Juno development, launch, and cruise, Including Earth flyby imaging Oct 9 2013 Options

[Spaceflight101]

Hi,

Apparently the Earth flyby is scheduled for October 9, with a closest approach of 541 km. The lowest pass is currently scheduled to be over SW Australia, though that's subject to some fine tuning. It'll be at 1400 GMT, which would be about 11 pm Sydney time.

The info over at my site is preliminary from pre-launch data, the location and timing could be off. So, I guess this is based on the most-recent data:

Nav says closest approach will be near South Africa (no idea how firm this is, so don't book your travel yet).

NASA has given 560 Kilometers for the flyby altitude in a recent release, but I guess that is not set in stone until after the Inner Cruise 3 TCMs.

And a big thanks to Propguy for those insights, I asked NASA public affairs about the details of the DSM-1 issue, but that's a lost cause...

Propguy, is there any info on the potential DSM Clean-Up Maneuver and whether that is going to be needed? DSM-2 +10 days is the info I have, but that comes from the way early stage of mission planning...

Patrick

[mcaplinger]

So, I guess this is based on the most-recent data...

Latest SPICE file ftp://naif.jpl.nasa.gov/pub/naif/JUNO/ker..._TCM5prelim.bsp shows perigee over South Africa.
Should get a reasonable view of the Americas on the inbound leg.

[Phil Stooke]

Maybe the Moon as well?

Phil

[propguy]

Propguy, is there any info on the potential DSM Clean-Up Maneuver and whether that is going to be needed? DSM-2 +10 days is the info I have, but that comes from the way early stage of mission planning...

Patrick

TCM5 is the makeup manuever for the two DSM burns. In a perfect scenario it would be zero and it would be cancelled, but we will be doing a fairly small, ~1.8 m/sec, burn on October 3.

[mcaplinger]

Maybe the Moon as well?

I haven't looked at this in detail yet, but I think the closest approach distance is around 200,000 km, so the Junocam view will not be that great (30 pixels or so.)

[propguy]

TCM5 was successfully completed today. Results are quick look but looks like hit required goal to within a few mm / sec. Now on track for Earth Fly By in October 2013.

[Mongo]

A possible new test of general relativity with Juno

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.

[Astro0]

One for the Juno crowd

[Paolo]

latest update:

May 22 update: Mission controllers received confirmation from the spacecraft today that its MWR, JEDI and Waves instruments were powered off as planned. The magnetometer experiment remains powered on at low data rates. The planned instrument shutdown was done in preparation for the spacecraft’s upcoming switch to its lower data rate antennas as it begins the next phase of its mission, dubbed “Inner Cruise 3” on May 29.

The solar-powered Juno spacecraft and its saucer-shaped high-gain antenna (or HGA) always point sunward, but while Juno is in the inner solar system, Earth’s position on the sky shifts dramatically. Earth’s movement means that Juno cannot always use its HGA and benefit from its high data rate connection. For this reason, the spacecraft has a suite of antennas that allow communications with Earth from other angles, but at the cost of lower data rates, resulting in a reduction in Juno’s ability to transmit science data during that time. Juno’s science instruments will be powered on again shortly before the Earth flyby, slated for Oct. 9.

[Doug M.]

A question about Juno's ground track. Eyeballing this, it looks like there's pretty significant inclination from the ecliptic -- at least 15 degrees, maybe more. Is that correct? Is Juno's orbit really that highly inclined? And if so, will it continue so out to Jupiter? I know its orbit around Jupiter will be highly inclined, but will it be swinging far out of the plane of the ecliptic on its way there?

Thanks,


Doug M.

[Paolo]

according to the Jonathan Space Report http://planet4589.org/space/jsr/back/news.645

On Aug 8 the probe left the Earth's gravitational sphere of influence and entered a 1.0 x 2.26AU x 0.1 deg solar orbit.

[mcaplinger]

Eyeballing this, it looks like there's pretty significant inclination from the ecliptic...

Eyeballing what? Hopefully not the image in my previous post, which is in the Earth-fixed frame and is probably misleading.

Energetically it doesn't make sense to go out of the plane of the ecliptic.

[Doug M.]

Energetically it doesn't make sense to go out of the plane of the ecliptic.

Okay, but then how do you get over South Africa and SW Australia without leaving the ecliptic? Most of SA is below the tropic line, as is almost all of West Australia.

I guess it works if the article was talking in approximate terms -- Southern Africa and West Australia.


Doug M.

[jamescanvin]

Even at the Earth's poles you are still only the tiniest fraction of a degree above or below the ecliptic.

Without some complex calculation the Earth ground tracks have very little connection to a solar orbit. Certainly not enough to say anything by eyeballing it.

[Doug M.]

Okay, but then how do you get over South Africa and SW Australia without leaving the ecliptic? Most of SA is below the tropic line, as is almost all of West Australia.

Ohh no, I'm a dope. I went away and thought about it for a bit, and then realized that Juno is now in a *heliocentric* orbit, not orbiting Earth. So a very small inclination in its solar orbit could cause it to pass Earth at a very high latitude. Of course.

[edit -- I see James Canvin beat me too it. Thank you, James.]


Doug M.