ISS Service Module Thruster Test Fails

Details developing

Burn automatically aborted pre-ignition.

Uh, isn't anyone interested in this 'non-event'?

"Jim Oberg" wrote
Details developing

Uh, isn't anyone interested in this 'non-event'?

Well, I was just trying to remember what propulsion on the station was
and was not working. Though I guess I was thinking of reboost
engines, and "thruster" could mean either that or attitude control.

I guess in a nutshell, I'm too ignorant, both in terms of background
and in terms of this latest event, to know whether to be interested or
not.

"Jim Oberg" wrote:

"Jim Oberg" wrote
Details developing

Uh, isn't anyone interested in this 'non-event'?

Uh, yes. But some of us do try and avoid uninformed speculation.

If you were expecting a chorus a 'do tell Jim, do tell' - you should
know better.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

MSNBC COSMIC LOG//. April 19, 2006 | 6 p.m. ET

http://www.msnbc.msn.com/id/12359455/#060419b
Space station test fizzles: Today was supposed to mark the first time in
six years that the engines were fired up on the international space
station's Zvezda service module. The test firing was aimed at raising the
orbital outpost's altitude by about half a mile (700 meters) - and also
finding out whether the engines still worked.

NBC News space analyst James Oberg was watching the test closely, and
reported that the firing was aborted because one of the valves on one of the
engines failed to open. Fortunately, the non-firing is basically a
"non-event," and there are no immediate plans to try the test again, Oberg
quoted NASA spokesman Rob Navias as saying.

The station will still be in an acceptable orbit for next week's
scheduled rendezvous with a Progress cargo ship, even without the engine
firing, Oberg said.

"Even if the engines never work, they are only a backup to propulsion
capability usually provided by visiting vehicles docked to the aft port," he
explained in an e-mail. "The loss of these engines has no impact on station
operations - the Russians were just curious if they would work after so
long, and they have their answer."

Jim Oberg wrote:

"Even if the engines never work, they are only a backup to propulsion
capability usually provided by visiting vehicles docked to the aft port," he
explained in an e-mail. "The loss of these engines has no impact on station
operations - the Russians were just curious if they would work after so
long, and they have their answer."

Losing a backup system has always got to be a Bad Thing (although Mir
spent nearly its entire life in the same situation, but for a different
reason).

It makes you wonder what other long-term dormant systems no longer work.
The failure of P6's array extension/retraction system would be extremely
bad, for example.

--Chris

"Jim Oberg" wrote:

NBC News space analyst James Oberg was watching the test closely, and
reported that the firing was aborted because one of the valves on one of the
engines failed to open. Fortunately, the non-firing is basically a
"non-event," and there are no immediate plans to try the test again, Oberg
quoted NASA spokesman Rob Navias as saying.

All-singing all-dancing, just a different tune and a different set of
steps.

The station will still be in an acceptable orbit for next week's
scheduled rendezvous with a Progress cargo ship, even without the engine
firing, Oberg said.

"Even if the engines never work, they are only a backup to propulsion
capability usually provided by visiting vehicles docked to the aft port," he
explained in an e-mail. "The loss of these engines has no impact on station
operations - the Russians were just curious if they would work after so
long, and they have their answer."

Ah, right. It's *OK* for backups to be faulty - we'll never need them
after all.

Ask the shades of the crew of the USS Thresher what they think of
that.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

"Even if the engines never work, they are only a backup to propulsion
capability usually provided by visiting vehicles docked to the aft port," he
explained in an e-mail. "The loss of these engines has no impact on station
operations - the Russians were just curious if they would work after so
long, and they have their answer."

Why doesn't this make me feel good.....they build backup systems for a
reason. Obviously you never want to use them (otherwise they're not
backup systems they're primary systems more or less) but it's sure
nice to know they'll work to save your butt if/when the need arises.

I'm just a computer jock here at a hospital system, but I can tell you
if our backup power systems in the data center don't pass the routine
tests we have for them we fix them pretty quick, if they are needed
and DON'T perform, I'm pretty sure a few of my co-workers will be
looking for a "new situation" as it was put by Charles Dickens a while
ago pretty soon after it fails.

What other "non-essential" backup systems don't function as expected
at this point?
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FWIW, the NASA internal status report for 4/20
http://www.spaceref.com/news/viewsr.html?pid=20338 says
"ISS Reboost: The test of the SM main engines scheduled yesterday at
3:49pm EDT was aborted without engine ignition when the onboard
software received no signal that the sun cover on engine #2 had
opened."

If it is truly an external cover, this sounds like something that might
be repairable with an EVA (earlier reports implied the failure was a
propellant valve, which seems like it would be a lot nastier to work
on). Or for that matter, it might be a sensor failure, or an issue that
could be worked around with different procedures (random speculation:
opening the cover in a different thermal environment or giving the
actuator more current or more time to open.)

They also note that a reboost using only one of the SM main engine is
still possible.