[X] My Assistant

[djellison]

http://www.nasa.gov/home/hqnews/2008/dec/H...MSL_Update.html

From the wording of this announcement, MSL is clearly still on, which is a good thing. We'll have to wait and see.

Doug

[Stu]

I know a lot of people involved with MSL lurk here, so our thoughts and best wishes go out to you guys during this difficult period of uncertainty and speculation, etc. It must be a million times harder for you than for us. We're with you, ok?

[SFJCody]

Might be a delay announcement

[djellison]

Might be a delay announcement

That's what I'm expecting. A quote I have on one slide on my "Cosmic Casualty" talk simply states

"Delay is preferable to error" - Thomas Jefferson

Doug

[centsworth_II]

I guess they can report on whether the actuators needed by the end of November to keep on track for a 2009 launch got there.

[mars loon]

It does sound more like a delay

especially in light of other recent official NASA comments, the naming contest, the landing site selection and this NASA MSL posting from Dec 1
http://mars.jpl.nasa.gov/msl/spotlight/20081201.html

This will be a great science mission when it launches. given the complexities, better to complete the testing and prudently delay as warrented

my best wishes to the team

ken

[Stu]

Anyone here who wants to watch the briefing but hasn't got a link to a good NASA TV site, here you go...

http://cosmos.bcst.yahoo.com/up/nasa/index.html

That's the one I use most.

[dvandorn]

And it's official -- launch delay to 2011, primarily due to the delay in actuator delivery.

-the other Doug

[MahFL]

NO !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[dvandorn]

I understand the feeling.

In addition, there is a prospective cost of about $400 million generated simply by the delay. That cost will be absorbed first by the Mars program and after that, if necessary, by the rest of the planetary program.

-the other Doug

[Stu]

Disappointing, I know, but much, much better to delay the launch and have all the problems sorted out than to have a "mad dash to launch" and send something to Mars that's not ready. This is a flagship mission, remember; if it crashed and burned it would crucify the Mars exploration program, especially in the current financial climate.

Teeth-gnashing news for us, but very hard on the people actually involved in MSL, many of whom are lurking here, or drop in on us now and again, so I hope others here will join with me in sending them support and best wishes. We'll get there, just not as soon as we wished.

[dvandorn]

Charles Elachi -- "It doesn't matter if you're one day short, or one week short, or one month short, you have to wait 26 months."

-the other Doug

[mcaplinger]

...very hard on the people actually involved in MSL...

To an extent, obviously, but at least I won't be sitting in our clean room doing calibration on Christmas as previously planned.

[dvandorn]

You sure, Mike? Griffin says that the coast thermal vac tests are going ahead on their current schedule. I'm assuming the calibrations would be part of that series of tests.

-the other Doug

[elakdawalla]

The 2011 launch window is in December, right? Does anybody know if it stretches into 2012?

--Emily

[dvandorn]

And for those of you who are hoping that your pet instrument might now be added onto MSL, per Doug McCuistion, "Is this an opportunity to update the payload? No." There will be no re-scoping or changes to the payload that aren't driven by engineering concerns that arise out of continued testing. In other words, no changes to the science payload.

On the other hand, Ed Weiler says that this delay is the perfect opportunity (albeit for the wrong reasons) to begin to design the architecture for MSR, Mars Sample Return.

-the other Doug

[dvandorn]

When asked why it's so important to have the actuators at this point for an '09 launch, McCuistion says "The actuators do everything we do on Mars. They turn the wheels, they stop the wheels, they move the robotic arm. If we get to Mars and we can't move, we can't move the arm, we can't take samples, we just have about a metric ton of junk on the Martian surface."

And someone just asked about the 2011 launch window -- McCuistion says the window extends from October through December, with highest likelihood of late October through early November. Sounds like it won't extend into 2012.

-the other Doug

[djellison]

2011 window is October to December - yet to be determined where in that window.

Doug

[elakdawalla]

My question was answered. 2011 goes from Oct through December potentially; most likely is late october to early november.

--Emily

[mcaplinger]

Griffin says that the coast thermal vac tests are going ahead on their current schedule.

