Galileo takes a close look at icy Europa
|Tweet|Galileo takes a close look at icy Europa
2 October, 1998: NASA's Jet Propulsion Laboratory reports
that the Galileo spacecraft completed a close-up flyby
of Europa on schedule and on target. On Friday, Sept. 25, at
8:54 p.m. PDT, Galileo skimmed over the icy moon at an altitude
of only 2,226 miles.
The spacecraft flew within 2300 miles of the mysterious
satellite last weekend
The flyby was performed in cruise mode without Galileo's gyroscopes, because the gyros activated a fault protection program last Thursday, Sept. 24. The on board star scanner was used instead as the primary reference for determining the spacecraft's orientation in space. Nevertheless, the flyby was considered a success.
Life under the ice?
The mounting evidence for an
ocean beneath Europa's frozen surface raising the exciting possibility
of life on that distant world. In recent years scientists have
discovered a new class of micro-organisms here on Earth that
can live or, at least remain viable, under very extreme conditions
-- from volcanic vents deep in ocean trenches, to ice more than
400,000 years old, to Siberian permafrost more than 5 million
years old. These microbes called archaeabacteria, or simply "archaea",
constitute a third branch of life on Earth, along with prokaryotes
(normal bacteria) and eukaryotes (plants and animals). Like prokaryotes,
the genetic material of archaeabacteria float freely throughout
the cell -- they are not contained within the cell nucleus like
eukaryotic organisms. However, the DNA of archaeabacteria more
closely resemble that of plants and animals than normal bacteria.
They are truly in a class by themselves, and if life is discovered
elsewhere in the solar system it may be similar to the archaeabacteria
The strongest clues to life on Europa may lie right here at home. In 1996, seismic and other tools revealed the the presence of an underground lake in Antarctica near the Russian Vostok Station. Lake Vostok is overlaid by about 3,710 meters (12,169 ft) of ice and may be 500,000 to 1 million years old. Since the discovery, drilling has gone slowly while procedures are worked out to keep it pristine. No one has seen or sampled the lake - the deepest ice sample is from 100 meters (328 feet) above the liquid surface - nor is anyone sure why it is liquid, hence the scientific curiosity. Scientists are hopeful that Lake Vostok can one day serve as a terrestrial laboratory to help us understand better the oceans on distant Europa.
Hitting the Beach on Europa
NASA scientists have several projects in the planning stages to explore Europa. One is the Europa Orbiter. It would use a radar sounder to study Europa's icy surface and attempt to determine the thickness of the ice and whether liquid water exists below the ice. Other instruments to study the surface and interior would include an imaging device with multiple filters to map the surface at a resolution of 100 meters and an altimeter to measure the topography and characterize the tidal response of the surface. The mission could launch in 2003 and would serve as a precursor to spacecraft that would actually send undersea explorers into the Europan oceans.
Galileo- Europa home page at JPL
Jet Propulsion Laboratory home page
Exotic-looking microbes turn up in ancient Antarctic ice
Space Tether may be best way to explore Europa
Clues to possible life on Europa may lie buried in Antarctic ice
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