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SUSHEELA SRINIVAS The world looks forward to Juno’s TORY communication to unravel and demystify the S hidden secrets of our solar system. All images courtesy NASA OVER OVE C HE fi h planet in our solar system, TJupiter, has always fascinated astronomers and space agencies. And rightly so – with its massive size (almost twice as much as all the other planets put together), its light and dark bands, the auroras at the poles, its four distinct moons and the enigmatic gaseous state – all make it worth the watch. NASA’s mission to explore the planet in depth has been massive too. While Pioneer and Voyager, on their interstellar missions, skimmed the planet and sent back spectacular images, the spacecra Galileo was exclusively commissioned in 1989 to reach Jupiter and study its moons. A probe was released to the surface in 1995 from Galileo. Flying by close to Io and Europa, two of the four moons of Juno blasts off on Jupiter, it sent amazing information about its journey to Jupiter them and the existence of sub-surface aboard the Atlas–V 551 oceans on them. Its mission completed, rocket the spacecra disintegrated in Jupiter’s atmosphere. ScienceSSciiencn e Reporter,RReportter SEPTEMBERSEPTEMBER 20201616 14 COVER STORY Jubilation as tracking centre records the successful locking of Juno into the orbit of Jupiter On 5 August 2011, another spacecra system of transmi ers and receivers planets. Galileo was designed to study was launched from NASA’s base in that communicate with interplanetary the moons in detail. Moreover, it could Florida, USA. Called Juno, the Jupiter- spacecra . not approach the planet nearer to record bound spacecra was carried aboard the There was jubilation all around in the studies; Atlas–V 551 rocket. The Juno mission the tracking centre on 4 July 2016. The In what way is the Juno probe is part of the New Frontiers Program monitors in the tracking centre recorded diff erent from the earlier ones? Why is managed at NASA’s Marshall Space the successful locking of Juno into the this mission so special and signifi cant? Flight Centre in Huntsville, Alabama. orbit of Jupiter. NASA released a video Well, Juno scores brownie points on Its mission was to reach the bright, big consisting of time lapse images that several accounts. planet and study it in much more detail. clearly show the four moons of Jupiter in Firstly, most spacecra s are designed The target distance: around 588 million tandem as recorded by Juno. to be powered by radioactive energy to kilometres (588,000,000 km at its closest accommodate the continuity of power to earth). A Special Mission supply in the absence of sunlight. The spacecra manufactured by Jupiter has been studied earlier too. In the However, Juno deviates from this in that it Lockheed Martin at an approximate cost previous eight missions, only Galileo was is a completely solar-powered spacecra . of 1.1 billion dollars (2011), is managed an exclusive spacecra sent to the planet, Secondly, Juno’s aim is to study by JPL – Jet Propulsion Laboratory at while all others were fl yby operations Jupiter’s core, presence of water in its the California Institute of Technology – – that is, fl ying past and returning or, atmosphere and the formation of the for NASA. JPL also supervises NASA’s gravity assists that is, taking Jupiter’s magnetosphere. These studies will throw Deep Space Network, a worldwide gravity to propel further to the target light on various theories. Juno will study in detail the evolution of the planet and other mysteries hidden in its core. This will help us gain more insight into the way our solar system was formed; it will give us clues as to how this planet has changed in the duration of 4.6 billion years – the life of our solar system so far. Thirdly, Juno will take a deep look at the fascinating auroras of Jupiter. This is a highly risky endeavour as it involves intense magnetic fi elds and currents. Juno’s technology has to withstand this Galileo extreme environment for around 20 spacecraft Jupiter exposures before degrading. www.jpl.nasa.gov was sent Fourthly, Juno is fi ed with a special exclusively to camera called JunoCam, made as an interactive module and available to the Jupiter public. NASA has provided the means to track JunoCam’s positioning in such 15 Science Reporter, SEPTEMBER 2016 COVER STORY National Aeronautics and Space Administration Built To Withstand Intense Radiation Environments WHAT PROBLEMS DOES INTENSE WHY DOES JUPITER HAVE SUCH IN- EARTH RADIATION CAUSE? TENSE RADIATION BELTS? • Spacecraft and instrument degradation • Very strong magnetic fi eld • Electric charging of the spacecraft • Jupiter’s magnetosphere extends out 100 • Noise from particles hitting detectors Jupiter radii on the sun-facing side-Earth’s is only 10 Earth radii • In addition to the solar wind, Io’s volcanic activity constantly releases gas into the RADIATION