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Title: A possible new test of general relativity with Juno
Authors: L. Iorio

The expansion in multipoles of the gravitational potential of a rotating body affects the orbital motion of a test particle orbiting it with long-term perturbations both at a classical and at a relativistic level. In this preliminary sensitivity analysis, we show that, for the first time, the J2 c^-2 effects could be measured by the ongoing Juno mission in the gravitational field of Jupiter during its yearlong science phase (10 November 2016-5 October 2017) thanks to its high eccentricity (e=0.947) and to the huge oblateness of Jupiter (J2=1.47 10^-2). The semi-major axis a and the perijove \omega\ of Juno are expected to be shifted by \Delta a =700-900 m and \Delta\omega = 50-60 milliarcseconds, respectively, over 1-2 yr. A numerical analysis shows also that the expected J2c^-2 range-rate signal for Juno should be as large as 280 microns per second during a typical 6 h pass at its closest approach. Independent analyses previously performed by other researchers about the measurability of the Lense-Thirring effect showed that the radio science apparatus of Juno should reach an accuracy in Doppler range-rate measurements of 1-5 microns per second over such passes. The range-rate signature of the classical even zonal perturbations is different from the 1PN one. Thus, further investigations, based on covariance analyses of simulated Doppler data and dedicated parameters estimation, are worth of further consideration. It turns out that the J2 c^-2 effects cannot be responsible of the flyby anomaly in the gravitational field of the Earth. A dedicated spacecraft in a 6678 km X 57103 km polar orbit would experience a geocentric J2 c^-2 range-rate shift of 0.4 mm s^-1.

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Juno's Two Deep Space Manoeuvres are 'Back-To-Back Home Runs'

NASA's Juno spacecraft successfully executed a second Deep Space Manoeuvre, called DSM-2 last Friday, Sept. 14. The 30 minute firing of its main engine refined the Jupiter-bound spacecraft's trajectory, setting the stage for a gravity assist from a flyby of Earth on Oct 9, 2013. Juno will arrive at Jupiter on July 4, 2016.
The manoeuvre began at 22:30 UT, when the Leros-1b main engine began to fire. The burn ended at 23:00 UT. Based on telemetry, the Juno project team believes the burn was accurate, changing the spacecraft's velocity by about 388 meters a second while consuming about 376 kilograms of fuel.

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Nasa's Juno spacecraft will execute the second of two big burns on its main engine on Tuesday.
The manoeuvre will put the probe on a path to flyby Earth in October next year. This sweep around the home planet will then give the mission a gravitational boost and the velocity required to get it out to Jupiter in July 2016.

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NASA's Jupiter-Bound Juno Changes its Orbit

Navigators and mission controllers for NASA's Juno mission to Jupiter watched their computer screens as their spacecraft successfully performed its first deep-space manoeuvre. This first firing of Juno's main engine is one of two planned to refine the spacecraft's trajectory, setting the stage for a gravity assist from a flyby of Earth on Oct 9, 2013. Juno will arrive at Jupiter on July 4, 2016.
The deep-space manoeuvre began at 22:57 UT yesterday, when the Leros-1b main engine was fired for 29 minutes 39 seconds. Based on telemetry, the Juno project team believes the burn was accurate, changing the spacecraft's velocity by about 344 metres a second while consuming about 376 kilograms of fuel.

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The Juno Jupiter mission launched on the 5th August, 2011, from Cape Canaveral, Florida



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Juno mission to Jupiter may get more science assignments

Juno's elliptical path calls for it to loop back around Earth next year to pick up a gravitational slingshot boost toward Jupiter.
The meetings at Marshall, which manages the NASA program that includes Juno, were to review the plan in terms of cost, staffing and schedule, NASA said. They were to make sure NASA and the Juno team were on the same page even though Juno is still a long way from Jupiter.

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 NASA's Juno Spacecraft Images Big Dipper

PIA15653.jpg

One of those instruments, JunoCam, is tasked with taking closeups of the gas giant's atmosphere. But, with four-and-a-half years to go before photons of light from Jupiter first fill its CCD (charge-coupled device), and a desire to certify the camera in flight, Juno's mission planners took a page from their childhood and on March 21, aimed their camera at a familiar celestial landmark

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NASA's Juno Spacecraft Refines its Path to Jupiter

NASA's solar-powered Juno spacecraft successfully refined its flight path Wednesday with the mission's first trajectory correction manoeuvre. The manoeuvre took place on Feb. 1. It is the first of a dozen planned rocket firings that, over the next five years, will keep Juno on course for its rendezvous with Jupiter.
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Juno spacecraft trajectory animation



Juno Jupiter orbit animation



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Juno Jupiter Mission
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Title: Jupiter's Moment of Inertia: A Possible Determination by JUNO
Authors: Ravit Helled, John D. Anderson, Gerald Schubert, David J. Stevenson

The moment of inertia of a giant planet reveals important information about the planet's internal density structure and this information is not identical to that contained in the gravitational moments. The forthcoming Juno mission to Jupiter might determine Jupiter's normalised moment of inertia NMoI=C/MRČ by measuring Jupiter's pole precession and the Lense-Thirring acceleration of the spacecraft (C is the axial moment of inertia, and M and R are Jupiter's mass and mean radius, respectively). We investigate the possible range of NMoI values for Jupiter based on its measured gravitational field using a simple core/envelope model of the planet assuming that J_2 and J_4 are perfectly known and are equal to their measured values. The model suggests that for fixed values of J_2 and J_4 a range of NMOI values between 0.2629 and 0.2645 can be found. The Radau-Darwin relation gives a NMoI value that is larger than the model values by less than 1%. A low NMoI of ~ 0.236, inferred from a dynamical model (Ward & Canup, 2006, ApJ, 640, L91) is inconsistent with this range, but the range is model dependent. Although we conclude that the NMoI is tightly constrained by the gravity coefficients, a measurement of Jupiter's NMoI to a few tenths of percent by Juno could provide an important constraint on Jupiter's internal structure. We carry out a simplified assessment of the error involved in Juno's possible determination of Jupiter's NMoI.

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