SAR or other Radar investigation of Saturn Options

[Guest_Max Power_*]

Will Cassini ever do a radar survey of Saturn proper?

Due to declining fuel and RTG power, the ability to do so decreases with time.

It is my understanding that in the Equinox orbits that there is a possibility for up to 3 close approaches of the dark side with RADAR in its lower resolution modes.

It is also my understanding that not that much reprogramming would be needed -- as the radar system has been fully mastered.

The risks of doing a radar swath would not increase substantially, versus any other close moon approach.


ADMIN - Thread title changed for clarity.

[djellison]

What mode of Radar, and for what purpose. What question are you trying to answer with such an observation?

Via Radiometer mode, I'm sure it already has been point at Saturn itself a great deal.

[Guest_Max Power_*]

What mode of Radar, and for what purpose. What question are you trying to answer with such an observation?

Via Radiometer mode, I'm sure it already has been point at Saturn itself a great deal.

There is not a single press release or scientific research paper to provide proof that this has been done.

A SAR RADAR survey of Saturn has not been done.

Only about 3 low rez SAR surveys would be needed, as its inner core can't be that interesting.

The RADAR system is mutli-modal, so a single swath could see a lot.

[ngunn]

I know the numbers don't reflect current membership, but those posts must count as a forum milestone of sorts (for sad numerical 'trainspotters' with nothing better to do on a cold Saturday morning). 5000 members have passed through these doors between questioner and responder.

[djellison]

There is not a single press release or scientific research paper to provide proof that this has been done.

http://www.cosis.net/abstracts/EGU06/05222...a619eee9e66d294

The thermal emission from Saturn’s atmosphere was mapped over most of its globe using the passive radiometer that is part of the Cassini RADAR instrument. The ra- diometer operates at a frequency of 13.78 GHz, or 2.18-cm wavelength, and uses the spacecraft’s main communication antenna to form a beam of 0.37o width at half power.

Someone who knows more about the different modes with Cassini's radar may be able to give you more information, but by gut feeling is that SAR mode radar at Saturn itself wouldn't return anything as the range to and density of material on the way to a Saturnian core are both too high. The short answer - the reason they've not mapped Saturns core with the RADAR is because I don't think they can. If they could - I'm sure they would have tried.

[Guest_Max Power_*]

http://www.cosis.net/abstracts/EGU06/05222...a619eee9e66d294

Someone who knows more about the different modes with Cassini's radar may be able to give you more information, but by gut feeling is that SAR mode radar at Saturn itself wouldn't return anything as the range to and density of material on the way to a Saturnian core are both too high. The short answer - the reason they've not mapped Saturns core with the RADAR is because I don't think they can. If they could - I'm sure they would have tried.

What you quote above is a passive radar study, not a core targeted SAR survey.

The highest rez SAR mode is out of the question, but all the other lower rez SAR modes will provide something -- if only the slushy reflections back due to the soppy He-H layer interactions (convection if you will) thought to be taking place.

Bouncing SAR radar at somewhat close range at the soppy inner parts of the gas planets has not been done or even tried.

The worst that could happen is total absorption of all the radar energy...

[imipak]

[my] gut feeling is that SAR mode radar at Saturn itself wouldn't return anything as the range to and density of material on the way to a Saturnian core are both too high.

That sounds plausible, but even confirmation of a theoretically-predicted null result would be useful. However, those best placed to work out whether the usefulness of that observation justifies the cost have declined to do it. Presumably therefore the cost doesn't justify the usefulness.

[djellison]

but all the other lower rez SAR modes will provide something

Evidence for this please? What are these lower 'rez' SAR modes?

[Greg Hullender]

This might be more interesting during those final orbits when Cassini is passing under the rings.

Assuming they ever do get around to approving the Solstice Mission, that is.

--Greg

[nprev]

Yeah...I was thinking that a SAR pass of the rings might be pretty illuminating, but I can't visualize a non-fatal trajectory that would allow Cassini to pass under or over them at close enough range to return useful (hi-res) data, to say nothing of the high relative velocities involved.

Even if such a maneuver was conducted as the coup d' grace prior to EOM, the spacecraft would still have to survive long enough for data playback.

[alan]

OT: just noticed the forum passed a milestone, Maxpower is member number 5001.

[Greg Hullender]

. . .I can't visualize a non-fatal trajectory that would allow Cassini to pass under or over them at close enough range to return useful (hi-res) data, to say nothing of the high relative velocities involved.

Then behold:




According to the Planetary Society, this really IS the plan.

http://www.planetary.org/blog/article/00001856


--Greg

[nprev]

Thanks for the reminder, Greg. I've no doubt that the rings will receive an excellent broadband optical exam then, but will Cassini get close enough to make SAR observations worthwhile? The outer edge of the F-ring & the inner edge of the D-ring might be close enough, but the average range to the rest of the system (esp. for perpendicular 'stare-down' observations) during these orbits will be several thousand km at least.

[djellison]

FWIW - current actual members = 2142. So 2850+ registrations have been spam, culled, trolled etc.

[rlorenz]

Will Cassini ever do a radar survey of Saturn proper?
ADMIN - Thread title changed for clarity.

We only do SAR within about 4000km of an object - we don't get that close to Saturn except
right at the end of the mission, and in any case Saturn is a gas giant -no surface to observe!
Ammonia opacity is significant at our wavelength, so radiometry (as other posters have noted)
is somewhat useful, but must compete both with other Cassini observations at Saturn, and for
our own manpower (which is concentrated towards Titan) to plan and execute the observations,
calibrate and archive the data.