IPB

Welcome Guest ( Log In | Register )

5 Pages V   1 2 3 > »   
Reply to this topicStart new topic
2009 Or 2011 ?, 1 or 2 ?
Marcel
post May 3 2005, 11:11 AM
Post #1


Member
***

Group: Members
Posts: 290
Joined: 26-March 04
From: Edam, The Netherlands
Member No.: 65



Does anybody know when and how many MSL will go, or when the decision on this will be made ?
Go to the top of the page
 
+Quote Post
djellison
post May 3 2005, 11:16 AM
Post #2


Administrator
****

Group: Chairman
Posts: 13709
Joined: 8-February 04
Member No.: 1



Theisinger's said that a judgement call on Skycrane needs to be made by the end of this year - and I'd imagine the call how many, and when, will be made shortly thereafter

Doug
Go to the top of the page
 
+Quote Post
Marcel
post May 3 2005, 11:30 AM
Post #3


Member
***

Group: Members
Posts: 290
Joined: 26-March 04
From: Edam, The Netherlands
Member No.: 65



QUOTE (djellison @ May 3 2005, 11:16 AM)
Theisinger's said that a judgement call on Skycrane needs to be made by the end of this year - and I'd imagine the call how many, and when, will be made shortly thereafter

Doug
*


Ah, but how are they going to decide on the skycrane, when there's no new experimental data on the subject ? I suppose there are no tests scheduled before the end of the year.....
Go to the top of the page
 
+Quote Post
djellison
post May 3 2005, 11:55 AM
Post #4


Administrator
****

Group: Chairman
Posts: 13709
Joined: 8-February 04
Member No.: 1



There's some testing happening this year on the skycrane idea I believe - there was a swathe of documents in JPLs aquisition website for a rig to simulate skycrane ops (although to be honest it doesnt appear to simulate anything even slightly complex which couldnt be done quicker and cheaper in a virtual simulation)

Doug
Go to the top of the page
 
+Quote Post
Guest_BruceMoomaw_*
post May 3 2005, 07:17 PM
Post #5





Guests






They're definitely going to run the ground tests this summer -- and I regard them as necessary, given the number of subtle aspects of this gadget (twisting, whiplash in the lines, etc.) which would be hard to simulate precisely in a virtual simulation. (Remember that Mariner 10 was almost ruined by a resonant flexing of its magnetometer boom that kept making it do the hula uncontrollably -- and which wasn't picked up on the ground because it existed only in 0-G. That's how subtle material interactions can be in spacecraft dynamics.)
Go to the top of the page
 
+Quote Post
Marcel
post May 4 2005, 06:48 AM
Post #6


Member
***

Group: Members
Posts: 290
Joined: 26-March 04
From: Edam, The Netherlands
Member No.: 65



QUOTE (BruceMoomaw @ May 3 2005, 07:17 PM)
They're definitely going to run the ground tests this summer -- and I regard them as necessary, given the number of subtle aspects of this gadget (twisting, whiplash in the lines, etc.) which would be hard to simulate precisely in a virtual simulation.  (Remember that Mariner 10 was almost ruined by a resonant flexing of its magnetometer boom that kept making it do the hula uncontrollably -- and which wasn't picked up on the ground because it existed only in 0-G.  That's how subtle material interactions can be in spacecraft dynamics.)
*

Why don't they use semi flexible booms, (say 3 or 4, to prevent twisting)extendable from the crane down, like telescopic fishing rods ? It will definately damp out unwanted movement of the rover with respect to the crane during the critical (final) stage before landing. I don't mean rigid, i don't mean rope like.....something in between.
Go to the top of the page
 
+Quote Post
edstrick
post May 4 2005, 09:58 AM
Post #7


Senior Member
****

Group: Members
Posts: 1869
Joined: 20-February 05
Member No.: 174



Regarding the number of MSL missions that should fly.. they SHOULD fly 3. Build them at 2 year intervals. Fly #1 in '09, #2 in '11 and #3 in '13.

There is a precedence for this. Pioneer Jupiter missions were launched 13 months <1 jupiter launch window interval> apart.

