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MAX-C/ExoMars, Dual NASA/ESA rovers slated for 2018 launch
briv1016
post Mar 18 2010, 08:25 AM
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In case anyone doesn't know the 22nd MEPAG meeting is going on March 17th and 18th.

On the presentations posted for the first day there is one titled "Mars Sample Return (three element architecture)." 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 specifications for the Atlas 5 launch vehicle 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

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Astro0
post Mar 18 2010, 09:01 AM
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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
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briv1016
post Mar 18 2010, 09:32 AM
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I'm not seeing where you're getting this 5.1816m figure from.
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Astro0
post Mar 18 2010, 10:06 AM
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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.
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briv1016
post Mar 18 2010, 10:19 AM
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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.
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Astro0
post Mar 18 2010, 11:02 AM
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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.
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briv1016
post Mar 18 2010, 11:26 AM
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Here's the source.

http://www.ulalaunch.com/site/pages/Products_AtlasV.shtml
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djellison
post Mar 18 2010, 11:44 AM
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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.
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abbath
post Mar 22 2010, 09:51 AM
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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.
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djellison
post Mar 22 2010, 11:10 AM
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Direct from the SpaceX Falcon 9 website
"Custom fairings are available at incremental cost."
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peter59
post Mar 8 2011, 06:44 PM
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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-t...ons/#more-83813


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http://members.tripod.com/petermasek/marinerall.html
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ugordan
post Mar 8 2011, 06:49 PM
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Why? It's not like it's going to be driving 100 km/h to exert some serious structural loads on those petals.


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djellison
post Mar 8 2011, 08:52 PM
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QUOTE (peter59 @ Mar 8 2011, 10:44 AM) *
. I do not think that something like this was possible and sensible to realization.

Why not?
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peter59
post Mar 9 2011, 07:19 AM
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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.


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Explorer1
post Mar 9 2011, 07:54 AM
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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.
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