Give me credit for knowing a little more about my instruments than Griffin.

In general, cruise T/V doesn't involve the surface payload.

[dvandorn]

OK, Mike -- thanks. I just figured that since the cruise thermal vac was including the entire stack, with the assembled rover inside the aeroshell, that anything you'd be doing to calibrate the instruments on it would be involved with the T/V. Thanks for the correction.

-the other Doug

[elakdawalla]

Dammit, they didn't get to me on the phone questions. These guys are too long-winded.

I got one in but not my other one, which was: When MSL arrives, MRO will have been in orbit for 6 years and no future telecom orbiter is planned. Isn't there risk in assuming MRO will survive for long enough to support MSL communications?

[dvandorn]

Spoke too soon, there, eh, Emily? Good to hear your voice!

-the other Doug

[djellison]

Damn good question Emily.

[dvandorn]

Also good to hear that the decay of the plutonium in the RTG will have an insignificant impact, and that they may well wait a while before fueling the MMRTG.

-the other Doug

[elakdawalla]

Is 5% insignificant, given the fact that the traverses were already going to be power-limited?

[ElkGroveDan]

I've been wondering that too Emily.

I just checked in, can anyone give me the short answer?

EDIT: (or blog about it later today )

[elakdawalla]

OK, and here's one more question that I wouldn't have gotten a straight answer to anyway. Can anybody here think of what planetary missions there are that would have big budgets in 2010 and 2011 for MSL to raid? The only one I can think of is Juno.

--Emily

[ugordan]

Can anybody here think of what planetary missions there are that would have big budgets in 2010 and 2011 for MSL to raid?

I really hope it doesn't get to that.

[sci44]

Wasn't there talk of Maven being delayed? Another question - will they need a bigger launch vehicle for 2011? I have an idea 2009 was a low energy trajectory year..

[jsheff]

OK, and here's one more question that I wouldn't have gotten a straight answer to anyway. Can anybody here think of what planetary missions there are that would have big budgets in 2010 and 2011 for MSL to raid? The only one I can think of is Juno.

--Emily

Outer Planets Flagship?

James Webb Space Telescope?

(I don't know what the funding profiles are like for either one.)



- John Sheff
Cambridge, MA

[RoverDriver]

Is 5% insignificant, given the fact that the traverses were already going to be power-limited?

What I heard is that the limitation on drives is due mostly to battery capacity, not overall energy availability.

Paolo

[elakdawalla]

Ah, I hadn't realized that. Thanks. --Emily

[ugordan]

Outer Planets Flagship?

Is the next flagship scheduled to receive any significant funding that early?

[stevesliva]

OK, and here's one more question that I wouldn't have gotten a straight answer to anyway. Can anybody here think of what planetary missions there are that would have big budgets in 2010 and 2011 for MSL to raid? The only one I can think of is Juno.

Mars missions that won't happen, no?

[elakdawalla]

The only other Mars mission NASA is currently developing is MAVEN, and that doesn't launch until 2013, so I would assume it doesn't start costing a ton of money until 2012 and 2013.

And I think the question about the flagship mission has already been asked and answered by somebody official, and you're right, ugordan, there's not a lot of money for it in 2010 and 2011. I don't think.

--Emily

[djellison]

Key point I got was that the $400m is not in addition to the $200m to finish in 09 - but it's instead of it. And instead of being $200M to find in FY09 - it's $400m to find over FY09,10,11,12,13 and 14 (if I heard Doug right) - so a much easier thing to manage.

Taking the $1.65B (the '06 figure when the mission was confirmed) +25% over-spend that was required for an '09 launch - (2.1B) - the mission will actually be $2.3 - 43% over - not great, but not totally un-known in this field. All things considered, appropriate for the flagship mission that it is (in everything but name)

MSL was NEVER a $600m mission. Smart Lander was - but Smart Lander isn't happening, MSL is. Lots of miss-information out there.

