In case anyone doesn't know the http://mepag.jpl.nasa.gov/meeting/mar-10/index.html is going on March 17th and 18th.
On the presentations posted for the first day there is one titled "http://mepag.jpl.nasa.gov/meeting/mar-10/Li2-MSR_Dis-for-MEPAG3-17_tech_updates.pdf" On the 5th slide it states that during to the "Team X" study, the aeroshell was increased in diameter from 4.5m to 4.7m in order to accommodate both MAX-C and ExoMars together. I took a look at the http://www.ulalaunch.com/site/docs/launch_vehicles/AVUG_Rev11_March2010.pdf and found on page 6-4 and 6-21 that the maximum diameter of the payload bay was 4.572m.
Is it possible to fit a 4.7m aeroshell in a 4.572m payload bay? I know this mission is still in the early planning stage and that these numbers should be taken with a huge grain of salt; but this looks like a pretty big oversight.
A brief Google search found this http://www.spacelaunchreport.com/atlas5.html
Atlas V 500 series has a 5.4metre diameter fairing and I think a 5.1816metre internal diameter.
Sounds like there's some room to move.
Pretty sure that the team would check these numbers.
I'm not seeing where you're getting this 5.1816m figure from.
Sorry briv, there are a few other references that I was looking at while searching online.
One reference noted that the payload size on an Atlas V 500 5.4m PLF can be 17 feet dia (5.1816m)
Reading further in the reference that you provided 6.1.2 notes that the PLF is designed to provide a 25mm space between payload and fairing.
On a 5.4m shroud that leaves 4.9m for the payload diameter.
In Section 6 (6.1) there's also a reference to them being able to create 'customer unique requirement' fairings and that PLFs up to 7.2m have been considered.
On the standard Atlas V 500 configuration, you're certainly right about the 4.572m diameter payload bay, but they seem to be able to accommodate a wider range of options.
Will first off, I think the 25mm is from the inner-wall of the fairing instead of the outer-wall. Even then you subtracted 500mm from 5.4m instead of 50mm.
Anyway, I guess there going with a custom fairing. Thanks for the clarification.
Thanks for the reference to that Atlas V document. Makes for some interesting reading.
I'd say that we can have confidence they will work out PLF vs Payload and make it work.
One thing I find interesting in that document is the mix of use of inches, feet, millimetres and metres (meters).
Obviously doesn't help when trying to work out what fits into what when they mix and round off so often on their quoted figures.
I guess that as this is a document cleared for the public, the detailed specs provided to customers might be a bit more specific.
Here's the source.
http://www.ulalaunch.com/site/pages/Products_AtlasV.shtml
Note this phrase
" launched on Atlas V 531 class vehicle."
CLASS vehicle.
There are flavours of Atlas V or Delta IV or even the Falcon 9H that could outperform a 531, and thus match its performance given the penalty of a larger custom fairing.
This is a non issue.
Full inline quote removed - ADMIN
Falcon 9 (as falcon 9h) has a fairing diameter of 5.2m, and an iternal diameter of 4.6 (http://www.spacex.com/Falcon9UsersGuide_2009.pdf pag.30), even less than a standard Atlas 5.4m fairing.
I don't know if Falcon 9 is able to support a custom-made payload fairing.
Direct from the SpaceX Falcon 9 website
"Custom fairings are available at incremental cost."
Maybe I'm an incurable skeptic, but this MAX-C rover seems a little too weird. I do not think that something like this was possible and sensible to realization. This type of solar panels seems to be ideal for stationary landers.
http://www.universetoday.com/83813/where-to-next-decadal-survey-prioritizes-future-planetary-missions/#more-83813
Why? It's not like it's going to be driving 100 km/h to exert some serious structural loads on those petals.
Firstly, I can not imagine riding in a very rocky terrain. Secondly, in the case of strong wind (dust devils, dust storms) forces acting on the panels will be huge and can easily destroy them. I remember how Phoenix's panels flapped. It's really a strange hybrid of MER and Phoenix.
Isn't the martian atmosphere of such low density that not even the strongest storms will move anything more substantial than dust? I recall that's the same reason why gliders aren't feasible for exploration.