If #1 blows it, like polar lander did, you can fix the booboo and fly #2. Engineernig tweeks and upgrades can be applied to #2 based on #1's early performance. #3 could have significantly upgraded or modified science payload. Each mission can be targetd based on science results of previous missions and orbital surveying done in the meantime.
Go to the top of the page
 
+Quote Post
djellison
post May 4 2005, 11:33 AM
Post #8


Administrator
****

Group: Chairman
Posts: 13709
Joined: 8-February 04
Member No.: 1



#3 is the only one that could derive engineering changes from #1.

You have 26 months from launch-to-launch

Call 8 months of that the cruise (sometimes more, sometimes less) - so you have 18 months.

The MER's spent about 6 months at KSC being checked out, bolted together and stock on a firework. - Giving you 12 months to define, design, build, test, rebuild, retest, integrate, and re-test at system level any changes you want - and then re-test at a system level to ensure your changes dont impinge on any other part of the spacecraft.

The only changes I could imagine being feasable are software or instruments.

Doug
Go to the top of the page
 
+Quote Post
Marcel
post May 4 2005, 01:08 PM
Post #9


Member
***

Group: Members
Posts: 290
Joined: 26-March 04
From: Edam, The Netherlands
Member No.: 65



QUOTE (djellison @ May 4 2005, 11:33 AM)
The only changes I could imagine being feasable are software or instruments.

*


And these changes can be important ones !

I agree though about the timeline and i still feel like i want to see 2 rovers leave in the same window. Make 2 other ones in the next window. Since the breathtaking succes of these two MER's, sending two should be the standard.

Not only because of the bigger chance of at least one succesfull mission,

not only because of the fact that you get the science of two locations if both succeed, but

also because if you start building these kind of machines, you might as well built another one (it's cheaper).

A dutch saying says: "on one leg you can't walk" (if someone asks you if you want a second beer). So yes, I want another one !!
Go to the top of the page
 
+Quote Post
tedstryk
post May 4 2005, 01:36 PM
Post #10


Interplanetary Dumpster Diver
****

Group: Moderator
Posts: 4200
Joined: 17-February 04
From: Powell, TN
Member No.: 33



QUOTE (Marcel @ May 4 2005, 01:08 PM)
QUOTE (djellison @ May 4 2005, 11:33 AM)
The only changes I could imagine being feasable are software or instruments.

*


And these changes can be important ones !

I agree though about the timeline and i still feel like i want to see 2 rovers leave in the same window. Make 2 other ones in the next window. Since the breathtaking succes of these two MER's, sending two should be the standard.

Not only because of the bigger chance of at least one succesfull mission,

not only because of the fact that you get the science of two locations if both succeed, but

also because if you start building these kind of machines, you might as well built another one (it's cheaper).

A dutch saying says: "on one leg you can't walk" (if someone asks you if you want a second beer). So yes, I want another one !!
*



I would think that, using Skycrane, it is a good idea to sent one in 2009, and make sure it sends engineering data all the way down, so if something goes wrong, we have an idea what went wrong. Then, begin sending them two by two in 2011, taking in to account the results in 2009. Granted, if it were a severe problem it couldn't be fixed that quickly, but at least the 2011 MSLs would not have launched yet, so they could be fixed and sent in 2013. I think that unless a safer landing technique is found, this is the way to go.


--------------------
Go to the top of the page
 
+Quote Post
Guest_BruceMoomaw_*
post May 4 2005, 07:57 PM
Post #11





Guests






[quote=Marcel,May 4 2005, 06:48 AM]
[[/quote]
Why don't they use semi flexible booms, (say 3 or 4, to prevent twisting)extendable from the crane down, like telescopic fishing rods ? It will definately damp out unwanted movement of the rover with respect to the crane during the critical (final) stage before landing. I don't mean rigid, i don't mean rope like.....something in between.
*

[/quote]
___________________________

No. That kind of semi-flexibility would be extremely difficult to program the descent rocket autopilot to compensate for, even after extensive ground testing. That, after all, is precisely how we got those self-reinforcing resonances in the Mariner 10 magnetometer boom, and the problem in this case would be far worse.