[ugordan]

Key point I got was that the $400m is not in addition to the $200m to finish in 09 - but it's instead of it. And instead of being $200M to find in FY09 - it's $400m to find over FY09,10,11,12,13 and 14 (if I heard Doug right) - so a much easier thing to manage.

Still, that's money that has to be found somewhere. Regarding MAVEN, when is its launch vehicle supposed to be selected? I'm assuming it'll be an Atlas V and if I remember correctly, it's a 30 month period between vehicle order and launch. That's bound to cost some chunk of cash. At which point in time is the vehicle actually paid for?

[mcaplinger]

MSL was NEVER a $600m mission. Smart Lander was - but Smart Lander isn't happening, MSL is. Lots of miss-information out there.

Thanks for pointing that out, Doug. It's gotten to the point that there are some sites (I think you know which one I mean speciifically) that I can't look at any more because of an overfocus on the Decadal Survey cost, which has almost nothing to do with the mission that NASA HQ ultimately selected for funding.

[Guest_Enceladus75_*]

It's somewhat disappointing to see that MSL has been delayed to a 2011 launch, but the upside is that there will be more time for testing of critical elements like the actuators which are critical and the all important skycrane which is a brand new technology.

It is better in my opinion for MSL to have a delay and a flawless flight/landing/surface operations than a rushed job resulting perhaps in at best a faulty rover that can't do good science on Mars and at worst a failed landing attempt and the consequences of that disaster. Beagle 2 and Mars Polar Lander paid the price of corner cutting and a big rush to launch.

That said, Emily's question regarding the riskiness of relying on MRO to support data downlink from MSL is very important. Might there now be a need to launch a dedicated Mars telecoms orbiter to support the surface missions , a plan that was scrapped a while back?

[mcaplinger]

Might there now be a need to launch a dedicated Mars telecoms orbiter to support the surface missions...

Need or not, there's no money for such a thing.

I guess if Odyssey and MRO (and MEx?, not sure about the politics there) have failed by the time MSL lands, then MSL will be DTE-only.

Would they launch MSL if all the orbital assets were failed at the time of launch? I have no idea.

[sci44]

It doesnt sound like NASA has funds for the Telecoms orbiter now. On another thread here someone calculated that MRO/MO have plenty of time left (decades), just based on mono-propellant usage - providing the rest of the craft holds out. If they did decide to do something maybe they should speak to the ESA, who will need an orbiter there for ExoMars in 2016 (Send it with Beagle-3 :-) ). MSL will have a direct to earth comms too, although that would be expensive in DSN time, I guess. I was rather looking forward to Oppy still being running for MSL arrival - I wonder what the odds are now? Worst of all would be if some bright spark ressurected the "turn off a rover" idea..
Does anyone know if the launcher-power remains the same for '11?
EDIT: MEX was going to be Beagles phone-home, and ESA did ask NASA for help trying to talk to Beagle with MGS, so I would guess the ESA would gladly reciprocate. There is a Chinese orbiter going with Phobos-Grunt too - now *that* would be tricky politics.. :-)

[djellison]

A failure of MODY, MRO AND MEX in 4 years? Highly unlikely.

[elakdawalla]

Yeah, I've little doubt that, barring some really really bone-headed error, MRO will be around when MSL lands. But MSL's prime mission is two years long. It could last a long, long time beyond that. It's those "out" years that I'm more worried about.

--Emily

[djellison]

By then, hopefully, we'll have Maven

[sci44]

But we may need to delay Maven to pay for MSL. There's a hole in my bucket, dear Liza.. :-)

(Edit: There's a hole in my Budget, dear Liza..)

[mcaplinger]

ESA did ask NASA for help trying to talk to Beagle with MGS, so I would guess the ESA would gladly reciprocate.

There's a big difference between a one-off, short term activity and ongoing operations for years. I'm not sure what kind of capability MEx would even have for that given its elliptical orbit.

[djellison]

But we may need to delay Maven to pay for MSL.

THat wasn't mentioned - infact, Maven was still explicitly stated with its orig. launch date. Of course, that may change - but then, for no relay - you're asking for the failure of Mars Odyssey, Mars Express, MRO AND the failure of Maven to launch on time. That's a LOT of 'ifs'.