I can't help thinking that a panel which can flap a bit would be a positive benefit on a solar-powered rover in a dusty environment.
Another nice advantage is the additional space on the deck when you have the solar panels out of the way, and also less shadows on the panel from objects on the deck.
Although panels as large as shown would probably dictate some special rules for tilt, otherwise they might hit the ground.
Edited the topic title to be more general.
Those are ridiculous examples John. Doug's point wasn't that engineers don't make errors. His point was that engineers designing a Mars Rover would not be so stupid as to design one where the solar panels were so faulty as to fail under known and foreseeable conditions, which is what Peter was implying:
Is it conceivable that MAX-C could land at, MSL's "outstanding samples" site ?
Wikipedia mentions something about that being a possibility. Take that for what it's worth.
Based on Jim Green's presentation to the PSS, MAX-C and ExoMars will be combined into one rover. Still will use skycrane for descent and landing, still will cache samples for return and the goal is to drill below the surface.
FWIW, issue 145 (Feb 2011),page 81 of ESA Bulletin has the following to say about ExoMars:
"NASA/JPL announced an architecture review for the 2018 mission that will consider two main approaches. One approach is to land two Rovers individually mounted on a platform...The other approach being considered by JPL is a single Rover landing with separation into two vehicles after landing. This architecture maximises the use of the NASA/JPL Mars Science Laboratory designs...but may require ESA to adapt significantly to the new approach."
I'm having a hard time visualizing how one rover can separate into two. If it's two rovers, isn't it essentially the same approach both ways?
Not from the perspective of systems interfacing. I'd call this significantly more complex than having two independent rovers on the same landing system; you've added a whole extra level of interfacing if you had two landers that were supposed to separate post landing. (Of course, we're reading into a top-level report; no idea what the detailed concepts--if there are any at this point--may have in mind.)
EDIT: Upon a bit more consideration, I think that defining the requirements of each rover is of paramount importance. If you want two rovers with essentially identical capabilites, then "twinning" them would make more sense. However, if you want two vehicles with complemetary (and different) capabilities, then you're just adding a lot of risk via the twinning approach.
But again, we don't know what's going on here very well in terms of mission concept. If one of them is minimally capable and is designed solely to be a paparazzi in order to document the science payload's adventures, then it's a lot less difficult.
NASA's contribution to this is $1.2B plus launch vehicle according to Jim Green. I hope this "one rover splitting into two" was a pre-Decadal idea, because it sounds awfully complicated, compex and expensive. Based on the budget reality and the experience with massive cost overrruns with MSL, I don't think the powers that be won't be as accommodating to cost overrruns and we could end up without a mission completely.
$1.2 B sounds like New Frontiers 5 instead of a Flagship Mission.
Edit: NF-6, not NF-5.
This is going a little off topic so I apologize.
What I meant was that none of the Flagship missions coming out of the decadal come anywhere close to $1.2B. (The least expensive being the Enceladus Orbiter at $1.9B.) I think it's more likely that they'll choose a fifth New Frontiers mission instead, with any leftovers being folded into other missions or the DSN. I really hope I'm wrong.
(Keep in mind that the mission costs from the decadal are only CATE studies, not final mission costs.)
Edit: NF-6 not NF-5.
I think I might have gotten lost in all the numbers. Let me know where I went wrong.
There was an original mission concept study that was presented to the decadal that estimated the NASA share of the total cost to be $2.2B. The decadal committee had a CATE study done that estimated the NASA share of the costs to be $3.5B. This was deemed too large a portion of the total budget so they performed second “descoped” CATE study where they joined the two rovers together and came up with a NASA cost of $2.4B. Now there saying that NASA’s contribution will only be about $1.2B.
It ultimately comes down to what they estimated the ESA costs to be in all these studies. Considering this was a joint mission from the beginning we can assume that it was not zero.
I think pages 9-14 through 9-16 of the decadal cover most of these points. I'm still not positive about the cost estimated on there decoped MAX-C. It's clear that a new feasibility study needs to be done. (Which I'm sure there doing as we speak.)
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