[X] My Assistant

[slinted]

This isn't really a Spirit only topic, but since she has been on Mars a bit longer, I'll give her the honor of this thread.

http://disney.go.com/disneypictures/rovingmars/

January 27 release

[djellison]

Just thought of a question and YOU would be the man to answer. Reading the Flight Director reports over at the MER Notebook, I and saw mention that using MGS MOC relay, they tended to have trouble with image file products. I know that they dropped the MGS UHF passes after, what, 6 months or so ( I assume to do more work with MGS's instruments instead of having to have science downtime for relay? ) - but any idea what/how/why/where the trouble w.r.t imaging products was?

I have the full Opportunity EDL as about 50 mins of DVD, but it's a lady at MSSS that time I think, not sure who - but she mentions that MOC had started taking 'the global image' which I presume is http://www.msss.com/moc_gallery/r10_r15/im...3/R1303894.html + http://www.msss.com/moc_gallery/r10_r15/im...3/R1303895.html ?

Doug

[mcaplinger]

Just thought of a question and YOU would be the man to answer. Reading the Flight Director reports over at the MER Notebook, I and saw mention that using MGS MOC relay, they tended to have trouble with image file products. I know that they dropped the MGS UHF passes after, what, 6 months or so ( I assume to do more work with MGS's instruments instead of having to have science downtime for relay? ) - but any idea what/how/why/where the trouble w.r.t imaging products was?

There were two factors. First, Odyssey has more a lot more memory onboard for UHF data, and it can send it to Earth 2-3x faster than MGS. So Odyssey was much preferred for UHF passes. Also, when MOC is used for UHF data it can't do much else, whereas the Odyssey science instruments can carry on pretty much normally through a UHF pass.

Second, the design of the Mars Relay on MGS didn't include any handshaking, so a small amount of data was probably dropped every 16 seconds, and this might have impacted image processing. I'm not really sure how the MER UHF handled the lack of handshaking, if at all.

You can read a lot more info about the MR on the MSSS website, http://www.msss.com/mars_images/mars_relay/mer/

I have the full Opportunity EDL as about 50 mins of DVD, but it's a lady at MSSS that time I think, not sure who - but she mentions that MOC had started taking 'the global image' ...

That was Elsa Jensen, the MOC operations supervisor at MSSS. She got a credit in Squyres' book and I didn't.

We took global maps on the landing orbit for both rovers. See http://www.msss.com/mars_images/moc/2004/01/07/
(doesn't look like we did a similar release for MER-B.)

[djellison]

(doesn't look like we did a similar release for MER-B.)

Allow me.... (attached)

Is it fair to describe MGS as being from the 'old school' of spacecraft systems, whereby much of it works based on 'data rates' - wheres Odyssey is more from the new school of spacecraft which simply generates files? I suppose this is a symptom of the carry over from '92.

Doug

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[mcaplinger]

Is it fair to describe MGS as being from the 'old school' of spacecraft systems, whereby much of it works based on 'data rates' - wheres Odyssey is more from the new school of spacecraft which simply generates files? 

Actually, the Mars Observer/MGS data architecture is amazingly clean -- each instrument gets its own allocation of downlink rate (most of it goes to MOC) and there's no need to adjudicate downlink usage; it's all pre-allocated. There's no waste because everyone uses their entire allocation (in the MGS case we have a lot of planning and sequencing software that insures this.)

Odyssey and MRO use "APIDs" -- ways of prioritizing how all the various data products are prioritized and sent down. It may have some benefits, but it also requires more coordination between data producers. Both systems work but the MGS scheme is simpler.

Odyssey can send more data simply because it has more memory -- its RAD6000 has 128 MB whereas MOC has 12 MB -- and its downlink is faster (about 128Kbits/sec max, compared to MGS's ~80 Kbps.)