Rescue mission challenges NASA

http://www.floridatoday.com/news/spa...3004rescue.htm

"Rescue mission challenges NASA"
_FLORIDA TODAY_ - March 30, 2004

Excerpt:

CAPE CANAVERAL-- It sounds so simple.

If NASA's next shuttle crew ends up in orbit with a crippled ship,
just launch another shuttle on a rescue. The stranded astronauts can
just wait on the International Space Station until the second shuttle
arrives to save the day.

But 14 months after the February 2003 Columbia accident and a year
before shuttle flights are to resume, NASA is finding that planning a
Hollywood-like mission is enormously complex.

See the URL for the rest of the article.

On Tue, 30 Mar 2004 22:11:18 -0500, in a place far, far away, "Scott
M. Kozel" made the phosphor on my monitor glow in
such a way as to indicate that:

http://www.floridatoday.com/news/spa...3004rescue.htm

"Rescue mission challenges NASA"
_FLORIDA TODAY_ - March 30, 2004

Excerpt:

CAPE CANAVERAL-- It sounds so simple.

If NASA's next shuttle crew ends up in orbit with a crippled ship,
just launch another shuttle on a rescue. The stranded astronauts can
just wait on the International Space Station until the second shuttle
arrives to save the day.

But 14 months after the February 2003 Columbia accident and a year
before shuttle flights are to resume, NASA is finding that planning a
Hollywood-like mission is enormously complex.

No question about it, which is why all the second guessing about what
NASA could or should have done if they'd gotten the satellite images,
given that they were totally unprepared for such an eventuality, is
speculative nonsense.

"Scott M. Kozel" wrote:

http://www.floridatoday.com/news/spa...3004rescue.htm

What is needed is a grapple point so that the Station arm can not only grapple
a shuttle, but also provide keep-alive power.

This way, station arm could take the stranded shuttle, undock it from PMA, and
move it out of the way while rescue shuttle arrives with spare parts etc. Once
repairs are done, and other shuttle gone, they could redock it (since shuttle
would get power from station's arm, they could still command the docking
mechanism to lock onto PMA2.)

The idea of ditching the shuttle before the next one arrives really bothers
me. There is a lot of parts that could/should be salvaged before it is
disposed of (if that is really the only option).

"Jorge R. Frank" wrote:
In the current ISS configuration, there is no place the SSRMS could hold
the stranded shuttle to get it completely out of the way of the rescue
shuttle without causing major control difficulties for ISS.

Isn't the whole architecture designed to make it easy to add additional
grapple points on the station ?

In *no* configuration of ISS is there a place where the SSRMS could hold
the stranded shuttle and still withstand plume impingement and docking
loads from the rescue shuttle.


I can understand plume impingement for the thin solar arrays. But franckly, is
this really a valid argument for a tile equipped shuttle being held by the arm
?

There is no ground commanding capability for the docking mechanism, nor is
there commanding capability for the post-contact thrusting required to trip
the capture latches.

If there is a data connection via the SSRMS, then couldn't the station send
the commands tyo trigger the locking motors ?

And if the shuttle is held by the SSRMS, can't the SSRMS provide the
equivalent of post contact thrusting to trip the latches ?

The SSRMS is capable of transmitting small amounts of
power, but the level of power required to allow an automated shuttle re-
docking is beyond the design limits.

All that is needed is keepalive power, as well as driving the docking motors.
The SSMR is the one who would perform the docking, no need to use shuttle's thrusters.

There are, at least in theory, 23 days to salvage parts from the damaged
shuttle before its consumables are depleted.

But wouldn't the point be to have the rescue shuttle bring the spare parts to
fix the broken shuttle ?

What about just letting shuttle go a day or two before the rescue one arrives,
and then the rescue shuttle could still approach the damaged one to EVA to it
and fix whatever is needed ?

John Doe wrote in :

"Scott M. Kozel" wrote:

http://www.floridatoday.com/news/spa...3004rescue.htm

What is needed is a grapple point so that the Station arm can not only
grapple a shuttle, but also provide keep-alive power.

This way, station arm could take the stranded shuttle, undock it from
PMA, and move it out of the way while rescue shuttle arrives with
spare parts etc.

In the current ISS configuration, there is no place the SSRMS could hold
the stranded shuttle to get it completely out of the way of the rescue
shuttle without causing major control difficulties for ISS.

In *no* configuration of ISS is there a place where the SSRMS could hold
the stranded shuttle and still withstand plume impingement and docking
loads from the rescue shuttle.

Once repairs are done, and other shuttle gone, they
could redock it (since shuttle would get power from station's arm,
they could still command the docking mechanism to lock onto PMA2.)

There is no ground commanding capability for the docking mechanism, nor is
there commanding capability for the post-contact thrusting required to trip
the capture latches. The SSRMS is capable of transmitting small amounts of
power, but the level of power required to allow an automated shuttle re-
docking is beyond the design limits.

The idea of ditching the shuttle before the next one arrives really
bothers me. There is a lot of parts that could/should be salvaged
before it is disposed of (if that is really the only option).

There are, at least in theory, 23 days to salvage parts from the damaged
shuttle before its consumables are depleted.

--
JRF

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

John Doe wrote in :

"Jorge R. Frank" wrote:
In the current ISS configuration, there is no place the SSRMS could
hold the stranded shuttle to get it completely out of the way of the
rescue shuttle without causing major control difficulties for ISS.

Isn't the whole architecture designed to make it easy to add
additional grapple points on the station ?

In *no* configuration of ISS is there a place where the SSRMS could
hold the stranded shuttle and still withstand plume impingement and
docking loads from the rescue shuttle.

