NASA comp. essay

“In the Solar System, Enceladus ought to be one of the highest priorities
for the world’s space agencies...”-David Catling.
Enceladus is a Saturnian moon, but what makes it special is that it has a
warm, salty underground ocean, and geysers which propel ice particles and
water vapor through deep canyons called “tiger stripes”. Each of the four tiger
stripes is sub-parallel and is approximately 84 miles long.
At first, when Voyager 1 and Voyager 2 went past Enceladus, NASA
scientists were convinced that it was nothing more than a ball of ice which was
314 miles across. Two decades later in 2005, while Cassini was passing
Enceladus, it noticed that the magnetometer detected a “disturbance in the
planet's magnetosphere around Enceladus's south pole.” During the second
flyby, the scientists confirmed that the disturbance was coming from the South
Pole and they also found out it was actually plumes of water vapors that were
resulting in the tiny atmosphere. Geysers shot ice particles at 800 mph, which
explains why they went all the way to Saturn’s E ring (which was the outermost
ring). Cassini found evidence that the ice particles were in Saturn’s E ring by
detecting some ice particles that came from Enceladus’s vents. Another thing
about the jets is that they shoot out organic materials, of which a sample
consisted of carbonated water and natural gas. 
Moving on, the other intriguing feature of Enceladus is its ocean. For
starters, the ocean went all around the planet, not just under the tiger stripes.
To be furthermore described, it is a warm, salty ocean consisting of saltwater
and a mixture of other organic chemicals. In 2006, Cassini was able to prove that
the plumes are feeding on liquid reservoirs of water, which proves Enceladus is
a reliable water source. Cassini also retrieved a sample of the plumes in 2008,
which was described as a dense “organic brew”. As the Cassini scientists got
more information, they also concluded in the years 2014 and 2015 that they were
dealing with an ocean of water, and that it covered the whole planet. They also
found out the ocean is warm because of the vents that are located on the ocean
surface, similar to “the hydrothermal vents that dot the ocean floor here on
Earth”. These vents also went up to about 200 degrees F, and as mentioned
before, they were the cause of some specific nanoparticles which were found in
Saturn’s E ring.
In conclusion, Enceladus is the best choice to research because of its
underground ocean and water-shooting plumes, as it is more likely to have life.
Its highly reflective surface also makes it easier to explore. Over the years,
instead of carrying out the three planned close flybys, the Cassini team added 20
more because Enceladus was so useful. “Those twenty flybys proved crucial to
developing an understanding of the mysterious icy world.” Many scientists now
are even arguing that Enceladus should have its own “unique craft”, designed
for its own environment.