magnetosphere, which gets ionized and CHALLENGE: energized, adding to the radiation EARTH Several instruments RADIATION JUPITER practiced making CHALLENGE: RADIATION measurements in Earth’s SPACE BELTS magnetosphere Radiation from…. • Solar energetic particles • Cosmic rays from outside the solar system RADIATION CHALLENGE: JUPITER WHAT PROTECTS JUNO FROM RADIATION EFFECTS? • Very intense radiation belts • Detectors and their electronics are built to withstand radiation • Particles trapped in the belts are • Most electronics shielded in ~1/2-inch thick titanium vault so fast they spiral from top to • On the outside of the spacecraft, the star tracker’s camera is bottom in only a few seconds about 4x heavier than even the biggest standard star trackers • These particles are moving at due to extra shielding nearly the speed of light! • Orbit is designed to avoid most intense pockets of radiation www.nasa.gov Juno’s aim is to study Jupiter’s core, presence of water in its atmosphere and the formation of the magnetosphere. These studies will throw light on various theories. Juno will study in detail the evolution of the planet and other mysteries hidden in its core. a way that any enthusiast can vote and JUNO’JOURNAL decide which parts of the surface can be photographed – just by using the Internet Launch: 5 August 2011 Speed on orbit: 0.17 km/sec and following NASA’s instructions on its website. Deep Space Exercises: Orbit height: 4300 km August/ September 2012 In orbit: 37 orbits spanning Great Challenges Earth fl yby assist (gravity assist or 20 months As Juno embarks on a mission to record a slingshot manoeuvre): the various aspects of Jupiter, it is fraught October 2013 with extreme conditions to be overcome. End of Mission (self-destruction): Being gaseous in nature, Jupiter Jupiter Arrival: July 2016 February 2018 off ers no solid base for probes to land on it. This is a big hurdle as any probe sent Science Reporter, SEPTEMBER 2016 16 COVER STORY APT AND INTERESTING According to Roman mythology, Juno (also known as goddess Hera) is Jupiter’s (also known as Zeus) wife, and she was capable of seeing through clouds which Jupiter surrounded himself with. The primary mission of Juno is to look into the gaseous atmosphere and the clouds surrounding Jupiter. Very apt, indeed! Aboard Juno are three Lego fi gurines represenƟ ng: Galileo, the astronomer who found Jupiter’s moons, he holds a replica of planet Jupiter and a telescope; Juno herself holding a magnifi er, symbolising the search for truth; and Jupiter, holding a lightning bolt, signifying the intense radiaƟ ons around the planet. The Italian Space Agency has donated a plaque carrying an inscripƟ on that states the original words of Galileo Juno – Built to withstand as he discovered and presented to the world the presence of Jupiter’s moons. NUMBERS SIGNIFICANT TO JUNO This fi nding broke the then understanding that Earth was the centre of the universe. 3 – The number of solar wings (panels) which provide the power to the equipment. 9 – Nine instrument units will be recording the planet from its core to the atmosphere. to the rotating parts of the spacecra and 20 – Juno will orbit Jupiter for a period of 20 months before plunging into the harsh probes. Electrical arcing o en occurs atmosphere of the planet and destroying itself. between rotating and non-rotating parts 32 – Juno will make 32 polar orbits around Jupiter during its mission. causing system failure. Earlier probes faced these radiations and a lot of data 5000 – This is the closest distance Juno will approach the planet’s atmosphere to make was lost. its studies. All these hurdles can cause severe 588 million – The target distance of Juno was 588 million km as per requirement. damage to Juno by making it highly electrically charged. This aff ects the 2.8 billion – Juno had to travel a distance of 2.8 billion km to reach Jupiter. The route functioning of the spacecra , disrupting taken was a circuitous one as the engines were not powerful enough to launch Juno the working of the electronics and directly. It had to take the Earth’s gravity assistance and was sling-shot into outer recording equipment. Additionally the space. noise generated by the hi ing particles deep into its atmosphere will be crushed radiations. Juno’s protective shield has to rapidly degrades the functioning of the and destroyed due to the intense pressure withstand these radiations too. equipment. of the atmosphere surrounding it. • Jupiter’s magnetosphere: The sheer Travelling into deep space and close size of this gigantic planet has contributed Built to Withstand to Jupiter, which no other spacecra to a strong magnetosphere that covers a To overcome this situation, Juno has been has done before, causes the spacecra distance equal to nearly 100 times the fi ed with a specially designed electronic to be exposed to intense radiations.
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