusing into our solar system from outside – this is yet another indicator that Voyager 1 is approaching the heliosphere.

The interplanetary probe was launched from Cape Canaveral Air Force Station’s Space Launch Complex 41 (SLC-41) on Sept. 5, 1977, Voyager 1’s sister ship, Voyager 2 is also in good health and is about 9 billion miles (15 billion kilometers) from the sun (it too was launched in 1977). The spacecraft itself was built by NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

“Voyager is a mission of discovery and it’s at the edge of the solar system still making discoveries,” said Stone said. “The stagnation is the latest in the whole journey of discovery. We are all excited because we believe it means we’re getting very close to boundary of heliosphere and the entry into interstellar space.”

493px-Titan_3E_with_Voyager_1 — Both of the Voyager spacecraft were thrust to orbit by the powerful Titan boosters - and both in the same year - 1977. Photo Credit: NASA

September 14, 2010December 24, 2015 by Fraser Cain

Voyager 2

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Voyager 2 is easily the most famous spacecraft sent from Earth to explore other planets. Launched on August 20, 1977, Voyager visited Jupiter and Saturn, and is the only spacecraft to have ever made a flyby of the outer planets Uranus and Neptune. It flew past Neptune in 1989, but it’s still functioning and communicating with Earth.

Voyager 2 and its twin spacecraft Voyager 1 were built at NASA’s Jet Propulsion Lab in Pasadena, California. The two spacecraft were built with identical components, but launched on slightly different trajectories. Voyager 2 took advantage of a rare alignment of the planets so that it could use a gravity assisting boost as it flew past each one. The increased velocity from Jupiter would help it reach Saturn, Saturn helped it get to Uranus and then to Neptune.

It made its closest approach to Jupiter on July 9, 1979, passing within 570,000 km of the planet’s cloud tops. It captured some of the first, highest resolution images of Jupiter’s moons, showing volcanism on Io, and cracks in the icy surface of Europa. Astronomers now suspect that Europa’s surface hides a vast ocean of water ice.

Voyager 2 then went on to visit Saturn on August 26, 1981, and then onto Uranus on January 24, 1986. This was the first time a spacecraft had ever encountered Uranus, and captured images of the planet close up. Voyager studied Uranus’ rings, and discovered several new moons orbiting the planet. Voyager 2 made its final planetary visit with Neptune on August 25, 1989. Here the spacecraft discovered the planet’s “Great Dark Spot”, and discovered more new moons.

Voyager 2 is now considered an interstellar mission. This means that it has enough velocity to escape the Solar System and travel to another star. Of course, at its current speed, it would take hundreds of thousands of years to reach even the closest star. Scientists think that the spacecraft will continue transmitting radio signals until at least 2025, almost 50 years after it was launched.

We have written many articles about Voyager 2 for Universe Today. Here’s an article about NASA’s diagnosed problems with Voyager 2, and here are some Voyager 2 pictures.

If you’d like more information on the Voyager 2 mission, here’s a link to Voyager’s Interstellar Mission Homepage, and here’s the homepage for NASA’s Voyager Mission Website.

We’ve recorded an episode of Astronomy Cast all about Interstellar Travel. Listen here, Episode 145: Interstellar Travel.

Source: NASA

June 10, 2010April 26, 2016 by Nancy Atkinson

Life-size Wooden Spacecraft Sculptures

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If you think about it, spacecraft are kind of ethereal in that once they are launched into space, we don’t ever see them again. Australian artist Peter Hennessey has created life-size wooden sculptures of several different spacecraft, giving people the chance to see and touch these objects that are immediately recognizable but which we will never actually experience. Hennessey says he wanted to “reverse the virtualization of physical things” by creating life-size reproductions of the spacecraft such as the Voyager space probe, Apollo Lunar Rover, the Hubble Space Telescope, and more. From Hennessey’s website: “By ‘re-enacting’ space traveling, scientific and military objects in plywood, galvanized steel and canvas, the artist creates ‘stand-ins’ that allow the viewer to contemplate their physical, symbolic and historical resonances as well as the political processes that they represent.”

I just think they are really cool, and I’d love to see them – Hubble has to be huge! See below.

'My Hubble (the universe turned in on itself)' by artist Peter Hennessey.

“My Hubble (the universe turned in on itself) is now on display in Sydney Australia as part of “Biennale of sydney 2010.” This life size ‘re-enactment’ of the Hubble Space Telescope was constructed “with the aim of giving the viewer a physical experience of the object.” It is constructed from lasercut plywood and steel and simultaneously enacts the scale and detail
of the original. This is an interactive sculpture: visitors are encouraged to play with, modify and create their own mini universes on the ground, which are then reflected by the telescope into the heavens.

According to the Design Bloom website, when creating his work Hennessey looked at 7 different images of the Hubble, and rather than using 3D software to model individual parts as one might expect, he used adobe illustrator. Building the telescope took about 3 months – in which 6 weeks were dedicated to laser cutting individual parts and building them into sections and the rest of the time was dedicated to assembling it.

'My Lunar Rover' by artist Peter Hennessey.

With ‘My Moon Landing’ Hennessey’s wanted to explore the “physicality, presences and symbolic power of the inaccessible objects that derive from the space race.”

Hennessey has even built a wooden replica of mission control.

Check out all his unique sculptures on his website.

Hat tip to Rachel Hobson!

November 11, 2009December 24, 2015 by Jean Tate

Nereid

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Nereid is the name given to the third largest of Neptune’s moons, and the second to have been discovered … by veteran outer solar system astronomer, Gerard P. Kuiper (guess who the Kuiper Belt is named after!), in 1949. Prior to Voyager 2’s arrival, it was the last moon of Neptune to be discovered.

In keeping with the nautical theme (Neptune, Roman god of the sea; Triton, Greek sea god, son of Poseidon), Nereid is named after the fifty sea nymphs, daughters of Nereus and Doris, in Greek mythology … the nautical theme continues with the names of the other 11 moons of Neptune, Naiad (one kind of nymph, Greek mythology; not a Nereid), Thalassa (daughter of Aether and Hemera, Greek mythology; also Greek for ‘sea’), Despina (nymph, daughter of Poseidon and Demeter (Greek); not a Nereid), Galatea (one of the Nereids), Larissa (Poseidon’s lover; Poseidon is the Greek Neptune), Proteus (also a sea god in Greek mythology; Proteus is the Neptune’s second largest moon), Halimede (one of the Nereids), Sao (also one of the Nereids), Laomedeia (guess … yep, another of the Nereids), Psamathe (ditto), and Neso (ditto, all over again).

Almost everything we know about Nereid comes from the images Voyager 2 took of it (83), between 20 April and 19 August, 1989; its closest approach was approximately 4.7 million km.

Nereid’s highly eccentric orbit (eccentricity 0.75, the highest of any solar system moon) takes it from 1.37 million km from Neptune to 9.66 million km (average 5.51 million km); unlike Triton, and like the other inner moons, Nereid’s orbit is prograde. This suggests that it may be a captured Kuiper Belt object, or that its orbit was substantially perturbed when Triton was captured.

For an irregular moon, Nereid is rather large (radius approx 170 km). Its spectrum and color (grey) are quite different from those of other outer solar system bodies (e.g. Chiron), which suggests that it may have formed around Neptune.

For more on Nereid, check out the Jet Propulsion Laboratory’s (JPL) profile of it!

Nereid is a bit of an orphan with regard to Universe Today stories, but there are some! Three new moons discovered for Neptune , and How Many Moons Does Neptune Have?.