[X] My Assistant

[Guest_AlexBlackwell_*]

I'm not sure exactly which forum this fits in but NASA has just released the AO for Discovery Program 2006 and Missions of Opportunity. See the Discovery Program Acquisition Home Page for more details. Click on the "Discovery AO" link to download the PDF.

[djellison]

Yup - the maths could get quite interesting. Is it worth spending perhaps $10m upgrading to a slightly heavier version of your ELV to get larger solar arrays so you can have a more powerfull transmitter and thus get more kbps and thus fewer sessions.

Might have had my maths a bit wrong earlier.....but this is all very very 'ballpark guestimation'

say 14 1hr passes of 35m coverage per week ( i.e. the daily uplink for MER plus beep back ) would be something like $2424/hr, or about $34k/week ( $1.7m/year ). The finances for doing MER Relay with Odyssey is probably quite interesting, I think it would probably be something like 1 hr of Odysseys downlink per day is MER related - so a similar figure.



Voyager

There were 90.3 hours of DSN scheduled support for Voyager 1 of which 32.6 hours were large aperture coverage
There were 76.5 hours of DSN scheduled support for Voyager 2 of which 25.9 hours were large aperture coverage

Say it's 28 sessions a week, 7 on 70m, 21 on 35m

$6745/hr for the 70m - $400k (as near as makes no difference)
$527k for the 35m - so that week's Voyager DSN ops cost about $927K.

Youch.

Very rough maths - probably very wrong to be honest.

7 x 8hr 70m passes per week, at 5kbps is $377,220 per week, for 984 MBytes - or $552 per floppy disk

Doug

[ugordan]

It just goes to show it's time to switch to optical telecoms. No matter how many watts you pump into your RF transmitter, the vast majority of the transmitted power is simply wasted. The only positive thing a radio comm-link does is loosen the required pointing accuracy, of course due to the same dispersal of the signal.

[mcaplinger]

It just goes to show it's time to switch to optical telecoms. No matter how many watts you pump into your RF transmitter, the vast majority of the transmitted power is simply wasted. The only positive thing a radio comm-link does is loosen the required pointing accuracy, of course due to the same dispersal of the signal.

I don't disagree, but...

Optical has the same problem, if you're counting as "wasted" any power that doesn't fall on the receiver's mirror. They're both EM radiation, after all. I'm not sure what the actual efficiency tradeoffs look like, but optical isn't such a slam dunk over RF from a system perspective, because the real engineering-acheivable efficiency gains aren't just the ratio of the wavelengths.

And there's cloudy days, what you do near conjunction, etc.

http://lasers.jpl.nasa.gov/PAGES/about.html has some good background, but obviously optical researchers aren't going to present a completely balanced story.

If you wanted to reduce operations costs for deep-space RF, there would be ways to reduce costs below those of DSN. Some Discovery teams have proposed using USN ( http://www.uspacenetwork.com/index.html ) instead of DSN to save costs.