Jupiter's moon Io [EYE-oh or EE-oh] is one of the most exotic places in the solar system. It is the most volcanic body known, with lava flows, lava lakes, and giant calderas covering its sulfurous landscape. It has billowing volcanic geysers spewing sulfurous plumes to over 500 kilometers high. Its mountains are much taller than those on Earth, reaching heights of 16 kilometers (52,000 feet).
Io orbits closer to Jupiter's cloud tops than the moon does to Earth. This places Io within an intense radiation belt that bathes the satellite with energetic electrons, protons, and heavier ions. As the Jovian magnetosphere rotates, it sweeps past Io and strips away about 1,000 kilograms (1 ton) per second of volcanic gases and other materials. This produces a neutral cloud of atoms orbiting with Io as well as a huge, doughnut shaped torus of ions that glow in the ultraviolet. The torus's heavy ions migrate outward, and their pressure inflates the Jovian magnetosphere to more than twice its expected size. Some of the more energetic sulfur and oxygen ions fall along the magnetic field into the planet's atmosphere, resulting in auroras. Io acts as an electrical generator as it moves through Jupiter's magnetic field, developing 400,000 volts across its diameter and generating an electric current of 3 million amperes that flows along the magnetic field to the planet's ionosphere.
And from the Washington Post on the proposed end of the Voyager mission:
In a cost-cutting move prompted by President Bush's moon-Mars initiative, NASA could summarily put an end to Voyager, the legendary 28-year mission that has sent a spacecraft farther from Earth than any object ever made by humans.
The probable October shutdown of a program that currently costs $4.2 million a year has caused consternation among scientists who have shepherded the twin Voyager probes on flybys of four planets and an epic journey to the frontier of interstellar space.
"There are no other plans to reach the edge of the solar system," said Stamatios Krimigis, a lead investigator for the project since before its launch in 1977. "Now we're getting all this new information, and here comes NASA saying, 'We want to pull the plug.'"
Some members of Congress have also criticized the aeronautics cuts, and last year several joined the public outcry over NASA's decision to cancel a servicing mission to the Hubble Space Telescope, a move apparently unconnected -- at least initially -- to the moon-Mars proposal.
"Voyager is the same [as Hubble] -- one of the classic American contributions to space," said research physicist Louis J. Lanzerotti, who last year led a Hubble study for the National Academies of Science. "Voyager's photographs are all over astronomy textbooks."
The two probes have discovered 22 moons at four planets. Voyager 1 has traveled farther than any other spacecraft, and took the first portrait of the solar system from the outside looking in.The probes found exploding volcanoes on Jupiter's moon Io, huge fault canyons on Uranus's moon Miranda, geysers on Neptune's moon Triton, and flew by Saturn's methane-enshrouded moon Titan almost 14 years before the European Space Agency's Huygens probe landed there this January.
The Voyager photographs blew my mind when I first viewed them; they completely changed how I saw the solar system. The planets were no longer blurred, glowing dots but vibrant worlds bursting with color and energy and light. A section of my poem "Conquest of Space" was about Voyager's inevitable fate and seems topical now:
On the dark side
of the quasar the Voyager spacecraft,
a low watt dot on star charts,
drifts above our cosmic plane,
approaches and crosses the heliosphere,
adjusts trajectory for Alpha Ophiuchus.
Inside autonomous computers and sensors
mosaics are forming, charts are still
imaging. Magnetic fields and charged
particles are monitored and recorded
for no human eye to see. With nothing
to orbit the blip is silent as solar
wind. It's dreaming of and praying to
I had a Voyager calendar hanging near my desk for many years after its practical use had gone out of date. One of the calendar's most striking photographs was of a live, erupting volcano on Io that was the inspiration for today's image -- made almost completely in XenoDream.
I'm strangely sad about the "death" of Voyager. Hamlet (who will sort of appear on the blog tomorrow) talked about traveling to "the undiscovered country." Apparently, because of Bush's grandstanding but empty sound bite of Mars madness, we will not receive the long awaited first field report from our only scout to ever reach this distant, unfamiliar realm.