[X] My Assistant

[Jeff7]

But, the loss of a little technology test probe pales in comparison to the loss of MCO due to the english vs metric unit thing. In my opinion, that blunder was embarassing and unforgivable. I'd give the guys responsible for that one a lot more time in the hairshirt than the JAXA guys who forgot to put in the software interlock.

Or Genesis. I seem to remember reading somewhere that the gravity sensor that would have told the parachute to deploy was put in upside down.


Ah, found a link. Here.

The Genesis space capsule that crashed into the Utah desert last month failed because four pencil stub-size gravity switches designed to trigger the release of the spacecraft's parachutes were installed backward, NASA officials said yesterday.

Oops.
Also of note, this was after MCO "buried," as Robin Williams put it.

[djellison]

BUT - Genesis worked - most of the samples, and all of the critical ones, survived fine. There was a delay to, but no loss of science.

Minerva was a last minute thing iirc - given that JPL was devloping a rover for Muses C but cancelled on them.

Doug

[Jeff7]

BUT - Genesis worked - most of the samples, and all of the critical ones, survived fine.  There was a delay to, but no loss of science.

Minerva was a last minute thing iirc - given that JPL was devloping a rover for Muses C but cancelled on them.

Doug

Really? Good to hear - I admit, I hadn't checked up on that project for quite some time. The website had gone months without any updates, other than to basically say "we found a few more large fragments, but they might be contaminated too." Checking the page now, well, it confirms what you said.
Still though, really - say one of the MER's had had this problem. (Polar Lander's issue perhaps?) Full speed right into the ground. Though the thought of the lander trying to deploy itself while buried in the center of a fresh crater is a bit amusing. It's a fairly important part though and it's in backwards. MSL would really suck if they put the Skycrane's retro-rockets in upside down.

[deglr6328]

BUT - Genesis worked - most of the samples, and all of the critical ones, survived fine.  There was a delay to, but no loss of science.....
Doug

eeeh? I don't know, have any papers even been published yet?

[Guest_Sedna_*]

I think Genesis worked okay, but failed in a very important point: to get the samples back flawlessly!! All the thing with the helicopters was "funny" while the proble hitted the ground, as a scientist I would have just dropped the whole thing into the rubbish bin (what a pain!). Now, they are trying to "save something" while they should know by now many conclusions about the samples...

[elakdawalla]

I think Genesis worked okay, but failed in a very important point: to get the samples back flawlessly!! All the thing with the helicopters was "funny" while the proble hitted the ground, as a scientist I would have just dropped the whole thing into the rubbish bin (what a pain!). Now, they are trying to "save something" while they should know by now many conclusions about the samples...

I think the scientists feel thankful every day that their samples survived an event that should have destroyed all hopes for any successful result from the mission. The Huygens Doppler Wind Experiment scientists feel the same way. It's heartbreaking to consider what they could have had, if their receiver had only been turned on aboard Cassini. Yet, thanks to some incredibly hard work, they do have a data set, and one that's sufficient to accomplish most of the stated goals of their experiment (though of course not everything they could have done if everything had gone right). I am sure the Genesis folks, while feeling rueful about the arduous task that they face, are eternally grateful that they've got data at all.

By the way, there are both talk and poster sessions of Genesis mission results planned for the 2005 Fall Meeting of the American Geophysical Union in San Francisco.

--Emily

[mcaplinger]

There are valid points on both sides of the discussion...
But,  the loss of a little technology test probe pales in comparison to the loss of MCO due to the english vs metric unit thing.  In my opinion, that blunder was embarassing and unforgivable. 

Gee, it must be nice to be infallible.

Calling it the "english vs metric unit thing" is something of an oversimplification. You might want to read
ftp://ftp.hq.nasa.gov/pub/pao/reports/1999/MCO_report.pdf before being so casually dismissive of those of us who spent several years on the MS98 project (not that I had anything to do with the nav error.)

[The Messenger]

Calling it the "english vs metric unit thing" is something of an oversimplification. 

Yes, there were three, or at least two-and-a-half navigation solutions, they ALL indicated the MCO should have been on a survivable track, and only one-of-the three contained the conversion error. The final chapter on Mars mission landing failures can't be written - not until there are better explanations for the thin upper atmosphere, hard landings, and harmonic gravitational degeneracies.

[odave]

Calling it the "english vs metric unit thing" is something of an oversimplification. 

Yes, I'm aware that it was a much more complex problem, but I was trying to keep the post short by summarizing, and that often gets me in trouble. I apologize for my harsh tone. I was in a surly mood yesterday and normally keep my mouth shut when I'm feeling like that, but alas...so I'll wear the hairshirt today

Still, the navigation error was an unfortunate oversight - one that would get those responsible at least a reprimand, if not a demotion, in many companies.