Doug

[mcaplinger]

Yeah, I've little doubt that, barring some really really bone-headed error, MRO will be around when MSL lands.

It should be noted that MRO had a failure in its telecom system in 2006 which rendered its X-band downlink single-string, so it is one amplifier away from losing the high-gain X-band downlink, and the Ka-band downlink is also suspect though it might be a usable backup. See "In-Flight Anomalies and Lessons Learned from the. Mars. Reconnaissance Orbiter Mission", Todd. J. Bayer, 2008 IEEE Aerospace Conference.

Of course, there's no explicit lifetime for electronics, so MRO could keep going for many years anyway.

[elakdawalla]

I just got an official reply to my question from Dwayne Brown, the PAO for SMD.

The orbiting assets that are expected to be available to support MSL operations when it arrives at Mars (on the revised schedule) include MRO, Mars Express, and Mars Odyssey. Although two years later, it is still expected that these orbiters will be in place and available for communications relay support for MSL.

Having multiple relay-capable orbiters in place allows the continuation of MSL support if one (or even two) of them should become inoperable. In the very unlikely event that all three orbiters should become unable to provide comm relay support, the MSL rover still has the ability to utilize direct-to-Earth (DTE) communications. Albeit slower, the MSL mission could be completed utilizing the DTE link only.

[OWW]

The MSL mission could be completed utilizing the DTE link only.

To me, this sounds like: "The Galileo mission could be completed utilizing the LGA link only."

[mars loon]

Overall I was encouraged by the decisions and progress announced at the press conference.

The mantra is "Failure is not an option" for this Flagship mission. The MSL team will do what it takes to be successful to the best of their ability. we cant ask for more.

These are difficult projects by design, so we attain valuable new science and technology. As they mentioned: The easy things have been done and we wont learn much by repeating that.

I was lucky to ask questions at the end. And i'm very encouraged that Ed Weiler said NASA will cooperate with ESA for future Mars missions. In response he said very likely this could include EXO MARS in a 2016 launch opportunity. The odds of a 2016 launch of something to mars have significantly increased compared to a few weeks ago

ken

[sci44]

So it sounds like they can use MEX too. I did have the idea I read (at the time) that Beagle was going to use MGS/MO for long term comms too..

To me, this sounds like: "The Galileo mission could be completed utilizing the LGA link only."

It would be rather better than that - it would be a high gain antennea, all be it direct DSN comms. The low gain on Galileo was 160 bits/sec (up from 16bits thanks to DSN), vs 134 Kbits/sec for high gain. It will be less, but not 1000 times less!

However there is a good point in there - doesn't MSL plan to generate much more data than MER? In that case having MRO there will make a big difference - the others have much more modest computing/transmission capacities..

[PaulM]

Does the two Year delay change the time of Year at which MSL would land at Southern Hemisphere landing sites?

I ask the question because I understand that if MSL had landed in 2010 at the Southern Hemisphere Eberswalde and Holden crater sites then the landing would have been in the depths of Winter and MSL might have been virtually immovable for the 6 months following the landing.

Does landing in 2012 move the time of landing in Southern sites to a more favourable season of the Year?

[mcaplinger]

[DTE data rate] will be less, but not 1000 times less!

True. Assuming it scales like MER does, DTE will only (!) be about 10-15x slower than relay (as far as I can tell, MER DTE rates are around 20Kbps maximum, while the Odyssey UHF is being run at 256K.)

[ElkGroveDan]

True. Assuming it scales like MER does, DTE will only (!) be about 10-15x slower than relay (as far as I can tell, MER DTE rates are around 20Kbps maximum, while the Odyssey UHF is being run at 256K.)

Any idea how long a typical DTE window or session is?

[djellison]

MER passes were typically 30 - 90 minutes, and MER peaked at 16.6 kbps via its HGA, so 59 Mbits/hour at that rate.

Doug

[ElkGroveDan]

True, but you had an orbiting satellite which has a relative velocity of it's own involved. I would intuitively expect that the DTE sessions would be longer.

