Promising Presence
Nasa.Science.gov; Aug, 28 2000; NASA Science News: “New Evidence for an Alien Ocean”
One
of the large Galilean moons of Jupiter may be hiding a salt-water ocean beneath
its water-ice crust. The possibility of water on Europa is raised by
readings made by the Galileo spacecraft -- now in its forth year orbiting
Jupiter. Liquid water would make this world a promising target in
the search for life beyond our planet.
The forth largest satellite of Jupiter has a fractured ice crust. Photographs suggest that uplift and rifts in the crust are evidence of a liquid ocean below -- when these formations formed. But scientists didn't know if these upwellings had ceased with the freezing of the ocean long-ago. Now measurements of Europa's magnetic polarity, made over the years by the Galileo spacecraft, open the exciting possibility of a salt-water ocean.
Jupiter's magnetic field induces electric current flow through a conducting medium near the Europa's surface. This in turn induces a secondary magnetic field on the moon. The magnetometer on Galileo recorded changes in this secondary field as the Jovan magnetic field at Europa changed. NASA researches at UCLA predicted how this field would fluctuate if an electrically conductive salt-water ocean was present. Measurements from Galileo on a Europa pass in January matched prediction.
If true, this would be the only world besides Earth known to have a liquid salt-water ocean. Definitive proof may come from a "Europa Orbiter" mission that is in the works. This probe will measure fluctuations in gravity field and surface altitude caused by the hidden ocean's tides.
Powerful Prediction
Discovery.com; Aug 30, 2000; News: “Meteor Showers Explosive on Mars”
Calculation
of the impact of meteors on the Red planet -- made by formerly "red"
scientists at the Russian Academy of Sciences -- indicate that the planet is
susceptible to giant dust storms and electrical discharge explosions visible
from Earth. This from "rocks" that would only cause a brief
flash in our planet's thicker atmosphere.
The atmosphere is the key. Most meteors striking Earth burn up high in the atmosphere due to entry heating. Martian meteors are more likely to explode near the ground after passing through an atmosphere 100 times thinner than ours. Shock waves and vortices from a blast so near the ground give rise to gigantic dust storms on the planet. The Russian study also predicts that the dry and dusty air of Mars causes an electrically charged path to form in the meteor's wake. This can create a huge flash visible to Earth based telescopes. These results were presented at the recent meeting of the Meteoritical Society in Chicago.
The Academy's calculations were carried out by adopting classified equations used to model nuclear blasts inside the Earth's atmosphere. Christian Koeberl, a University of Vienna impact specialist, is quoted as saying that the Russian team is one of a few worldwide that has access to such classified equations. "They're doing good work," he said.
Planets Possibilities Problematic
Sky & Telescope, October 2000, NewsNotes: “Planets Come Up Missing in a Globular Cluster”
Isaac Asimov once wrote a short-story about a civilization that orbited a multi-sun world. Only in the circumstances of a very rare eclipse would the stars emerge in a night sky. But the onset of this event would cause the civilization on that world to collapse and start over again. Now consider a civilization orbiting a star in a globular cluster -- how bright would the night be? On second thought, don't bother. Recent research presented at the June meeting of the American Astronomical Society indicates that there may be no globular cluster planets to imagine a civilization on.
An experiment with the Hubble Space Telescope made 645 images of the globular 47 Tucanae over an 8.3 day period. These were examined for tell-tail signs of brightness changes in over 34 thousand stars. Statistics indicated that 17 "Jupiter class" extra-solar planets, in the globular, would be detected if they existed in the same proportion as in our local region of space. But none of the stars examined were dimmed by the presence of such a planet.
Speculation on the dearth of planets in globulars centers on two ideas. One is that there is insufficient heavy elements for particles to accrete onto to form planets. The other is that the proximity of stars in the cluster cause planets to be thrown out of stable orbits when one stars passes close to another.
Pluto Probe Procrastination
Cosmiverse.com; Aug 7, 2000; Space News: “Update: Pluto Mission in Jeopardy”
The
last planet discovered, Pluto, is also the last planet not to have been
surveyed by robotic probes (from Earth at least). The "Pluto-Kuiper
Express" mission may or may not be launched to examine the planet,
its moon Charon and the region of space beyond, inhabited by small icy bodies,
known as the "Kuiper Belt." This August a rumor floated
that the mission had been canceled due to budget problems. While a
final decision has not been made, the mission is under scrutiny.
Currently a 2004 launch date is planned to allow for a gravity assist from Jupiter. This will speed the "Express" to the edge of our planetary system in only 8 or 9 years. Scientists would like to study Pluto's tenuous atmosphere, before it refreezes due to the planet's orbit taking it further from the sun. These requirements make pushing back the launch date hard to justify. But increasing launch costs and NASA's budgeting system may keep the probe grounded past the required launch date. NASA is currently working with scientists to salvage the mission.