Juno - Jupiter Orbiter Options

[PhilHorzempa]

I thought that it was time to start a new thread devoted to the JUNO Jupiter
Orbiter mission. This New Frontiers Mission #2 seems to be a "stealth" project
with little information available on the Web. In fact, the official NASA JUNO
web site is quite pitiful. It contains the minimal amount of information on what
seems to be an intriguing mission, in terms of both science and engineering.

Does the UMSF community have information on this mission that has not
been widely seen before?

Another Phil

[Guest_Richard Trigaux_*]

Will the effect of these bulges be detectable by analysing Juno's position?

Analysing this position alone will be a great chalenge, as, if Juno changes speed and trajectory relative to the bulges, the moons too will do this. So assessing the trajectory alone will already be very complex, especially if the only reference is the set of jovian moons. With my opinion, we need some other stable references:
-ultra stable radio uplink from Earth
-using pulsars or other stable galactic source
-measuring star position.



Once the movement known, analysing tidal effects will too be complicated. Tides are basically waves, which want to propagate at their own speed, independently of the astronomical cause. On Earth such waves can resonate into large oceans, giving a different tide regime for the atlantic ocean and the pacific ocean. On Jupiter, we can think that we shall have resonances along the equator, or more likely different spherical vibration modes. Some will be directly excited by one of the moons, some will on the countrary opose to the excitation by one of the moons.

In a first approximation, we shall have linear waves, or more accurately a spectrum of discreet vibration modes. This will already allow us to sense the depth of the atmosphere and obtain a pressure profile. (if the waves go deep enough. This is not sure, and in heliosysmology there is still a lack of modes involving the core).

In a second step, discrepancies to the linear models will allow us to search for non linear effects, such as damping, elliptic shape of the layers, movements, layers of helium or layers of hydrogen, etc.

The dream would be, like as in heliosysmology which is now able to sense the presence of spots on the opposite side, to see inner Jupiter features like large storms, solid surface features, or convection patterns. After a computer model which was made several years ago, Jupiter would contain a set of several vortexes, paralel to its rotation axis, but avoiding the solid core.


What will be ultimately possible to see will depend on the accuracy of trajectory measurement, I think. This is worth adding some weight, like a telescope (to sense stars) or a set of large antennas.

[JRehling]

Will the effect of these bulges be detectable by analysing Juno's position?

Analysing this position alone will be a great chalenge, as, if Juno changes speed and trajectory relative to the bulges, the moons too will do this.

I think the key will be to measure the doppler shift of a continuous Juno-to-Earth radio signal to determine Juno's velocity and compare that to the no-bulge expectations of velocity. That's how mascons were discovered on the Moon (and Ganymede). Actually, since merely detecting the bulges is not the point, I think the analysis will be to construct models of how the ten tidal bulges alter Jupiter's shape, make predictions of what Juno's velocity should be, and refine the model based on the data. The bulges will not be moving "hills of atmosphere", though -- they should have manifestations at depth as well, which makes the models more complex, but also more informative. That will help us, in a roundabout way, understand Jupiter's interior.

Using a Juno flyby to calculate the planet's moment of inertia is also/instead a way to go about this. And with that, I find the need to read up on more mathematics.

[Guest_Richard Trigaux_*]

A doppler analysis of a permanent signal will give us only one dimention of a three dimentional problem. Maybe it would be fine to also have a pulsar or something as a second doppler source in a perpendicular direction. But this implies a large dish...