[mcaplinger]

I would intuitively expect that the DTE sessions would be longer.

Certainly. A typical UHF pass is only 5-10 minutes long (satellite rise to set), whereas a DTE pass in theory could be for as long as the Earth was in view, less DSN station handoff. MER DTE passes are as short as they are for power and thermal reasons. DTE is much less efficient than relay on an energy/bit basis, and that's probably the big disadvantage of DTE.

[djellison]

That is DTE session.

UHF sessions with orbiters are 10-15 minutes, 128 or 256kbps, and anything from 1 to about 150 Mbits

[Guest_Bobby_*]

Oppy & Spirit will still be Trucking Along in 2012

[sci44]

Oppy & Spirit will still be Trucking Along in 2012

By that time Oppy will probably be excavating that Fossil bed on the far side of Endeavour.. :-)
This graphic illustrates why having MRO around at that time will be useful (I know its total data return, not bps, but still..) It will be interesting to find out how much more data might come back from MSL compared to the MERs..

[nprev]

Hmm. You know, if (a big if indeed, I know) the MERs are still doing their thing in 2012, can we in a worst-case scenario of being down to one relay orbiter still get max data return from three rovers?

The MERs are on opposite hemispheres, of course, but MSL's gonna be somewhere in between them. The surviving orbiter's transceiver would have to work pretty hard; does it have a duty cycle? Might be difficult to select an optimal orbital plane to maximize coverage as well.

Just curious to know if any modeling of such a contingency situation has been done.

[mcaplinger]

Can we in a worst-case scenario of being down to one relay orbiter still get max data return from three rovers?... Might be difficult to select an optimal orbital plane to maximize coverage as well.

Changing planes is expensive in delta-v and unlikely to be done unless needed to cover the MSL EDL.

Having three rovers to service given the relatively low UHF rates that MER can use shouldn't really be very stressing if MRO is the relay. The return from two MERs is lost in the noise of what we expect to get from MSL. If Odyssey were the relay, it would be more constrained, and you might see the MERs using more DTE than they do now, depending on their condition in this scenario.

[elakdawalla]

As much as I love and admire the MERs, I think having three rovers and one orbiter in 2012 is a much less likely scenario than having three orbiters and one rover.

--Emily

[nprev]

True, Emily. Playing "what-if" is a very popular & actually addictive game in space systems engineering, though...

Mike, thanks for the answer. I assume then that the limiting factor is the orbiter-Earth link bitrate, not the rover-orbiter link?

[Tesheiner]

Does the two Year delay change the time of Year at which MSL would land at Southern Hemisphere landing sites?

I ask the question because I understand that if MSL had landed in 2010 at the Southern Hemisphere Eberswalde and Holden crater sites then the landing would have been in the depths of Winter and MSL might have been virtually immovable for the 6 months following the landing.
<snip>

Don't forget that MSL is nuclear powered so seasons are not a constraint for power generation.

[monitorlizard]

If I'm interpreting Ed Weiler correctly, NASA and ESA working jointly on a 2016 ExoMars rover would not only greatly help ESA's funding problems, but would save NASA a tremendous amount of money in not sending its own Mars rover in 2016. That could really help NASA pay back money it will "borrow" from the Mars program to pay for the MSL delay.

A little aside: I'm delighted that there will now be two extra years of MRO (especially HiRISE) returning maximum science data from Mars. I didn't want it to happen this way, but you might as well be an opportunist about such things.

[mps]

Can anybody here think of what planetary missions there are that would have big budgets in 2010 and 2011 for MSL to raid? The only one I can think of is Juno.

Assuming there will be no more delays (which isn't very realistic), there will be four (sic!) planetary missions launched in 2011: LADEE, Juno, GRAIL and MSL
I'm afraid that NASA will find tempting to cancel the first one in the list - although it has a small budget (ca $100M), it's still in early phase and isn't such a sexy mission for public's eye.

[PaulM]

Don't forget that MSL is nuclear powered so seasons are not a constraint for power generation.

