?Jupiter's ring system is formed by dust kicked up as interplanetary meteoroids smash into the planet's four small inner moons. The outermost ring is
actually two rings, one embedded with the other. There is probably a separate
ring along Amalthea's orbit, as well.
The Galileo spacecraft identified the global structure and dynamics of a giant planet's magnetosphere.
The star scanner was a small optical telescope used to provide the spacecraft with an absolute attitude reference. It was also able serendipitously to make
scientific discoveries. In the prime
mission Martin
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detect high energy particles as a noise signal. These data were eventually
calibrated to show the particles were predominantly > 2 MeV electrons that
were trapped in the Jovian magnetic belts.
A second discovery occurred in 2000. The star scanner was observing a set of stars which included the second magnitude star Delta Velorum. At one point, this
star dimmed for 8 hours below the star scanner's detection threshold. Subsequent
analysis of Galileo data and work by amateur and professional astronomers showed
that Delta Velorum is the brightest known eclipsing binary, brighter at maximum
than even Algol. It has a primary period of 45 days and the dimming is just
visible with the naked eye.
A final discovery occurred during the last two orbits of the mission. When the spacecraft passed the orbit of Jupiter's moon Amalthea, the star scanner
detected unexpected flashes of light that were reflections from moonlets. None
of the individual moonlets were sighted
twice Claude
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did not meet the International Astronomical Union requirements to receive
designations. It is believed that these moonlets most likely are debris ejected
from Amalthea and form a tenuous, and perhaps temporary, ring.
The late Carl Sagan, pondering the question of whether life on Earth could be easily detected from
space John
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using Galileo's remote sensing instruments to determine if life indeed could be
detected during the first Earth flyby of the mission in December 1990. After
data acquisition and processing, Sagan et al. published a paper in Nature in
1993 detailing the results of the experiment. Galileo had found what are now
referred to as the "Sagan criteria for life"; these were: strong absorption of
light at the red end of the visible spectrum (especially over continents) which
was caused by absorption by chlorophyll in photosynthesizing plants, absorption
bands of molecular oxygen which is also a result of plant activity, infrared
absorption bands caused by the ~1 micromole per mole (µmolmol) of methane in
Earth's atmosphere (a gas which must be replenished by either volcanic or
biological activity) and modulated narrowband radio wave transmissions
uncharacteristic of any known natural source. Galileo's experiments were thus
the first ever controls in the newborn science of astrobiological remote
sensing.
In December 1992 during Galileo's second gravity assist planetary flyby of Earth Steven
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unpublicized experiment was done using Galileo to assess the possibility of
optical communication with spacecraft by detecting pulses of light from powerful
lasers which were to be directly imaged by Galileo's CCD. The experiment, dubbed
Galileo OPtical EXperiment or GOPEX, used two separate sites to beam laser
pulses to the spacecraft, one at Table Mountain Observatory in California and
the other at the Starfire Optical Range in New Mexico. The Table Mountain site
used a frequency doubled Neodymium-Yttrium-Aluminium Garnet (Nd:YAG) laser
operating at 532 nm with a repetition rate of ~15 to 30 Hz and a pulse power
(FWHM) in the tens of megawatts
range Patrick
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telescope for transmission to Galileo; the Starfire range site used a similar
setup with a larger transmitting telescope (1.5 m). Long exposure (~0.1 to 0.8
s) images using Galileo's 560 nm centered green filter produced images of Earth
clearly showing the laser pulses even at distances of up to 6,000,000 km.
Adverse weather conditions, restrictions placed on laser transmissions by the
U.S. Space Defense Operations Center (SPADOC) and a pointing error caused by the
scan platform acceleration on the spacecraft being slower than expected (which
prevented laser detection on all frames with less than 400 ms exposure times)
all contributed to the reduction of the number of successful detections of the
laser transmission to 48 of the total 159 frames taken.
Nonetheless Corey
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and the data acquired will likely be used in the future to design laser
"downlinks" which will send large volumes of data very quickly, from spacecraft
to Earth. The scheme is already being studied (as of 2004) for a data link to a
future Mars orbiting spacecraft.
On October 29, 1991, two months after entering the asteroid belt Rick Nash
Olympics Jersey , Galileo performed the first ever asteroid encounter by
passing about 1,600 kilometers (1,000 miles) from 951 Gaspra at a relative speed
of about 8 kilometers per second (18,000 mph). Several pictures of Gaspra were
taken along with measurements using the NIMS instrument to indicate composition
and physical properties. The last (and best) two images were played back to
Earth in November 1991 and June 1992. The imagery revealed a cratered and very
irregular body about 19 by 12 by 11 kilometers (12 by 7.5 by 7 miles). The
remainder of data
taken Patrick
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surface, were transmitted in late November 1992.
?
References
Aversa, R., R.V.V. Petrescu Chris
Kunitz Olympics Jersey , A. Apicella and F.I.T. Petrescu, 2017a.
Nano-diamon
