msnbc - Low-level sensors crucial to safe shuttle ascent

Low-level sensors crucial to safe shuttle ascent

On two launches, sensors have shut off engines in flight for safety

http://www.msnbc.msn.com/id/8572372/

By James Oberg, NBC News space analyst

MSNBC // Updated: 1:58 p.m. ET July 14, 2005

When a low-level sensor in Discovery's propellant tank malfunctioned
during Wednesday's countdown, mission commander Eileen Collins must have had
that "déjà vu" feeling. And she would have had no objection to calling off
the launch - because the proper functioning of exactly such a sensor may
have saved her spaceship, even her life, on her previous launch in 1999.

http://www.msnbc.msn.com/id/8572372/

By James Oberg, NBC News space analyst


snip

It was just 0.15 seconds prior to the nominal shutdown. Since the shuttle
was accelerating at 3 G's, three times the force of gravity (32.2
feet/second/second), it was still picking up speed at a rate of about 100
feet per second every second. In terms of the orbit it was aiming for, it
was raising the far end of its circular earth-girdling path by about 60
miles every second.

So if the shutdown had been ordered only a second earlier in the 520-second
climb into space - if the hydrogen leak had been a fraction of a percent
faster - Columbia would have fallen short of a stable, safe orbit. It would
have had to immediately head back to Earth for an emergency landing in West
Africa.



I'm not an expert on this, but it seems to me that an one second earlier
engine shut down would not result in a TAL landing, at the rate it was
already picking up speed, that 1 second would (I think) result in a lower
than planned orbit, but no TAL landing..Maybe a Abort Once Around
landing.....in California...

There are perhaps readers who now more on this....

Also, There are no longer TAL landing sites in Africa in use only two in
Spain and now one in France for TAL landings...


--
--------------


Jacques :-)

www.spacepatches.info

"Jim Oberg" schreef in bericht
.. .
Low-level sensors crucial to safe shuttle ascent

On two launches, sensors have shut off engines in flight for safety

http://www.msnbc.msn.com/id/8572372/

By James Oberg, NBC News space analyst

MSNBC // Updated: 1:58 p.m. ET July 14, 2005

When a low-level sensor in Discovery's propellant tank malfunctioned
during Wednesday's countdown, mission commander Eileen Collins must have
had
that "déjà vu" feeling. And she would have had no objection to calling off
the launch - because the proper functioning of exactly such a sensor may
have saved her spaceship, even her life, on her previous launch in 1999.

Well Jim, once more you've defined yourself as a spin doctor. Your NBC
client must be desperate to cast the recent three-strike prelaunch
situation at Pad B in a favorable light for the Bush administration.
It's too late to reach the MSNBC readers you've unethically influenced,
but it's not too late to call you to task here.

Earlier this morning you asked these two forums for help. You were
immediately advised that NASA can now validate pure sensor failures, by
differentiating such failures from failures in the subsystems/systems
they are designed to support. During Eileen Collins' STS-93 mission,
low-level sensors (plural) *did their job* in reporting the results of
*other* failures. Without technical documentation which any of us could
ever have been aware, you extrapolated one such mission to two.

After confirming my recollection with considerable shuttle research, I
also advised you that I was unaware of any post-launch shutdown
triggered by a *single* low-level sensor. Brian Perry went to the
trouble of confirming with the Flight Director for STS-93 that no
*single* low-level sensor had ever triggered a shutdown for that
mission. You have misled the public by convoluting the facts. An
objective reporter would promptly recant and retract.

Challenger's Ghost

Jim Oberg wrote:
Low-level sensors crucial to safe shuttle ascent

On two launches, sensors have shut off engines in flight for safety

http://www.msnbc.msn.com/id/8572372/

By James Oberg, NBC News space analyst

MSNBC // Updated: 1:58 p.m. ET July 14, 2005

When a low-level sensor in Discovery's propellant tank malfunctioned
during Wednesday's countdown, mission commander Eileen Collins must have =
had
that "d=E9j=E0 vu" feeling. And she would have had no objection to callin=
g off
the launch - because the proper functioning of exactly such a sensor may
have saved her spaceship, even her life, on her previous launch in 1999.

On Thu, 14 Jul 2005 21:44:11 +0200, Jacques van Oene wrote:

http://www.msnbc.msn.com/id/8572372/

By James Oberg, NBC News space analyst


snip

It was just 0.15 seconds prior to the nominal shutdown. Since the shuttle
was accelerating at 3 G's, three times the force of gravity (32.2
feet/second/second), it was still picking up speed at a rate of about 100
feet per second every second. In terms of the orbit it was aiming for, it
was raising the far end of its circular earth-girdling path by about 60
miles every second.

So if the shutdown had been ordered only a second earlier in the 520-second
climb into space - if the hydrogen leak had been a fraction of a percent
faster - Columbia would have fallen short of a stable, safe orbit. It would
have had to immediately head back to Earth for an emergency landing in West
Africa.



I'm not an expert on this, but it seems to me that an one second earlier
engine shut down would not result in a TAL landing, at the rate it was
already picking up speed, that 1 second would (I think) result in a lower
than planned orbit, but no TAL landing..Maybe a Abort Once Around
landing.....in California...

There are perhaps readers who now more on this....

Also, There are no longer TAL landing sites in Africa in use only two in
Spain and now one in France for TAL landings...

No, one second earlier would have been only 100fps low, they would have
made it to orbit. Maybe a little lower, but still in orbit.

--
Craig Fink
Courtesy E-Mail Welcome @

On Thu, 14 Jul 2005 18:55:19 GMT, "Jim Oberg"
wrote:

When a low-level sensor in Discovery's propellant tank malfunctioned
during Wednesday's countdown, mission commander Eileen Collins must have had
that "déjà vu" feeling.

Wouldn't it have been better to say that she must have had 'that "déjà
vu" feeling all over again'?

Mary "not your ordinary bear, Yogi"

--
Mary Shafer Retired aerospace research engineer
We didn't just do weird stuff at Dryden, we wrote reports about it.
or