Adrastea, Jupiter's moon, discovered 1979

Adrastea, discovered in photographs taken by Voyager 2 July 8, 1979, is the small of the inner four moons of Jupiter. It is the first natural moon to be discovered by images taken by a spacecraft, instead of a telescope.  Two more inner moons Thebe and Metis were discovered in images taken by Voyager 1 a few months earlier.

It has a strange shape, measuring 20x16x14 km across.  It orbits Jupiter every 7 hours.

Voyager 1 launched 1977

Voyager 1, launched September 5, 1977, was the fist man-made object to cross into interstellar space.  It was launched 16 days after Voyager 2 and flew by Jupiter in March 1979.

It made a flyby of Saturn in November 1980, including an encounter with Titan.

NASA still receives signals from both Voyager craft, but Voyager 1 might run out of fuel by 2025.

Voyager 2 enters interstellar space!

Voyager 2, launched in August 1977, has finally reached interstellar space, beyond the heliosphere, the protective bubble of particles and magnetic fields created by the sun.  Voyager 1 crossed into interstellar space in 2011.

Voyager 2 is now just over 11 billion miles from Earth, but still within our solar system.  The Oort Cloud, a collection of small bodies under the influence of the sun's gravity, is considered the boundary of the solar system.  NASA expects it will take Voyager 2 about 300 years to reach the inner edge of the Oort Cloud, and possibly 30,000 years to fly through it.

Voyager 2 flies by Neptune 1989

Proteus

Launched in August 1977, Voyager 2 made a flyby of the planet Neptune August 25, 1989.  It is the only spacecraft to have visited Neptune and Uranus.  During its pass, it took photographs of Triton, Neptune's largest moon and discovered Proteus, the second largest moon.

Voyager 2 is expected  to enter interstellar space in 2019 or 2020.  It is still sending weak signals and will continue to do so until about 2025.

Voyager 2 flies by Jupiter 1979

Voyager 2, launched August 20, 1977, flew by Jupiter July 9, 1979.  It was launched 16 days before its twin Voyager 1, but it took longer to get to Jupiter since it took a different trajectory, because it was on the way to Saturn, Uranus and Neptune.

It's still in operation but may run out of power and stop sending signals about 2025.

Voyager 2 visits Uranus 30 years ago

Voyager 2 made its closest approach to Uranus, January 24, 1986, being the first and only time this planet has been visited, by us, at least.  The spacecraft made a number of surprising discoveries.  For example, Uranus is the coldest planet despite not being the farthest from the sun, because it has no internal heat source.  Neptune radiates over 2.5 more energy into space than Uranus does from the energy received from the sun.

It was already known that Uranus rotates on its side and the northern hemisphere is always in the sun, while the southern perpetually in the dark.

Voyager 2 discovered more moons and the count is 27 now. 

 

Ariel

 

 

Miranda

 

 

Oberon

 

 

Umbriel

Triton discovered by William Lassell in 1846

The largest Neptunian moon Triton was discovered by William Lassell on October 10, 1846.  He had been studying Neptune which had been discovered the month before.  Lassell was trying to confirm Neptune had rings like Saturn but instead discovered the first of 13 moons.

In 1989, Voyager 2 passed by Triton and gave us the first glimpse of the strange new world.

Triton was the last solid object visited by the Voyager 2 spacecraft on its epic 10-year tour of the outer solar system. Voyager mapped only the hemisphere that faces Neptune, but revealed a very young surface scarred by rising blobs of ice (diapirs), faults, and volcanic pits and lava flows composed of water and other ices.

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA12187

Science news this week: Europa, Mars and a Super-Moon!

When Voyager 2 flew past the Jovian moon Europa in 1979, Earthlings received images of a flat white surface, no craters, just mysterious brown streaks across the moon’s exterior.  The lack of features meant some force was present to erase the evidence of asteroid impacts.  I even remember reading news reports saying the closer Voyager 2 got to Europa, the younger the moon looked.  In fact, according to Popular Science, the discoveries prompted Arthur C. Clarke to write a sequel to his highly successful 2001: A Space Odyssey.  In his novel 2010, they beings warned the Earthlings, “all these words are yours – except Europa.  Attempt no landing here.”  Author Corey S. Powell reports that this warning has become a in-joke and a taunt to scientists.

