STS-114 Landing Ground Tracks

In the map for the long-range ground track
(http://www.nasa.gov/images/content/1...sc201_long.gif),
what is the red symbol at 40N, 65W? What are the numbers along the
right vertical axis of the map and what measurement unit are they in?

Then on the short-range ground track map
(http://www.nasa.gov/images/content/1...c201_short.gif),
what are the two red triangles on the circle at the 60 deg azimuth?


Andrew Yee

Andrew Yee wrote in news:7ArJe.1263$7K5.76386
@news20.bellglobal.com:

What are the numbers along the
right vertical axis of the map and what measurement unit are they in?

Distance north/south of KSC, in nautical miles.

--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
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"Andrew Yee" wrote:
Then on the short-range ground track map
(http://www.nasa.gov/images/content/1...c201_short.gif),
what are the two red triangles on the circle at the 60 deg azimuth?

The groundtrack map is a "real time" display of Orbiter position (current =
circle, next two predicted positions = triangles - as seen on
http://www.nasa.gov/images/content/1...sc201_long.gif), as
well as plotting the "planned" entry groundtrack.

It's coincidental that they took screenshots with the real-time ground
position (from Orbiter telemetry) in view.

Roger
--
Roger Balettie
former Flight Dynamics Officer
Space Shuttle Mission Control
http://www.balettie.com/

So they aren't worries about Central American Cubans or South Floridian OK I
thought they were coming in over the Gulf not the Caribbean

"Roger Balettie" wrote in message
...
"Andrew Yee" wrote:
Then on the short-range ground track map
(http://www.nasa.gov/images/content/1...c201_short.gif),
what are the two red triangles on the circle at the 60 deg azimuth?

The groundtrack map is a "real time" display of Orbiter position (current
=
circle, next two predicted positions = triangles - as seen on
http://www.nasa.gov/images/content/1...sc201_long.gif), as
well as plotting the "planned" entry groundtrack.

It's coincidental that they took screenshots with the real-time ground
position (from Orbiter telemetry) in view.

Roger
--
Roger Balettie
former Flight Dynamics Officer
Space Shuttle Mission Control
http://www.balettie.com/





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"Lynndel K. Humphreys" wrote:
So they aren't worries about Central American Cubans or South Floridian OK
I
thought they were coming in over the Gulf not the Caribbean

The groundtrack is a function of where the landing site is from the original
orbit. You don't *really* get a lot of groundtrack change capability. It's
a matter of geometry.

Roger
--
Roger Balettie
former Flight Dynamics Officer
Space Shuttle Mission Control
http://www.balettie.com/

Is TACAN the controlling force for landing? Does it say "Here I am at x
altitude traveling a y velocity and decelerating at Z nm an hour In order to
get to point P I need to be at an angle of attack of such and such degrees
and need to veer to the left or right in order to remain "on energy". ( And
it does this all by a little gremlin or gnome and his pocket calculator.)


The groundtrack is a function of where the landing site is from the
original
orbit. You don't *really* get a lot of groundtrack change capability.
It's
a matter of geometry.

Roger
--
Roger Balettie
former Flight Dynamics Officer
Space Shuttle Mission Control
http://www.balettie.com/





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"Lynndel K. Humphreys" wrote in
:

Is TACAN the controlling force for landing?

It's a navigation aid, not a controlling force.

Does it say "Here I am at
x altitude traveling a y velocity and decelerating at Z nm an hour In
order to get to point P I need to be at an angle of attack of such and
such degrees and need to veer to the left or right in order to remain
"on energy".

Boiling the process down to the essentials, it really goes like:

The navigation software says, "Here I think I am with position vector P
and velocity vector V".

The IMUs say, "Here you are decelerating at rate A".

The navigation software integrates acceleration over time to get
velocity, and velocity over time to get position, and says, "Here's my
new position vector P and velocity vector V".

The TACAN says, "Here you are at range R and azimuth Z relative to me,
the TACAN station."

The navigation software says, "Based on P and V and where I know that
TACAN station is, I was expecting different values of R and Z. So I'll
subtract what I expected from what I got. If that difference is too big,
I'm not going to trust the TACAN station. Otherwise, I'll update P and V
by some fraction of that difference."