Have a look at the posts by Tim and Emily on the following page:

http://www.unmannedspaceflight.com/index.p...=4565&st=15

Tim's post contained the following paragraph:

"Holden and Terby came very close to not making the final list. They are both very interesting scientifically, but we were told by the engineers that because of their high southern latitudes and cold temperatures that if MSL landed at one of those sites it would have to lie dormant for the first month or so and then operate at only a 30-50% duty cycle. There was a lot of debate about whether the science that could be done at those sites outweighs those limitations. In the end it was a close vote, but both were kept on the final list."

There seemed to be real concerns a Year ago that if the Holden Crater landing site was selected then for the first month or so most of MSL's power generation would have to be used to power survival heaters.

My question is whether the Season in the Southern Hemisphere will be any different at the new MSL landing date?

[elakdawalla]

It's a good question but I don't know what the landing date would be. Hazarding a guess that it'd be midsummer 2012, you're looking at Ls around 130, which is midwinter in the southern hemisphere. That's bad for power (because MSL would have to use lots of power just to warm up motors before moving), but depending on how you look at things it might not be as bad as it would be for a 2009 launch, where it'd arrive in early winter. The 2010 landing might have better temperature conditions on the day of landing, but there'd be a long period of things not getting better after landing. The 2012 landing might have about the worst temperature conditions of the year on the day of landing, which should be steadily improving with time, so there would be a shorter period of relative inactivity following landing.

--Emily

[Doc]

3 of the landing sites currently being considered are in the southern hemisphere (Mawrth is in the north).
However should they decide to take Gale it would spare them the brunt of the southern winter when they land during the assumed Ls 130 (at -4.49 degrees)

[brellis]

Alan Stern had something to say about this today: Article

[peter59]

I would like notice that the postponement Mars Science Laboratory mission and the consequent increase costs may cause the termination of the mission Opportunity and Spirit. The consequences of this delay will be unpredictable, and Spirit and Oppy may be their first victims. I expect that shortly will begin dispute in NASA about this topic. The future does not look too good in my oppinion.
PS.
I know that I can be banned by Doug due spreading defeatism. But that's not defeatism, we must be realistic. I think that this option we should also take into account.

[dvandorn]

At the risk of continuing this divergence in the thread, I'll point out that extended mission ops are the cheapest portion of a planetary mission. The biggest costs are for the DSN time to get the data back to Earth. The remaining costs are mostly for the manpower -- the salaries and benefits of the teams working the missions. And in the case of the MERs, many of those are only working part-time on Oppy and Spirit, spending much of their time on MSL and other projects, as well. (Amortized costs of things like the computers used by the MER teams, the office space they take up, etc., are really pretty irrelevant, after all; it's not like they buy new equipment and rent new facilities for each mission extension. Those capital investments have long since been paid for and depreciated in the bookkeeping.)

Extended ops are the biggest "bang for the buck" you can get out of these things, and NASA has been pretty good about avoiding the penny-wise, pound-foolish approach of cutting $10 million from extended ops to try and make up a $400 million shortfall elsewhere. They're more likely to delay or cancel whole programs before they start racking up their major design and construction costs than they are to cut off assets already in place.

That said, there may be pressure to cut back on Spirit operations if she continues to be power-starved and barely mobile. I don't foresee a project shutdown for Spirit, but you have to admit, we're not getting a huge amount of science data from her recently. Then again, we're not spending nearly as much time (and therefore money) on her as we are on Oppy, either.

-the other Doug

[djellison]

I know that I can be banned by Doug due spreading defeatism.

You can be banned by any admin for breaking the forum rules. Being a realist isn't a crime. ANY mission in extended ops is at risk at any time. $400m over the, I think, 5 years that Doug Mc. described at the press conference, however, shouldn't lead to mission termination's. I believe Ed Weiler has gone on record saying MER wouldn't be a victim however. I can't find it - but I do remember it. MSL may change things, but I doubt it. DSN time is negligible given that downlink is almost exclusively on the back of MRO/MODY downlink anyway, and the DSN almost always has one asset mars pointed. It could be mega-cheap if they rode on the back of MRO given it's high downlink speed would mean even at MRO's lowest downlink rate, and a really good MER pass, it would take less than 4 minutes. ( 150mbits at 0.7mbps). Not sure how MER pays for relay and downlink - perhaps as a percentage of total downlink multiplied by DSN cost for the relaying spacecraft.

