As the final flight of Challenger
approached, the Space Shuttle Program
and the operations community at JSC,
MSFC, and KSC faced many pressures
that made each sensitive to maintaining
a very ambitious launch schedule. By
1986, the schedule and changes in the
manifest due to commercial and
Department of Defense launch
requirements began to stress NASA’s
ability to plan, design, and execute
shuttle missions. NASA had won
support for the program in the 1970s by
emphasizing the cost-effectiveness and
economic value of the system. By
December 1983, 2 years after the
maiden flight of Columbia, NASA had
flown only nine missions. To make
spaceflight more routine and therefore
more economical, the agency had to
accelerate the number of missions it
flew each year. To reach this goal,
NASA announced an ambitious rate of
24 flights by1990.
NASA flew five missions in 1984 and a
record nine missions the following year.
By 1985, strains in the system were
evident. Planning, training, launching,
and flying nine flights stressed the
agency’s resources and workforce, as
did the constant change in the flight
manifest. Crews scheduled to fly in 1986
would have seen a dramatic decrease
in their number of training hours or the
agency would have had to slow down
its pace because NASA simply lacked
the staff and facilities to safely fly an
accelerated number of missions.
By the end of 1985, pressure mounted
on the space agency as they prepared to
launch more than one flight a month the
next year. A record four launch scrubs
and two launch delays of STS-61C,
which finally launched in January 1986,
exacerbated tensions. To ensure that
no more delays would threaten the
1986 flight rate or schedule, NASA cut
the flight 1 day short to make sure
Columbia could be processed in time
for the scheduled ASTRO-1 science
mission in March. Weather conditions
prohibited landing that day and the
next, causing a slip in the processing
schedule. NASA had to avoid any
additional delays to meet its goal of
15 flights that year.
The agency needed to hold to the
schedule to complete at least three
flights that could not be delayed.
Two flights had to be launched in
May 1986: the Ulysses and the Galileo
flights, which were to launch within
6 days of each other. If the back-to-back
flights missed their launch window,
the payloads could not be launched
until July 1987. The delay of STS-61C
and Challenger’s final liftoff in January
threatened the scheduled launch plans
of these two flights in particular. The
Challenger needed to launch and deploy
a second Tracking and Data Relay
Satellite, which provided continuous
global coverage of Earth-orbiting
satellites at various altitudes. The shuttle
would then return promptly to be
reconfigured to hold the liquid-fueled
Centaur rocket in its payload bay.
The ASTRO-1 flight had to be launched
in March or April to observe Halley’s
Comet from the shuttle.
On January 28, 1986, NASA launched
Challenger, but the mission was
never realized. Hot gases from the
right-hand Solid Rocket Booster motor
had penetrated the thermal barrier
and blown by the O-ring seals on the
booster field joint. The joints were
designed to join the motor segments
together and contain the immense heat
and pressure of the motor combustion.
As the Challenger ascended, the leak
became an intense jet of flame that
penetrated the ET, resulting in
structural failure of the vehicle and
loss of the crew.
Prior to this tragic flight, there had
been many O-ring problems witnessed
as early as November 1981 on the
second flight of Columbia. The hot
gases had significantly eroded the
STS-2 booster right field joint—deeper
than on any other mission until the
accident—but knowledge was not
widespread in mission management.
STS-6 (1983) boosters did not have
erosion of the O-rings, but heat had
impacted them. In addition, holes were
blown through the putty in both nozzle
joints. NASA reclassified the new
field joints Criticality 1, noting that the
failure of a joint could result in “loss of
life or vehicle if the component fails.”
Even with this new categorization,
the topic of O-ring erosion was not
discussed in any Flight Readiness
Reviews until March 1984, in
preparation for the 11th flight of the
program. Time and again these
anomalies popped up in other missions
flown in 1984 and 1985, with the
issue eventually classified as an
“acceptable risk” but not desirable.
The SRB project manager regularly
waived these anomalies, citing them as
“repeats of conditions that had already
been accepted for flight” or “within
their experience base,” explained
Arnold Aldrich, program manager for
the Space Shuttle Program.
Senior leadership like Judson
Lovingood believed that engineers
“had thoroughly worked that joint
problem.” As explained by former
Chief Engineer Keith Coates, “We
knew the gap was opening. We knew