IPB

Welcome Guest ( Log In | Register )

7 Pages V  « < 5 6 7  
Reply to this topicStart new topic
MRO MOI Events Timeline, Time Zone Friendly
Bob Shaw
post Mar 16 2006, 04:21 PM
Post #91


Senior Member
****

Group: Members
Posts: 2488
Joined: 17-April 05
From: Glasgow, Scotland, UK
Member No.: 239



QUOTE (Bubbinski @ Mar 16 2006, 05:47 AM) *
More and more spacecraft will hopefully make it to Mars in the near future....it might be prudent now to start on a more extensive COLA/tracking/space debris reduction program before it becomes an issue. Same with the Moon.


Lunar orbits tend to be quite unstable, especially low ones, so there's almost certainly nothing other than SMART-1 in Lunar orbit at present - we're a long way from needing traffic cops there!

Bob Shaw


--------------------
Remember: Time Flies like the wind - but Fruit Flies like bananas!
Go to the top of the page
 
+Quote Post
Guest_BruceMoomaw_*
post Apr 26 2006, 09:56 AM
Post #92





Guests






An odd note from the March 6 Aviation Week: The pre-MOI repressurization of the hydrazine tank "caused a little anxiety because Mars Observer was lost at the same point in 1993, believed due to overpressurized tanks from a faulty orifice in the pressure regulator sensing line."

This is a totally different theory for Mars Observer's loss from the one I've always seen listed as most probable: nitrogen tetroxide oxidizer leaking past a check valve into the hydrazine lines and setting off an explosion in the latter when the hydrazine first came down them. Is AW mistaken and the pressure-regulator theory is just one of the less likely alternate possible causes listed in the MO failure report, or has there been some recent rethinking on the most probable cause of the accident?
Go to the top of the page
 
+Quote Post
edstrick
post Apr 26 2006, 10:25 AM
Post #93


Senior Member
****

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



I was looking at that report and wondering the exact same thing....

I suspect a lot of the engineers and reporters have never read or essentially forgotten the full range of plausible failure modes ... I sure have forgotten all but the "somewhat most plausible" one.... and the reporter may be quoting one engineer or manager's take on the MO failure who's also working from memory.
Go to the top of the page
 
+Quote Post
Jim from NSF.com
post Apr 26 2006, 10:43 AM
Post #94


Member
***

Group: Members
Posts: 321
Joined: 6-April 06
From: Cape Canaveral
Member No.: 734



Maybe this was the only plausible failure mode applicable to MRO
Go to the top of the page
 
+Quote Post
edstrick
post Apr 26 2006, 11:19 AM
Post #95


Senior Member
****

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



Engineers and mission controllers on these missions have incredible regenerative abilities .... they routinely chew their fingernails back to their armpits during the runup to these mission critical events.
Go to the top of the page
 
+Quote Post
mcaplinger
post Apr 26 2006, 01:01 PM
Post #96


Senior Member
****

Group: Members
Posts: 1292
Joined: 13-September 05
Member No.: 497



QUOTE (BruceMoomaw @ Apr 26 2006, 02:56 AM) *
Is AW mistaken and the pressure-regulator theory is just one of the less likely alternate possible causes listed in the MO failure report, or has there been some recent rethinking on the most probable cause of the accident?

The latter. From "Propulsion Lessons Learned from the Loss of Mars Observer", Carl S.Guernsey, JPL, 2001:
"This paper presents an overview of the potential failure modes identified by the JPL review board and presents evidence, discovered after the failure reviews were complete, that the loss was very likely due to the use of an incompatible braze material in the flow restriction orifice of the pressure regulator."

Complete paper is online at
http://www.klabs.org/richcontent/Reports/F...y_a01-34322.pdf


--------------------
Disclaimer: This post is based on public information only. Any opinions are my own.
Go to the top of the page
 
+Quote Post
Guest_BruceMoomaw_*
post Apr 27 2006, 12:09 AM
Post #97





Guests






Ah! This is a big item that's totally new to me. Thanks.
Go to the top of the page
 
+Quote Post
tuvas
post Oct 13 2006, 11:25 PM
Post #98


Member
***

Group: Members
Posts: 428
Joined: 21-August 06
From: Tucson, AZ
Member No.: 1062



QUOTE (BruceMoomaw @ Apr 26 2006, 02:56 AM) *
An odd note from the March 6 Aviation Week: The pre-MOI repressurization of the hydrazine tank "caused a little anxiety because Mars Observer was lost at the same point in 1993, believed due to overpressurized tanks from a faulty orifice in the pressure regulator sensing line."

This is a totally different theory for Mars Observer's loss from the one I've always seen listed as most probable: nitrogen tetroxide oxidizer leaking past a check valve into the hydrazine lines and setting off an explosion in the latter when the hydrazine first came down them. Is AW mistaken and the pressure-regulator theory is just one of the less likely alternate possible causes listed in the MO failure report, or has there been some recent rethinking on the most probable cause of the accident?


If I remember right, the pressurization was such a big deal because there was a fairly last-minute change in the code, as I recall, it was set up so there wasn't a redundancy previous to a reprogramming only a few weeks before MOI. I attended a MOI party at the University of Arizona with the HiRISE team (This was right before I joined, my hiring was contitional upon the safe MOI of MRO, imagine that!), and I think that was the story that I heard at the UA MOI party... But, it's been quite a while... Also, please note that I wasn't a HiRISE team member at this point in time, so I don't know if that's really the reason. If that was the reason, then it just goes to show that NASA isn't taking any more chances with it's spacecraft, they are constantly checking things to make them better. MRO has performed almost flawlessly, even with it's more complex than normal instruments.
Go to the top of the page
 
+Quote Post

7 Pages V  « < 5 6 7
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 24th October 2014 - 09:20 PM
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.