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Submitted by Arthur - N1ORC

  Oct. 7, 2002 

Atlantis aims for liftoff today 

NASA scrambles to resolve 2 technical issues 

By Chris Kridler - "Florida Today"

There have been months of delays. Cracks and repairs. A hurricane. If
mission managers can iron out a couple of technical issues in time,
shuttle Atlantis should lift off today on a journey to add to the
backbone of the International Space Station. 

Two issues worried mission managers Sunday. Of most concern was a heater
on the orbiter that's running too hot. It keeps water, a byproduct of the
power-producing fuel cells on board, from freezing so the liquid can be
vented into space. That's if the water's not first diverted to a tank for
crew use or for cooling. 

Though venting of the water is considered a third-string option for
getting rid of it, it is an important function. Too much water could
reduce the fuel cells' ability to produce electricity, possibly hindering
Atlantis' chances of a safe landing. 

"I am very, very hopeful that the engineering community will be able to
show us that that third path is still fully capable," Jim Halsell,
shuttle launch integration manager, said Sunday. 

The heater, which normally operates at 170 degrees Fahrenheit, is setting
itself at a safety point between 230 and 250 degrees, he said. If its
controller should fail completely, the temperature could soar to 700
degrees. Engineers are trying to determine whether it's safe to turn it
off or fly as is. 

A repair would mean a delay of several days, launch director Mike
Leinbach said. The possibility of working around the problem is on the
agenda for a meeting this morning. 

Another potential problem is the possibility Atlantis was contaminated by
ground equipment at Dryden Flight Research Center at Edwards Air Force
Base in California. The equipment serviced the shuttle when it landed
there in February 2001. A trace amount of oil has been found in the
equipment, but engineers are doing calculations to confirm that Atlantis
-- which has flown twice since then -- is clean. 

There's an 80 percent chance of acceptable weather for today's 3:46 p.m.
liftoff, forecaster Kathy Winters said. The 11-minute launch window,
announced Sunday afternoon, begins at 3:40 p.m., but the 3:46 p.m.
official launch time means NASA will have about five minutes to get
Atlantis off the ground. 

The Boeing-built trusses' cooling system pumps ammonia through radiators
to shed excess heat into space. Each mostly aluminum truss contains three
radiator panels and can provide cooling equivalent to air-conditioning
about four 2,000-square-foot homes. 

Ammonia is the coolant of choice because it has a low freezing point and
can transfer heat efficiently. 

Once activated, after more pieces of the station are in place, the new
cooling system will replace an older one that cools components of the
U.S. laboratory Destiny. The new radiators also will help release heat
from the growing power system. 

In addition, the S1 truss holds a communications system, two television
cameras and a hand cart that future spacewalkers will use as a mobile
work platform. The price tag for the truss and the cart is $390 million. 

Some 15 miles of cabling runs through the truss. 

As with every new component, new software is sent to the station, too.
The lines of computer code on board the space station are nearing 3
million, Boeing's Tom Russell said. 

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