[dvandorn]

I just went looking for a rate table of DSN fees, and found the following item in a .pdf file ( http://deepspace.jpl.nasa.gov/advmiss/docs...MEX_AO_2007.pdf ) that describes, among other things, the services and rates for the DSN. There was no actual rate chart; there was a formula for calculating what is called the Aperture Fee:

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 FY08).
AW = aperture weighting:
= 0.80 for 34-meter High-Speed Beam Waveguide (HSB) stations.
= 1.00 for all other 34-meter stations (i.e., 34 BWG and 34 HEF).
= 4.00 for 70-meter stations.
FC = number of station contacts, (contacts per calendar week).

The weighting factor seems to be a multiplier based on a function of aperture size (34m vs. 70m) and number of weekly contacts. An accompanying chart shows the weighting factor for a 70m dish used 28 times per week (i.e., 4 times per day), for example, is 15. The same dish used 14 times a week (twice a day) has a weighting multiplier of a little more than 9. The same numbers of weekly contacts using a 34m dish give you weighting mutiplier of 9 for 28 contacts and 2.5 for 14 contacts.

So, a probe that requires four comm passes a day using a 70m dish looks like it would cost something on the order of $15,865 per hour. That's 28 times $15,865 per week, times 52 per year. That would be $444,220 per month, and $23,990,440 per year. That's based on a reading of the chart, not by plugging numbers into the above formula.

A twice-a-day contact through a 70m dish, again based on the chart, would cost $9,500 or so per comm pass, times 14 passes per week ($133,000), for an annual cost of $6,916,000.

And that all assumes that you're only paying for a single hour of DSN time per pass. In actuality, with calibration times, you're likely going to have pay for a minimum of two hours' worth per pass, possibly more (*). So you might have to double those numbers.

However you slice it up between the various data sources coming through on a MODY or MRO comm pass, total DSN costs add up to millions of dollars a year. So I still think one of the biggest chunks (if not the biggest) of mission operations, extended or otherwise, is DSN time.

-the other Doug

* -- the assumption that each comm pass lasts *at least* an hour is built into the rate structure, I think. At least it says in there: "A station contact may be any length but is defined as the lesser of the spacecraft’s view period, the scheduled pass duration plus calibration times, or 8 hours. For a standard pass, a 45-minute set-up and a 15-minute tear-down time must be added to each scheduled pass to obtain the station contact time (other calibration times apply to Beacon Monitoring and Delta-DOR passes). Note that scheduled pass-lengths should be integer multiples of 1-hour." So even if your comm pass only lasts 12 minutes, it doesn't look like you get the benefit of a pro-rate... dvd

[djellison]

So even if your comm pass only lasts 12 minutes, it doesn't look like you get the benefit of a pro-rate...

We've discussed those figures some time ago when talking about discovery missions.

You're not thinking about it properly though - Mars is somewhat unique in that it's almost always locked up with one dish or another. The comms pass will be a 7 hour downlink from MRO and MODY (some of the antennae can and do listen to multiple missions at once) A tiny chunk of that downlink will be MER's - piggybacked on a much much longer session for MODY or MRO. I don't think you can take the generic formula and apply it to MER in that simple a fashion, or indeed any Mars mission. Yes - the DSN costs for MER are not negligible. BUT - they're simply chipping in with a DSN cost that's already there anyway for other Mars missions. The total cost to the Mars Program for DSN costs if you dropped MER would not, I would have thought, drop much, if at all. There's still going to be near continuous downlink from MRO and MODY (and occasionally MEX - although New Norcia and Madrid handle that mostly now). You can't suggest they bill MER for repointing at Mars for each daily downlink when there's a dish already pointing at Mars, and already locked up on the spacecraft that going to do the relay.

