When NASA’s Juno spacecraft flew past Earth on Oct. 9, 2013, it
received a boost in speed of more than 8,800 mph (about 7.3 kilometer
per second), which set it on course for a July 4, 2016, rendezvous with
Jupiter, the largest planet in our solar system. One of Juno's sensors, a
special kind of camera optimized to track faint stars, also had a
unique view of the Earth-moon system. The result was an intriguing,
low-resolution glimpse of what our world would look like to a visitor
from afar.
"If Captain Kirk of the USS Enterprise said, ‘Take us home, Scotty,’
this is what the crew would see," said Scott Bolton, Juno principal
investigator at the Southwest Research Institute, San Antonio. “In the
movie, you ride aboard Juno as it approaches Earth and then soars off
into the blackness of space. No previous view of our world has ever
captured the heavenly waltz of Earth and moon."
The Juno Earth flyby movie is available at: http://www.youtube.com/watch?v=_CzBlSXgzqI&feature=youtu.be . The music accompaniment is an original score by Vangelis.
The cameras that took the images for the movie are located near the
pointed tip of one of the spacecraft's three solar-array arms. They are
part of Juno's Magnetic Field Investigation (MAG) and are normally used
to determine the orientation of the magnetic sensors. These cameras look
away from the sunlit side of the solar array, so as the spacecraft
approached, the system's four cameras pointed toward Earth. Earth and
the moon came into view when Juno was about 600,000 miles (966,000
kilometers) away -- about three times the Earth-moon separation.
During the flyby, timing was everything. Juno was traveling about
twice as fast as a typical satellite, and the spacecraft itself was
spinning at 2 rpm. To assemble a movie that wouldn't make viewers dizzy,
the star tracker had to capture a frame each time the camera was facing
Earth at exactly the right instant. The frames were sent to Earth,
where they were processed into video format.
"Everything we humans are and everything we do is represented in that
view," said the star tracker's designer, John Jørgensen of the Danish
Technical University, near Copenhagen.
Also during the flyby, Juno's Waves instrument, which is tasked with
measuring radio and plasma waves in Jupiter's magnetosphere, recorded
amateur radio signals. This was part of a public outreach effort
involving ham radio operators from around the world. They were invited
to say "HI" to Juno by coordinating radio transmissions that carried the
same Morse-coded message. Operators from every continent, including
Antarctica, participated.
"With the Earth flyby completed, Juno is now on course for arrival at
Jupiter on July 4, 2016," said Rick Nybakken, Juno project manager at
NASA's Jet Propulsion Laboratory in Pasadena, Calif.
The Juno spacecraft was launched from Kennedy Space Center in Florida
on August 5, 2011. Juno’s launch vehicle was capable of giving the
spacecraft only enough energy to reach the asteroid belt, at which point
the sun’s gravity pulled it back toward the inner solar system. Mission
planners designed the swing by Earth as a gravity assist to increase
the spacecraft’s speed relative to the sun, so that it could reach
Jupiter. (The spacecraft’s speed relative to Earth before and after the
flyby is unchanged.)
After Juno arrives and enters into orbit around Jupiter in 2016, the
spacecraft will circle the planet 33 times, from pole to pole, and use
its collection of science instruments to probe beneath the gas giant's
obscuring cloud cover. Scientists will learn about Jupiter's origins,
internal structure, atmosphere and magnetosphere.
Juno's name comes from Greek and Roman mythology. The god Jupiter
drew a veil of clouds around himself to hide his mischief from his wife,
but the goddess Juno used her special powers to peer through the clouds
and reveal Jupiter's true nature.
NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Juno
mission for the principal investigator, Scott Bolton, of Southwest
Research Institute in San Antonio. The Juno mission is part of the New
Frontiers Program managed at NASA's Marshall Space Flight Center in
Huntsville, Ala. Lockheed Martin Space Systems, Denver, built the
spacecraft. JPL is a division of the California Institute of Technology
in Pasadena.
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