The largest of Juno’s six MWR antennas (shown here)
takes up a full side of the spacecraft. Credit: NASA
In order to avoid the highest levels
of radiation coming from Jupiter’s
radiation belts, while still getting the
spacecraft very close to the planet
to allow the science package to
complete the assigned tasks, Juno’s
scientists have designed the orbits to
be highly elliptical.
The spacecraft approaches the
gas giant from the north, zipping
down over the north polar region of
the planet coming in as close as 2600
miles, then comes out from the southern polar region and heads out away
from the planet before curving back
for another pass.
While each science orbit lasts
62
62
nearly 14 days, most of the instrument
observations are taken while Juno
passes closest to Jupiter. These close
passes are from pole to pole as Juno
is flying a polar orbit, and the closest
encounters only last around two hours
since Juno is still travelling at a very
fast velocity, although the instruments
are still collecting data during the approach and departure also.
The final phase of the mission is
called the Deorbit phase. Designed
to send Juno into the atmosphere
of Jupiter, this will end up in the destruction of the probe as it was not
designed to operate in the extreme
environment of Jupiter’s atmosphere.
After the science pass on orbit 37,
a deorbit burn will occur which will
set the lowest point of the next close
pass to be below the clouds tops.
On February 20, 2018 Juno will
have completed its mission. The destruction of the spacecraft in Jupiter’s
atmosphere ensures that its orbit
would never place it on a collision
course with the Jovian moons Europa, Ganymede, or Callisto. Such an
impact would violate NASA’s planetary protection requirements.
As of this writing, Juno is currently in
its first capture orbit, speeding back
towards Jupiter, the science instruments are on and while the first orbit
is not technically a science orbit,
some readings, and certainly some
images will be gained during the pass
around Jupiter.
The first actual science orbit
doesn’t begin until the middle of
November. In the months ahead,
more science and images will come
back from Jupiter. What will we discover and what will we see?
To learn more about Juno and follow its mission, the following websites
are very informative :
https://www.missionjuno.swri.edu/
http://www.nasa.gov/mission_pages/
juno/main/index.html
To find out where Juno is and “fly
along” with the spacecraft, check
out NASA’s Eyes on the Solar System
program. It’s an internet-based tool
that you download to your PC or
Mac and use to see many objects in
the solar system, including Juno:
http://eyes.jpl.nasa.gov/juno
Credit: NASA/JPL/Caltech
Imager/Spectrometer will be collecting their nest data on that orbit, but
the Gravity Science experiment will
still be operating during that orbit, but
with only the X-Band instrument collecting data, the Ka-Band translator
(Kat) is off since it requires the spacecraft to be oriented towards Earth.
Then on a GRAV oriented orbit, when
the spacecraft is oriented towards
Earth, the Kat can download data to
Earth in real-time, but the orientation
reduces the amount of data collected by other instruments.
The design of the orbits should allow Juno to cover the entire planet
with its instruments, giving scientists
a good picture of all of Jupiter from
their various instruments.
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