NASA’s JUNO mission scripted a new history

America couldn’t have asked for more on its birthday. NASA has yet again scripted a momentous success through insertion of Juno Spacecraft into Jupiter’s orbit on a very special day. NASA has accomplished such astounding feats earlier on the historically important July 4^th, the independence day of America. Previous successes include-landing of Sojourner of Mars Pathfinder Mission on Martian surface in 1997 and the collision of  Deep Impact with Comet Tempel 1 in 2005. Juno mission assumes extraordinary significance since, it aims to unravel the origins of our Solar System by understanding the origin and evolution of Jupiter.

Around four and half million years ago, a giant cloud of gas and dust, called nebula collapsed to form our solar system. Sun formed first, and later on the swirling cloud condensed to form various planets, asteroids and comets. The first planet formed from the Hydrogen and Helium left after the birth of Sun was Jupiter. It is the largest, oldest planet of our Solar System. Unlike earth, it retained the remnants of original nebula, making it an ideal planet to trace the origins of Solar System. Juno Mission was commissioned to understand the unique atmosphere composition of Jupiter, determine the amount of water in its atmosphere, global structure and composition, map magnetic rings, gravity fields, explore and study its magnetosphere, northern and southern lights at its poles i. e., auroras. The mission is aptly named as Juno, because as per the Roman Mythology, Jupiter, the King of Gods camouflaged with clouds to hide his mischief. Jupiter’s wife Goddess Juno could penetrate the clouds and decipher the mystery. Juno spacecraft is now assigned the task of unfolding the mysteries of this largest terrestrial planet. While it is known that Jupiter largely contains Hydrogen and Helium, the search is now on to know the composition of other heavy elements present in the planet. Besides, the enchanting characteristic features like swirling clouds, bands, storms, the great red spot had enthused scientists to explore the planet.

The crushing weight of Jupiter resulted in generation of extreme temperature and pressures deep inside. Consequently the gaseous hydrogen is squeezed into electrically conducting liquid metallic hydrogen causing the production of extremely strong magnetic field similar to solar magnetic field. As a result any charged particle flying through the space gets pulled into Jupiter’s magnetic field. The material so caught is channeled towards poles creating an intense light showers or aurorae or the Northern and Southern light (similar to polar auroras on earth). Evading the pull of powerful magnetosphere of Jupiter became a formidable task for the Space scientists contemplating Jupiter missions. Juno spacecraft was scientifically designed to carry powerful instruments on board to observe and capture the aurora lights in ultraviolet radiation that can enhance our understanding of Jupiter’s magnetic field.

 Juno spacecraft, designed under the New Frontiers Program was hoisted into space by the expendable launch vehicle Atlas 551 rocket on August 5^th 2011 from Cape Canaveral, Florida. Equipped with nine instruments-microwave radiometer for atmospheric sounding and composition (MWR), vector magnetometer (MAG), plasma and energetic particle detector (JADE and JEDI), Ultra violet imager/spectrometer (UVS), infrared imager/spectrometer (JIRAM), radio/plasma wave experiment (waves), gravity/radio science system (Gravity science) and Junocam the spacecraft will orbit around Jupiter 37 times and pass over the planet within 3100miles range to make all crucial observations. Strength of gravity will aid in calculating mass and a measure of magnetic radiation helps in knowing composition. Powered by three extended solar panels of 20mts jutting out from a hexagonal body Juno spins at 2 revolutions per minute to remain stable. To protect the spacecraft from the high energy radiations emanated by Jupiter (20,000 times as intense as earth’s magnetic field), it was armored with 180kg of titanium shields.

After travelling for two years, in October 2013, Juno made earth’s flyby (was within 350 miles of Earth’s reach). Earth’s gravity propelled Juno towards Jupiter. Atlas rocket provided half of the energy needed for Juno to reach Jupiter and the other half was provided by earth’s flyby. When Juno arrived near Jupiter, it was moving faster than any human-made object ever fired, moving at a speed of hundred and sixty-five thousand miles an hour. To enter the Jupiter’s orbit it had to slow down. It was precisely at this moment on July 4^th, 9pm, Pacific Standard Time, engines were fired for 35 minutes. Juno’s rotation rate increased to 5rpm and altitude is changed to enter the Jupiter’s orbit or capture orbit. Even the speed was reduced to 1212 miles per hour to facilitate insertion into Jupiter’s orbit. Accurate firing of the engine made the $1.1 billion worth mission a tremendous success.  Any discrepancy at this stage would have doomed it. In 1995 NASA’s previous mission to Jupiter, Galileo arrived at the planet in 1995 but its instruments including antenna were irreparably damaged by radiation. Galileo indeed captured breathtaking images of the ammoniac clouds swirling around the planet.  

Juno is now almost five hundred forty million miles from earth, electronic signals would take 48 min to travel.  Juno’s orbital insertion was tracked by Jet Propulsion Laboratory (JPL), Pasadena, California and Lockheed Martin Juno Operations Centre, Colorado.  Juno entered the capture orbit where the probe will stay for 107 days. Scientist preferred this long route rather than direct insertion, 14-day orbit, as this requires more fuel. Capture orbit on the other hand, needs less fuel and scientists would get a chance to recheck the functioning of all the instruments on the board and can make some initial observations. On November 2^nd, Juno’s first science orbit would begin when engine is burned again to increase its speed.  In order to minimize the effect of radiations, Juno will fly along a long elliptical orbit with a closet range of 3100 miles at the south of the orbit and extends to 1.2 million miles from Jupiter (flying beyond the orbit of Jupiter’s moon Castillo). Extended elliptical orbits would keep the solar panels in sunlight.

Data collection from the instruments would begin from October 2016. Juno’s mission life is 2 years. Engines will be fired for the final time in February 2018 when it will crash into Jupiter’s atmosphere as planned. While the spacecraft would trigger its own annihilation, instruments on board will capture data.

 

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