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Unmanned Spaceflight.com _ Past and Future _ MAX-C/ExoMars

Posted by: briv1016 Mar 18 2010, 08:25 AM

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. huh.gif


Posted by: Astro0 Mar 18 2010, 09:01 AM

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. wink.gif

Posted by: briv1016 Mar 18 2010, 09:32 AM

I'm not seeing where you're getting this 5.1816m figure from.

Posted by: Astro0 Mar 18 2010, 10:06 AM

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.

Posted by: briv1016 Mar 18 2010, 10:19 AM

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.

Posted by: Astro0 Mar 18 2010, 11:02 AM

Thanks for the reference to that Atlas V document. Makes for some interesting reading. smile.gif
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.

Posted by: briv1016 Mar 18 2010, 11:26 AM

Here's the source.

http://www.ulalaunch.com/site/pages/Products_AtlasV.shtml

Posted by: djellison Mar 18 2010, 11:44 AM

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.

Posted by: abbath Mar 22 2010, 09:51 AM

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.

Posted by: djellison Mar 22 2010, 11:10 AM

Direct from the SpaceX Falcon 9 website
"Custom fairings are available at incremental cost."

Posted by: peter59 Mar 8 2011, 06:44 PM

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

Posted by: ugordan Mar 8 2011, 06:49 PM

Why? It's not like it's going to be driving 100 km/h to exert some serious structural loads on those petals.

Posted by: djellison Mar 8 2011, 08:52 PM

QUOTE (peter59 @ Mar 8 2011, 10:44 AM) *
. I do not think that something like this was possible and sensible to realization.

Why not?

Posted by: peter59 Mar 9 2011, 07:19 AM

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.

Posted by: Explorer1 Mar 9 2011, 07:54 AM

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.

Posted by: peter59 Mar 9 2011, 08:05 AM

QUOTE (Explorer1 @ Mar 9 2011, 08:54 AM) *
Isn't the martian atmosphere of such low density that not even the strongest storms will move anything more substantial than dust?

The answer is in this picture.

Posted by: AndyG Mar 9 2011, 10:47 AM

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.

Posted by: djellison Mar 9 2011, 01:28 PM

QUOTE (peter59 @ Mar 9 2011, 12:05 AM) *
The answer is in this picture.


And did the arrays get blown off, did they drop of, was it actually a problem?

No.

Your concern is totally and utterly unwarranted, and the inference that engineers would be so dumb as to build solar panels that would be 'totally destroyed' by a dust storm is frankly, insulting.

Have you forgotten just how thin the Martian atmosphere is?

Posted by: hendric Mar 9 2011, 11:06 PM

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.

Posted by: ElkGroveDan Mar 9 2011, 11:37 PM

QUOTE (peter59 @ Mar 9 2011, 12:05 AM) *
The answer is in this picture.

The wings on a 747 do that.

Posted by: elakdawalla Mar 9 2011, 11:39 PM

Edited the topic title to be more general.

Posted by: JohnVV Mar 10 2011, 12:50 AM

QUOTE
and the inference that engineers would be so

well things have been known to happen .Just look at the "Tacoma narrows bridge "
or the first passenger jet the de Havilland "Comet " the pressuring and square windows caused metal fatigue - the whole top of the aircraft came off IN FLIGHT
or the Apollo #1 fire
the issue of 100% o2 at sea level pressure was a known problem but....
so things do happen

Posted by: ElkGroveDan Mar 10 2011, 01:57 AM

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:

QUOTE (peter59 @ Mar 8 2011, 11:19 PM) *
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.

It's not as if people sit around a bar dreaming these things up and sketching out the final blueprints on a cocktail napkin, or for that matter by chatting with their keyboards on a discussion forum. There are extensive and rigorous years-long planning stages, drafting, simulations, testing, and more and more and more testing involving hundreds of people's expertise and input along the way. In fact far more eventualities and potentially destructive factors are taken into account than most of us ever imagine. The fragile craft Peter is imagining wouldn't make it past the first round of launch vibration tests.

Posted by: eoincampbell Mar 10 2011, 04:00 AM

Is it conceivable that MAX-C could land at, MSL's "outstanding samples" site ?

Posted by: Hungry4info Mar 10 2011, 07:29 AM

Wikipedia mentions something about that being a possibility. Take that for what it's worth.

Posted by: Drkskywxlt Apr 20 2011, 04:30 PM

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.

Posted by: monitorlizard Apr 21 2011, 02:55 AM

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?

Posted by: nprev Apr 21 2011, 03:08 AM

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.

Posted by: Paolo Apr 21 2011, 05:24 AM

QUOTE (Drkskywxlt @ Apr 20 2011, 06:30 PM) *
the goal is to drill below the surface.


I find it rather funny that the drill will be a derivative of the Italian DeeDrill that was under study for the Mars Surveyor 2003 sample return. I worked on that for my thesis in 1999, and it now seems that it will eventually fly... in 2018!

Posted by: Drkskywxlt Apr 21 2011, 10:59 AM

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.

Posted by: briv1016 Apr 22 2011, 09:16 AM

$1.2 B sounds like New Frontiers 5 instead of a Flagship Mission. sad.gif

Edit: NF-6, not NF-5.

Posted by: vjkane Apr 22 2011, 01:53 PM

QUOTE (briv1016 @ Apr 22 2011, 01:16 AM) *
$1.2 B sounds like New Frontiers 5 instead of a Flagship Mission. sad.gif

ESA would invest another ~$1.2B plus NASA would pay for the launch worth perhaps $2-300M. Together that's more than $2.5B, at a New Frontiers investment level for each space agency.

Posted by: djellison Apr 22 2011, 03:14 PM

QUOTE (briv1016 @ Apr 22 2011, 01:16 AM) *
$1.2 B sounds like New Frontiers 5 instead of a Flagship Mission. sad.gif


Nope - NF is <$1B + LV.

This is nearly half a discovery mission more than that.

Moreover, the budget is essentially none existant to think about spending significantly more than that.

Posted by: briv1016 Apr 22 2011, 07:11 PM

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.

Posted by: djellison Apr 22 2011, 09:53 PM

QUOTE (briv1016 @ Apr 22 2011, 11:11 AM) *
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.


That's because the none of the mission were proposed that could do that, moreover, the Decadal survey was done with a budget in mind that is now clearly not going to be available. Plus - that's the NASA part of the project budget... the total expenditure would still be very very firmly in the $2B+ range.

Thus take the Max-C architecture and split it between US and ESA and it becomes affordable and the logical next mission going on the recommendations of the Decadal.

This new idea essentially gets both NASA and ESA a large stake in a flagship mission, and little more than New Frontiers costs to each.

Posted by: briv1016 Apr 23 2011, 02:19 AM

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.

Posted by: djellison Apr 23 2011, 03:11 AM

QUOTE (briv1016 @ Apr 22 2011, 06:19 PM) *
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.


I think you went wrong right away - none of the decadal plans had a shared cost plan involved. They didn't infer or assume any ESA involvement at all.

QUOTE
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.


I don't think that happened either.

QUOTE
Now there saying that NASA’s contribution will only be about $1.2B.


By removing the NASA rover entirely.

QUOTE
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.


It was zero. The decadal could not estimate, guesstimate, assume or infer an ESA contribution. In every mission it was 'how much would it cost US to do all of this'

The only odd-ball was JEO which didn't need to worry about JGO. They're independent.

Posted by: briv1016 Apr 23 2011, 09:50 AM

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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