The guidance software says, "Based on that updated P and V, here's the
angle of attack and bank angle we need to stay on energy and reach the
runway."

The control software says, "Based on our current attitude, here's how we
need to deflect the aerosurfaces and fire the RCS jets to get to that
angle of attack and bank angle."

That's simplified a bit - in addition to TACAN, the software can also use
DRAG H (altitude derived from acceleration), the air data probes, and MLS
to update the state vector. Or even just replace the entire state vector
with the GPS state vector. And there are multiples of each one: three
IMUs, three TACANs, four air data transducers, three MLSs, and the
software has to figure out which ones are "good".

( And it does this all by a little gremlin or gnome and
his pocket calculator.)

Gerbils and their AP-101S's, actually, but same difference...

--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.

On or about Sun, 07 Aug 2005 13:31:47 -0400, Andrew Yee made the sensational claim that:
In the map for the long-range ground track
(http://www.nasa.gov/images/content/1...sc201_long.gif),
what is the red symbol at 40N, 65W? What are the numbers along the
right vertical axis of the map and what measurement unit are they in?

Then on the short-range ground track map
(http://www.nasa.gov/images/content/1...c201_short.gif),
what are the two red triangles on the circle at the 60 deg azimuth?

Anyone else think those are the WORST maps for determining what's water and
what's not? Hell, I live at 28.4/-80.6 and I have a hard time telling at a
glance.
--
This is a siggy | To E-mail, do note | Just because something
It's properly formatted | who you mean to reply-to | is possible, doesn't
No person, none, care | and it will reach me | mean it can happen

Roger Balettie wrote:
"Andrew Yee" wrote:
Then on the short-range ground track map
(http://www.nasa.gov/images/content/1...c201_short.gif),
what are the two red triangles on the circle at the 60 deg azimuth?

The groundtrack map is a "real time" display of Orbiter position (current =
circle, next two predicted positions = triangles - as seen on
http://www.nasa.gov/images/content/1...sc201_long.gif), as
well as plotting the "planned" entry groundtrack.

It's coincidental that they took screenshots with the real-time ground
position (from Orbiter telemetry) in view.



Okay, where on the NASA site is the realtime track for Discovery? I
finally found the map for ISS, and could get Skywatch sighting
predictions, but that's not the same. Guess I'll have to download the
2-lines and fire up STSPLUS.

/dps

PS What is the current orbit number?

Anyone know the computer language used by the nav computer?


"Jorge R. Frank" wrote in message
...
"Lynndel K. Humphreys" wrote in
:

Is TACAN the controlling force for landing?

It's a navigation aid, not a controlling force.

Does it say "Here I am at
x altitude traveling a y velocity and decelerating at Z nm an hour In
order to get to point P I need to be at an angle of attack of such and
such degrees and need to veer to the left or right in order to remain
"on energy".

Boiling the process down to the essentials, it really goes like:

The navigation software says, "Here I think I am with position vector P
and velocity vector V".

The IMUs say, "Here you are decelerating at rate A".

The navigation software integrates acceleration over time to get
velocity, and velocity over time to get position, and says, "Here's my
new position vector P and velocity vector V".

The TACAN says, "Here you are at range R and azimuth Z relative to me,
the TACAN station."

The navigation software says, "Based on P and V and where I know that
TACAN station is, I was expecting different values of R and Z. So I'll
subtract what I expected from what I got. If that difference is too big,
I'm not going to trust the TACAN station. Otherwise, I'll update P and V
by some fraction of that difference."

The guidance software says, "Based on that updated P and V, here's the
angle of attack and bank angle we need to stay on energy and reach the
runway."

The control software says, "Based on our current attitude, here's how we
need to deflect the aerosurfaces and fire the RCS jets to get to that
angle of attack and bank angle."

That's simplified a bit - in addition to TACAN, the software can also use
DRAG H (altitude derived from acceleration), the air data probes, and MLS
to update the state vector. Or even just replace the entire state vector
with the GPS state vector. And there are multiples of each one: three
IMUs, three TACANs, four air data transducers, three MLSs, and the
software has to figure out which ones are "good".

( And it does this all by a little gremlin or gnome and
his pocket calculator.)

Gerbils and their AP-101S's, actually, but same difference...

--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.




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