Something like Cassini - yeah - take that formula and the schedules and you can find out. The Mars program is more complex than that. How the bill is split up between the missions, we don't know. MER will be paying a lot LOT less than if it were on its own at Mars (which is what your maths infers)

[dvandorn]

Oh, agreed. And obviously, according to the formula itself, the amount of time charged for each chargeable comm pass is a maximum of 8 hours per day ("the lesser of the spacecraft’s view period, the scheduled pass duration plus calibration times, or 8 hours"). MER DTE sessions would be liable for the full cost of such a comm pass, obviously, but that's a tiny fraction of the communications with the rovers. (It's hard from the information I found to tell how much of the calibration times are required for each Mars asset pass even though your dish is already pointed at Mars; I imagine some of that calibration time is necessary each time you shift from one asset to another, but again we don't have enough operational detail to tell for sure.)

The important information missing is the prorate of relay DSN costs that are passed on to the MERs. But you're absolutely right in this case -- you wouldn't be saving any of that money, since you'd be using pretty much the same amount of DSN time whether or not the MERs are reporting data through the relays. You'd have to cancel one or more of the orbiter DSN passes per day (or simply cancel the extended missions of MODY or MRO entirely) in order to save any money from the DSN side of things, and since that would, in effect, be canceling the extended missions of the orbiters *and* the rovers, I don't see that happening. That's too much loss of bang per buck saved. And I, for one, would be pretty durned uncomfortable with a decision to put one or both orbital assets into "cold storage" for several years just to save the DSN charges.

So, as you've noted, it's unlikely that NASA will cancel or curtail the extended missions of MER-A, MER-B, MODY or MRO to find the extra money needed for MSL. I think a delay of MAVEN is more likely, but it's hard to say. We really just need to see what the numbers come out like over the next several months; speculation at this point as to what might be cut or delayed isn't very useful, since we don't have enough information yet to make intelligent guesses.

-the other Doug

[ilbasso]

Maybe USMF members can all point their satellite TV dishes at Mars twice a day and form a collective DSN. Take distributed computing to the next level!!!

[RoverDriver]

Maybe USMF members can all point their satellite TV dishes at Mars twice a day and form a collective DSN. Take distributed computing to the next level!!!

Neat idea. Unfortunately most of the LNBs in typical TV satellite systems have a C/N figure that would make it extremely difficult.

Paolo

[ilbasso]

No, I didn't think this was physically possible, but wouldn't it be great if it were!

It's hard to fathom how expensive the DSN charges are - interesting analysis, oDoug. That's the tradeoff for putting lightweight/low wattage transmitters and receivers in the spacecraft. It never ceases to amaze me that we can still pick up Voyager signals from so far out in the Solar System, with only a 20-watt transmitter on the spacecraft.

[imipak]

Per "The Problem With Wikipedia" ( http://xkcd.com/214/ ) : LNBC , C/N ratio (I think?) , satellite dish, Allen Telescope Array ...as they used to say in South Park, "I've learned something today". Not sure I'll be able to recall it tomorrow though

[RoverDriver]

Suppose you are in your livingroom and want to hear the birds in the park 2mi away. It is a nice and quiet summer night big windows open, cup your hands near your ears. That's DSN.

Suppose you are in your livingroom and want to hear the same birds 2mi away. It is Thanksgiving, your grandma's hearing aid batteries are low and she is shouting at you. Your relatives try to explain to her she is shouting and start to shoult as well. The kettle in the kitchen is whistling, the door bell rings, the dog starts barking, your newborn triples start crying. That's your TV dish/LNB/reciver. The only reason your TV can receive the satellite signals is beacause the birds in the park are now using a 500KW rock concert PA system.

Paolo

[ElkGroveDan]

Perfect example Paolo! (you crack me up).

[Pando]

Paolo, you just made my day...

[Guest_Oersted_*]

2 years delay = 2 MSL´s?

I am sure they can scrounge together some engineering parts, copy the rest and book an extra place on a rocket by then...

[djellison]

2 years delay = 2 MSL´s?

No. Just no.