Last week, NASA reported a huge global sub-surface ocean on the Saturnine moon Enceladus but this week they reported Europa as being the wettest known world in the solar system with more than twice the water on earth.  Life needs water.  Everywhere water exists on Earth so does life.  So to find alien life, one must look for alien water.  Europa has about 3 million cubic kilometers of it.

Life also needs good and energy, which Europa also contains.  Scientists suggest the oceans could be ‘nourished by a drizzle of organic chemicals’ stirred by volcanic vents.

Proving it will be a task worthy of Jupiter himself.  It’s about 600 million miles from here to Europa and that could take about 6 years.  The surface of the moon receives an average radiation dose of 500 rem/day, which can fry unshielded electronics in just a few days.  Lastly, the ice shell is about 10 miles thick, much more than the ice covering the Antarctica.  Many scientist are saying we should try, though.

The last probe to visit Jupiter and her moons was Galileo in 1995 and lasted until 2003 when the mission ended.  In May this year, NASA began developing a probe to visit Europa sometime in the 2020’s.

We might never find out what is below the surface of Europa unless we ignore the warnings of Arthur C. Clarke and put a lander on it.

 

In other news this week, it has been one year since NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) entered orbit above the Red Planet. Among its objectives, MAVEN will try to figure out where the water went.

 

 

Gases escaping from Mars:

And don’t miss the lunar eclipse with a Super-Moon, this Sunday, Sept 27.

Voyager 2 launched 38 years ago!

The Energizer Bunny has noting on the Voyager 2 spacecraft, launched 38 years ago today.  Thanks to a serendipitous alignment of planets, Voyager 2 set out to visit the four giant outer planets of our solar system, something no probe has ever done.  With is mission complete in 1989, Voyager 2 is now far beyond the orbit of Pluto.

Now it will continue to collect data and beam it back to Earth for another five years when it will not be able to generate enough power to run its on-board instruments.

Its closest approach to Jupiter was July 9, 1979; Saturn on August 25, 1981; Uranus, January 24, 1986; and Neptune, August 25, 1989.

Besides an array of scientific equipment, Voyager 2 carries a 12-inch gold plated copper disc encased in a protective aluminum jacket.  It is to be played as a phonograph so there is a needle and a cartridge plus instructions because by the time Voyager 2 is discovered by aliens, like us, they will have forgotten how to play vinyl.  It is doubtful they will be able to locate a turn-table.

But, if they are successful, they can hear nature sounds like wind and thunder, whales, and music such as Bach, Beethoven and Berry (as in Chuck Berry’s Johnny B. Goode).

Io

Voyager 2 observed volcanic eruptions on Io, one of Jupiter’s moons.  Its high-resolution images of Europa left scientists baffled at the lack of topological features.

Saturn with moons Tethys, Dion and Rhea

Both Voyager 1 and 2 discovered interesting aspects of Saturn’s rings that resembled spokes of a wheel.  However, Voyager 1 headed out of the solar system while Voyager 2 set course for Uranus and Neptune.

Uranus

Being the first and only to visit, Voyager 2 found 10 new moons around Uranus and revealed many unique features that should keep scientists busy for years to come.

           

High altitude clouds on Neptune

Neptune has a Great Dark Spot, similar to Jupiter’s Great Red Spot, about the size of Earth.

Now Voyager 2 is sending back data on the heliopause, the outermost boundary of the solar wind.  May it continue to collect data long after it loses the ability to transmit it.

And then not get caught in a black hole and transported to the far side of the galaxy where it becomes the monstrous V-Ger and heads back to Earth to find its creator and eliminate all the carbon units only to be foiled by the USS Enterprise.