and liftoff.
liftoff of the 25th Space Shuttle mission and it has cleared the tower.
roger roll Challenger
good roll program confirmed.
Challenger now heading downrange.
January 28th was the final heartbreaking flight of the Space Shuttle Challenger and a tragedy
that could have been avoided.
Engines beginning throttling down now at 94%.
Normal throttle for most of the flight is 104%.
People around the world, including millions of children, watched as seven astronauts,
Dick Scobee, Michael Smith, Ronald McNair, Ellison Onizuka, Judy Resnik, Gregory Jarvis
and Christa McAullife, braved the frigid cold temperatures and wild winds, to fly one last time
2257 feet per second.
Altitude 4.3 nautical miles.
Downrange distance 3 nautical miles.
What should have been a celebration of our achievements in spaceflight, quickly turned
into heartbreak.
Challenger, GO at throttle up.
Roger GO at throttle up.
One minute fifteen seconds, velocity 2900 feet per second, altitude 9 nautical miles,
downrange distance 7 nautical miles.
The devastated families needed answers for what
went wrong and how those freezing temperatures and wild winds played a role.
When Space Shuttle Challenger launched that fateful day in January 1986, the weather was awful
No other shuttle mission launched in conditions anywhere near what occurred that morning.
Florida was experiencing some unusually cold temperatures around 18 degrees Fahrenheit
the night before launch and wind and ice were causing problems with huge icicles forming
on the launch platform.
Engineers were concerned that ice could break off and damage the vehicle, and engineers
from Morton Thiokol that worked on the shuttle’s solid rocket boosters, were very concerned
that the rubber O-rings sealing the booster’s segments would not be flexible enough come
launch time and would not properly seal the joints.
In fact, the engineers had actually seen O-ring blow-by occur seven times prior to the Challenger disaster
With the first instance observed after STS-2.
In all those cases, the secondary O-ring prevented a major disaster, but the fact that this was
so common was one of the reasons why mission managers, ignored or minimized engineers concerns
about o-ring failures for the Challenger launch.
So what was different in January 1986?
The ice problem was mostly resolved before launch, but the extreme cold no doubt still
played a role.
At least a few of the SRB engineers thought that the shuttle stack would explode instantly
as soon as the solid rocket boosters ignited, but they were relieved when it seemed to launch
just fine.
Now, though.
the boosters had to last for 2 minutes.
Solid rocket boosters in general, can’t be shut down or throttled once they’re ignited.
You also can’t jettison them until they’re done, otherwise they could crash in the vehicle.
And it seemed like Challenger was going to be just fine, but what they didn’t know, though,
was that one of the boosters was hanging on by a thread.
For the first two seconds after launch, an O-ring seal, both the primary and the secondary,
did in fact fail, but it’s believed that the breach was quickly sealed by aluminum
oxides from the burning propellant.
This is what allowed the flight to continue, but the final failure may have been due to
the vehicle responding to severe upper level wind shear.
The winds that day at 45,000 ft. were measured at nearly 125 knots.
As the vehicle ascended, there was also a change in wind direction of about 80 degrees
making the forces imparted on the vehicle very abrupt.
Challenger experienced the strongest wind shear ever felt during a Space Shuttle launch,
but technically, the winds were within design limits and not a direct cause for the failure.
Challenger experienced severe wind shear from 37 seconds to 64 seconds which forced the
shuttle’s engines to perform course corrections in response.
This led to flexing in the boosters which investigators believe may have caused the
aluminum oxide plug to break free in the middle of those winds around 58 seconds into the flight
This is what ultimately sealed their fate, because while those boosters were firing,
there was no option to abort.
The now leaking booster caused tank ruptures and structural failure which led to the destruction
of the vehicle.
Contrary to some popular beliefs the shuttle actually didn’t explode, it just disintegrated….
Rapidly.
It’s not known whether or not the astronauts survived the initial disintegration, but there
some that believe they did.
Would Challenger have survived if it weren’t for those upper level winds?
There’s no way to know.
What’s certain is that no one survived in the end.
Dick Scobee, Michael Smith, Ronald McNair, Ellison Onizuka, Judy Resnik, Gregory Jarvis
and Christa McAullife.
These brave astronauts tragically gave their lives to further spaceflight and today’s
spaceflight is much safer because of their sacrifice.
So it’s important to remember them on this January 28th and every January 28th for we
will never forget that devastating day in 1986.
The crew of the space shuttle Challenger honored us by the manner in which they lived their lives.
We will never forget them, nor the last time we saw them, this morning, as they prepared
for their journey and waved goodbye and "slipped the surly bonds of earth" to "touch the face of God."
Thank you.