STS-90
Report # 28 
Thursday, April 30, 1998 - 6:30  p.m. CDT 
 
  Flight controllers will continue to review information and evaluate
whether further crew action is required to remove an apparent blockage
in Columbia's waste water dump line, after efforts today to bypass a
clogged filter, did not resolve the problem.

  Commander Rick Searfoss and Pilot Scott Altman bypassed the clogged
filter, routing a hose through a spare filter and venting waste water
overboard.  Flight controllers initially saw a good flow rate, which
then became more sporadic indicating a blockage likely still exists.
Adequate waste water stowage is available on board Columbia through
its planned landing on Sunday without further action by the crew.
However, flight controllers may ask the crew to dump some water
overboard or into contingency waste containers (CWC's) tomorrow to
keep the waste tank level as low as possible. The CWC's provide
additional water stowage capacity in the event weather keeps Columbia
from landing on Sunday.

  The Mission Management Team decided today not to extend the Neurolab
mission, after the science community indicated an additional day of
science would not be necessary.  Coupled with weather conditions,
which are expected to deteriorate in the early part of next week, the
decision was made to land on Sunday as originally scheduled. Landing
currently is set for 11:09 a.m. CDT on Sunday, May 3.

  Today, Columbia's science crew -- Mission Specialists Rick Linnehan
and Dave Williams and Payload Specialists Jay Buckey and Jim Pawelczyk
^V completed the second and final inflight dissections of the adult
male rats on board to support studies on how the adult nervous system
adapts to a changing environment.

  During conversations today with science managers, the STS-90 crew
said that as a group, the youngest group of rats on board continue to
be improve for the most part.  One additional neonate died late
yesterday, bringing to 52 the total number of unexpected neonate
deaths.  Of the remaining 38 rats in the youngest age group most are
stable and eating well with a few being tended to by Columbia^Rs
astronauts.

  One of the rats in the Animal Enclosure Module which lost the
hypderdrive unit attached to its head, had been scheduled to be
euthanised as part of scientific protocols designed to keep the animal
from suffering.  However, Linnehan reported that the animal appeared
very healthy, did not appear to be suffering in any way, and Linnehan
therefore elected to let the animal live.

  Before going to sleep tonight, Mission Specialist Kay Hire, along
with Buckey and Pawelczyk will don specialized gear designed to
monitor their breathing, muscle activity, and eye motion as they
sleep.  Investigators believe that altered breathing patterns while on
orbit may affect the astronauts' ability to sleep.

  Columbia remains in a 153 x 133 nautical mile orbit, circling the
Earth every 90 minutes.

The next STS-90 status report will be issued about 6 a.m. Friday or as
events warrant.

###

NASA Johnson Space Center Mission Status Reports and other information are available

automatically by sending an Internet electronic mail message to 

jscnews-request@listserver.jsc.nasa.gov. In the body of the message (not the 

subject line)  users should type "subscribe" (no quotes). This will add the email address 

 that sent the subscibe message to the news release distribution list. The system will reply 

with a confirmation via E-mail of each subscription. Once you have subscribed you will 

receive future news releases via e-mail.