The Challenger Disaster

Sequence of events till disaster:

The Flight of the Challenger

The events that followed lift off were brief:

Launch Time                                        Event

- 6.6 sec.                                                Space Shuttle engines ignition

O sec.                                                     Solid Rocket Booster ignition

+ 7 sec.                                                  "Roll program." (Challenger)

                                                                "Roger, roll, Challenger." (Houston)

+ 24 sec.                                               Main engines throttled down to 94%

+ 42 sec.                                               Main engines throttled down to 65%

+ 59 sec.                                               Main engines throttled up to 104%

+ 65 sec.                                               "Challenger, go at throttle up."

                                                               (Houston) "Roger. Go at throttle up." (Challenger)

+ 73 sec.                                               Loss of signal from Challenger

After the 73rd second mark there was an explosion killing everyone on board of the space shuttle.

Facts and Figures:

the amount of money that it takes to launch a space shuttle is 450 million per mission. So, the loss for the disaster of the challenger was 7 human lives along with 450 million dollars for the mission and another couple million for the space shuttle itself.

Cause of the Explosion:

The consensus of the Commission and participating investigative agencies is that the loss of the Space Shuttle Challenger was caused by a failure in the joint between the two lower segments of the right Solid Rocket Motor. The specific failure was the destruction of the seals that are intended to prevent hot gases from leaking through the joint during the propellant burn of the rocket motor. The evidence assembled by the Commission indicates that no other element of the Space Shuttle system contributed to this failure.

In arriving at this conclusion, the Commission reviewed in detail all available data, reports and records; directed and supervised numerous tests, analyses, and experiments by NASA, civilian contractors and various government agencies; and then developed specific failure scenarios and the range of most probable causative factors.

Physics behind the failure:

The physics principal behind this disaster is Potential Energy, because of the destruction of the seals that are intended to prevent hot gases from leaking through the joint during the propellant burn of the rocket motor.

New Regulations, Designs, Policies

1. The Space Shuttle Solid Rocket Boosters (SRB) were extensively redesigned. This
involved recertifying the boosters through a series of static test firings at the Morton
Thiokol test facility in Utah.
The redesign effort added an extra O-ring to the joints between the SRB segments
and greatly strengthened the physical connections between these segments. Heaters
were also added to the joints between the SRB segments to prevent cold weather
from affecting the sealing capability of the O-rings.
2. Although landing system safety obviously was not a factor in the Challenger
explosion, the Rogers Commission did uncover basic flaws in the safety of the Space
Shuttle landing system.
The Space Shuttle tires, brakes and nose wheel steering mechanisms were
upgraded. A drag chute system was added to the Space Shuttle to help reduce its
speed upon landing.
3. Numerous hardware, software and safety improvements were incorporated into
the Space Shuttle. These included the addition of a crew escape system which would
allow astronauts to parachute from the Space Shuttle in certain conditions.
Astronauts, who had previously been boarding the Space Shuttle dressed in
jumpsuits and helmets, were required to instead wear pressurized flight safety suits
during launch and landing operations.
4. New and strict risk identification and reduction programs were applied to all
Space Shuttle operations. NASA and contractor quality control work forces were
strengthened.
5. The Space Shuttle program was reorganized and decentralized to make sure all
pertinent information was made available to management personnel at all levels.
Where possible, experienced astronauts were placed in key NASA management
positions to assure that the unique astronaut perspective would be consulted in
launch decisions.
6. Documentation from all previous Space Shuttle missions was reviewed, and all
documented waivers to existing flight safety criteria were revoked and forbidden.
These included, but were not restricted to, previous decisions that allowed Space
Shuttles to be launched in overly windy, cloudy and/or rainy conditions.
Certain launch commit weather criteria, especially those concerning temperature,
winds and cloud cover, were reviewed and made more strict. Requirements were
enacted which forced NASA and the contractor community at all management levels
to be in complete agreement regarding launch decisions.
7. Any technical issues arising during preparation for a particular Space Shuttle
mission were opened up to review by independent government agencies, such as
the National Research Council, who would in turn relay their analysis and opinions
to NASA.
8. A series of open reviews were enacted to discuss all significant and outstanding
issues prior to a particular Space Shuttle mission. These discussions were elevated
to the level of the NASA Associate Administrator for Space Flight and the NASA
Associate Administrator for Safety.
These open reviews would afford discussions of all occurring or potentially
occurring issues surrounding a Space Shuttle mission, with participation
encouraged from all levels of NASA and contractor management, engineering and
safety personnel.
9. A mechanism was put into place that would allow NASA and contractor personnel
to provide open and anonymous reporting of Space Shuttle safety concerns without
fear of reprisal.

Sources:

http://www.spaceline.org/challenger.html#5

http://history.nasa.gov/rogersrep/v1ch2.htm

Location of the explosion

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