Now, I myself did seriously consider the possibility of a COMPLETELY rigid attachment between the rover and the descent stge, or at least as rigid as we could make it -- using either a pyramid of 3 or 4 cables fastened from the corners of the lander to the corners of the rover, or else a lightweight telescoping metal boom made out of a flat metal strip that curled its edges into a tube as soon as it was unrolled from the descent stage (a technique that's often used for spacecraft booms, including the sampling arm on the Vikings). I thought that this, by eliminating any swinging or twisting by the rover as it's being lowered, would simplify the problem -- but Nick Hoffman heaped scorn and wrath on my head, and then MSL engineer Pete Theisinger himself confirmed at the Mars Roadmap meeting that it causes more trouble than it solves. Such a rigid linkage makes the descent stage itself tilt back and forth, and apparently the control difficulties of cancelling this out with its descent engines are actually harder than having the descent stage keep itself hovering stable while lowering the rover on a loose cable (or, in reality, 3 cables fastened to corners of the rover but converging at a single point on the descent stage to allow swinging and twisting). Not being an engineer, I bow to their judgment -- apparently the only valid choices are a free-dangling Skycrane or no Skycrane at all.
Go to the top of the page
 
+Quote Post
Guest_BruceMoomaw_*
post May 4 2005, 08:06 PM
Post #12





Guests






QUOTE (edstrick @ May 4 2005, 09:58 AM)
Regarding the number of MSL missions that should fly.. they SHOULD fly 3.  Build them at 2 year intervals.  Fly #1 in '09, #2 in '11 and #3 in '13. 

There is a precedence for this. Pioneer Jupiter missions were launched 13 months <1 jupiter launch window interval> apart.

If #1 blows it, like polar lander did, you can fix the booboo and fly #2.  Engineering tweeks and upgrades can be applied to #2 based on #1's early performance.  #3 could have significantly upgraded or modified science payload.  Each mission can be targetd based on science results of previous missions and orbital surveying done in the meantime.
*


They may actually do that -- but a far better scheme is, I think, to launch them at 4-year intervals. The main purpose for flying more than one MSL, as I've mentioned above, is to have each one look for trace organics at one place on Mars -- after which they'll send a sample return to the same place. If they launch just one MSL and it finds no organics, they'll be Up That Creek as to where to send the sample return mission -- and if MSL-1 finds no organics, they'll want to take some time to decide the best place to send MSL-2, instead of having to launch it to a predetermined landing site almost as soon as MSL-1 comes up empty-handed. (They may very well also want to modify MSL-2's instruments depending on MSL-1's results.) Ditto for MSL-3 if #2 also comes up empty. And with this wider gap between missions, you also have the ability to simply cancel the remaining MSLs without going to the expense of building them -- and move instead directly to the huge sample-return mission -- as soon as one MSL does find organics.
Go to the top of the page
 
+Quote Post
Guest_BruceMoomaw_*
post May 4 2005, 08:09 PM
Post #13





Guests






Footnote: I was told by an Inside Source yesterday that MSL-1 may well be launched in 2009 after all -- but he wasn't free to tell me his own reasons for thinking so. As I say, I rather hope they don't do it; the first Mars Telecom Orbiter should go up 2 years in advance -- and I think they should also launch the right kind of Mars Scout mission in 2009 instead (such as a methane-mapping orbiter).
Go to the top of the page
 
+Quote Post
MaDeR
post May 12 2005, 09:35 PM
Post #14


Newbie
*

Group: Members
Posts: 9
Joined: 12-May 05
Member No.: 387



My 2 cents: If I have to choose between 2009 with 1 MSL and 2011 with 2 MSL, I choose 2011. Two year longer wait is worth it. Two big, heavy and RTG-powered powerful rovers...

(music)Must not think, must not think, wet dream bad thinnng... tongue.gif


--------------------
Sanity is overrated.
Butterfly.
Go to the top of the page
 
+Quote Post
Marcel
post May 20 2005, 11:42 AM
Post #15


Member
***

Group: Members
Posts: 290
Joined: 26-March 04
From: Edam, The Netherlands
Member No.: 65



QUOTE (MaDeR @ May 12 2005, 09:35 PM)
My 2 cents: If I have to choose between 2009 with 1 MSL and 2011 with 2 MSL, I choose 2011. Two year longer wait is worth it. Two big, heavy and RTG-powered powerful rovers...

(music)Must not think, must not think, wet dream bad thinnng...  tongue.gif
*


http://www.space.com/missionlaunches/05052...masterplan.html

Only one MSL ohmy.gif .... sad.gif
Go to the top of the page
 
+Quote Post

5 Pages V   1 2 3 > » 
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 1st August 2014 - 09:49 AM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.