I can understand plume impingement for the thin solar arrays. But
franckly, is this really a valid argument for a tile equipped shuttle
being held by the arm ?

Yes. The arm is the weak point; the moments on the arm from the plumes will
damage it.

There is no ground commanding capability for the docking mechanism,
nor is there commanding capability for the post-contact thrusting
required to trip the capture latches.

If there is a data connection via the SSRMS, then couldn't the station
send the commands tyo trigger the locking motors ?

That is not as trivial as it sounds. You need a command interface at the
ISS end *and* a path on the shuttle side to send the commands to the
docking mechanism. The docking mechanism is Russian - currently *all*
commanding is done by switches on the Russian-supplied control panel. Data
goes *out* from the docking mechanism to the computers and the ground but
there's no *path* for commands to go the other way.

And if the shuttle is held by the SSRMS, can't the SSRMS provide the
equivalent of post contact thrusting to trip the latches ?

No. It's not strong enough.

The SSRMS is capable of transmitting small amounts of
power, but the level of power required to allow an automated shuttle
re- docking is beyond the design limits.

All that is needed is keepalive power, as well as driving the docking
motors. The SSMR is the one who would perform the docking, no need to
use shuttle's thrusters.

Incorrect. The SSRMS is not strong enough. You need the thrusters, plus the
RJDs, flight-critical MDMs, and at least two GPCs (one GNC to command the
thrusters, one SM to command the docking mechanism). Then you need to
activate at least enough of the ECLSS to keep all that equipment cool.

There are, at least in theory, 23 days to salvage parts from the
damaged shuttle before its consumables are depleted.

But wouldn't the point be to have the rescue shuttle bring the spare
parts to fix the broken shuttle ?

What about just letting shuttle go a day or two before the rescue one
arrives, and then the rescue shuttle could still approach the damaged
one to EVA to it and fix whatever is needed ?

Once the damaged shuttle has given up all its consumables to keep the crew
alive to wait for the rescue shuttle, there won't be enough consumables for
it to keep itself alive until the rescue shuttle can get to it. The plan is
to leave just enough capability (~2 hours) after undocking for the damaged
shuttle to destructively deorbit itself after undocking.


--
JRF

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

I am presuming that NASA would attempt to autoland a damaged Shuttle
rather than ditching it in the ocean (assuming that an automatic
system to lower the nose gear is in place).

Also, concerning Shuttle consumables, isn't there a system in
development to allow Shuttle to receive power from ISS?

Lastly, why couldn't a damaged Shuttle move to PMA-2 at Node 1 to
allow a 2nd Shuttle to dock with PMA-3 at the Lab?

(Explorer8939) wrote in
om:

I am presuming that NASA would attempt to autoland a damaged Shuttle
rather than ditching it in the ocean (assuming that an automatic
system to lower the nose gear is in place).

With the latter assumption (and it's *all* the landing gear, not just the
nose gear), yes. However, that will not be in place for RTF, and may not
get funded at all. The current plan is destructive re-entry over the ocean;
the orbiter would perform the deorbit burn using the OPS-2 orbit software,
then maneuver to point the open payload bay doors at the velocity vector.

Also, concerning Shuttle consumables, isn't there a system in
development to allow Shuttle to receive power from ISS?

Yes. That will not necessarily help the safe-haven duration, especially in
cases where the shuttle is crippled due to life-support or thermal control
system failures. And as far as I know, it will only work through PMA-2.

Lastly, why couldn't a damaged Shuttle move to PMA-2 at Node 1 to
allow a 2nd Shuttle to dock with PMA-3 at the Lab?

You have the PMAs reversed. PMA-2 is on the lab and PMA-3 is on Node 1. A
shuttle cannot dock to PMA-3 in its current location (Node 1 portside CBM)
due to collision with the P1 radiator and inadequate clearance with the Ku
antenna. A shuttle could dock to PMA-3 if it were relocated to Node 1 nadir
with nose-portside clocking, but only if the payload bay were emptied first
(clearance with Quest) and no Soyuz is docked to FGB nadir. RCS plume
impingement during such an approach will be quite high due to proximity of
sensitive station structures, and damage to the station is a strong
possibility.


--
JRF

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

"Jorge R. Frank" wrote:
get funded at all. The current plan is destructive re-entry over the ocean;
the orbiter would perform the deorbit burn using the OPS-2 orbit software,
then maneuver to point the open payload bay doors at the velocity vector.

Why be so destructive ?

From a point of view of research, wouldn't it be better to actually try to
land the orbiter in the ocean and see how it actually performs (or how long it
remains intact/flyiable ?)

If they targetted Edwards, wouldn't debris fall in the ocea if it didn,t
survive re-entry ? If the orbiter survived re-entry, how much damage would it
cause to edwards if it made a belly landing ?

John Doe wrote in :

"Jorge R. Frank" wrote:
get funded at all. The current plan is destructive re-entry over the
ocean; the orbiter would perform the deorbit burn using the OPS-2
orbit software, then maneuver to point the open payload bay doors at
the velocity vector.

Why be so destructive ?

To assure breakup at maximum altitude, minimizing the amount and size of
debris that survives to the ground, thereby minimizing public risk. It also
happens to have fewer risks in execution, minimizing the number of commands
that need to be sent from the ground.

From a point of view of research, wouldn't it be better to actually
try to land the orbiter in the ocean and see how it actually performs
(or how long it remains intact/flyiable ?)

The minimize-public-risk side of the debate appears to be winning against
the research side.

--
JRF

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