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HOUSTON - As NASA's return to flight draws closer, engineers at the Kennedy
Space Center in Florida have been discovering and resolving a torrent
of "loose ends" involving the shuttle launch system. One of
the most dramatic fixes involved a potential threat to the system that
allows ground controllers to blow up the shuttle's rocket boosters if
the spacecraft veers uncontrollably toward a populated region.
The problem and the fix were detailed in documents supplied to MSNBC.com
by members of the shuttle launch team on condition of anonymity —
and on Tuesday, a NASA official discussed the issue openly in response
to reporters' questions.
A couple of months ago, NASA engineers found that a recently installed
mobile radio system could interfere with the frequency for the range-safety
system that would issue an auto-destruct command, test director Jeff Spaulding
said. For this week's scheduled Discovery launch, team members working
within the launch danger zone have been issued walkie-talkies tuned to
a different frequency, he said.
Spaulding said the interference could have affected communications within
1 to 2.6 miles of the launch site, depending on the strength of the radio
signal.
He downplayed the issue during Tuesday's news conference. "It's a
very specific concern, and it's a very small concern," Spaulding
said.
However, in private e-mail communications with MSNBC.com, another member
of the launch team was more worried. Two weeks ago, before the workaround
was found, the source wrote, "Technically we are no-go."
The source expressed surprise that the problem was discovered so late
in the launch preparation: "Odd that this frequency conflict wasn't
identified until now," he said in the e-mail.
Internal NASA documents showed that transmissions from the launch site's
mobile radio system, which had been installed after the loss of the shuttle
Columbia, could interfere with commands issued from the U.S. Air Force's
Range Operations Control Center at Cape Canaveral Air Station, known as
the ROCC. By law, the Air Force is responsible for ensuring public safety
during all launches from Florida's Space Coast.
If the shuttle, with its thousands of tons of structure and fuel, lost
control and turned toward the coast, the controllers at the ROCC would
have to make the grim decision to trigger explosive charges in the solid-rocket
boosters. The astronauts on board the shuttle would most likely die, but
hundreds or thousands of lives would be saved on the ground.
In an internal NASA document dated July 8, shuttle launch director Mike
Leinbach said the interference problem was discovered after a launch-pad
test of Discovery's external fuel tank in May.
Leinbach emphasized that there was no concern about the "inadvertent
arming and firing" of the explosive charges on the boosters. Instead,
engineers were worried that the radios could interfere with a destruct
command and prevent the firing of the charges in an emergency.
Giving launch site workers different radios was just one part of the short-term
fix, according to the internal documents and MSNBC's source. NASA also
made arrangements to reduce the number of channels used for communications
during the critical period surrounding launch. If a "real contingency"
arises, "hopefully the deleted frequencies can be quickly restored,"
the source wrote.
Experience has shown that communications problems can arise even in a
routine situation. "Some people may not get a frequency when they
key their radios, since these frequencies are extremely busy even in a
normal launch," the source said.
Leinbach's report said that the lessons learned during Discovery's launch
will be incorporated into the plan for the next shuttle launch, currently
scheduled for September.
The report said a "long-term solution has yet to be determined,"
but Spaulding said the frequencies of the mobile radio system could be
adjusted to rule out the possibility of interference completely.
James Oberg, space analyst for NBC News, spent 22 years at the Johnson
Space Center as a Mission Control operator and an orbital designer. MSNBC.com's
Alan Boyle in Cape Canavarel contributed to this story.
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