[X] My Assistant

[ElkGroveDan]

This was brought up in the MER forums but I figured it might be useful here where discussion of strategy and planning for missions goes on.

Having visited a DSN station this year I have a new found interest in the amazing mission these sites are tasked with. Unfortunately like everything in these belt-tightening days the DSN is underfunded for what it is they need to accomplish. That said a friend pointed out to me that there is a simple formula to calculate the DSN costs for a mission:

Missions calculate DSN costs using this formula: AF = RB [AW (0.9 + FC / 10)]

Where:
AF = weighted Aperture Fee per hour of use.
RB = contact dependent hourly rate, adjusted annually ($1057/hr. for FY09).
AW = aperture weighting:
= 0.80 for 34m High-Speed Beam Waveguide (HSB) stations.
= 1.00 for all other 34m stations (i.e., 34m BWG and 34m HEF).
= 4.00 for 70m stations.
FC = number of station contacts, (contacts per calendar week).

Online tools available:
DSN Aperture Fee Tool - Excel file 706k
DSN Services Catalogue - PDF 675k

The DSN is so critical to nearly everything we discuss here. Everyone should take the time to learn more about it, and if possible try to schedule a visit or tour. The people who work there are the unsung heroes of the headline grabbing feats that NASA and JPL accomplish.
http://deepspace.jpl.nasa.gov/

[Greg Hullender]

It would be interesting to see, per mission, how the costs divide between cost of the probe, cost of the launch, salaries to manage the probe, salaries to analyze the data, and (of course) cost of using the DSN. Among other things, that breakdown would make it easier to see what to try to optimize. Given limited budget dollars, I'd far rather see NASA (and other agencies) optimize the process rather than cut probes.

But I don't think I've ever seen this kind of cost breakdown for any probe -- ever. Does it even exist? That is, does even NASA know?

--Greg

[tedstryk]

I know it exists in the proposals (Discovery, etc.) I don't know whether or not there is a final report available. As I said, I am not criticizing wanting to know what it costs. It is the attitude of the posts that I find offensive (the earlier ones more so than the latest one).

[mcaplinger]

It is the attitude of the posts that I find offensive...

I'm a little bemused about why this is so offensive when all kinds of technical misinformation, unfounded opinions, etc, to my ear more technically grating, go uncommented upon in this forum. Seems a bit fanboyish to me.

[djellison]

I'm a little bemused about why this is so offensive

It's getting to be time to attack the real funding-drain of any and all deep space missions -- the astronomical (pun intended) fees being charged for communicating with the spacecraft.

This statement is what has offended people. The statement that DSN time was 'astronomical' and should be 'attacked'. I would like to see some numbers to establish if indeed the charges are 'astronomical' before making such a bold statement. Wouldn't you? It's quite a bold claim.

If wanting some numbers and evidence before claiming something needs to be attacked for being astronomical means I'm a fanboy - then I am a fanboy.

Let's try and make an estimation. Looking at the MER Analyst notebook - you can see MER schedules. Sol 1798B, for example.

CODE

2009-02-13T11:09:16 - Sol_1798_AM_HGA
2009-02-13T11:38:17 - Sol_1798_new_master_blip
2009-02-13T11:50:16 - r1218_DRIVE_DRIVE_FOR_TIME_sol_1798_Drive

The HGA starts at 11:09 - and including beep, it must be finished by 11:50. The same pattern is on all sols I can found where uplink was done. Let's round up to an hour.

1hr DSN pass + 45min setup and 15min setdown (that's a req in the docs) is 2 hrs of DSN time. Twice a day. 4 hrs per day.

AF = $1057 * ( 1 * (0.9 + 14/10) ) =, I think, $2431 / hr.

So - I get about $3.55M / year.

I'm not even accounting for the fact that the DSN can now operate multiple spacecraft from one dish at the same time - thus the costs can be shared across multiple missions in some way. Furthermore, for some significant swathes of MER ops - they don't uplink daily - especially during very low power periods. But let's ignore that - and stick with the $3.55M / year.

If the figure I've heard of around $20M/year for MER ops is true - then about 17% of MER costs would be required for 1 x 1hr uplink, per rover, per day.

The costing of downlink is going to be far more complex as it's tied in to Odyssey DSN fees. When Dan and I were at the DSN - it was the 70m dish that was Mars pointed (which costs 4x as much ). BUT - a 15 min UHF pass might generate 30-60 mins of MODY downlink budget. So perhaps it's fair to basically double that $3.55M / year figure for the MER share of downlink as a ballpark estimation. That basically comes out to DSN being 1/3rd of the alleged MER budget at, what I would classify, a worst case rough estimation.

Now - is that astronomical - does it need attacking? I don't think so.

Hands up if you do.