I don't work on spacecraft, but I do work on projects that require a lot of creative energy and long, toiling hours. I know how badly I feel when something I've worked so hard on goes down the tubes, and no doubt you all on the MCO team felt like you were kicked in the stomach. I'm sorry for any hurt feelings my post may have caused.

What I should have said is that the most important thing is *not* to point the finger and kick the dog, it's to make sure that a lesson was learned and processes put in place to make sure it does not happen again.

[Guest_Analyst_*]

Reaction wheels have historically been a bug-a-boo. Roughly a third of the Galileo planetary science runs were compromised by reaction wheel problems.

Galileo had a spinning part with the f&p instruments, RTG and Mag booms and the engine/probe section and an unspun part with the HGA and pointed instruments. I don't see any use for reaction wheels on a (partly) spinner. Are you talking about the gyros (used for measuring the position in space instead of changing it)? The science runs on Galileo were compromised by safe mode entries because of cosmic ray hits in various subsystems (computer memory, camera...). I doubt Galileo had any reaction wheels. Cassini has four (one backup).

Analyst

[ljk4-1]

Galileo had a spinning part with the f&p instruments, RTG and Mag booms and the engine/probe section and an unspun part with the HGA and pointed instruments. I don't see any use for reaction wheels on a (partly) spinner. Are you talking about the gyros (used for measuring the position in space instead of changing it)? The science runs on Galileo were compromised by safe mode entries because of cosmic ray hits in various subsystems (computer memory, camera...). I doubt Galileo had any reaction wheels. Cassini has four (one backup).

Analyst

Is there anything more efficient and less prone to problems that reactions wheels that future probes could use?

[The Messenger]

Galileo had a spinning part with the f&p instruments, RTG and Mag booms and the engine/probe section and an unspun part with the HGA and pointed instruments. I don't see any use for reaction wheels on a (partly) spinner. Are you talking about the gyros (used for measuring the position in space instead of changing it)?

Yes, I tend to look at reaction wheels as gyros-on-steroids, but I shouldn't lump them together.

The science runs on Galileo were compromised by safe mode entries because of cosmic ray hits in various subsystems (computer memory, camera...).

This may or may not be true; Reading through the Galileo event logs, NASA was having a tough time with Galileo hiding in her shell on close approach to Jupiter's moons - Near IO, this was blamed upon the intense EM Field, but most of the time the shutdowns were atributed to Cosmic Rays.

As I mentioned before, I have a problem with this simplistic explanation, because the probe invariably clammed up on closest-approaches to Jupiter's moons, then responded more or less normally while 'coasting' between them. This is why I suspect an ESD component, or something that we do not quite have a handle on.

It would be interesting to know precisely where and when Cassini has experienced reaction wheel problems, because I would like to be able to rule-out a scenario similar to what I just descibed.

[ljk4-1]

Yes, I tend to look at reaction wheels as gyros-on-steroids, but I shouldn't lump them together.
This may or may not be true; Reading through the Galileo event logs, NASA was having a tough time with Galileo hiding in her shell on close approach to Jupiter's moons - Near IO, this was blamed upon the intense EM Field, but most of the time the shutdowns were atributed to Cosmic Rays.

As I mentioned before, I have a problem with this simplistic explanation, because the probe invariably clammed up on closest-approaches to Jupiter's moons, then responded more or less normally while 'coasting' between them.  This is why I suspect an ESD component, or something that we do not quite have a handle on.

It would be interesting to know precisely where and when Cassini has experienced reaction wheel problems, because I would like to be able to rule-out a scenario similar to what I just descibed.

I wonder how we are ever going to have probes explore the inner Galilean moons without their being fried by the radiation and not have to bring a ridiculously heavy amount of shielding with them?

[Bob Shaw]

I wonder how we are ever going to have probes explore the inner Galilean moons without their being fried by the radiation and not have to bring a ridiculously heavy amount of shielding with them?

The answer - once adequate power sources are available - will be some form of active EM shielding, essentially a mini-magnetosphere within which the vehicle resides. Obviously, it'll play silly buggers with particles and fields experiments, but them's the breaks!

There was some coverage of a sort of 'inside out' ion drive which could provide both propulsion and shielding several years ago - it was being proposed under one of NASA's 'blue-sky' programmes for looking at unorthodox - but perhaps buildable - engines (etc).

Bob Shaw

[Phil Stooke]

I think this discussion needs to be moved!

Phil